Evaluation of methods to estimate foliage density in the understorey of a tropical evergreen forest

Foliage density and leaf area index are important vegetation structure variables. They can be measured by several methods but few have been tested in tropical forests which have high structural heterogeneity.In this study, foliage density estimates by two indirect methods, the point quadrat and photographic methods,were compared with those obtained by direct leaf counts in the understorey of a wet evergreen forest in southern India. The point quadrat method has a tendency to overestimate, whereas the photographic method consistently and significantly underestimates foliage density. There was stratification within the understorey, with areas close to the ground having higher foliage densities

Diversity and Distribution of Herbaceous Plants along a Tropical Rainfall Gradient in Western Ghats, India

Tropical forests hold most of the vascular plant life on earth. Much of our understanding on the diversity patterns and drivers of plants in tropical forests is based on studies on trees, which form only a quarter of the plant diversity in these forests. Over 40% of plant diversity in some tropical forests is comprised of understory herbaceous angiosperms (herbs). Despite such high species richness, and their critical role in the functioning of forest ecosystems, our knowledge on the diversity patterns and drivers of herbs is poor, compared to trees. This knowledge gap not only precludes any claim on a comprehensive understanding of tropical forest ecosystems, but also hinders our ability to predict changes to plant communities and forest ecosystems as a whole. With ongoing changes to climate and increasing human pressure threatening to drastically change tropical forest ecosystems, it is critical to understand the patterns and drivers of herb community diversity and composition, and include them in conservation and restoration strategies. In my dissertation, I investigated the spatial and temporal patterns and drivers of herb communities in 13 one-ha plots across a rainfall gradient in a seasonally dry tropical forest landscape in the Western Ghats, a global Biodiversity Hotspot, in southern India.In the first chapter, I examined the drivers of herb diversity (α-diversity) at the landscape (across 1-ha plots) and at local scales (among 1x1m subplots). At the landscape scale, herb diversity was strongly and negatively correlated with rainfall and soil moisture, contrasting with previous studies on tropical forest trees, including in the same forest plots. As water was not limiting, it appears that understory light, which was negatively correlated with rainfall, was driving this diversity pattern along the gradient. The seasonal impact of water limitation on herbs became evident during the dry season, when diversity was uniformly low throughout the gradient. Once water limitation was lifted during the rainy season, herbs in more open (drier) plots took advantage of higher light availability, increasing the diversity. Herb diversity in subplots also increased with light availability, and its effect was stronger at wetter (more closed-canopy) plots. Herb diversity showed a negative relationship with increasing subplot soil moisture in all sites and seasons, which suggested that high moisture is negatively affecting herb diversity, due to water-logging or via other factors related to moisture (e.g., pathogens). In short, my results showed that while understory light limited herb diversity at both local and landscape scales, both lack of water during the dry season and the excess of water also were found to limit diversity. In the second chapter, I compared the spatial patterns and drivers of compositional variation (β-diversity) of herbaceous versus tree communities along the gradient. Given that herbs have seemingly lower dispersal abilities, higher evolution rates, lower drought tolerance, etc., compared to trees, I expected among-plot compositional variation of herbs to differ from that of trees. I estimated the taxonomic and phylogenetic β-diversity of both