Paper · 2010 · Biodiversity Science

Effect of forest fragment size on tree diversity and population structure of humid subtropical forest of Meghalaya, India

Prakash Tripathi Om; Rangdajied Reynald Khongjee

13
claims
21
verbatim quotes
4
citations
3
research areas
—
Not open access

Abstract

The present study was conducted in subtropical humid forests of Meghalaya to study the distribu- tional pattern of species, floristic composition, community structure and tree population structure. Forest fragments of varying sizes (0.5 ha, 1 ha, 2 ha and 5 ha) were used in the study. All of the forest fragments are distributed within the same altitudinal range, and had similar rainfall and temperature regimes. Four forest fragments were sampled using random quadrats to analyze the impact of fragment size on tree diversity and population structure. Indices were used to compare the dispersion pattern of plant species, species diversity among fragments, and the heterogeneity and homogeneity of the fragments. A total of 45 tree species were recorded from all the fragments and simple correlation showed that the species richness was positively re- lated to fragment size (n = 4, P<0.05). Other measures such as stand density, basal cover, diversity and dominance indices were unrelated to fragment size. Forest canopy was composed mainly of Castonopsis in- dica, C. armata, Schima khasiana and Engelhardtia spicata in all of the fragments. A majority of woody tree species were contagiously distributed which made the forest community highly patchy in nature. Low values of Sorensen's similarity index and high values of Whittaker's β-diversity index between the fragments sug- gest marked difference in the species composition among the fragments. The maximum stand density, basal area, Shannon diversity index and Simpson dominance index was recorded in a 5-ha fragment. Trees in lower girth classes (15-55 cm circumference at breast height, CBH) accounted for 52-86% of stand density in all fragments except in 0.5-ha fragments where middle girth class (55-95 cm CBH) accounted for 47% of the total stand density. The overall density of seedlings, saplings and adult trees formed a pyramidal structure, indicating that the period between the sapling and adult stage was a critical stage in tree life cycles, as the maximum mortality occurred during this period. These groves are mildly/highly disturbed by communities using forests for their timber and fuel wood requirements as well as cattle and goat grazing. Tree regeneration was apparently not limited, as was evidenced by high density of saplings. These human activities may have been responsible for a decrease in tree diversity in the smaller fragments. Large fragments that were less dis-

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Claims 13

Associationobservedoriginal resultsignificant (as stated)measured

Claim · model-written summary

Species richness of tree species was positively related to forest fragment size.

Taxon
tree speciese1
Treatment
fragment sizee2
Outcome
species richnesse2
Direction
positivelye2
Qualifier
n = 4e2
Setting
subtropical humid forests of Meghalayae0

Verbatim

e0

“subtropical humid forests of Meghalaya”

✓ located verbatim in the source · abstract, characters 35–73 · show in text ↑
e1

“A total of 45 tree species were recorded from all the fragments”

✓ located verbatim in the source · abstract, characters 716–779 · show in text ↑
e2

“species richness was positively re- lated to fragment size (n = 4, P<0.05)”

✓ located verbatim in the source · abstract, characters 819–893 · show in text ↑
Associationobservedoriginal resultno effectmeasured

Claim · model-written summary

Stand density and basal cover of tree species were unrelated to forest fragment size.

Taxon
tree speciese1
Treatment
fragment sizee3
Outcome
stand density, basal covere3
Direction
no_changeinferrede3

Verbatim

e1

“A total of 45 tree species were recorded from all the fragments”

✓ located verbatim in the source · abstract, characters 716–779 · show in text ↑
e3

“Other measures such as stand density, basal cover, diversity and dominance indices were unrelated to fragment size”

✓ located verbatim in the source · abstract, characters 895–1009 · show in text ↑
Associationobservedoriginal resultno effectmeasured

Claim · model-written summary

Diversity and dominance indices of tree species were unrelated to forest fragment size.

Taxon
tree speciese1
Treatment
fragment sizee3
Outcome
diversity and dominance indicese3
Direction
no_changeinferrede3

Verbatim

e1

“A total of 45 tree species were recorded from all the fragments”

✓ located verbatim in the source · abstract, characters 716–779 · show in text ↑
e3

“Other measures such as stand density, basal cover, diversity and dominance indices were unrelated to fragment size”

✓ located verbatim in the source · abstract, characters 895–1009 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

A majority of woody tree species were contagiously distributed, making the forest community highly patchy.

Taxon
woody tree speciese4
Outcome
contagiously distributede4
Qualifier
highly patchy in naturee4

Verbatim

e4

“A majority of woody tree species were contagiously distributed which made the forest community highly patchy in nature”

✓ located verbatim in the source · abstract, characters 1147–1265 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Between the fragments, low Sorensen similarity and high Whittaker beta-diversity indicate marked difference in tree species composition.

