implication of climate change on forest ecosystems: case study of insect outbreaks in alnus...

8/9/2019 Implication of climate change on forest ecosystems: case study of insect outbreaks in alnus nepalensis in Ilam distri

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CONTENT

Abstract 1

Chapter 1

.1 Introduction 2

.2 Statement of Problem 4

.3 Description of Study Area 4

Chapter 2: Literature Review 6

2.1 Climate Change 6

2.1.1 Implications for Ecological System 6

2.1.2 Relation between Climatic Anomalies & Insect Outbreaks 9

2.1.2.1 Diapause & Winter Mortality: Fate of Insects with Changing Climate 15

2.2.1.2 Relation of Insect outbreaks with other factors 16

2.2Alnus nepalensis 17

Chapter 3: Justification of Study 18

Chapter4: Objectives of Study 19

Chapter 5: Scope & Limitation of Study 20

5.1 Scope of Study 20

5.2 Limitations 20


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Chapter 6: QECC Approach 21

Chapter 7: Methodology 22

7.1 Research Elements 22

7.2 Research Steps 22

7.3 Statistical Tools 23

7.4 Sample size 23

7.5 Sources of Information 23

7.5.1 Primary data 23

7.5.1.1 Quadrate Sampling 24

7.5.1.2 Interview with famers and technical officers 24

7.5.2 Secondary data 24

7.6Site Selection Criteria 24

7.7 Data Analysis 24

Chapter 8: Result & Discussion 25

8.1 Insect infestation at study sites 25

8.1.2 Insect causing infestation 29

8.2 People's perception to changing climate in Ilam 31

8.3 Climatic Analysis 33


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8.3.1 Temperature 33

8.3.2 Rainfall 39

8.4 Discussion 41

Chapter 9: Conclusion & Recommendation 44

9.1 Conclusion 44

9.2 Recommendation 45

10. References 46

Annexes 58


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LIST OF FIGURES

Figure No. Name of Figure Page No.

1 Development time of insect depending on temperature 14

2 Relationship between rate of population growth of insects and temperature of four insect species14

3 Drought influences on host plants, phytophagous insects and their natural enemies leading to insectoutbreaks 15

4 QECC Diagram showing major aspects of research approach 21

5 Diagram showing degree of infestation in Utis at sampling sites 27

6 Diagram showing amount of infested trees at Okhre 27

7 Diagram showing amount of infested trees at Balangau 28

8 Diagram showing amount of infested trees at Kanyam Tea Estate 28

9 Diagram showing amount of infested trees at Sankhejung 29

10 Diagram showing infestation in Utis at 4 study sites 29

11 High infestation in Utis Tree (Scarabaeidae in inset) 30

12 Number of people with variable perceptions to the various evidences of climate change 33

13 Mean annual temperature of 20 years at Ilam meteorological station 34

14 Mean annual temperature of 20 years at Kanyam meteorological station 34

15 Temperature variation in Ilam meteorological station in 20 years 35

6 Temperature changes in Kanyam meteorological station in 20 years 35


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7 Temperature trend of 20 years in wet season at Ilam meteorological station 36

8 Temperature trend of 20 years in wet season at Kanyam meteorological station 37

9 Temperature trend of winter months in 20 years at Ilam meteorological station 37

20 Temperature trend of winter months in 20 years at Kanyam meteorological station 38

21 Mean annual rainfall of 20 years at Ilam meteorological station 39

22 Mean annual rainfall of 20 years at Kanyam meteorological station 39

23 Trend of mean annual temperature and mean annual rainfall in 20 years at Ilam meteorological

station 40

24 Trend of mean annual temperature and mean annual rainfall in 20 years at Kanyam meteorological

station 41

LIST OF TABLES

Table No. Name of Table Page No.

1 Comparison of degree of insect infestations in commonly found tree species 25-26

2 People's perception about climate change and its evidences 31-32


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ACRONYMS

DHM: Department of Hydrology & Meteorology

GoN: Government of Nepal

HMG: His Majesty Government

PCC: Intergovernmental Panel on Climate Change

FAO: Food & Agricultural Organization

GCM: General Circulation Models

HDR: Human Development Report

NEF: New Economics Foundation


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Abstract

Forest ecosystem, being one of the major portions of biome, is facing permutation of impacts due

to changing climate. Insect infestations are one of the major threats to forest which in many

parts of the world has been triggered by the temperature and rainfall anomalies. The study of

Utis (Alnus nepalensis), a pioneer woody vegetation-prominently found in the hills of Ilam

district, showed them to be highly affected by the beetle outbreaks in the study period. The beetle

of the Order Scarabaeidae has substantially been damaging the Utis tree. Results from quadrate

sampling showed 6% of high infestation and 94% of medium infestation in Utis. The study of

climate in Ilam explicitly indicates increasing annual mean temperature with the decreasing

trend in the annual rainfall. The study at four different elevations, where Utis were dominantly

found, however showed no staggering differences in the result in terms of insect outbreaks. Utis

at all study sites in Ilam district were infested with common trend that left them with low utility-

a future threat to the economy of farmers- in their money-spinning market of plywood. The

increased annual mean temperature presumably have shortened the period of life cycle of beetles

- hence increasing their population - and decreased annual rainfall have proliferated the

physiological stress of Utis-hence favouring insect attacks to it. One of the major assumptions of

the study is the trend in winter temperature that has decreased the hibernating periods of insects,

hence increasing their rates of survival. Most of the local farmers were swayed with the

changing climate and they feared of them to be enduring. They showed a great concern to

improvise their farming tactics to recover any impoverishments in the days ahead.


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Chapter 1: Introduction

1.1 Background

Climate change is not skeptical anymore. There are array of evidences to suggest that changes inclimate are taking place globally with varying degrees of impacts (IPCC, 2007). Climate changetriggered by global warming is expected to have widespread consequences such as sea-level riseand possible flooding of low-lying areas; melting of glaciers and sea ice; changes in rainfallpatterns with implications for floods and droughts; and more climatic extremes (especially hightemperatures). These effects will have major impacts on ecosystems, health, water resources andkey economic sectors such as agriculture and fishery. The uncertainties brought about by climatechange in turn can increase the hardship in the lives of human through extreme and unexpectednatural events. Climate change certainly is evident and it would only increase the disaster risks .

Global warming has already become a reality for many marginal communities around the world.

According to NEF (2003) rising tides have cut one of the Carteret atolls off Papua New Guineain half, salinising soils and drinking water supplies, and forcing the island's 1,500 inhabitants torely on food aid from the mainland. The government of Tuvalu is making provisions for thegradual relocation of its low-lying population to New Zealand. NEF (2003) predicts furtherhazards harsher droughts, stronger windstorms, more frequent floods, and greater exposure todisease to follow.

So far, the impacts of global environmental change have been largely discussed with emphasison water and water related fields. Glacier melt or sea level rise are in the focus because theevidence of global warming is seen clearly in retreating glaciers (Mool et al., 2001) or on risingtides, which are being monitored with keen interest globally. However, the impact of rising

temperature has its implication in many other areas of ecosystem and subsequently on the well-being of the human society. For example, migrating plant species, shortening of ripening periodof crops, and increased instances of diseases, are some of the impacts that have been seenaffecting the farming community.

There is increasing evidence which suggests that forest or woodland which presently cover abouta third of land surface of the earth will be profoundly affected by the climate change (FAO,2007). The evidences are more pronounced and appear early in the temperate regions where aslight increase in average temperature can lead to visible changes. In Alaska and Canada, forexample, increased temperature has accelerated the reproduction and increased the wintersurvival and geographic range of insect pests that may make forests more vulnerable to fire by

killing more trees (Kristie et al. 2007). Insect infestations are predicted to increase with changein the global environmental change and can cause rapid changes in vegetation with concomitantchanges also in microclimate (Classen et al. 2005).

