Publications by authors named "Suresh H S"

Populations of forest trees exhibit large temporal fluctuations, but little is known about the synchrony of these fluctuations across space, including their sign, magnitude, causes and characteristic scales. These have important implications for metapopulation persistence and theoretical community ecology. Using data from permanent forest plots spanning local, regional and global spatial scales, we measured spatial synchrony in tree population growth rates over sub-decadal and decadal timescales and explored the relationship of synchrony to geographical distance.

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Background: Patients in low- and middle-income countries (LMICs) have substantial treatment abandonment and non-adherence with outpatient oral medications. This work sought to investigate outcomes of postoperative discitis treated with debridement and a novel technique focused on reducing outpatient antibiotic requirement in an LMIC setting.

Methods: This study, conducted and reported following STROBE guidelines, reviewed outcomes of all patients with postoperative discitis who had been debrided by 1 neurosurgeon in a resource-limited setting during 2008-2020.

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Tree size shapes forest carbon dynamics and determines how trees interact with their environment, including a changing climate. Here, we conduct the first global analysis of among-site differences in how aboveground biomass stocks and fluxes are distributed with tree size. We analyzed repeat tree censuses from 25 large-scale (4-52 ha) forest plots spanning a broad climatic range over five continents to characterize how aboveground biomass, woody productivity, and woody mortality vary with tree diameter.

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The growth and survival of individual trees determine the physical structure of a forest with important consequences for forest function. However, given the diversity of tree species and forest biomes, quantifying the multitude of demographic strategies within and across forests and the way that they translate into forest structure and function remains a significant challenge. Here, we quantify the demographic rates of 1961 tree species from temperate and tropical forests and evaluate how demographic diversity (DD) and demographic composition (DC) differ across forests, and how these differences in demography relate to species richness, aboveground biomass (AGB), and carbon residence time.

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Article Synopsis
  • Darwin's observations in the Galapagos led him to theorize that species divergences are influenced by interactions with other diverging species in similar environments.
  • Researchers analyzed data from sixteen forest diversity plots worldwide, identifying significant negative density-dependent interactions among trees that affect their distribution and growth.
  • By creating and testing a custom data set, the study demonstrated how unique patterns of species interactions may provide insights into both ecosystem dynamics and the evolutionary processes shaping these interactions.
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Among the local processes that determine species diversity in ecological communities, fluctuation-dependent mechanisms that are mediated by temporal variability in the abundances of species populations have received significant attention. Higher temporal variability in the abundances of species populations can increase the strength of temporal niche partitioning but can also increase the risk of species extinctions, such that the net effect on species coexistence is not clear. We quantified this temporal population variability for tree species in 21 large forest plots and found much greater variability for higher latitude plots with fewer tree species.

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Article Synopsis
  • Understanding the biogeographic affinities of tropical forests helps explain regional differences in their structure, diversity, and responses to global changes.
  • The study classifies the world's tropical forests into five main floristic regions based on their phylogenetic relationships: Indo-Pacific, Subtropical, African, American, and Dry forests.
  • Findings challenge the traditional division of tropical forests and suggest a connection between northern-hemisphere Subtropical forests in Asia and America, as well as the existence of a global dry forest region.
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The extent to which interspecific niche differences structure plant communities is highly debated, with extreme viewpoints ranging from fine-scaled niche partitioning, where every species in the community is specialized to a distinct niche, to neutrality, where species have no niche or fitness differences. However, there exists a default position wherein niches of species in a community are determined by their evolutionary and biogeographic histories, irrespective of other species within the community. According to this viewpoint, a broad range of pair-wise niche overlaps-from completely overlapping to completely distinct-are expected in any community without the need to invoke interspecific interactions.

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  • The study analyzed how factors like rock type, land shape, plant life, and fire impact soil differences in a small tropical forest area in southern India.
  • The research found that lower elevation soils generally have less moisture and fewer nutrients, with their distribution influenced by the chemical composition of different rock types present.
  • It concluded that the variation in rock types plays a significant role in shaping soil properties and overall landscape features in the forest, while fire and the presence of certain tree species had minimal impact on soil characteristics.
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The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼ 40,000 and ∼ 53,000, i.e.

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Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change.

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Long-term surveys of entire communities of species are needed to measure fluctuations in natural populations and elucidate the mechanisms driving population dynamics and community assembly. We analysed changes in abundance of over 4000 tree species in 12 forests across the world over periods of 6-28 years. Abundance fluctuations in all forests are large and consistent with population dynamics models in which temporal environmental variance plays a central role.

