Tropical forests are highly diverse ecosystems with significant carbon sequestration potential. Above-ground biomass (AGB) represents a key carbon pool in these forests. We estimated AGB along with diversity, structural, and environmental attributes, from eight one-hectare permanent plots in the tropical forests of the Western Ghats, India. The relationships between these attributes and biomass were assessed. Shannon diversity (Pearson's r = 0.63), mean diameter at breast height (DBH) (r = 0.99), and total basal area (r = 0.76) showed positive correlations with AGB. The AGB value ranged between 228.6 and 746.8 Mg/ha, while species richness varied between 47 and 95 ha(-1). Large woody plants (DBH >= 60 cm) had the highest contribution (5.9-62.13 %) to AGB despite their low prevalence (0.18-3.14 %). AGB also showed strong positive correlations with large tree definitions (r = 0.70-0.82), highlighting their crucial role in carbon storage. These findings highlight that conserving large trees and maintaining species diversity is critical for sustaining carbon stocks, underlining the need for targeted forest management strategies that enhance both biodiversity and climate mitigation outcomes.

The present study highlights delineation of the distribution of understorey invasive plant species (IPS) in Mudumalai Tiger Reserve (MTR), Western Ghats, India using very high resolution airborne imaging spectroscopy images by evaluating the performance of a Multiple Endmember Spectral Mixture Analysis (MESMA). Lantana camara L. and Chromolaena odorata (L.) R.M.King & H.Rob. have imposed a serious threat to natural ecosystems in MTR by altering the ecosystem processes. The Airborne Visible-Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) based analysis delineated the distribution of understorey IPS, viz., L. camara and C. odorata in MTR, with an overall accuracy of 87 % (k = 0.84) and 84 % (k = 0.8), respectively, with minimal root-mean-square error (RMSE) of MESMA classification (0.001 to 0.0025). In MTR, both the IPS were distributed in large parts and in association with all dominant canopy tree species barring Eucalyptus species. L. camara was majorly found in the southern parts of central MTR with 'high' to 'very high' presence covering 23.09 % and 11.51 % of the total area of central MTR, respectively, in association with Terminalia anogeissiana Gere & Boatwr. and Tectona grandis L.f. Whereas, C. odorata was dominantly found with high (18.11 % area of central MTR) to very high (11.85 % area of central MTR) intensity in the south and southeastern parts within the vicinity of T. anogeissiana and Terminalia elliptica Willd. The study highlights the utilization of high spectral agility in mapping of understorey IPS through spectral differentiation of the patchy distribution of IPS and its intermixing with other local species may be helpful in ecological restoration, conservation of

When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands’ physical similarity, members of species that had dispersed to them recently were beginning to diverge from each other. He postulated that these divergences must have resulted primarily from interactions with sets of other species that had also diverged across these otherwise similar islands. By extrapolation, if Darwin is correct, such complex interactions must be driving species divergences across all ecosystems. However, many current general ecological theories that predict observed distributions of species in ecosystems do not take the details of between-species interactions into account. Here we quantify, in sixteen forest diversity plots (FDPs) worldwide, highly significant negative density-dependent (NDD) components of both conspecific and heterospecific between-tree interactions that affect the trees’ distributions, growth, recruitment, and mortality. These interactions decline smoothly in significance with increasing physical distance between trees. They also tend to decline in significance with increasing phylogenetic distance between the trees, but each FDP exhibits its own unique pattern of exceptions to this overall decline. Unique patterns of between-species interactions in ecosystems, of the general type that Darwin postulated, are likely to have contributed to the exceptions. We test the power of our null-model method by using a deliberately modified data set, and show that the method easily identifies the modifications. We examine how some of the exceptions, at the Wind River (USA) FDP, reveal new details of a known allelopathic effect of one of the Wind River gymnosperm species. Finally, we explore how similar analyses can be used to investigate details of many types of interactions in these complex ecosystems, and can provide clues to the evolution of these interactions.