Climate change has also been seen as responsible for declining number of plant speciesworldwide. Changes in crop phenology provide important evidence of responses to recentregional climate change (IPCC, 2007). Seasonal variations are seen across the world withvarying degree of impacts to plants. Over the past decades, there has been a positive trend in the


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advancement of spring season across the Northern Hemisphere (Schwartz et al. 2006). Shiftingseasonal patterns of abiotic conditions and resource availability affect the timing of phenologicalevents, such as reproduction and migration of various organisms (Chadwick et al. 2006).Consequently, the environmental change will have direct impacts on insects and one mayimagine insects to response faster to these changes than other organisms due to their higher

proximity to climate. A recent study indicated that, on one hand, 1385% of butterflies and otherinvertebrates could be threatened with extinction under climate change within 50 years(Hellmann & Sanders, 2007). On the other hand, evidences of increasing mosquito-bornediseases in higher altitudes due to emerging climate change have also been recorded. Health ofpeople might get worsened in even temperate regions by the insect-related diseases (Epstein etal. 1998).

Climate change is altering the productivity of soil, reducing the crop-resilience, and increasingthe plant diseases across the globe. FAO (2005) warns that climate change would lead to anincrease in lands that are arid and lands with moisture stress with particular warning todeveloping world.

Temperature observations in Nepal from 1977-1994 show a general warming trend where thetemperature differences are most pronounced during the dry winter season, and least during theheight of the monsoon Warming at higher elevations in the northern part of the country issignificantly greater than at lower elevations in the south (Agrawala et al. 2003). The impact ofrising temperature has been seen in retreating glaciers of Himalayas. The long termconsequences of retreating glaciers have been projected. ICIMODs study indicate that if thetrend of glaciers retreat continues at current rate and if glacial lakes continue to expand, thefuture of Nepals potential to produce hydroelectricity will be seriously affected during the dryperiod when the rivers get water from the melting snow (Mool et. al. 2001). When the glaciersbecome too small most of the snow-fed rivers will get low flow due to loss of snow reserve andit will also be a potential hazard resulting in GLOF. However, the impact of climate change isnot restricted to the high altitude only. The rise in temperature and its subsequent impacts onlocal climate must have happened at lower altitudes as well. The impacts are difficult to monitoror identify because they are not as evident as melting of snow and further the rise in temperatureis comparably less noticeable at lower altitudes. It is important to begin exploring the impacts ofclimatic anomalies at lower altitudes mainly due to higher concentration of population andhigher diversity of ecosystems supporting multiple economic activities. One of the indications ofclimate change that could be observed is the rise in the cases of insect outbreaks on plants.

Insect pests and diseases routinely affect the health of trees and have an important role in forestdynamics. Occasionally, insect populations grow rapidly to damaging proportions and majordisease outbreaks occur. Such abrupt outbreaks are held due to several factors. Boa (2003) haveargued temperature to be one of the major abiotic factors to accelerate sudden outbreaks ofinsects but they last long if other factors such as soil conditions, water, chemicals like pesticidesand others become favourable to the outbreaks.

This study intends to explore insect outbreaks on Utis ( Alnus nepalensis) in the hills of Ilamdistrict and examine if the trend can be attributed to climate change, because a warmer climate islikely to affect the incidence and severity of pest and disease outbreaks in native forests and


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plantations. Firstly, changes in average or extreme values of climate variables can affect the lifecycles of pest populations and the severity of disease. Secondly, increased summer temperaturesare likely to accelerate the development rate and reproductive potential of insect pests, whilewarmer winters will increase over-winter survival (Old & Stone, 2005).

Alnus nepalensis called Utis in Nepal, Maibau in Burma, and Indian or Nepalese alder inEnglish, is one of 35 species of Alder worldwide. It is one of the native woody vegetations ofNepal. It is one of 15 genera of trees that fix nitrogen but are not in the legume family. Utis is adeciduous or semi-deciduous tree with a straight trunk that may reach up to 30 m in height and60 cm (occasionally to 2 m) in diameter. The bark is dark green or grey, often with yellowishpatches and short, raised lenticels. The leaves, which are frequently damaged by insects, arealternate, elliptical, 6-20 cm long, 5-10 cm wide, entire, denticulate or sinuate. The upper leafsurface is dull or shiny dark green, the lower is pale with dot-like, yellow-brown scales(www.winrock.org/forestry/factnet.htm). Utis is very susceptible to be attacked by defoliators(Oreina sp., Anomala sp.) (www.winrock.org/forestry/factnet.htm).The study intended toobserve the activities of insects inAlnus nepalensis and its relation with increasing temperature.

1.2 Statement of Problem

Alnus nepalensis is well known as a species that gives some stability to slopes that tend to slipand erode. In Burma, Alnus nepalensis has been effectively used to reforest abandoned taungyaareas (www.winrock.org/forestry/factnet.htm). Cardamom is planted as under-story crop ofA.nepalensis forest in eastern Nepal including about 80% of cardamom plantations in Ilam District(Ghimire, 1985). On terraced slopes in Nagaland State, India, Alnus nepalensis is commonlyused for poles and interplanted with crops such as maize, barley, chili, etc.(www.winrock.org/forestry/factnet.htm). The trees provide fuelwood, green leaf manure, andhelp in soil conservation. Farmers in India cultivate Alnus nepalensis on the berms (moundedearth borders) of crop fields (www.winrock.org/forestry/factnet.htm). Alnus nepalensis has beenincreasingly used in making plywood and therefore is benefitting the owners financially.

Alnus nepalensis has been increasingly affected by the defoliators in many parts of Nepal. TheIlam district where Alnus nepalensis is widely found also has been affected by insects,particularly in recent years. The study aims to relate this dire change with the climatic anomaly.The study is confined in the Ilam District of Nepal where Alnus nepalensis has tremendouseconomic value due to its use as a shade for Cardamom plants, a major source of fuelwood forlocal population (Lamichhaney, 1995), and plywood manufacturing-which is considered highlyprofit-making sector of the region. The study would help to examine insect outbreak as a case tounderstand the impact of emerging climate stress.

1.3 Description of the Study Area

Ilam district lies in the eastern part of Nepal at an altitudinal range from 150 to 3700 masl. Ilamis geologically diverse in nature with majority of population depending on agriculture. . Thedistrict has an area of 1714 square kilometers and population of 2, 82, 822 (according to 2001census). The four sites selected for study were Balangao (1200-1300m), Okhre (1300-1400m),Kanyam (1500-1600m) and Sankhejung (1700-1900m). These sites were selected on the basis of


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their altitudinal variations in order to examine the influence of altitude in relation to insectoutbreaks.

Map 1: Study areas in Ilam District shown in circles


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Chapter 2: Literature Review2.1 Climate Change

Global warming and resulting climate impact have become a reality. According to Banskota etal. (2007) out of the 10 warmest years of the last 125 years, nine were recorded during the lastdecade. With a mean global temperature of 14.5C, 2005 was the second warmest year of the last

125 years. Lovejoy & Hannah (2005) have found clear evidences for substantial variations in theEarths climate, both globally and regionally, that range from years to many millennia. Thewarming of the earth is expected to affect other parameters of climate such as spatial distributionand amount of precipitation and its seasonal pattern. There are increased understanding of howprojected impacts have emerged the sensitive areas. A study by Chinese Scientists (Liu et al.1998) show that the climate has generally been warming during this century and precipitation hasgenerally been increasing over the last 30 years in Tibetan plateaus. In much of the Indiansubcontinent global warming is likely to enhance the hydrological cycle and intensify severity offloods (Banskota et al. (2007). Moench & Dixit (2004) also suggest that there are clearindications of global warming occurring in the Indian Subcontinent. Studies show that anaverage temperature increasing approximately 0.5C annually with greater increases during the

winter (1.13C) and the post monsoon period (0.89C) is likely.

Similarly the impacts on the broader ecology and how organisms would respond to changingtemperature regime have been documented by scientists and researchers. Haslett (1997) hasreported that the increase in greenhouse gases is expected to have great impact on climate andvery important implications for the broad-scale distribution of terrestrial ecosystem, especially inthe mountains.

