presentation on land-use management

7/30/2019 Presentation on Land-use Management

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Land-usemanagement

Soe Moe Win

Myanmar

19.10.2012, Friday


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Land Use

Changing ever-evolving human needs Forest grown and cut for needs

Grasslands-turned into crop fields

Crops fields-cultivated and fallowed forsome reasons

Fields-consumed by growing urbanization

Demand for biofuel crops involves riskthat land-use intensification increase

Lead to a decrease in soil biodiversity


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F

O

R

E

S

T

S

G

RA

S

Slands

C

RO

P

lands

U

RB

A

NLands


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Forest

temperature extremes

light availability

wind speed

Soils

extensive root systemsand leaf litter layers

habitat and foodto soil fauna

Offera protectivemicroclimate

Reduce

moisture

Increase

Provide


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Coniferous forest

soilsmore acidic (mor)

Deciduous forests

soilsnon acidic (mull)

Soils


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Have a good aeration

Allow ion exchanges

Favor a high soil biodiversity

Exhibit high C:N ratios (10:15)

Deciduous forests soils

non acidic (mull)


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Can be characterized by

Fungal-dominated food-web(fungal to

bacterial biomass ratio 5:1 to 10:1) Fungi-eating protists

Nematodes andHigh densities of microarthropods

and anecic earthworms

3 of 27 species of earthworms

associated with forest environment

Others at low densities.


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Have lower biological activity

Restrict microbial activity and thefunctional groups.

More heavily fungal-dominated (fungalto bacterial biomass ratios 100:1 to1000:1).

Ecosystem-engineer communities-dominated by epigeic earthworms andenchytraeids

Coniferous forest soils

more acidic (mor)


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C:N ratioCarbon nitrogen present in SOM

Low ratio

carbon close to nitrogen

High ratio higher mass of carbon for

each gram of nitrogen in OMAlways more carbon than nitrogen inOM

A measure of quality of SOMLeaves much lower than wood

Influences rates of decomposition

C:N


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Decompositionoccur

fungal-dominated decomposition

Fungi BacteriaBased pathway

prefer carbon-richfood (cellulose)

prefer nitrogen-rich food (leaves)

Higher C:N

slower turnover rates

lower nitrogen mineralisation


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Grasslands

Ground covered by grass-dominatedvegetation

Have Little or no tree cover

Soil present the richest soil biodiversity


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- Extensive rootsystems

- Limited amountsof leaf litter

- Low level of leaflitter

- Fungal dominatedfood web with

microbial biomass

lands

Characterize


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Europe

Host most diverse

and abundantearthwormcommunities

Some -dominatedby endogeic

speciesOthers by

anecic species

Temperate

Most biomass -

explained byearthworm familyLumbricidae

Represent 70-80 % of total soil

biomass in lowtillage system


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Croplands

Soil biodiversity - so much lessSoil contains few arbuscular mycorrhizal

fungi and few earthworms

Soil community adapted to regulardisturbance

Food chains based on bacteria-basedpathways


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Conventionally cropped soils result

stressed and depleted soil food webs.

Intensively cropped, arable soils-characterized low organic matter inputs

Low soil fungal/bacterial ratios

Depleted bacteria-dominated chemicalengineers communities

Biological regulator communities-reduced

Dominated by opportunistic bacterial-feedingfauna

Reduce earthworm and mycorrhizal fungi

communities


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Successive cropping culture

Soil-borne diseases not drop anymore Beet cyst nematode or potato cyst

nematode

Need 3 years of non-crop to reducenematode population

Shorter rotation nematode not decline

Necessary to use biocides for control Bad soil invertebrates, ground and

surface water quality


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Management practices vary Severely impact soil biota

Soil biodiversity peaks at intermediatemanagement intensities

Species diversity and abundance

Increase low-intermediate disturbance

Peak at moderate agri disturbance

Decrease with strong agri disturbance


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Reducing management intensity ofan intensive cropping with

Some degree of organic inputs Continuous plant cover

Limited tillage

Lead to the good environment Can enhance soil biodiversity


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Effects -depend on intensity & depth

plowing ripping turning

Impacts of tillage

Deep tillage

Softer tillageIntensity


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Impacts of tillage

Obvious effect negative correlation

between organisms size - biomass

Disrupts scales of action-biological

regulators & ecosystem engineers

Devastate key groups of organisms

fungi & earthworms


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damaged or killed byintensive

Light higher diversityof large worms thanconventional

Effects differ-species

disrupted

&myceliabroken


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Population ofbeneficialorganisms high

Soil water holdingcapacity improve

Crop left-overspromote diseasetransmission

Weeds - lesscontrollable


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Organic farming practices

Provide a lower level of stress & higherorganic inputs for food web

Increase potential niches for soil fauna

Change relative abundance among soilorganisms group

Promote some specific taxa-earthworms


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Organic manure

Promote soil

microbial

biomass

Slow down

microbial activity

Farmyard manure

Promote abundance of

biological regulators &

ecosystem engineers Promote generalist

predators above ground


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Conclusion Of CroplandsClear agri-intensification have negative

consequences

At local scales (increase erosion, lower

soil fertility)