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Tubular particles presenting heterogeneous regions of chemistry on the tube-ends versus the side are fabricated and are shown to control the particle orientation on the surface of live lymphocytes. Controlling the orientation of anisotropic microparticles on cell surfaces is of interest for biomedical applications and drug delivery in particular, since it can be used to promote or resist particle internalization.

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Neutral and niche theories give contrasting explanations for the maintenance of tropical tree species diversity. Both have some empirical support, but methods to disentangle their effects have not yet been developed. We applied a statistical measure of spatial structure to data from 14 large tropical forest plots to test a prediction of niche theory that is incompatible with neutral theory: that species in heterogeneous environments should separate out in space according to their niche preferences.

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Niche differentiation has been proposed as an explanation for rarity in species assemblages. To test this hypothesis requires quantifying the ecological similarity of species. This similarity can potentially be estimated by using phylogenetic relatedness.

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In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and in primary productivity, as well as shifts in plant species composition favouring fast-growing species over slow-growing ones. This pervasive alteration of mature tropical forests was attributed to global environmental change, such as an increase in atmospheric CO2 concentration, nutrient deposition, temperature, drought frequency, and/or irradiance. We used standardized, repeated measurements of over 2 million trees in ten large (16-52 ha each) forest plots on three continents to evaluate the generality of these findings across tropical forests.

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Article Synopsis
  • - Tree diameter growth in tropical dry forests, particularly at Mudumalai in southern India, is highly impacted by rainfall and varies significantly across different time periods (1988-2000) with the lowest growth rates occurring during the driest period.
  • - Species identity plays a crucial role in tree growth, accounting for up to 16% of growth variation, while tree size has minimal impact, explaining less than 10% of the variation in growth rates.
  • - Despite fluctuations in growth rates due to environmental conditions, these variations do not significantly affect tree survival; thus, understanding tree dynamics in these dry forests requires consideration of both species and local climate changes.
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Most ecological hypotheses about species coexistence hinge on species differences, but quantifying trait differences across species in diverse communities is often unfeasible. We examined the variation of demographic traits using a global tropical forest data set covering 4500 species in 10 large-scale tree inventories. With a hierarchical Bayesian approach, we quantified the distribution of mortality and growth rates of all tree species at each site.

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Tropical forests vary substantially in the densities of trees of different sizes and thus in above-ground biomass and carbon stores. However, these tree size distributions show fundamental similarities suggestive of underlying general principles. The theory of metabolic ecology predicts that tree abundances will scale as the -2 power of diameter.

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Article Synopsis
  • The theory of metabolic ecology suggests specific links between tree size (like diameter and height) and their growth and mortality rates, which could impact carbon flux estimates in forests.
  • Researchers analyzed data from 10 old-growth tropical forests, studying over 1.7 million trees to test these theories and developed alternative predictions focusing on how light availability affects tree size.
  • Findings showed no consistent growth or mortality patterns related to tree size across the tropical forests, supporting the alternative model in one site, while contradicting the predictions of metabolic ecology in all sites.
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Article Synopsis
  • An ecological community's species diversity decreases over time due to factors like random extinction, competition, and unstable interactions among species.
  • Short-term diversity loss can be mitigated if rare species either recruit well or have higher survival rates, which helps maintain diversity over time.
  • Census data from tropical forest plots show that older and larger trees, which tend to be more diverse, have higher survival rates, especially for rare species, leading to greater diversity as these ecosystems age.
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Background: The outcome in children with head injury is distinctive because of the different biophysical properties of the child's skull and brain, and their reaction to injury.

Methods: In this retrospective study of three hundred and forty children with head injury, managed from January 1993 to December 1998, at NIMHANS, the factors influencing outcome were analyzed.

Results: On admission there were 40 children in GCS 3-5, 55 children in GCS 6-8, 96 in GCS 9-12 and 152 children in GCS 13-15.

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  • The study analyzed genetic diversity in three montane plant species from the Western Ghats, India, using intersimple sequence repeat (ISSR) markers to assess variation within and between populations.
  • Results showed that Symplocos laurina exhibited higher total heterozygosity compared to the other two species, with significant variation observed between geographically distant populations of S. laurina.
  • Findings could help inform strategies for conserving these plant species both in their natural habitats and through cultivation.
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