2.1.1 Implications for ecological systems

Broadly speaking, the ecosystems are the results of existing climate of the area. Diverse climaticcondition results in diverse ecological settings as has been seen in the Himalayan region. Within

a short horizontal distance of less than 200 kilometers, Nepal has more than 118 ecosystems dueto its topographic variation, which in turn has produced all possible climates found on the surfaceof earth (HMG, 2002). When varieties of climates are present in a small area the transition fromone type of climate to next is experienced often as one move from one elevation or aspect to thenext. Any change in existing climate of a particular area also changes the transition between thetwo regions, which has profound impacts on the entire setting of ecological equilibrium vis--visbiotic-abiotic relationship of the area. Banskota et al. (2007) reports that with increasing globalwarming, species and ecosystems are likely to shift from lower to higher latitudes and altitudes.Temperatures decrease by altitude at the rate of 5-10C/km across various mountains of theworld. Species would need to migrate upward in order to survive. However, the upwardmovement of alpine species occurring near mountain peaks is likely to be restricted by the lack

of space and soil. Some of the important alpine species of the Himalaya that may face immediateextinction includes the oak Quercus semecarpifolia (Singh et al. 1997), birch (Betula utilis),some rhododendrons, several herbs of medicinal value, and mammals like pikas, brown bears,and snow leopards ( Banskota et al. 2007).

A FAO framework report (2007) suggests that agriculture, forestry, and fisheries are all sensitiveto climate. Therefore their production processes whether for food, feed, fiber, beverage, energyor industrial crops, or for livestock, poultry, fish or forest products are likely to be impacted by


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climate change. In general, impacts in temperate regions are expected to be positive, and those intropical regions negative, although there is still considerable uncertainty about how projectedchanges will play out locally, and projected impacts could also be altered by adoption of riskmanagement measures and adaptation strategies that strengthen preparedness and resilience.

Epstein & Mills (2005) warn that agriculture is to face warming, more extremes and morediseases. More drought and flooding under the new climate, and accompanying outbreaks ofcrop pests and diseases can affect yields, nutrition, food prices and political stability. Chemicalmeasures to limit infestations are costly and unhealthy.

Several studies have described the effects of climate change on plant species. Malcolm & Pitelka(2000) note that changing temperature may cause many plant species to alter their ecologicaldistributions. These shifts in major vegetation types due to global warming parallel the responsesof the individual species that comprise these ecosystems. Thus, with global warming, shifts inthe distributions of individual species are expected in particular, a general polewardmovement of distributions. Species have shifted their distributions in the past in response to

changing climates; however, estimates of the rate of warming suggest that it may occur relativelyquickly, some 10 times faster than the warming at the end of the recent glacial maximum, forexample. It is not known whether species will be able to keep up with the rapidly shiftingclimatic zones.

Siddiqui (1997) finds that a temperature rise by global warming would cause the existing foreststo move towards more northerly/southerly latitudes and up elevational gradient from theirpresent locations. High temperature and carbon dioxide concentration would also enhance theactivities of insect herbivores and plant pathogens. Siddiqui (1997) in his study study ofPakistans forest response to climate change reveals that in regions without temperate climate,large climate change resulting in too hot and dry conditions may exceed the tolerance of existingtree species and may therefore cause the death of forests. These changes will require allconcerned with promotion and development of forest resources to respond with effectivemanagement practices to protect and maintain forest health and productivity.

Ramkrishna et al. (2003) also found that impacts of climate change on forest ecosystems includeshifts in forest boundaries by latitude and upward movement of tree lines to higher elevations;changes in species composition and vegetation types; and an increase in net primary productivity(NPP). Jianchu et al. (2007) find that in the eastern Himalayas, forest vegetation will expandsignifi cantly; forest productivity will increase from 1-10%; and it is expected that forest firesand pests such as the North American pinewood nematode ( Bursaphelenchus xylophilus) willincrease as dryness and warmth increase. Asch et al. (2007) suggest that many plant species willsee changes in their phenology such as trees starting leaf earlier, plants flowering earlier andsimilarly many birds will breed earlier.

Human Development Report (HDR) 2006 has clearly indicated that the overall impact of climatechange on the forest ecosystems can be negative. Increases in temperature and water stress areexpected to lead to a 30% decrease in crop yields in Central and South Asia by the mid-21stcentury.


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Biological responses such as hibernation or migration of species which are sudden andunexpected notify the story of abruptly changing climate. There is an evident sign of advancingunfolding, blossoming, and ripening in the leaves and fruit of wild plants; and of hibernation,migration, and breeding of wildlife in mountain regions where temperature are ascending (Jianchu et al. 2003).

Lovejoy & Hannah (2005) have found that although most General Circulation Models (GCMs)predict that global warming will induce the greatest changes in temperature at high latitudes, theseverest impact on biodiversity may occur in the tropics. Because moist tropical systems holdsuch huge diversity, and because the vast majority of those species are thought to have narrowlyrestricted niches (e.g. small elevational ranges, specific moisture requirements, single foodplant/host), the potential exists for small climatic perturbations to have a profound effect.

Macqueen & Vermeulen (2006) suggest challenges to forest-based livelihoods are numerous andvery much dependent on location due to changing climate. Loss of land for production in lowlying areas may go hand in hand with increasing pressure on land because of changes in growing

conditions or new environmental immigrants. There will be changes in the survival of indigenousspecies, and new conditions for production of commercial exotics. Events such as fires, floodsand landslides will increase risks. Change and resilience elsewhere also matter. Global climatechange will affect the comparative advantage of growing timber and non-timber forest productsin different localities, with potentially major shifts in international markets ( Macqueen &Vermulen, 2006).

Walther et al. (2002) finds evidences that indicates the warmer spring weather in Europe whichhas disrupted the synchrony between winter moth (Operophtera brumata) hatching and oak budburst, leading to a mismatch between the peak in insect availability and the peak food demandsof great tit (Parus major) nestlings. Such disharmonization of fine-tuned events may poseconsequences for species interactions and the persistence of ecological communities across anarray of ecosystems.

Tews & Jeltsch (2004) in their study ofGrewia flava, a common fleshy-fruited shrub species inthe southern Kalahari, found that despite the high resilience capacity of Grewia flava towardsdrought, it may be strongly affected when rainfall decreases as predicted, or increases inperiodical fluctuations.

Paulsen (1994) suggests that when the optimal range of temperature values for a crop in aparticular region is exceeded, crops tend to respond negatively, resulting in a drop in yield. Theoptimal temperature varies for different crops. Temperatures greater than 36C cause corn pollento lose viability, while temperatures higher than 20C depress tuber initiation and bulking in

potato.

Shibles et al. (1975) finds that high temperatures during reproductive development areparticularly injurious for example, to corn at tasseling, to soybean at flowering, and to wheat atgrain-filling. Climate change certainly has negative impact on the forests where as deforestationfurther worsens the global warming scenario by increasing burden of methane and carbonmonoxide in the atmosphere ( FAO, 2007).


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A report from Sri Lanka suggested that tea yield, which is major foreign exchange to country, isvery prone to decline due to projected rainfall patterns as by increasing temperature.(www.aiaccproject.org/meetings/Manila_04/Day3/peris_nov4doc.doc).

National Parks Conservation Association in USA (2008) reports that blossoms and leaves are

appearing earlier in the spring, birds are migrating and reproducing earlier, and winters are nolonger cold enough to control insect and other pests.

2.1.2 Relations between Climatic Anomalies & Insect Outbreaks

Lives of insects are highly dependent on climatic components such as temperature, rainfall, andhumidity. Any change in one of these parameters can subsequently alter the insect populationand its behavior. For example, Hedden (1987) noted that raised temperatures may produce moregenerations of some insects in a year, since they have high reproductivity potential, making themlikely to adapt and evolve at least an order of magnitude more quickly than the current 30- 100-year life cycle of forest tree species serving as their hosts.

Lombardero et al. (2000) suggest that temperature has broad effects on the physiology andbehavior of virtually all insects in all developmental stages. Temperature influences metabolicrate, flight activity, reproduction, nutrition, development, and survival. The ability to surviveannual temperature minima can be a critical determinant of insect distribution limits.

Williams et al. (2000) have found that as poikilotherms, insects grow as a function oftemperature: their growth rates, generation times, fecundity, and intrinsic survivorship areprimarily temperature-dependent. Battisti (2008) suggests that the number of insects per unit areais inversely related to latitude and elevation and thus can be assumed that the increase oftemperature would allow the spreading of insect species northward and upward, especially forthose species that have wide ranges, as many forest pests have. Dale (1997) suggests that insectoutbreaks are a function of the prevailing moisture and temperature conditions, insects

physiological responses to extremes, and plant stress.