Regional scales(pollution of groundwater)

Global scales (reduce climate regulation)

Cultivation systems long-term effectOn microbial community structures

Soil communities in general


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Urbanlands

Cities-expanding faster than populations

Consist-highly modified habitats Covered by pavement and buildings

Soil-subject to sealing and compaction Face environmental stresses - air & heav

metal pollution, increased temperature


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Buildings & pavedarea modify -

Chemical &physicalequilibrium of soils

Connectivity toother ecosystems

Remaining space

Involve nature, treeslanes, lawn, cultivated

areas and parks, urbanforests, wetlands, lakesand streams

Face intensivemanagement anddisturbance, involving

intensive chemical sue

Urbanlands


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Sealed areas Non-sealed areas

Have severely depleted

soil biodiversity Stop exchanges between

soil fauna and externalinputs

Chemical engineers go indormancy

Bacteria-dorminated

High chemical inputs forpest control

Biological regulatorsdominated by

microarthropods

Earthworms absent-onlyin urban parks or forests

Urban lands


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Each land(m2) face some to many changes

Involve an initial disturbance phase before a

new ecosystem equilibrium Modify quality and quantity of available

organic & mineral inputs Leads to a redistribution of soil community

Occur large biodiversity changes locally


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Soil community

Native soil community-experiencereduction in diversity and abundance

Non-native-sometimes invasive

Species - find suitable conditions andresources

Replace native species

In new ecosystem:

Biodiversity more/equally/less

abundant than previous one


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Impact of the main land-use changes

Forests

grasslands Grasslands crop lands

Agricultural lands

urban areas


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Impact of the main land-use changes

A sharp switch from one soil typecommunity to another occur

Greater when forests to agriculturallands or urban areas

A general decline in soil biodiversity

occur during transition phase


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A switch within a fungi-dominated

system


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Increased disturbance -results - lower soilmicrobial activity

Reduced activity of anecic earthworms -hiders - their movement

Reduction in activity of chemical engineers- reinforced

Communities of biological & ecosystemengineers - more diverse

Switch-reduces nutrient cycling, regulation

of carbon flux and climate control services


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A switch from low to moderate or

high management intensity


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Render available previously protectedorganic matter

Provoke local bursts of microbialactivity and significant losses in soil C

Machinery use and low food availability

- reduces abundance of springtails &earthworms

- some field - no earthworms


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Disrupt chemical engineers andearthworm communities

Hinder nutrient cycling, carbon regulation &climate control

Communities of mutualist and non-

pest microbes and biologicalregulators become poor Reduce plant protection and growth, impacting

soil fertility The change in chemical engineers

communities -alter - self-regulation

ecosystem


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The prevalence of soil sealing

G l d/ l d U b l d


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Grassland/cropland Urban land

Abundance and diversity of all native

soil species reduces dramatically Some exotic soil species or some urban

exploiters may flourish

Sewage sludge deplete

Soil invertebrate communities and

soil trophic structureMainly parasitic and predatory mites

Predatory and omnivorous

nematodes

O ll d li i ll t f


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Overall decline in all components ofsoil biodiversity - result - loss of

almost all services Litter decompositionmade redundant

Reduced litter quantity and man-

made management practices involved

Carbon storage and climate controlservices impaired

Reduction in natural water regulation

fully not compensated

Urban forest


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Represent havens of soil biotic activityHave little organic residues and litter

Heavily impacted by humans Favor earthworms to dig down to deep

organic matter stores

Urban forest


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Spatial Scale Temporal Scale

S ti l S l


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Impact soil foodwebs and biotic

interactions Thus dynamic

equilibriumwithin a soilcommunity

Dispersal-key factor

Determine amount

and type of transfersof soil biotas

Non- native species-colonize newecosystem andpotentially become

invasive

Spatial Scale

The importance of landscape scale


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The importance of landscape scale

Soil services-still provided over whole

To maintain biodiversity and ecosystemservices

Creating refuges for living organisms

Focusing on stocks of seeds in soil

Biodiversity Sources ofliving organism

Increaseresilience of

ecosystem

Provide Crucial

Temporal Scale


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Temporal Scale

Organisms living on plant

roots days to months

Land-usechange &its effect

Each change comes

-further modifications- potential damages tosoil diversity

Cumulative

Occur after a certain

time lag

Mineralizing microbes

survive for years

Soil biodiversity restoration


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Soil biodiversity restoration

Not all groups reach equilibrium numberat the same pace.

Restoration not easy task

Loweringintensity ofland use

practices

soilbiodiversityenhance

This process takes several years to take effect.

Future Trends


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Future Trends

2020 2035

Arable landdecrease 5%

Total forest areaincrease -5%

Urban areas

increase 1%

Grasslandsdecrease 10%

Agriculture surfacedecrease slightly

Organic agriculture

surfaces-increase


48/49Future trends

Rural AreasLand use

changing faster

Urban AreasSoil biodiversity

poor


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