Studies comparing the relative strengths of multiple key drivers of forest dynamics are rare, but can inform both our fundamental understanding of plant communities as well as community-ecology theory. We studied the dynamics of a woody plant community in a southern Indian seasonally-dry tropical forest (SDTF) in relation to environmental factors (precipitation, temperature, fire, soil nutrients, and topography) and conspecific and heterospecific plant neighborhoods to identify which of these best predicted recruitment, survival and growth of dominant species over a 24-year study period. We also assessed the relative prevalence of density-independent and density-dependent responses in the community. Climate and fire were more important than plant neighborhoods and topographic and edaphic variables in explaining variation in plant performance. Recruitment, survival and growth were lower during periods of low precipitation and immediately following fires. Recruitment increased, and growth and survival largely decreased, with increasing temperatures. Smaller-sized individuals were disproportionately strongly affected by the vagaries of climate and fire. Conspecific negative density-dependence, a population-fluctuation stabilizing process, was relatively unimportant. Density-dependent effects decayed rapidly with distance from the focal plant (growth, survival) or quadrat (recruitment); positive density-dependence was frequently found in recruitment, possibly resulting from limited dispersal and/or facilitation. Woody plant dynamics in this SDTF appear to be responding largely to fluctuations in environmental conditions, particularly precipitation, temperature, and fire. In contrast to wetter forests, population-fluctuation stabilizing processes in this ecosystem appear to be relatively weak. Changes in climatic or fire regimes are likely to result in large compositional shifts in this SDTF.

QuestionsWater availability is known to be a first-order driver of plant diversity; yet water also affects fire regimes and soil fertility, which, in turn, affect plant diversity. We examined how precipitation, fire and soil properties jointly determine woody plant diversity. Specifically, we asked how woody plant diversity varies along a sharp precipitation gradient (about 600-1,800mm mean annual precipitation [MAP]within a similar to 45-km distance) exhibiting considerable variation in long-term fire burn frequency and soil fertility, in a southern Indian seasonally dry tropical forest (SDTF) landscape. LocationMudumalai, Western Ghats, India. MethodsWoody plants 1-cm DBH were enumerated in 19 1-ha permanent plots spanning a range of tropical vegetation types from dry thorn forest, through dry and moist deciduous forest to semi-evergreen forest. Burn frequencies were derived from annual fire maps. Six measures of surface soil properties - total exchangeable bases (Ca+Mg+K), organic carbon (OC), total N, pH, plant available P and micronutrients (Fe+Cu+Zn+Mn) were used in the analyses. Five measures of diversity - species richness, Shannon diversity, the rarefied/extrapolated versions of these two measures, and Fisher's - were modelled as functions of MAP, annual fire burn frequency and the principal components of soil properties. ResultsMost soil nutrients and OC increased with MAP, except in the wettest sites. Woody productivity increased with MAP, while fire frequency was highest at intermediate values of MAP. Woody plant diversity increased with MAP but decreased with increasing fire frequency, resulting in two local diversity maxima along the MAP gradient - in the semi-evergreen and dry thorn forest - separated by a low-diversity central region in dry deciduous forest where fire frequency was highest. Soil variables were, on the whole, less strongly correlated with diversity than MAP. ConclusionsAlthough woody plant diversity in this landscape, representative of regional SDTFs, is primarily limited by water availability, our study emphasizes the role of fire as a potentially important second-order driver that acts to reduce diversity in this landscape.

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. We develop a method that can test for both habitat associations and niche differences along an arbitrary number of spatial and temporal niche dimensions and apply it to a 24-yr data set of the eight dominant woody-plant species (representing 84% and 76% of total community abundance and basal area, respectively) from a 50-ha permanent plot in a southern Indian tropical dry forest, using edaphic, topographic, and precipitation variables as niche axes. Species separated into two broad groups in niche space-one consisting of three canopy species and the other of a canopy species and four understory species-along axes that corresponded mainly to variation in soil P, Al and a topographic index of wetness. Species within groups tended to have significantly greater niche overlap than expected by chance. Community-wide niche overlap in spatial and temporal niche axes was never smaller than expected by chance. Species-habitat associations were neither necessary nor sufficient preconditions for niche differences to be present. Our results suggest that this tropical dry-forest community consists of several tree species with broadly overlapping niches, and where significant niche differences do exist, they are not readily interpretable as evidence for niche differentiation. We argue, based on a survey of the literature, that many of the observed niche differences in tropical forests are more parsimoniously viewed as autecological differences between species that exist independently of interspecific interactions.

We examined the roles of lithology, topography, vegetation and fire in generating local-scale (<1 km2) soil spatial variability in a seasonally dry tropical forest (SDTF) in southern India. For this, we mapped soil (available nutrients, Al, total C, pH, moisture and texture in the top 10 cm), rock outcrops, topography, all native woody plants ≥1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3(-)-N nor NH4(+)-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief.