Wright (2007) has suggested that mountain pine beetle is damaging Canadian forests in higherrates than in the past. The increasing infestation by mountain pine beetle is partly the result ofbeetle itself but also the function of climate change. Beetle epidemic in Canadian forests is veryprobably a strong harbinger of climate change (Wright 2007). Similarly changes in insect timingcan be very marked: Zhou et al. (1995) reported that a 1 C increase in temperature couldadvance aphid migration by up to 19 days. Harvell et al. (2002) suggest that there is nonlinearrelation between the temperature and growth of insects, and therefore the effect of climatewarming on insect growth rate will depend not only on changes in mean temperature, but also ontemperature variability.

Insect outbreaks in forests not only are influenced by warmer climate but also by the dominanceand aging of plant species present in the forest area. Netherer et al. (2002) suggest thatpopulations of Spruce Bark Beetles ( Ips typographus), the most severe forest pest in CentralEurope, have expanded and intensified due to favorable climate change and more frequentlyoccurring extreme weather conditions, and may increase in severity in the future. The situationhas been aggravated by the fact that, after the World War II, most of the forest stands in CentralEurope were planted mainly with spruce. The total area of such plantations in Austria alone


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amounts to 1 million hectares. These stands are now approaching a critical age where they areattacked readily by the beetle; therefore an abundance of appropriate brood material is availableto support devastating outbreaks of this bark beetle species.

Similarly insects can affect the trees also with the decrease in tree's immune power due to

climatic conditions; increase in temperature being one of them. Hunter & Price (1998) havenoted climate as a strong factor to influence insect population and the physiological capacity oftrees to resist attacks by insects.

Insects if get favourable environment can reproduce into large numbers than expected andthereafter increase their activities especially on their hosts. Dunn & Crutchfield (2008) havenoted two dominant environmental factors influencing insect infestations which are changes intemperature and moisture. Changing insect-host relationships and non-host species impacts, suchas predation and disease, also play essential roles. Since insects are cold-blooded orpoikilothermic, they are extremely sensitive to temperature, being more active at warmertemperatures. As winter temperatures increase, there are fewer freezing conditions that keep

insect populations in check. Shortened winters, increasing summer temperatures, and fewer late-spring frosts correlate to increased insect feeding, faster growth rates, and rapid reproduction.

Williams and Liebhold (2002) in study of trends of beetle outbreaks in the forests of the UnitedStates suggest that one expected effect of global climate change on insect populations is a shift ingeographical distributions toward higher latitudes and higher elevations. Area of outbreaks bySouthern pine beetle has remarkably increased in the United States with higher temperature andgenerally is moving northward. Projected outbreak areas for mountain pine beetle decreased withincreasing temperature and shifted toward higher elevation.

Casola et al. (2005) in their study of impacts of climate change in Washington note that pestsmay become more prevalent, as higher temperatures enhance reproduction rates. Milder winterscould increase survival rates for insect larva and adult reproductive rates may increase, allowingpests to increase their abundance. Pests could also capitalize on heat- or moisture-stressedforests, as these trees are more susceptible to infestation. Looking at the past decade, we see apotential harbinger of climate change impacts as the observed warming trend has been correlatedwith more frequent and severe outbreaks of bark beetles in the forests of the PNW and BritishColumbia.

Kehlenbeck & Schrader (2007)find that climate change will have essential effects on plants andplant pests including pathogens, influencing their establishment, spread and reproduction rate.This may cause changes of ecosystems and influence for example the balance of existingcomplex interactions between plants and plant pests. As a consequence, biodiversity could bedirectly or indirectly affected.

Climate change resulting in increased temperature could impact crop and forest insectpopulations in several complex ways. Petzoldt & Seaman (2006) suggest that even if someclimate change temperature effects might tend to depress insect populations, most researchersseem to agree that warmer temperatures in temperate climates will result in more types andhigher populations of insects.


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Battisti et al. (2000) conducted a study between the periods of 1985-1992 and found that therewas a sudden outbreak of insects in the Southern Alps during which the populations developedan annual life cycle and grew exponentially, causing repeated defoliations, which ultimatelycaused tree death in over hundreds of hectares. The most likely reasons for such a change in thelife cycle of the insect have been explored through an analysis of the local climate, which

showed that the years preceding the outbreak were characterized by an abnormally warm and dryweather during the feeding period of the larvae.

Hanely et al. (2001) have found that the two species of bug native to Alaska seemed set to causeincreasing amounts of economic damage due to global warming. The western black-headedbudworm Acleris gloverana damages spruce trees by laying its eggs in buds tied shut with silk.When the larvae hatch out, they eat the spruce needles and can kill the tree. The beetles lifecycle has halved from two years to one recently, meaning more beetles, whilst more trees arebecoming stressed due to warmer, drier summers ( Hanely et al. 2001). The effects of such pestscan damage 65% of the worlds northern forest due to global warming ( Hanely et al. 2001). Inthe last five years, 40,000 ha. of Alskan Forests have been affected.

Battles et al. (2006) studied the impact of climate change on the California forests and found thatforest pests are likely to expand their geographic and potentially their host ranges underincreasing temperature. Furthermore, increasing summer drought conditions will leave host treesmore susceptible to forest pests that tend to attack less vigorous trees. These include rootdiseases, such as Armillaria spp. and many bark beetles (such as Ips spp.). While tree specieswill slowly expand their ranges further north and into higher elevations, forest pests are likely toexhibit faster range expansions. On the other hand, decreasing snow levels may decreaseincidence of overwintering insects by causing increased winter mortality. Likewise, pathogensthat thrive under snow insulation will also decrease in incidence (such as snow mold).

Hogg et al. (2001) have studied climatic variation and insect defoliation in Canadian aspen forestduring the period of 1950-2000. They found that defoliation have remarkably increased by insectinfestations and diseases after the year 1998, which was the warmest year in the region.

Outbreaks of mountain pine beetle in the forests of Western Canada were examined by Moore etal. (2005). They concluded that winter mortality of mountain pine beetle has readily decreasedthus increasing the number of beetles and damaging the forest. The increasing temperature in theregion for more than two decades is the major reason behind the lower winter mortality.

Fleming and Candau (1998) report that insect outbreaks are a major disturbance factor inCanadian forests. If global warming occurs, the disturbance patterns caused by insects maychange substantially, especially for those insects whose distributions depend largely on climatesuch as spruce budworm (Choristoneura fumiferana) which already have been turning lethal inthe region.Community interactions among insect species are also key factor to catalyze insect outbreaks.Stireman et al. (2005) for example suggest that climate change will increase frequency andintensity of insect outbreaks by directly disturbing community interaction. They have suggestedthat parasitism among insects might increase with climatic changes.


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Kamata et al. (2002) studied the dieback incidents of oaks and concluded that the oak diebackepidemic in Japan probably resulted from the warmer climate that occurred from the late 1980swhich made possible the fateful encounter ofP. quercivorus with Q. cripsula by allowing thebeetle to extend its distribution to more northerly latitudes and higher altitudes. Future globalwarming will possibly accelerate the overlapping of the distributions of P. quercivorus and Q.

crispula with the result that oak dieback in Q. crispula will become more prevalent in Japan.Insect pests have also been studied in agricultural plants. Crop yield has been affected by insects.Peng et al. (2004) in a research on the relationship between increasing temperature and rice yieldby using data from irrigated field experiments from 1979-2003 at International Rice ResearchInstitute Farm in Philippines found that temperature has increased by 0.35C to1.13C resulting10% decline in rice productivity, also by the increased pest activity. Rosenzweig et al. (2000)suggest that since the 1970s, U.S. agriculture has achieved enhanced productivity, but has alsoexperienced greater variability in crop yields, prices, and farm income. The changes in variabilityare, in part, climate-related, either directly (through extreme weather events) or indirectly (due toagricultural pests and diseases). Pest and disease occurrences often coincide with extreme

weather events and with anomalous weather conditions, such as early or late rains, and decreasedor increased humidity, which by themselves can alter agricultural output. Recent climate trends,such as increased nighttime and winter temperatures, may be contributing to the greaterprevalence of crop pests.

