Birds, traditional coffee plantations and spatial complexity: the diversity puzzle

As the current accelerated and increasing loss of biological diversity have become apparent land managers and ecologists have sought to identify significant habitats to the preservation of biodiversity. A critical component of biodiversity protection is the understanding of the ecological forces shaping the species diversity patterns. The aim of this study is to gain insight in the local and regional factors ultimately controlling species persistence and coexistence. The conceptual background of this study is that of a diversified multiple-use landscape matrix, that is used and managed and where "natural areas" can be embedded. Neotropical bird species are currently under threat as their breeding grounds suffer from degradation and loss because of intensification of land use. The fieldwork of this thesis was conducted in the northeasternmountain range of Puebla, Mexico. This region represents an important area for the conservation of resident and migrant birds, as it is located in a strategic position at the Nearticand Neotropicalbiogeographicboundary. It also forms part of the migratory route for Nearctic-Neotropicalbirds. Moreover, despite the loss of primary forests in the region, one of the main land uses in the study area is traditional shade coffee plantations which remain as an important forested habitat for birds.An important issue in conservation biology is the monitoring of community trends to provide reliable information of species diversity and their status, for fast and efficient identification of conservation priorities. In chapter 2, we analyse the use of a double-observer point count approach and mist netting for assessing bird species richness during migration. We assess the relative biases, costs and efficiency of both techniques to aim optimisation in the design of large-scale monitoring. We found that the double-observer point count technique was the most effective in the total species richness completeness and presented lower total effort in comparison to mist netting. The performance of point counts is higher than mist netting in the detection of new bird species in the research area, even after a large sampling effort.However, mist netting significantly detected a higher proportion of understoryspecies in comparison to point counts, though we found opposite results for migrant species.Finally, the cost-efficiency analysis showed that the modified double-observer point counts required less total effort thus decreasing total monetary costs compared to mist netting. One of the main problems in conservation in Latin America is the accelerated deforestation and conversion to monocultures and grazing lands that has direct effects on Neotropicalavian communities (i.e. resident and migrants) leading to a major loss of habitat, and landscape fragmentation. In chapter 3, we analyse how fragmentation and habitat loss in the landscape influences the bird species richness patterns. We examine the relative individual and combined influence of these two factors on species richness in an avian metacommunity. Moreover, we compare the difference in explanatory power of individual and combined influence of both factors. The response of species richness to habitat fragmentation shows a unimodalresponse at landscape level, anda negative response to habitat loss. The combined influence of fragmentation and habitat loss did not offer a better approximation of species richness response. This suggests that there is no interaction between the effects of fragmentation and habitat loss. Assessment of the effects of habitat fragmentation and loss under the current situation of growing human perturbation in natural habitat is fundamental in conservation and landscape management.An important ecological force structuring ecological communities is interspecific competition. Body mass is an easily determined characteristic of animals that probably influences competition strength. In chapter 4, our objective is to examine the effect of body size (mass) on competitive interactions between competing pairs of bird species. Our results indicate that there is a significant negative relationship between bird body mass ratio and the competition strength i.e.; the larger the body mass ratio, the lower the competition strength thereby suggesting that high variation in body sizes amongst sympatric species may promote coexistence in communities. Moreover species that have a greater overlap in resource use tend to exhibit stronger competition than species that overlap less in their resource use. In chapter 5, the influence of spatially explicit bio-physical variables at multiple scales on a bird community is analysed. We argue that biological communities are organised at multiple functional spatial scales and interactions between these scales determine both local and regional