Space observation is acknowledged as quintessential for providing reliable monitoring strategies for vegetation at multiple scales over extensive territories with a low population and limited accessibility. Optical satellite imagery represents the major source of data and covers an ample continuum of image resolution and swath. Yet vegetation monitoring in both the dry and wet tropics has long been hampered by insufficient pixel resolution that renders the well-mastered, pixel-wise classification techniques inefficient. The increasing availability of images with high spatial resolution (HSR, pixels of 10 m or less) to very high spatial resolution (VHSR, pixels of less than 2 m) has opened up new prospects by allowing the inference of vegetation properties from image texture features (i.e., inter-pixel variability with respect to distance). In the present talk, we aim to illustrate this potential through published case studies dealing with semiarid vegetation monitoring and baseline above ground biomass assessment in moist tropical forests. In both cases, we applied variants of a method called FOTO (Fourier-based textural ordination) to obtain textural features from the images and relate them to meaningful vegetation properties, such as patterns of vegetation vs. bare ground in drylands, or crown and gap size distribution in forest canopy images. Textural ordination based on Fourier spectra provides a powerful and consistent framework for identifying prominent scales of landscape patterns and comparing scaling properties across landscapes. In the case of forest landscapes, texture features relate to crown size distribution and sometimes to inter-crown gaps and therefore are often good predictors of stand structure and biomass. We also use the radiative transfer model DART as to generate canopy images from three-dimensional forest stand mockups parametrized from pantropical field plots. Simulated canopy images allowed us testing the relevance of texture approaches to retrieve stand characteristics and to explore the complementary with FOTO of features provided by Gabor and continuous wavelet transforms.

Keywords: above ground biomass, canopy grain, FOTO method, patterned semiarid vegetation, tropical moist and wet forest, continuous wavelet transform

If you are interested in a Ph.D. program at CES, don’t wait till next year, apply now! The Centre for Ecological Sciences, Indian Institute of Science is now accepting applications for mid-term admissions.

Online applications will be open from 1 Oct 2017 to 31 Oct 2017.

Short-listed candidates will be called for an interview on 20-21 November 2017, and the semester will begin for accepted students on 1 Jan 2018.

Eligibility criteria and application forms can be found here http://ces.iisc.ac.in/new/?q=ces-phd-program and http://iisc.ac.in/admissions/.

If you are interested in a Ph.D. program at CES, don’t wait till next year, apply now! The Centre for Ecological Sciences, Indian Institute of Science is now accepting applications for mid-term admissions.

Online applications will be open from 1 Oct 2017 to 31 Oct 2017.

Short-listed candidates will be called for an interview on 20-21 November 2017, and the semester will begin for accepted students on 1 Jan 2018.

Eligibility criteria and application forms can be found here http://ces.iisc.ac.in/new/?q=ces-phd-program and http://iisc.ac.in/admissions/.

TBA

Dear All,

As all of us know that it is time to handover ESS command to new set of people for the upcoming academic year, we had sent out a broadcasting asking interested people to volunteer. Unfirtunately, we didn't receive even a single nomination. This situation has compelled us to think about the viability of ESS in current scenario. Department chairperson has decided to meet students and discuss further action plan for the role and existence of ESS. We request all the students ( PhDs, Post docs, Project assistants) to join this meeting and help in formulating future direction for ESS.