Kiritani (2006) in study of the impacts of global climate change on arthropods in Japan finds thatincreasing damage due to rice- and fruit-infesting bugs, their simultaneous outbreaks and thepoleward geographic spread observed for six species may be triggered by global warming. Thewinter mortality of adults ofNezara viridula and Halyomorpha halys is predicted to be reducedby 15% by each rise of 1C. More than 50 species of butterflies showed northward rangeexpansions and ten species of previously migrant butterflies established on Nansei Islands during19661987. Global warming may be responsible for the recent decline in abundance of Plutellaxylostella and the increase in Helicoverpa armigera and Trichoplusiani. In general, globalwarming may work in favour of natural enemies (except for spiders) by increasing the number ofgenerations more than in their host species (see Kirtani 2006). Fleming & Tatchell (1995) instudy of crop pests in Britain found that the flight period of five species of aphids has become 3-6 days earlier as a result of climate change. Dukes & Mooney (1999) in study of relation betweeninvasive species and global climate change find models which suggest that warmer temperatureswill decrease the generation time of insects, increase their winter survival, and cause species toshift their ranges poleward and up in elevation.

Evolutionary changes are also seen in insects as a result of increased temperature (Pearson &Dawson, 2003). Thomas et al. (2001) who examined insect species that have expanded theirgeographical ranges in Britain over the past 20 years found that two species of bush cricket(Conocephalus discolor and Metrioptera roeselii) were seen to have increased fractions oflonger-winged (more dispersive) individuals in recently founded populations, whilst twobutterfly species (Hesperia comma andAricia agestis) have increased the variety of habitat typesthat they can colonize.Sparks & Menzel (2002) have reported that the UK butterfly fauna seemto have been affected by warming of climate. Trends to earlier first and peak appearance have


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been noted, and flight periods have been lengthened in multibrooded species, suggestingadditional generations achieved in a year, and most of this correlates well with temperature.

Climate change will also have direct effects on the physiology of both plants and plant-eaters(herbivores). Ayres (1993) suggest that anticipated patterns of climate change can induce

surprisingly large effects on interactions between plants and their herbivores for example a minorincrease in average temperature (1 degree Celsius) altered the interactions between mountainbirch and a principal insect herbivore enough to triple the potential rate of population growth ofthe insect.

Many insects are active in summer and inactive in winter however this trend may be altered withsubstantial temperature rise in summer and winter seasons. Virtanen & Neuvonen (1999) havestudied the performance of moth larvae on birch in relation to temperature in Finland and haveconcluded the potential frequency and area ofEpirrita autumnata (moth larvae) outbreaks in thecontinental parts of Fennoscandia in Finland would become larger than at present if wintertemperatures increase as predicted where as the severity of Epirrita autumnata would probably

decrease with predicted warm temperatures of summer.Kipfmueller et al. (2002) studied the mountain pine beetle outbreaks in forest of Idaho State ofUnited States and found that abnormally cool and warm temperatures are related to the mountainpine beetle epidemics in the region. Warm temperatures may have both direct and indirect effectson mountain pine beetle populations. Direct effects include increasing the probability of survivalof over wintering broods that can attack large numbers of hosts. Indirectly, warm temperaturesmay act in concert with reduced precipitation to reduce hosts capacity to repel mountain pinebeetle attacks. Cold temperatures, particularly during the winter months may result in significantover-wintering mortality of mountain pine beetle broods resulting in a temporary reduction inbeetle activity during the subsequent summer.

Studies have invariably showed influence of temperature in insects' life cycle. Different insectshave different responses to changed temperature regime however change in distribution has beenquite universal. Vanhanen et al. (2007) carried out a simulation based research in changingdistribution of defoliators with rise in temperature. The study suggested the increase in thenumber of the defoliators due to shortening of their life cycles. Ferganani et al. (2008) studiedthe response of ants to increasing temperature and have found that two species of ants L. picinusand L. valdiviensis have direct relations with temperature but the sign of the relationship wasdifferent. The increment of temperature implies an increase of L. picinus abundance but adecrease of L. valdiviensis abundance. The reason for this result may be that the species usedifferent habitats ( Ferganani et. al 2008).

Many native insect species might turn into invasive species with climatic changes and thereforevarying their distribution and impacts. Millar et al. (2007) note the changes of such kinds inMountain Pine Beetles (Dendroctonus ponderosae) east of the Continental Divide in Canada.

Rainfall also largely influences the insect outbreaks. Hulme (2005) suggests that decreasedrainfall can produce physiological stress on trees facilitating the outbreaks of forest pests


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whereas periods of intense rainfall can increase the mortality of surface-feeding insectherbivores.

Bale et al. (2002) suggest that insect populations are not likely to be affected by small increase ordecrease in temperature or other climatic conditions however unpredictability in climatic system

if increases can then affect insect population and activities very much. Bale et al. (2002) alsosuggest that the effects of temperature on insect performance may vary on different host plants.Climate may have less influence on species feeding on determinate compared to indeterminateplant species. The ability of insects to deal with a range of different host plants, including lowquality ones, may indicate their ability to cope with climate change. Bale et al. (2002) havesuggested a model showing how the relative development rates (time) of an insect and its hostplant at different temperatures might set the distribution limits of host-specific insect herbivorespecies (see figure: 1).

Figure 1: Development time of insect depending on temperature (Bale et al. 2002)

Savage et al. (2004) in study of relationship between temperature and rate of population growthof insects (r max) have performed experiments to see the activity of four insect species in various

temperatures under controlled environments and found typical temperature profile at whichinsects' population growth got null, optimum, boomed and again declined ( see figure: 2).

Figure 2: Relationship between rate of population growth of insects (r max) and temperature offour insect species (Savage et al. 2004).

Insect population increases after temperature increase and decreases after crossing a thresholdvalue of temperature. For example Fields (1992) argues that stored-product insects and mitepests will die in temperature above 35 C and below 13 C.


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Mattson & Hack (1987) offered a set of components increasing insect's outbreak due to droughtconditions. A set of components act together to cause increment in insect outbreak triggered bydroughts (see figure: 3).

Vanhen (2008) suggest that seasonal climate patterns, particularly moisture and temperature, can

be crucial for introduced forest pathogens. To infect suitable hosts, develop a disease andsurvive, correct temperature (e.g. warmer winters, milder summers) and correct moisture content(e.g. fog, rainfall, less snow cover) at a critical season are the prerequisites.

2.1.2.1 Diapause & Winter Mortality: Fate of Insects with Changing Climate

Insects generally cannot tolerate freezing temperatures. Most species survive winter byundergoing a state of prolonged dormancy, called diapause, which is similar to hibernation(www.gcsaa.org). Declining day length in autumn typically triggers diapause. During diapause,breathing and heartbeat are nearly halted, and growth and development are put on hold. To avoidfreezing, many species reduce their water content and elevate concentrations of glycerol (naturalantifreeze) in their blood (see Potter 1983). Insects cannot survive winter without diapause;

diapause is a key life history trait that ensures that an insect's life cycle is synchronized withseasonal changes of environment (Tauber et al. 1986). Diapause gets shortened with increase intemperature in winter. Fielding (2006) in his study of diapause strategies of grasshopper suggestthat diapause can alter with temperature variability.

Doleal & Sehnal (2002) find that warmer climate favours insect's survival in winter. In theirstudy of Bark beetle ( Ips tygraphus) they conclude the favourable temperature as the keycomponent for reproduction and diapasue in Bark beetles; reproduction gets faster and diapasueends faster in warmer climate than optimum.

Logan and Powel (2001) have studied the adaptability of mountain pine beetles with temperaturerise and found that as temperatures warm, the thermal environment actually would become lessfavorable for the mountain pine beetle until a threshold was reached, at which point the thermalenvironment suddenly would become dramatically more favorable for the beetle. This predictionis ominous in that increasing temperatures could unexpectedly release an endemic or invadingmountain pine beetle populationin whitebark pine with little or no warning.


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Figure 3: Drought influences on host plants, phytophagous insects and their natural enemies

leading to insect outbreaks. (Mattson and Haack, 1987).

2.2.1.2 Relation of Insect outbreaks with other factors

There might be other reasons to increase insect outbreaks besides climate however climatecannot be wholly excluded. Smith et al. (2000) suggest that climate (especially temperature),changes in competitors and resource availability are three major factors influencing the life cycleof insects. Lobo et al. (2007) discuss the role of altitude in determining the insect population inmountain ecosystems. In their study of dung beetles, they conclude that rates of beetle's richnessincrease or decrease with altitude both for total species and narrowly distributed species.