patterns of species richness. We use a multiple scale approach with plot, patch and landscape level variables using abundance and presence-absence data. Our results demonstrate that landscape variables explain most of the variation in bird species in both abundance and presence-absence analyses in all explanatory sets. Interestingly, results demonstrate that variation in community structure was described best at family-level than at genera- or species-level. Our results show that shade coffee plantations is one of the main land covers that positively influence the species richness, thus providing habitat for neo-tropical migrants and forest-dependent birds (e.g.; in this study some endemic and protected species). Thus, selecting the appropriate scale(s) of management in conservation strategies is essential in conservation of bird communities.The use of remotely sensed data has great potential to aid in explaining species diversity and community assemblage patterns at multiple scales. Besides, it can help to optimise sampling strategies or to allow testing of hypotheses regarding the spatial correspondence of species diversity patterns among different taxonomic groups. In chapter 6, we review how remote sensing has been used to assess terrestrial faunal diversity, with emphasis on proxies and methodologies, while exploring prospective challenges for the conservation and sustainable use of biodiversity. We grouped and discussed papers dealing with the faunaltaxamammals, birds, reptiles, amphibians, and invertebrates into five classes of surrogates of animal diversity: 1. habitat suitability, 2.photosynthetic productivity, 3. multi-temporal patterns, 4. structural properties of habitat, and 5.forage quality. It is concluded that the most promising approach for the assessment, monitoring, prediction, and conservation of faunal diversity appears to be the synergy of remote sensing products and auxiliary data with ecological biodiversity models, and a subsequent validation of the results using traditional observation techniques.In chapter 7, I present the conservation implications of shade coffee plantations as a refuge for Neotropicalbirds. The scenarios of loss and conversion of shade coffee plantations for biodiversity conservation and carbon sequestration emphasise on the ecological services that this agro-ecosystem provides. The reduction of shade coffee plantations in the studied region will have a deleterious effect on the species richness of e.g., resident birds with an estimated decline of 0.006 in species richness for every hectare the coffee area is reduced. These results could have significant consequences for conservation strategies as the amount of traditional shade coffee plantations has a positive linear relationship with the species richness of resident birds ( p <0.001). Moreover, in our research area the calculated carbon stock of the total area covered by shadecoffee plantations is257,789 t C, which represents 1,288,943 USD in carbon credits. Thus, with a reported current conversion rate of 0.4 % the results in carbon loss will be devastating in just one year. Although the conversion rate for the research area is unknown we approximate an almost negligible rate of conversion compared to the previously reported. The potential for the coffee producers as suppliers of carbon sequestration is calculated in approximately 105 USD/ha, which represents a considerable income compared to approximately an average of 59 USD/ha per coffee harvest. In addition, the value of shade coffee plantations as a component of the anthropogenic matrix is stressed in this study. Traditional shade coffee plantations are cultivated mainly by small-scale community-based growers, the majority of them belong to some indigenous group.The indigenous form of utilisation of this tropical agroecosystemsdenotes a multiple use strategy, which can be called adaptativemanagement. This indigenous adaptativemanagement has obvious socio-economic as well as ecological benefits. The ecological advantages of shade coffee agroecosystemsare clear: a) high biodiversity maintenance, b) regulation of carbon cycle, c) soil protection, d) regulation of hydrological cycle-> can I translate this with "buffer drying out the soil. I cant think of a good word for regulate ande) preservation of forest cover. The economic benefits derived from this tropical agroecosystemsare sources of goods, services and energy for household subsistence and products for local, regional and international markets. To increase the effectiveness of conservation management, the value of suitable land for multiple uses, as a component of the anthropogenic matrix should be considered. For example, in the case of tropical bird species, such linkages could be maintained by using the man-modified landscapes, e.g.; traditional shade coffee plantations as these areas also harbour an ecological value as habita