plant groups and partitioned the relative influences of spatial and environmental predictors (rainfall, temperature, soil and fire) on the β-diversity values. Against my expectations, both taxonomic and phylogenetic β-diversity patterns for herbs and trees along the gradient were remarkably similar. Both plant groups also showed high species and phylogenetic turnover among communities. Also, against expectations, spatial predictors explained taxonomic compositional variation of herbs and trees similarly, and more deep phylogenetic compositional variation in trees than in herbs. Most of the compositional variation of both herbs and trees were explained by rainfall and temperature, while the influence of fire and soils were low and varied among groups and metrics used. The results suggest a strong impact of environmental filtering, and that both plant groups have spatially unique compositions along the gradient. This, and the specific influence of rainfall and temperature found are relevant for conservation and management strategies of these plant communities, particularly considering the ongoing global changes. In the third chapter, I examined the temporal (seasonal) variation of herb community composition (β-diversity) in the 1-ha plots along the rainfall gradient. I calculated the temporal β-diversity of each plot and examined how it varied along the gradient. Specifically, I tested whether temporal β-diversity was related to seasonal variation in four abiotic factors: soil moisture, soil temperature, land surface temperature, and understory light. I also classified herb species into three groups based on their ecological strategies with respect to dry-season drought (escapers, evaders, and endurers) and regressed the community-level proportion of dry-season strategies of herbs against temporal β-diversity and seasonal variation in abiotic factors. As expected, I found low-rainfall plots showing higher temporal β-diversity. I found that temporal β-diversity increased with an increase in the proportion of annual plants (escapers) in the community, decreased with an increase in the proportion of plants whose above-ground parts live through the dry season (endurers), and showed no relationship with that of plants that survive the dry season by shedding above-ground parts (evaders). Land surface temperature emerged as an important factor, correlating with temporal β-diversity and all dry-season strategies. Soil moisture was correlated with temporal β-diversity and two of the strategies. The results suggest that herbs adopt dry-season strategies more as a response to heat stress than to water deficit, and that air temperature, not root-zone temperature, is critical in shaping herb diversity and composition. Given that ongoing climatic changes are thought to alter seasonal variations of precipitation and temperature, these results are relevant from a conservation perspective. To summarize, in this dissertation, I present multiple facets of diversity variation of herbaceous communities along a strong resource gradient in one of the most threatened tropical ecosystems. Both herbaceous plants and SDTFs are among the least studied plant groups and forest types, respectively, in tropical regions, and my work reveals fresh and valuable insights into both. Specifically, I showed that while patterns of one aspect of herb diversity (α-diversity) can differ from that of tree communities in a forest landscape, the patterns of another aspect of diversity (β) of both groups could be remarkably similar to each other. I also showed how seasonal variation in critical abiotic factors influences herbaceous communities, and how plant adaptations to those factors play a crucial role in sustaining diversity and shaping community composition. The results provide support for the critical role of environmental filtering in shaping patterns of both diversity and composition of plant communities in tropical forests. The findings add considerably to the current understanding of tropical plant ecology and offer insights to guide biodiversity conservation and restoration decision-making