Gonzlez-Megias (2005) studied the nature of beetles in an altitude gradient (2474m- 2940m)and found the density of beetles increase with the increase in altitude however the density of hostplants decrease causing higher vulnerability for extinctions in beetle population at largerproportion compared to lower altitudes. They also concluded that extinction of species are morevulnerable at the boarder of distribution where as population is more stable at the center of thedistribution.


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Chown & Klok (2003) argues that insect's body size differ with the altitude and hence swaystheir activity. They studied the monophyletic group of weevils from two regions that differsubstantially in seasonality. Their finding was different for two regions; at one the size ofweevils increased with altitude and at other reverse was true. They however concludedtemperature and resource availability to be the major two driving factors to cause variation in the

result. Hawkins & Devries (1996) suggest that body size changes across latitudinal andaltitudinal gradients. However, in insect species such as butterflies, size does not vary regularlywith elevation. Some species are larger at higher elevations, some smaller and some show nochange at all decided by the adaptive nature of them.

2.2Alnus nepalensisLamichhaney (1995) finds that Alnus nepalensis- widely known in Nepal by one of its localnames, Utis- was identified by International Union of Forestry Research Organization (IUFRO)as one of the most important tree species indigenous to Nepal. This large, deciduous or sub-deciduous tree grows to a height of 20-35 m with a clear stem for 10-13 m. It is found naturallyin moist, cool or subtropical mountain monsoon climates, with an average annual rainfall of 500-

2500 mm and a 4-8 month dry season. Mean annual temperatures range from 13-26C. Soils tendto be moist and well-drained, varying from loam and loamy sand to gravel, sand, and clay. Atlower altitudes particularly, Utis occurs on moist sites, such as near rivers and in ravines, but itwill colonize rocky sites exposed by landslips, or lands abandoned following cultivation. Itoccurs naturally in both pure and mixed stands (http://nzdl.sadl.uleth.ca/cgi-bin/library).

Alnus nepalensis is found in the Schima/Castanopsis forests of Ilam District (1000-2000m) ofEastern Nepal. It is a pioneer species of degraded lands (Lamichhaney, 1995). It is dominantalong water courses and colonizes landslips (Olsson, 1983). It grows well in full light and ismoderately shade tolerant (Storrs and Storrs, 1984).Alnus nepalensis according to Begg (1985)is the most popular shade tree grown over cardamom in east Nepal. Besides providing shade for

the cardamom, it also supplies fuelwood for drying the crop (Lamichhaney, 1995). Excess woodis used as a domestic fuel (Thunberg & Werner, 1981).

The major pest to attack the Alnus nepalensis is defoliators (Lamichhaney, 1995;www.winrock.org/forestry/factnet.htm). In Kaski District of Nepal the most virulent defoliatorhas been identified as Oreina aurata foriopienctata- Chrysomelidae (Lamichhaney, 1995).


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Chapter 3: Justification of the study

HDR (2007) of the UNDP clearly enunciates that climate change will be one of the definingforces shaping prospects for human development during the 21st Century. It adds that through itsimpact on rainfall, temperature and weather systems, and subsequently on ecology global

warming will directly affect all countries. Nobody will be immune to its consequences. Theaverage surface temperature of the earth has warmed by about 0.6C (1F) since the late1800s, largely due to increased atmospheric greenhouse gas concentrations (Wigley,1999). As these gases continue to accumulate, the earth's temperature is expected to continue torise, with models predicting an increase of 1C to 4C (1.8F to 7.2F) over the next century. Amain conclusion of the Intergovernmental Panel on Climate Change (IPCC) Fourth AssessmentReport of 2007 was that it is very likely that most of the global warming during the last 50 yearsis due to the increase in human-made greenhouse gases.

Climate change is no longer an argument though an issue that needs urgent actions withcomprehensive consensus among global community. The study in totality is not trying to prove

the changing climate rather trying to diminish the gap of understanding the nature and trend ofimplications on ecosystem and their services brought by the climate change. For this, integratedevidences, situation assessments, peoples response have all to be well assessed. Climate changecan have profound effects on the vegetation of several types mainly by altering the requiredclimatic conditions, thus increasing pests, eventually increasing the probability of plant diseasesand hence their declining population. Climate change succinctly can have adverse effects inlower latitudes compared to the higher; the study has therefore rationale in its objectives.

Pest activities increase due to increase in temperature (Lonsdale and Gibbs 1996; Rosenzweig etal. 2000; Vanhanen et al. 2007). The IPCC warned that it is very likely that pest and diseaseoutbreaks in forests will be increased by global warming. Climate warming can also change the

disturbance regime of forests by extending the range of some damaging insects, as observedduring the last 20 years for bark beetles in the USA (IPCC, 2007). Wildfire and extensive forestmortality as a result of insect and disease are primary sources of unintentional carbon emissionsfrom forests in western United States (Stephens & Ruth, 2005), and can lead to widespread lossof centuries worth of carbon storage. This effect will likely be exacerbated in coming decadesunder continued warming, with increasingly severe fire years leading to what have been modeledas widespread brown-downs for many western and eastern forest types (Westerling et al.2006). Insect infestations in forest therefore have cause and effect relationship with climatechange.The national communication report of Nepal has reported that there are evidences of rise intemperature in the Himalayan region (HMG 2004). Higher the altitude the increase in

temperature is higher. Though, there are times when insect related problems in the forests havebeen recognized, the evidence of insect infestation in the forest of middle mountains have beenreported by electronic media from time to time in recent years. Most of the infestation cases havebeen reported from forest dominated by Alnus nepalelnsis. This study aims to examine if theinsect problems reported from Ilam district has any bearing with the change in temperature or thehumidity of the area. The study will focus on the impacts of increasing temperature and otherclimatic anomalies with the instances of insect infestations in Alnus nepalensis at a particulargeographic area.


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Chapter 4: Objectives of Study

The objective of the study is to examine ecological responses to changing temperature andrainfall pattern in forests of the mid hills of Nepal with specific focus onAlnus nepalensis.

The specific objectives of the study are as following:

To examine the impacts of changing temperature and rainfall pattern on Alnus nepalensiswith reference to insect infestation.

To understand trends of insect infestation on the Alnus nepalensis and its effect on localusers.

To understand the responses of ecological systems vis--vis climatic anomaly in aparticular altitudinal gradient.


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Chapter 5: Scope and Limitation of the Study

5.1 Scope of the Study

Climate is the context for life on earth. Global climate change and the ripples of that change willaffect every aspect of life from municipal budgets for snowplowing to the spread of disease.

Climate is already changing, and quite rapidly. With rare unanimity, the scientific communitywarns of more abrupt and greater change in the future (Epstein and Mills, 2005). With suchsituation the human kind needs to develop adaptive methodologies for the resilience to setbackthe detrimental consequences.

This study aims to incorporate underlying evidences contributed by the changes in temperatureand rainfall of a short period in a confined area. The scope of the study is to document theinstances of insect infestation in time and space particularly toAlnus nepalensis within a band of1200 to 1900 meter elevation and record if any new insects have been noticed. The study willrecord anecdotal evidences from local people of any new insects and document the trend ofinfestation. It will document in words as well as in photographs the evidences of insect

infestation. The findings of the study later can fetch understanding of complexity of implicationsposed by the global climate change which then can assist in maneuvering resilient adaptivestrategies to reciprocate on the consequences of climate change. The study also seeks tounderstand the social dynamism with the changing situation, which ultimately is of the highestpriority to plan adapting climate change.

5.2 Limitations

The study was carried out using limited field visits of about a month during the rainy season in2008. Since getting long-term data on rainfall and temperature was a problem, the study wasbased on the available secondary information from the Department of Hydrology andMeteorology, which were available from only limited areas for a limited period. Since the study

was carried out during the wet season accessibility to the sites where infestations were highprobably was difficult. Study period was also limited to a total of three months which did notallow monitoring some of the growth and spread of the insects. Another prominent problem wasto get the records of the population of Alnus nepalensis of past years in the study sites whichcould have contributed in measuring the effect of insect infestations on Alnus nepalensis in atime gradient.Most of the study relied on secondary information and on anecdotes.


