Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

Biomass and carbon stock assessment in two savannahs of Western Ghats, India

Carbon inventory was done on two savannah ecosystems (sites I & II) of Kanyakumari Wildlife Sanctuary, Western Ghats, India. Ten plots of 20 m × 20 m each were laid in each site to study woody vegetation and a total of forty quadrats (4 in each plot) of 1 m × 1 m were laid in each site for the understorey. Both sites showed remarkable variations in biomass and carbon accumulation patterns. Site I (213 Mg C/ha) had higher woody biomass carbon than site II (185.9 Mg C/ha). However, the latter had greater understorey biomass carbon (site I – 3.2 Mg C/ha; site II –20.7 Mg C/ha). Overall, the total vegetation carbon accounted to 216.2 Mg C/ha in site I and 206.6 Mg C/ha in site II. On the other hand, soil carbon was higher in site II (183.5 Mg C/ha) than site I (172.3 Mg C/ha). Soil bulk density increased with increase in soil depth in both sites. Cumulatively, even though both sites had almost equal carbon stocks, they show considerable variation in the amount of carbon stocked in their carbon pools. Woody biomass was the largest carbon pool, followed by soil and understorey biomass. The observed variations could be due to differences in terrain characteristics, edaphic factors, incidence of fires, etc. The study emphasizes the important role of savannahs in stocking considerable amounts of carbon in their different carbon pools

Structure of plant community in tropical deciduous forests of Kanyakumari Wildlife Sanctuary, India

Abstract. Kothandaraman S, Sundarapandian S.2017. Structure of plant community in tropical deciduous forests of Kanyakumari Wildlife Sanctuary, India. Biodiversitas 18: 391-400. Plantcommunity structure of two tropical deciduous forest sites (I and II which are in different locations with different terrain characteristics viz., elevation and slope pattern) in Kanyakumari Wildlife Sanctuary, Western Ghats were assessed using standard phytosociological methods. Ten plots of 20 m x 20 m each were laid for woody species enumeration and 40 quadrats of 1 m x 1 m (4 in each plot) for understorey vegetation (herbs and plant species that are < 1 m in height) in each site. Overall, 76 plant species were recorded from 41 families, of which 23 contribute to understory. Site I (62) was twice as speciose as site II (31). Greater diversity index of adult woody vegetation was observed in site I (2.30) than site II (2.01). The woody individuals (diameter at breast height, DBH ≥ 10 cm) were more abundant in site I (518 individuals ha-1) than site II (448 individuals ha-1). The basal area of adult trees in sites I and II are 34.7 m2 ha-1 and 30.8 m2 ha-1 respectively. Euphorbiaceae was the most speciose family in both the sites. Twenty-five families in site I and seventeen families in site II were represented by singletons. Diameter class-wise distribution of adult trees showed a typical ‘reverse J-shaped’ curve indicating good regeneration status. Concerning understory, site I (19 species) has a greater diversity than site II (six species). The observed differences in the vegetation patterns between the two deciduous forest sites are possibly due to variations in elevation, terrain features and edaphic characteristics. Keywords: Phytodiversity, species richness, tropical forests, Western Ghat

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025 degrees x 0.025 degrees) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from similar to 1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers