power point diversity

8/2/2019 Power Point Diversity

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They assessed the effects of latitude,altitude and climate on the alpha

diversity of rain forest trees in the WesternGhats (WG) of India.


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STUDY AREA

The WG, a global biodiversity hotspot

(Myers, 1990), is a chain of mountains1600 km in length, running parallel to thewestern coast of the Indian peninsulafrom above 8 N to almost 21 N latitude.


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Plot characteristics

Tree inventories from 40 small plots,

located at sites from c. 824

to 14

51

'N

latitude, were used to assess patterns oftree diversity.

Total area sampled was 4.65 ha.These plots, although laid by differentinvestigators.


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Plot sizes ranged from 0.09 to 0.2 ha

Eight of the plots were from publishedsources and 32 from unpublished data.

Twenty-six of the plots were south, and 14north.


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32 from unpublished data

Twenty-five plots, 30 X 30 m in dimension

(0.09 ha) and Seven 0.16-ha plots

Measuring the diversity they used fishers

alpha


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Rainfall data were available betweenthe years 1990 and 2002 for many sites.

For 28 plots, the mean annual rainfalland dry season length were obtained forperiods from 1 to 13 years, frommeteorological stations located close to

the site. Some of these plots wereclustered within 5 km and shared astation.


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South of 9 N latitude, the transitional limitbetween low and medium elevation

forests is near 800 m. As most of themedium elevation plots but two fell southof 9 N


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The proportion of stems on a plotbelonging to its most abundant species

was used as an index of dominance. We derived an index of rarity by totalling

the number of species in a plotrepresented by just one individual, andtaking the proportionate representationof these species among the plots stems.


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Patterns of rainfall and seasonality

Annual rainfall and seasonality

increased significantly from south tonorth (Fig. 2), but were not significantlycorrelated with each other (Fig. 2, Tables1 & 2).

However, regional patterns differed andrainfall and seasonality were significantlycorrelated for the SWG sites, but not forthe CWG sites (Fig. 3).


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These results suggest that inter-yearvariation in climatic parameters

between sites is a result of the varyingeffect of the monsoon regime over theGhats.


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Fishers alpha was not significantlycorrelated with either annual rainfall or

altitude, but decreased significantly withincreased seasonality in all plots.

Fishers alpha was lower for the mediumelevation plots than for low elevationplots(fig.4)


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Fishers alpha decreased significantlywith increasing tree dominance in plots(Fig. 5), and increased significantly withthe prevalence of rarity (Fig. 5).Dominance and rarity were significantlynegatively correlated Dominanceincreased significantly with increasingseasonality (Fig. 5), whereas raritydeclined significantly with increasingseasonality (Fig. 5).


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This study demonstrates that seasonalityinfluences rain forest tree diversity in the

WG of India.

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