In group-living animals, sociality maybe impacted by both ancestral relationships, and current socioecological factors. Assessing their relative/dynamic effects on the evolution of diverse social systems has been a major challenge for researchers. I present aspects of my research that focus on examining the impact of phylogenetic relatedness, group-size and resource-competition, and most recently human impact, on nonhuman primate social structure and/or zoonotic infection risk. In this regard, macaques (genus: Macaca) are an ideal genus, with their similar social organizations and well-established phylogenies, but diverse (despotic-to-tolerant) social styles, geographic ranges, and degrees of overlap with human landscapes. First, I use a comparative approach to reveal that the structure of
dominance relationships across macaques show strong phylogenetic signals, i.e. members of the Sulawesi lineage show more shallow hierarchies and less transitivity/certainty in their dominance networks than those of the Arctoides and/or Fascicularis lineages. In contrast, grooming network structure seems more labile to the influence of group-size, with larger groups showing more modular, less dense network connections than smaller groups. Second, I describe contrasting evidence that sociodemographic factors impact within-species differences in macaque sociality. Among free-ranging rhesus macaques, larger group-size and/or intense resource-competition appear to generate greater degrees of despotism, i.e. more asymmetry in dominance and lower rates of post-conflict
affiliation. However, among wild Tibetan macaques, larger group-size/severe rangerestriction appeared to lower degrees of despotism, i.e. shallow dominance hierarchies and greater reciprocity in grooming on account of a decreased demand for rank-related benefits such as support in conflicts. Thus some aspects of social behavior maybe linked to ancestry, whereas others are labile to socioecological and/or supply-and-demand biological markets conditions. My current research is implementing the conceptual framework of coupled-natural-and-human-systems to assess the impact of anthropogenic
factors on variation in macaque social networks and susceptibility to zoonotic bacterial pathogens. Further, work on captive rhesus macaques is revealing that increased social network connections may either socially buffer individuals from microbial infection risk, or enhance such risk owing to contact-mediated sharing/transmission of microbes. This may depend on pathogen-specific modes of transmission and/or overall social context. This naturally sets the stage for future investigations of the socioecological bases of zoonotic infection/ transmission through networks of free-living primate populations. I
end by conceptualization group social structure as social reaction-norms, i.e. where groups may respond similarly to variation in extrinsic factors, but may have inherently different ranges of responses to the same conditions.

Ever since the satellite strategy was observed as an alternative reproductive tactic in males, various conditions have been manipulated to determine what affects the mating success of individuals using calling versus satellite strategies in crickets. These conditions include empirically manipulating densities of male crickets, and manipulating predation risk using simulations. We carried out experimental manipulations of predation risk to examine its effect on mating success in the tree cricket species Oecanthus henryi. Instead of treating reproductive strategies as categories, we considered propensity to communicate as a continuous trait. Since communication includes not just a distribution of calling effort in males, but also variable amount of searching by females, we addressed this question in both male and female crickets. Using field enclosure experiments, we tested whether increased predation risk affects mating success of male and female crickets via reduced survival or decreased propensity to communicate (ie. call or search). We increased predation risk faced by crickets inside enclosures and made behavioural observations using low and high resolution scan sampling. Whether mating success is dependent on male calling effort or survivorship was determined using a mixed model framework.

The engines of speciation have long been a matter of much debate. This talk will discuss the potential role of magic traits in assortative mating and disruptive selection leading to speciation in sympatry. It will provide a historical and contemporary view of the ideas and evidence for mechanisms that could result in sympatric speciation.

Please note that before the talk, there will be brief presentations on recent publications by Shruti Unnikrishnan, Sabiha Majumder, Pratibha Yadav and Sanjeeta Sharma Pokharel.

Introduction to library facilities for the newcomers

This thesis is spurred by the overarching question “why is a plant where it is in space and time?”, asked in the context of a tropical dry forest plant community in southern India, based on long-term research conducted in a large (0.5 km2) permanent sampling plot. We attempted to deconstruct the structure and dynamics of the plant community by first establishing the spatial structure of soils, topography and lithology in the plot. We then assessed how this spatial structure, together with temporal variation in precipitation, affected abundances of the eight most dominant species in the plot. Finally, we broke up abundance variation into the components of recruitment, mortality and stem radial growth and assessed how these respond to variation in environmental factors (precipitation, temperature, soils, topography and fire) and biotic neighborhoods.
Local-scale lithological variation was an important first-order control over soil variability at the hillslope scale in this tropical dry forest, by both direct influence on nutrient stocks and indirect influence via control of local relief. 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. 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 parsimoniously viewed as autecological differences between species that exist independently of interspecific interactions. Temporal environmental factors (time since last fire, precipitation, and minimum and maximum temperatures) appear to be the strongest drivers of dynamics in this community, followed by conspecific and heterospecific neighborhoods, followed by spatial environmental factors (soils and topography). It is hoped these results will provide information relevant to understanding, managing, and predicting the future of this ecosystem and contribute towards the development of general theories of plant community ecology.