Seasonally dry tropical forests (SDTFs), a varied and extensive ecosystem type in the tropics, are characteristically adapted to seasonal water stress in zones of low rainfall. Land-use change, resource extraction, alien invasives, changes to the atmosphere, and changing fire and climatic regimes may have serious implications for the continued persistence of SDTFs. This paper assesses the extent to which SDTFs may be resilient in the face of these threats, considering their dynamics, community-level characteristics, and functional traits of constituent species. There is evidence that some SDTF biodiversity- and structure-related properties are resistant to low-to moderate-intensity disturbances and have the potential to recover after severe, even chronic, disturbances, at timescales in the order of decades. Although global SDTFs are, on average, not necessarily more resilient than moist tropical forests (MTFs), they may be more resilient to particular disturbances such as fires and drought. SDTFs are vulnerable to regime shifts and there is considerable uncertainty about their future under a changing climate and its interactions with other anthropogenic effects.

The dry forest biome covers extensive areas of the global tropics. However, the understanding of these forest formations from both human and biophysical perspectives varies widely both geographically and in terms of disciplinarity. While considerable resources have been made available for the sustainable management of the humid tropical forests, there has been a lack of comparable sustained attention on their dry forest equivalents. This special issue is an attempt to provide further insights into the state of the knowledge of global dry forests, and identify research gaps that could contribute to their long-term sustainability, both for human well-being and ecological integrity.

Accuracy in tree woody growth estimates is important to global carbon budget estimation and climate-change science. Tree growth in permanent sampling plots (PSPs) is commonly estimated by measuring stem diameter changes, but this method is susceptible to bias resulting from water-induced reversible stem shrinkage. In the absence of bias correction, temporal variability in growth is likely to be overestimated and incorrectly attributed to fluctuations in resource availability, especially in forests with high seasonal and inter-annual variability in water. We propose and test a novel approach for estimating and correcting this bias at the community level.In a 50-ha PSP from a seasonally dry tropical forest in southern India, where tape measurements have been taken every four years from 1988 to 2012, for nine trees we estimated bias due to reversible stem shrinkage as the difference between woody growth measured using tree rings and that estimated from tape. We tested if the bias estimated from these trees could be used as a proxy to correct bias in tape-based growth estimates at the PSP scale.We observed significant shrinkage-related bias in the growth estimates of the nine trees in some censuses. This bias was strongly linearly related to tape-based growth estimates at the level of the PSP, and could be used as a proxy. After bias was corrected, the temporal variance in growth rates of the PSP decreased, while the effect of exceptionally dry or wet periods was retained, indicating that at least a part of the temporal variability arose from reversible shrinkage-related bias. We also suggest that the efficacy of the bias correction could be improved by measuring the proxy on trees that belong to different size classes and census timing, but not necessarily to different species.Our approach allows for reanalysis - and possible reinterpretation of temporal trends in tree growth, above ground biomass change, or carbon fluxes in forests, and their relationships with resource availability in the context of climate change. (C) 2014 Elsevier B.V. All rights reserved.

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. At some sites we identify clear environmental drivers, such as fire and drought, that could underlie these patterns, but at other sites there is a need for further research to identify drivers. In addition, cross-site comparisons showed that abundance fluctuations were smaller at species-rich sites, consistent with the idea that stable environmental conditions promote higher diversity. Much community ecology theory emphasises demographic variance and niche stabilisation; we encourage the development of theory in which temporal environmental variance plays a central role.

This discussion paper assesses the state of knowledge on tropical dry forests as it relates to CIFORs strategy and identifies research opportunities that align with CIFORs strategic goals. Over the past two decades, CIFOR has accumulated a substantial body of work on dry forests, with a particular focus on African dry forests. This paper is intended to build on that work, by gathering wider research from around the world, as CIFOR seeks to widen the geographic scope of its research on dry forests. The present assessment explores five themes: climate change mitigation and adaptation; food security and livelihoods; demand for energy; sustainable management of dry forests; and policies and institutional support for sustainable management. These themes emerged as priority areas during discussions on dry forest research priorities held at CIFORs Dry Forests Symposium in South Africa in 2011. Research on these themes should be considered a priority, given the importance of dry forests to people and ecosystems around the world and the threats posed to them.