Taxon
tree speciese1
Outcome
species compositione6
Qualifier
Low values of Sorensen's similarity index and high values of Whittaker's β-diversity indexe5

Verbatim

e1

“A total of 45 tree species were recorded from all the fragments”

✓ located verbatim in the source · abstract, characters 716–779 · show in text ↑
e5

“Low values of Sorensen's similarity index and high values of Whittaker's β-diversity index between the fragments”

✓ located verbatim in the source · abstract, characters 1267–1379 · show in text ↑
e6

“marked difference in the species composition among the fragments”

✓ located verbatim in the source · abstract, characters 1390–1454 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

The maximum stand density, basal area and Shannon diversity index of tree species were recorded in the 5-ha fragment.

Taxon
tree speciese1
Outcome
maximum stand density, basal area, Shannon diversity indexe7
Setting
5-ha fragmente7

Verbatim

e1

“A total of 45 tree species were recorded from all the fragments”

✓ located verbatim in the source · abstract, characters 716–779 · show in text ↑
e7

“The maximum stand density, basal area, Shannon diversity index and Simpson dominance index was recorded in a 5-ha fragment”

✓ located verbatim in the source · abstract, characters 1456–1578 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

The maximum Simpson dominance index of tree species was recorded in the 5-ha fragment.

Taxon
tree speciese1
Outcome
Simpson dominance indexe7
Qualifier
maximume7
Setting
5-ha fragmente7

Verbatim

e1

“A total of 45 tree species were recorded from all the fragments”

✓ located verbatim in the source · abstract, characters 716–779 · show in text ↑
e7

“The maximum stand density, basal area, Shannon diversity index and Simpson dominance index was recorded in a 5-ha fragment”

✓ located verbatim in the source · abstract, characters 1456–1578 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Trees in lower girth classes accounted for 52-86% of stand density in all fragments except the 0.5-ha fragments.

Taxon
Treese2
Outcome
stand densitye2
Value
52-86%e2
Qualifier
in all fragments except in 0.5-ha fragmentse2

Verbatim

e2

“Trees in lower girth classes (15-55 cm circumference at breast height, CBH) accounted for 52-86% of stand density in all fragments except in 0.5-ha fragments where middle girth class (55-95 cm CBH) accounted for 47% of the total stand density”

✓ located verbatim in the source · abstract, characters 1580–1822 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

In the 0.5-ha fragments, middle girth class trees accounted for 47% of total stand density.

Taxon
Treese2
Outcome
stand densitye2
Value
47%e2
Qualifier
middle girth class (55-95 cm CBH)e2

Verbatim

e2

“Trees in lower girth classes (15-55 cm circumference at breast height, CBH) accounted for 52-86% of stand density in all fragments except in 0.5-ha fragments where middle girth class (55-95 cm CBH) accounted for 47% of the total stand density”

✓ located verbatim in the source · abstract, characters 1580–1822 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

The overall density of seedlings, saplings and adult trees formed a pyramidal structure.

Taxon
seedlings, saplings and adult treese0
Outcome
overall densitye0
Qualifier
formed a pyramidal structuree0

Verbatim

e0

“The overall density of seedlings, saplings and adult trees formed a pyramidal structure”

✓ located verbatim in the source · abstract, characters 1824–1911 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

The sapling-to-adult period was the critical stage in tree life cycles, with maximum mortality during this period.

Taxon
treee0
Organ / stage
the period between the sapling and adult stagee0
Outcome
maximum mortalitye0

Verbatim

e0

“the period between the sapling and adult stage was a critical stage in tree life cycles, as the maximum mortality occurred during this period”

✓ located verbatim in the source · abstract, characters 1929–2070 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Tree regeneration was not limited, as shown by a high density of saplings.

Taxon
Treee0
Outcome
high density of saplingse0
Qualifier
regeneration was apparently not limitede0

Verbatim

e0

“Tree regeneration was apparently not limited, as was evidenced by high density of saplings”

✓ located verbatim in the source · abstract, characters 2222–2312 · show in text ↑
Mechanismhypothesisoriginal resultnegativemeasured

Claim · model-written summary

Human activities may have decreased tree diversity in the smaller fragments.

Taxon
treee0
Treatment
These human activitiese0
Outcome
decrease in tree diversitye0

Verbatim

e0

“These human activities may have been responsible for a decrease in tree diversity in the smaller fragments”

✓ located verbatim in the source · abstract, characters 2314–2420 · show in text ↑