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Figure 4:

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Chapter 7: Methodology7.1 Research Elements

This study designed to examine the impacts of change in rainfall and temperature on Alnusnepalensis in relation to insect infestation has been carried out in the district of Ilam in NepalResearch elements included an intense literature review on climate change and its ecological

implications. Insect infestation in forest tree species and its relation with climate change alsowere thoroughly studied as a part of literature review.

The field works were carried out at four different sites of different elevationsduring themonsoon of the year 2008 as insect activities cannot be traced in winters (Gray & Keena, 2005).The primary and secondary data were collected in the field and from the published materials. Thedata were analyzed using statistical operators using computer software like MS Excel and SPSS.Results have been tabulated and discussed on the basis of finding and supportive literatures andeventually conclusion and recommendations are depicted.

7.2 Research Steps

The study focused in areas within the range of 1200m-2000m elevations above sea level, wheremeteorological stations of Department of Hydrology and Meteorology (DHM), Nepal are inoperation. The temperature and rainfall record from the meteorological stations namely Ilam TeaState (2655N, 8754E) at elevation of 1300 masl (DHM, 1991), and Kanyam Tea Estate (2652N, 8804E) at elevation of 1678 masl (DHM, 1991) were used in the study. Besides 4focus areas were selected for sampling of trees on the basis of altitude.The study collected meteorological records of 20 years. The meteorological records include theinformation on the annual mean temperature and monthly rainfall of two stations at Ilam andKanyam. The study also used information collected through interviews with the local farmerswith the objective to gather information on climatic changes and their implications to the area.Interviews were also carried out with the local forest and agricultural officers of the government

to collect comprehensive insights on the local climate and the past-present analysis of availablevegetations, status of forest, trend in agriculture and insect-related facts.

The research is based also on quantifying the impacts caused by increasing insects in Utis treeswhich eventually would contribute significantly in understanding the qualitative nature ofclimatic anomalies upon Utis. Insect infestations in Utis therefore were categorized in threegroups based on the degree of impact as high, medium, and low as described below:


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Degree of Infestation Indicators Utility

High Infestation Completely dry stems

Completely dry and fallen leaves

(No sign of photosyntheticactivity)

Domestic cooking and firing

No Commercial use

Medium InfestationInnumerable holes in most of theleaves

Availability of dry branches

Less green in visibility

Domestic cooking and firing

Lower valuation in commercial usesuch as plywood manufacturing

Poor shade to Cardamom

Low InfestationOnly some leaves with holesGreen in visibility

Higher valuation in plywoodmanufacturing

Good shade to Cardamom

7.3 Statistical Tools

The statistical operations were applied in analyzing the results of quadrate sampling andtemperature and rainfall data to draw statistical diagrams. Mean of 20 year temperature andrainfall is calculated and presented in diagram. Similarly people's opinion towards changingclimate also was tabulated and statistical diagram of the same was prepared.

7.4 Sample size

Four sites were selected with varying altitude however in desired range as per the demand of theresearch problem. At every site three quadrate sampling of size 25m25m were carried out tosample the amount of infested trees. These samplings were based on the region where Alnusnepalensis were available with other trees and were in the easy access of farmers. The interviewwith farmers was carried out who resided near by the quadrate sampling sites. About 5 farmersfrom all the sites were interviewed summed 20.

7.5 Sources of Information

As mentioned above two sources of information were used in this research viz. primary andsecondary. Information about climate change and changes in rainfall and temperature in thestudy area were collected from secondary sources. The information about Ilam district and aboutthe forest sources were also collected from secondary sources. Information about insects and thedegree of infestation was collected from field as primary sources. The primary sources includedthe respondents in the field, photographic evidences of insects and identification of the in sectsfrom direct communication with the experts.

7.5.1 Primary data

Primary data included the result from the quadrate sampling of trees, evidences of infestation,degree of infestation, damage in the trees and information from the local farmers about their


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perception and understanding about the problem. The information about insects also was aprimary data.

7.5.1.1 Quadrate Sampling

Quadrate sampling is one of the pervasive methods in ecological sampling to determine

distribution characteristics of plants in ecosystem. The technique was used in the study in orderto measure the quantity of infested trees at different sites on the basis of altitude. An area of25m25m quadrate was employed while sampling the trees.

7.5.1.2 Interview with farmers and technical officers

Interviews mainly focused to gather the experiences of farmers and technical officers working inthe sector of forest and agriculture in relation to the consequences of climate changes. Apartfrom basic questions onAlnus nepalensis and insect affecting it, the respondents were asked theirdegree of consensus on different themes related to apparent implications and evidences ofclimate change. Their highest degree of agreement on the theme was given score 2, mediumagreement was given 1 and if disagreement 0 was the score. For example if a respondent got

agreed on the theme that rainfall is highly varying since some years, it was given 2 as a score andif disagreed on the same, the result was 0 score.

7.5.2 Secondary data

The secondary data in the study are temperature and rainfall data from two meteorologicalstations. Ilam Tea Estate at an elevation of 1300 masl and Kanyam Tea Estate at elevation of1678masl were the two available meteorological stations in the study area. The temperature andrainfall records were purchased from the DHM. The temperature and rainfall trend of 20 yearswere analyzed on the basis of year against temperature and rainfall. The results have beenpresented in graphs.

7.6Site Selection CriteriaThere are plenty of literatures (see literature review section 2.2.1.2) supporting the relation ofinsect infestation with varying altitude. Hence four sites at different altitudes were selected toexamine the influence of altitude and insect infestation in Alnus nepalensis. The four sites wereBalangao (1200-1300m), Okhre (1300-1400m), Kanyam Tea Estate (1500-1600m) andSankhejung (1700-1900m). The aim was to see the causes of infestation, if it was, not only withtemperature but with other factors as well. However altitude plays major role in temperaturevariation but altitude as suggested by many literatures can be key independent reason toaccelerate or retard insect infestations in forest.

7.7 Data Analysis and presentation

Both primary and secondary data were separately tabulated and analyzed. Later on theirinterrelations were studied, interpreted and synthesized. The results have been given in tablesand graphs. Visible evidences have been presented in pictures.


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Chapter 8: Result & Discussion

8.1 Insect infestation at study sites

Alnus nepalensis (Utis)is the dominant tree species in the study area. The other commonly foundtrees species are Malato( Macaranga pustulata), and Chilaune(Schima wallichii). Alnusnepalensis grows naturally in wetter slopes where they are planted by people to use as shade inCardamom farming and for timber and fuelwood. Insect infestations in Alnus nepalensis weredominant at all four study sites of various altitudes. Table: 1 shows the comparison amongcommonly found trees and insect infestations on them at all study sites based on 25m 25mquadrate sampling of trees which was performed three times at different locations of the studysites.

Site: Okhre Altitude: 1300-1400m

Tree Species Degree of Infestation (Defoliation)

High Medium Low

Q1 Q2 Q3 T Q1 Q2 Q3 T Q1 Q2 Q3 T

1. Utis 1 0 1 2 12 13 15 40 0 0 0 0

2. Malato 0 0 0 0 0 0 0 0 3 1 0 4

3. Chilaune 0 0 0 0 0 0 0 0 0 0 0 0

Site: Balangau Altitude: 1200-1300m


High Medium Low

Q1 Q2 Q3 T Q1 Q2 Q3 T Q1 Q2 Q3 T

1. Utis 0 1 0 1 13 17 14 44 0 0 0 0

2. Malato 0 0 0 0 0 0 0 0 0 0 1 1

3. Chilaune 0 0 0 0 0 0 0 0 0 0 0 0


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Site: Kanyam Tea Estate Altitude: 1500-1600m


High Medium Low

Q1 Q2 Q3 T Q1 Q2 Q3 T Q1 Q2 Q3 T

1. Utis 1 1 1 3 14 17 16 47 0 0 0 0

2. Malato 0 0 0 0 0 0 1 1 2 1 2 5

3. Chilaune 0 0 0 0 0 0 0 0 0 0 0 0

Site: Sankhejung(Nepaltar) Altitude: 1700-1900m


High Medium Low

Q1 Q2 Q3 T Q1 Q2 Q3 T Q1 Q2 Q3 T

1. Utis 2 1 2 5 16 17 15 48 0 0 0 0

2. Malato 0 0 0 0 1 0 0 1 0 1 1 2

3. Chilaune 0 0 0 0 0 0 0 0 0 0 0 0

Table 1: Comparison of degree of insect infestations in commonly found tree species

The result shows insect infestation very evident in Utis. Highly infested or completely defoliated

Utis were almost dead. Every Utisat sampling sites were infested by insects resulting in poortree condition and increased probability of dying. Medium infestation occurred in most of theUtis trees (see figure: 5) at every sampling sites.