Summary The relationship between species richness and ecosystem function, as measured by productivity or biomass, is of long‐standing theoretical and practical interest in ecology. This is especially true for forests, which represent a majority of global biomass, productivity and biodiversity. Here, we conduct an analysis of relationships between tree species richness, biomass and productivity in 25 forest plots of area 8–50 ha from across the world. The data were collected using standardized protocols, obviating the need to correct for methodological differences that plague many studies on this topic. We found that at very small spatial grains (0.04 ha) species richness was generally positively related to productivity and biomass within plots, with a doubling of species richness corresponding to an average 48% increase in productivity and 53% increase in biomass. At larger spatial grains (0.25 ha, 1 ha), results were mixed, with negative relationships becoming more common. The results were qualitatively similar but much weaker when we controlled for stem density: at the 0.04 ha spatial grain, a doubling of species richness corresponded to a 5% increase in productivity and 7% increase in biomass. Productivity and biomass were themselves almost always positively related at all spatial grains. Synthesis. This is the first cross‐site study of the effect of tree species richness on forest biomass and productivity that systematically varies spatial grain within a controlled methodology. The scale‐dependent results are consistent with theoretical models in which sampling effects and niche complementarity dominate at small scales, while environmental gradients drive patterns at large scales. Our study shows that the relationship of tree species richness with biomass and productivity changes qualitatively when moving from scales typical of forest surveys (0.04 ha) to slightly larger scales (0.25 and 1 ha). This needs to be recognized in forest conservation policy and management.

A herbarium-based database (virtual herbarium) is a referral system for plants that maximizes the usefulness of the collections. The information content of such a database is essentially built on the voucher specimens that the herbarium has in its care. The present article reports on the construction of a 'virtual herbarium' for the state-wide collection of flowering plants in the Herbarium JCB housed at the Centre for Ecological Sciences, Indian Institute of Science, Bangalore, that is expected to be launched soon. The taxonomic data on each species include all information presented on the herbarium specimen label, namely species name, author citation, sub-species if any, variety if any, family, subfamily, collection number, locations, date of collection, habitat and the collector's name. The data further comprise 'flora' in which the species are described. Additional information includes the nomenclature update according to 'The Plant List', a detailed description, phenology, species distribution, threat status and comments on any special features of the taxon. The live images of the species provided in the database form an information synergy on the species. This initiative is the first of its kind for herbaria in peninsular India.

In this paper we present successful navigation of a mechanically linked insect moth-pair, using light-weight and low-power actuators, demonstrating insect powered micro air vehicles (MAVs). These MAVs can fly for long periods of time, consuming only a small fraction(1%) of power compared to purely mechanical MAVs. We demonstrate strategies for harnessing the high energy-density biofuel and high efficiency muscle actuators of insects using tissue-embedded and externally attached miniature insect generated momentum redirectors. Commercial off-the-shelf tail motor, a rudder that exploits flow behind the insect wings, and a steering mechanism that misaligns the thrust directions of two insects were all separately used to control yaw of the hawkmoth, Manduca Sexta, in tethered flight. Untethered flight control of two hawkmoths over 60 m was achieved using a 6 gm backpack, including a 3 gram helium balloon to keep the backpack airborne, for over 5 to 30 minutes of flight time.

Following from early work demonstrating that early pupal- stage inserts are accepted by insects [9], a microprobe based microsystem platform was designed with respect to the position of the muscle bundles, and was inserted into the thorax at 4 days of the pupal stage. The platform is roughly 8times7times1.5 mm3 in size with probe thickness of 200 mum and weighs 500 mg, which the moth is able to successfully carry in the adult stage. In addition to the microsystem, an anchor to easily manipulate the adults was successfully formed in the insect by placing a glass-capillary through the pupae. The pupae emerged successfully, and the microsystem was used to characterize the potential for flight control. As part of the work to determine the microplatform design, we determined the strength-interval profiles of the pulses needed for direct muscle actuation. Two sets of flight muscles, which are symmetrically present on either side of the thorax, were differentially electrically actuated, which potentially influences the individual wing beat frequency and amplitude resulting in controlled turning behavior during flight.

Segmentation of a 3-dimensional (3D) polygonal mesh is a method of breaking the mesh down into \meaningful" connected subsets of vertices called regions. The method used here is based on the watershed segmentation scheme which appears prominently in the image segmentation literature and was later applied to the 3D segmentation problem. The watershed algorithm is based on a scalar value (curvature) assigned to every mesh vertex which purports to capture some essence of the local mesh shape. Accuracy of the curvature estimate at mesh vertices is critical to the quality of the resulting segmentation. The basis of this paper is one such watershed based 3D mesh segmentation scheme, described in [17], wherein two discrete curvature estimation schemes were used, i.e. the curvature was extracted directly from the mesh geometry. This paper considerably improves on the quality of segmentation in the original paper primarily by applying more accurate and robust curvature estimation techniques. The results are illustrated on data sets which are inherently noisy, such as the ones obtained from laser digitizers.