Tropical fruit tree diversity: good practices for in situ and on-farm conservation

Farmers have developed a range of agricultural practices to sustainably use and maintain a wide diversity of crop species in many parts of the world. This book documents good practices innovated by farmers and collects key reviews on good practices from global experts, not only from the case study countries but also from Brazil, China and other parts of Asia and Latin America

Analysis of biodiversity and soil C storage in the south Konkan coast of Maharashtra (India)

This thesis presents an analysis of floral diversity, soil C carbon storage and bird diversity in the south Konkan coast of the Western Ghats of India. The objectives of the investigation were to study structure, composition, distribution, richness and diversity of vegetation under different land-use types, to determine soil organic carbon bontent and to determine species composition, richness and diversity of birds under different land-use types. For the investigation, agricultural, forest, casuarina plantation, grassland, mango plantation, homegarden and mangrove sites were selected randomly over a 460 km2 area. At the forest, casuarina, homegardens and mangrove sites quadrate sampling technique was used for phyto-sociological analysis. Soil organic matter was determined by the weight loss-onignition method on soils collected as selected sites. A point transect survey method based on distance sampling was used to study seasonal variation in bird species richness and diversity in different land-use types. The sample based rarefaction curves were computed using Estimates 8.2.0 and Eco-sim version free software applications. The bird data was analyzed using Distance 6.2 release 2 software. Floristic analysis revealed that the study area is home for 407 plant species belonging to different I 04 families. The most dominating families are Fabaceae, Cucurbitaceae, Euphorbiaceae, Malvaceae, Apocynacaeae, Asteraceae, Caesalpiniaceae, Convolvulaceae, Poaceae, Acanthaceae, Mimosaceae, Rubiaceae, Verbenaceae and Rhizophoraceae. The high species richness was recorded in the forest followed by homegardens and casuarina plantation, while it was lowest in the mangrove vegetation. The highest Shannon-Weaver index of diversity was recorded for the homegardens > forests > casuarina plantation > mangrove vegetation. The highest value of species evenness and Simpson's index of diversity was recorded for the forests and lowest in the casuarina monoculture. The highest total C storage up to 50 cm depth was found in forest soils > mango plantation > mangrove > agricultural land soils > casuarina monoculture soils. The study revealed that the top 30 cm layer contains about 61-69% of the total C stock. SOC content decreased vertically with increase soil depth. SOC content showed significant positive correlation with soil moisture content and soil salinity, and significant negative correlation with soil pH and bulk density. In a total of 4796 encounters, 9348 individual birds belonging to 114 species and 51 families were detected from seven · habitats in two seasons during the study period. The highest species richness was observed in the monsoon season. Overall 72% bird species were common in the both seasons. The most dominating families are Accipitridae, Columbidae, Hirundinidae, Muscicapidae, Ardeidae, Corvidae, Cuculidae and Sturnidae. In the dry season the highest species richness and Shannon-Weaver diversity index was observed in the forest land. In the monsoon, season the highest species richness and Shannon-Weaver diversity index was observed in the grassland The research findings on floral analysis of different land-use types suggest that the region is ecologically and ethno-botanically rich. The wide variety of floral and avian species indicates the high species richness and diversity in the study area. The region is prone to drastic anthropogenic land-use changes such as deforestation, conversion to agriculture, industrialization (especially, nuclear power generation), shrimp farming, construction works and chira mining. This study provides a basis for developing measures for the conservation and management of natural resources in south Konkan coast of Maharashtra. The present study conclude that land clearing, land breaking, nuclear power project installation will affect the floral and faunal biodiversity as well as carbon balance. Therefore, the study suggests that the nuclear power project should not be started on the site for future environmental health and safety, public health and security and to avoid future hazards of loss of biodiversity in the south Konkan coast of Maharashtra state. x

Vegetation Index and Dynamics

The book contemplates different ways of approaching the study of vegetation as well as the type of indices to be used. However, all the works pursue the same objective: to know and interpret nature from different points of view, either through knowledge of nature in situ or the use of technology and mapping using satellite images. Chapters analyze the ecological parameters that affect vegetation, the species that make up plant communities, and the influence of humans on vegetation

Book of abstracts, 4th World Congress on Agroforestry

International audienc

Understanding mountain soils : a contribution from mountain areas to the International Year of Soils 2015

In Mexico, 45 percent of the country suffers from land degradation, 12 percent of which, or some 23 million ha, are degraded due to water erosion. In Michoacán, a state in west-central Mexico, the figure rises to 27 percent. A study of the soil in Michoacán determined that overgrazing was a cause of degradation and a strategy was drawn up to promote cropping of agave, which is used in production of a high-value alcoholic drink as well as in medicines and cosmetics. The agave’s high value would mean farmers would need fewer cattle. While waiting for the agave to mature, the farmers intercrop trees, plants and grasses that produce marketable products and women earn income in greenhouses by selling small agaves from the seeds they have collected. This project, which started in 2011, is still ongoing

Environmental Management

Environmental Management - Pollution, Habitat, Ecology, and Sustainability includes sixteen chapters that discuss pressing environmental issues in diverse locations around the world. Chapters discuss methods, technologies, analyses, and actions that may enlighten and enable decision-makers and managers in their quests for control of environmental problems. The authors present the facts and the challenges behind the assorted issues and offer new perspectives for contending with natural, social, economic, and political aspects of management

Understanding mountain soils : a contribution from mountain areas to the International Year of Soils 2015

In the highlands of southern Colombia and northern Ecuador, soils developed on volcanic ash deposits have specific properties: high water retention, high hydraulic conductivity and high carbon (C) contents. The main role of the soils is to regulate the water available for the dense population living in the valleys. Soil properties and land use depend on their altitudes. Any important modification of land-use change has a serious effect on soil properties and consequently the ecosystem properties such as water regulation and flood control. This can be a threat for a city that relies on the ecosystem for its water supply, as is the case in Ecuador's capital, Quito