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.

at Balanga

tree samp

tes at slightion. Howev

anyam Tea

n above w

altitude am

died. Utis

ling at dif

ly lower altier, about 5

state

ich Utis is

ng the sam

was domin

erent

tude.% of

not a

pling

nt in


35/67

The studinfestati

at higher

8.1.2 Ins

Insects i

(Colioptbefore. I

in the re

families

Figur

y sites at din was high

altitude sa

Fig

ects causin

nfecting U

ra: Beetlesterviews w

ion. Broadl

Coleoptera,

9: Diagra

ferent altituwhere Utis

pling sites

ure 10: Dia

infestatio

is at all f

. Accordinith farmers

y, three typ

Curculionid

showing a

de do not swas domin

ompared to

ram showin

ur sites w

to the loclso suggest

es of insect

ae, Lepido

35

mount of in

ow substanntly availa

lower altit

g infestatio

as identifi

l farmers tthat there i

are affectin

tera (Cater

ested trees

tial differenle. High in

de samplin

in Utis at

d as that

is insect han increasi

g Alnus neillars), and

t Sankheju

ces in resulestation wa

sites (see f

study sites

of the fam

d not beenng trend of

alensis. Th

Nettle Gru

g

, however is more pre

igure 10).

ily Scaraba

seen in theinsect infest

se insects

s; out of th

nsectalent

eidae

areaation

re of

m is


36/67

Coleopte

Utis tree.

Scarabae

than oth

seasonsrainy sea

Accordilength fr

mm. Sm

are depe

processegenetic

vary wit

Beetles

dynamic

dispersalUndoubt

and to d

climatic

ra is newly

idae eats th

r time of th

however loson.

Fig

g to Crowm 0.25 m

ll size has

ndent on en

s affecteddaptation (

in the geog

ave surviv

s, and their

. The geoedly, beetle

y length (A

anomalies.

seen and i

leaves of

day. Scara

al farmers

ure 11: High

on (1981),to several

nsured that

vironmental

y climateatterson et

raphic rang

ed times of

ability to d

raphic rans will adapt

shworth, 20

creasing in

tis (see fig

baeidae and

have found

infestation

most beetlentimeters.

their activi

temperatur

include lifal., 1999).

s of species

past clima

isperse. Bee

es of somgenetically

01). The inc

36

all study si

ure 11). Sca

other insec

that the in

in Utis Tre

es (ScarabaAverage le

ies mostly

es during a

span duratiactors such

(Ashworth,

tic change

tles can un

e speciesto differen

reasing bee

tes of the r

rabaeidae a

s are comp

ect activiti

(Scarabaei

eidae) aregth is estim

o unnotice

ll phases o

on, diapauas growth

2001).

because of

oubtedly r

will expanes in diurn

les in Ilam

gion with

e more acti

ratively mo

s have incr

ae in inset)

mall organated to be i

. Beetles ar

their life c

e, dispersalrates and ti

their small

spond to cl

and othel and seaso

can therefor

igher impa

e in the ev

re active in

eased even

isms, rangithe range

e ectotherm

ycles. Life

, mortality,ing of dia

size, popul

imate chan

s will connal temper

e be attribut

ct on

ning

rainy

after

g inf 4-5

s and

cycle

andause

ation

e by

tract.tures

ed to


37/67

37

8.2 People's perception to changing climate in Ilam

Local farmers in all of the study sites were interviewed in order to understand their experienceswith changing climate within a particular period of time. A majority of respondents respondedwith consensus about increased temperature and rise in pests and insects in their region. Table 2shows the degree or extent of the way people have perceived different themes that can be

attributed to climate change. The people's views were categorized on basis of degree of theiraffirmation to the emerging changes as High, Medium and Low. The higher percentage of peopleagreed on climatic anomalies and increment in insect infestations. Very few people agreed onextinction of any plant or animal species in the region. Though they have experienced variationin rainfall they have not experienced drought in the region. The people's perceptions are given infigure 12.

People at all sites of different altitudes agreed that there is an increase in insect outbreaks in theregion. According to them insect outbreaks are frequently taking place in the months whereoutbreaks rarely was observed in the past. Water sources are observed drying in lower altitudestudy sites. Private forest area has increased however national forest has remarkably decreased

in the region.

Theme Study Site Peoples'

perception

Observed

period

1. Increasing Warmth Balangao & Ilam Bazar

Altitude Range: 1200-

1300m

High 5-6years

2. Rainfall Anomaly High 5-6years

3. Increase in pest High 2-3years

4. Drying of water sources High 10 ears

5. Extinction/Migration of any wild

species

Low 10 ears

6. Increment in natural hazards Low 10 ears

7. Drought Low 10 ears

1. Increasing warmth Okhre

Altitude Range: 1300-1400m

Medium 5-6years

2. Rainfall anomaly Medium 5-6years

3. Increase in pest High 2 years

4. Drying of water sources Low 10 ears


38/67

38


species

Okhre


Low 10 ears


7. Drought Low 10 years

1. Increasing Warmth Kanyam


High 5-6years





species

Low 10 ears


7. Drought Low 10 ears

1. Increasing Warmth Sankhejung


High 5-6years





species

Low 10 ears


7. Drought Low 10 years

Table 2: People's perception about climate change and its evidences


39/67

Figur

People ihigh de

agree thalready i

8.3 Clim

The temdata fro

8.3.1 Te

The mea14).

e 12: Numb

the regionendency o

t plant diss evident lo

atic Analys

erature and1987-2006

perature

n annual te

22

3

0

De

er of people

were sensitclimatic c

ases in theering card

is

rainfall datwas used i

peratures

20

5

greeofpe

with variab

ive enoughomponents

region aremom produ

a from twoanalyzing

t both stati

24

10

rception

Hi

39

le perceptio

change

to respondfor agricult

on the inction which

meteorologhe climatic

ns were fo

5

0

mongresch

gh Medi

ns to the var

to the alterural practic

rease . A thas taunted

ical stationscharacterist

und to be i

22

18

pondentsnge

um Low

ious eviden

tions in clies. Many o

ypical disethe econom

were analyics of the re

creasing (s

2

21

oneviden

es of clima

ate due tof the respo

se in carday of farmer

zed. The 20ion.

e figures 1

21

22

cesofCli

te

theirdent

mom.

year

and

01

24

ate


40/67

Annualfrom av

declinin

annualHoweve

variation

temperatCelsius

and ther

F

Figure 13:

ean temper

rage 19C

trend, how

ean temperannual m

in maxim

ures at metarks in rec

fore have

igure 14:M

ean annua

ature in Ila

to 20C. T

ever the te

ature in recan temper

m tempera

orologicalent years. S

ade people

ean annual t

l temperatur

meteorolo

he tempera

perature r

nt years atture in bot

tures result

stations areuch temper

o feel war

emperature

40

e of 20 year

gical station

ture trend l

cords confi

Kanyam hh stations

ing into cli

highly incture variati

er than bef

of 20 years

s at Ilam m

has increas

ine in case

rm increasi

s reached 1eems to fl

matic ano

reasing andons are bei

re in the re

at Kanyam

teorologica

ed by almos

of Kanya

g day time

6C from 1uctuate mai

alies. The

reaching wg observed

ion (see fig

eteorologi

station

t 1C in 20

shows sli

temperatur

5C in 20nly due to

daily maxi

ell in 30 dmuch frequ

ures 15 & 1

al station

years

ghtly

; the

ears.high

mum

greeently

6).


41/67

The tem

abnorma1990). T

bo

implication of climate change on forest ecosystems: case study of insect outbreaks in alnus...

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