Vegetation and Lepidoptera in Seasonally Dry Tropical Forests. Community structure along climate zones, forest succession and seasonality in the Southern Yucatán, Mexico

Seasonally dry tropical forests are worldwide recognized as important ecosystems for biodiversity conservation. Increasing agricultural activities (e.g., slash-and-burn agriculture) leads to a heterogeneous landscape matrix; and as ecological succession takes over in abandoned fields, plant and animal communities endure shifts in species richness and composition. This book presents the analysis on plant and Lepidoptera (caterpillar) communities and their species turnover along forest succession and along a gradient from dry to humid seasonal forests in the Southern Yucatan Peninsula, Mexico. We discuss the contribution of climate zones, forest age and seasonality to the comunity structure of plant and Lepidoptera assemblages. The study of these environmental gradients may serve to understand and forecast future changes in species diversity in response to increasing human activities and climate change. This book aims to encourage comprehensive research in the field of community ecology of plants and insects, and will also be of interest to those working in conservation, land use management and climate change in seasonally dry tropical forests

Bird Community Composition in a Shaded Coffee Agro-ecological Matrix in Puebla, Mexico: The Effects of Landscape Heterogeneity at Multiple Spatial Scales

This study examined the importance of habitat heterogeneity on the avian community composition, and investigated the scale at which species abundances respond to habitat variables. The study was conducted within a diverse landscape matrix of a shaded coffee region in Mexico. To detect at which characteristic spatial scale different species and foraging guilds respond most strongly we analyzed the effect of plot-, patch- and landscape-level variables at different spatial extent (i.e., different kilometer radii) on species composition and foraging guilds. We used redundancy analysis to identify species–environment correlations, and to identify predictor variables that best explained the bird community structure, quantified the influence of plot-, patch- and landscape-level variables on the bird community composition. In addition, we used the 4th-corner method to detect significant relationships between the dietary guilds and plot-, patch- and landscape-level variables. We recorded 12,335 individuals of 181 bird species; 105 bird species were recorded foraging within the shaded coffee plantations. We found that plot- and landscape-level variables significantly explained the bird community composition best across all scales, and were significantly correlated with the abundance of the dietary guilds. In contrast, patch-level variables were less important. Habitat composition variables (i.e., coffee, forest and agricultural area) were among the most important predictors. Canopy structure was more important than other vegetation structure variables in explaining dietary guild structure. Hence, the maintenance of a heterogeneous landscape with a high-quality matrix within an agro-ecological region enhances bird conservatio

Linking species-environment relationships and multiple spatial scales in community ecology

Biological communities are organised at multiple functional spatial scales and interactions between these scales determine both local and regional patterns of species richness. Despite the recognition that species-environment relationships are scale-dependent many ecologists have neglected the influence of scale on species richness patterns and processes. We analysed the influence of spatially explicit bio-physical variables on a bird community in a Mexican region denominated as an important area for bird conservation. Using a multiple scale approach with plot, patch and landscape level variables using abundance and presence-absence data, we demonstrated that landscape variables explained most of the variation in bird species in both abundance and presence-absence analyses in all explanatory sets. Interestingly, results demonstrated that variation in community structure was described best at family-level than at genera- or species-level. In addition, shade coffee plantations could provide habitat forneo-tropicalmigrants and forest-dependent birds (e.g.; endemic, protected species). Selecting the appropriate scale(s) of management in conservation strategies could have important implications for conservation of bird communities in Cuetzalan region

Influence of body size on coexistence of bird species

Theory suggests that body size is an important factor in determining interspecific competition and, ultimately, in structuring ecological communities. However, there is a lack of pragmatic studies linking body size and interspecific competition to patterns in ecological communities. The objective of the present study was to determine the effect of body size (mass) on competitive interactions between bird pairs and to investigate the influence of food guilds. Point-counts were carried out in nine sites every month from November 2002 to November 2003 in the Cuetzalan Region, Mexico, and we used presence/absence and abundance data for the analyses. To calculate the strength of competition we used the Angle Frequency Method to extract form factors from 20 pairwise interactions. A prototype competition interaction and random pairs were also constructed. We used clustering techniques (PCA) to calculate the dissimilarity scores (distances, D) of each of the pairwise interactions to the prototype competition and random pairs and one-way ANOVA to test for differences between the means of the random and competitive pairs. The ratio in body mass (lnBM) for each of the interacting pairs was calculated, and the association between the lnBM ratio and the strength of competition (D) was tested using a Pearson product-moment correlation coefficient. To test for the influence of foraging guilds we used a univariate general linear model. Our results demonstrate a significant negative relationship between bird body mass ratio and competition strength ¿ i.e. competition strength increased when the body masses of the birds became more similar. We did not find a significant influence of foraging guild on the relationship between body mass ratio and competition strength. On the basis of these results, we suggest that high variation in body sizes amongst sympatric species promotes coexistence in communities

Bird Community Composition in a Shaded Coffee Agro-ecological Matrix in Puebla, Mexico: The Effects of Landscape Heterogeneity at Multiple Spatial Scales

This study examined the importance of habitat heterogeneity on the avian community composition, and investigated the scale at which species abundances respond to habitat variables. The study was conducted within a diverse landscape matrix of a shaded coffee region in Mexico. To detect at which characteristic spatial scale different species and foraging guilds respond most strongly we analyzed the effect of plot-, patch- and landscape-level variables at different spatial extent (i.e., different kilometer radii) on species composition and foraging guilds. We used redundancy analysis to identify species–environment correlations, and to identify predictor variables that best explained the bird community structure, quantified the influence of plot-, patch- and landscape-level variables on the bird community composition. In addition, we used the 4th-corner method to detect significant relationships between the dietary guilds and plot-, patch- and landscape-level variables. We recorded 12,335 individuals of 181 bird species; 105 bird species were recorded foraging within the shaded coffee plantations. We found that plot- and landscape-level variables significantly explained the bird community composition best across all scales, and were significantly correlated with the abundance of the dietary guilds. In contrast, patch-level variables were less important. Habitat composition variables (i.e., coffee, forest and agricultural area) were among the most important predictors. Canopy structure was more important than other vegetation structure variables in explaining dietary guild structure. Hence, the maintenance of a heterogeneous landscape with a high-quality matrix within an agro-ecological region enhances bird conservatio