Fabiola López-Barrera

Toward Integrated Analysis of Human Impacts on Forest Biodiversity: Lessons from Latin America

Although sustainable forest management (SFM) has been widely adopted as a policy and management goal, high rates of forest loss and degradation are still occurring in many areas. Human activities such as logging, livestock husbandry, crop cultivation, infrastructural development, and use of fire are causing widespread loss of biodiversity, restricting progress toward SFM. In such situations, there is an urgent need for tools that can provide an integrated assessment of human impacts on forest biodiversity and that can support decision making related to forest use. This paper summarizes the experience gained by an international collaborative research effort spanning more than a decade, focusing on the tropical montane forests of Mexico and the temperate rain forests of southern South America, both of which are global conservation priorities. The lessons learned from this research are identified, specifically in relation to developing an integrated modeling framework for achieving SFM. Experience has highlighted a number of challenges that need to be overcome in such areas, including the lack of information regarding ecological processes and species characteristics and a lack of forest inventory data, which hinders model parameterization. Quantitative models are poorly developed for some ecological phenomena, such as edge effects and genetic diversity, limiting model integration. Establishment of participatory approaches to forest management is difficult, as a supportive institutional and policy environment is often lacking. However, experience to date suggests that the modeling toolkit approach suggested by Sturvetant et al. (2008) could be of value in such areas. Suggestions are made regarding desirable elements of such a toolkit to support participatory-research approaches in domains characterized by high uncertainty, including Bayesian Belief Networks, spatial multi-criteria analysis, and scenario planning.

Abundance responses of frugivorous bats (Stenodermatinae) to coffee cultivation and selective logging practices in mountainous central Veracruz, Mexico

Shifting and permanent cultivation, selective logging, cattle production and coffee plantations are among the most important factors in montane cloud forest conversion and disturbance. Although shaded-coffee plantations can contribute to the preservation of local species richness, abundance of organisms could be determined by habitat resource availability in agricultural landscapes. We compared abundance of Sturnira and Artibeus bats (Phyllostomidae, Stenodermatinae), in shade coffee plantations and disturbed cloud forest fragments, which represent habitats with different chiropterochorous plant density. We also investigated the relationship between bat species abundance and food plant richness, abundance and diversity. We captured 956 bats, 76% in cloud forest fragments and 24% in shaded coffee plantations. Abundance of Sturnira spp. (small bats) was greater in cloud forest than in coffee plantations, but Artibeus spp. (large bats) abundance was similar in both habitats. Chiropterochorous plant abundance was positively related with bat abundance for Sturnira spp., while chiropterochorous plant richness and diversity were negatively related for Artibeus spp. This suggests that frugivorous bats with different morphological and ecological characteristics respond differentially to anthropogenic activities. For landscape management purposes, the maintenance and augmentation of diverse food resources, for frugivorous bats with different foraging requirements in coffee plantations, will benefit the resilience of bats to modification of their natural habitat.

Influence of litter on emergence and early growth of Quercusrugosa: a laboratory study

Species-rich old-growth forests dominated by Quercus wereextensive in the highlands of Chiapas until a few decades ago. Current land-use is resulting in replacement of Quercus by Pinusspp. in the canopy of the remaining forest fragments, which areless diverse, drier, and more exposed to freezing temperatures.Forest floor and soil are also modified and may limit theregeneration of many woody species. We studied the influence oflitter type (pine needles vs. oak leaves), litter depth (0, 3, 6and 14 cm), and litter cover (3 cm vs. 0 cm of loose litter ontop of sowed acorns) on the emergence and growth of seedlings ofQuercus rugosa, a dominant tree in pine-oak forests. Seedlingemergence and establishment were affected by the interaction ofexperimental factors. Uncovered acorns on pine litter were moreexposed to desiccation; this effect was more evident with deeperlitter. Acorns sowed on oak litter were not affected by levels oflitter cover and litter depth. The results can be of use indefining further field studies, and practices of direct seedingfor restoration of pine-dominated stands.

Fragmentation and edge effects on plant-animal interactions, ecological processes and biodiversity.

Summary of studies measuring ecological processes, patterns and microclimate at the forest edge (zero metres) compared to forests interior (except in the case of ecological fl ows), showing higher or lower values of the response variable at the edge, or no difference. Modulators are factors that conditioned the observed response. Potential effects No on species Response variable Region Modulators Higher Lower difference richness Reference Dynamic processes Seed rain Chiloe Only fleshy- X Positive Armesto et al . (2001) fruited species Chiloe Landscape X Neutral Jana et al . (Box 4.1) typeAvian nest predation Chiloe X Negative Willson et al . (2001) Chiloe X Positive De Santo et al . (2002) Seed germination Chiapas Species X Positive Lopez-Barrera and identity Newton (2005) Seed removal and/ Chiapas Only non- X Uncertain Lopez-Barrera et al . (2005)or predation masting years Veracruz X Guzman-Guzman and Williams-Linera (2006) Chiloe Species X Neutral Diaz et al. (1999) identity, season and canopy openingSeedling herbivory Chiloe X Positive Chacon and Armesto (2005) Chiapas Edge specific: X Negative in Lopez-Barrera

Ecology of Acorn Dispersal by Small Mammals in Montane Forests of Chiapas, Mexico

The highlands of central and eastern Mexico are the major centre of diversity (60–75 species) for the genus Quercus (Nixon 1993; Chap. 1). Oaks are canopy dominants in many forests in the mountains of Mexico, and provide a wide range of biological resources for insect, mammal and bird species (QuintanaAscencio et al. 1992; Tovar-Sanchez et al. 2003; Chaps. 14, 16 and 20). The occurrence of temporal fruiting synchronicity in oak populations (usually termed masting or mast seeding) has cascading effects in acorn consumers. Understanding such mast-dependent ecological chain reactions is important for predicting, managing and conserving montane forests. In more northern temperate forests, small mammal populations rely on acorns as an important food source (Wolff 1996), and acorns rely on small mammals as potential seed dispersers (Price and Jenkins 1986; Steele and Smallwood 2002). However, there is little information available on the extent to which oaks rely on dispersal in Neotropical montane forests. Most oak species suffer reproductive failure under their own canopies (Crow 1988; Lorimer et al. 1994; Figueroa-Rangel and Olvera-Vargas 2000; Chap. 28), relying instead on the dispersal of acorns to forest edges or clearings where establishment success is increased (Lopez-Barrera 2003, see Chaps. 14 and 16). In the Chiapas Highlands, the traditional land use of slashand-burn agriculture, existing since pre-Columbian times, has resulted in forest mosaics comprised of small clearings (0.5–2 ha; pastures, cornfields and shrublands), surrounded by fragments of secondary forest, evergreen cloud forest, oak forest, and pine–oak forest with various levels of disturbance (see Chap. 16), and resulting in the creation of different forest edge types varying in sharpness, such as hard and soft edges (Fig. 13.1). Oak regeneration in this landscape of small-scale, scattered forest disturbances (Gonzalez-Espinosa et al. 1991; Chap. 16) is primarily due to oak resprouting ability and the activity of acorn dispersers. This landscape con-

Amphibian species and functional diversity as indicators of restoration success in tropical montane forest

Tropical forest restoration is increasingly seen as an activity that may counteract or reduce biodiversity loss. However, few studies monitor fauna or consider measures of functional diversity to assess restoration success. We assessed the effect of a tropical montane forest restoration program on species and functional diversity, using amphibians as the target group. We compared amphibian assemblages in three types of land use: restoration areas, tropical montane cloud forest (TMCF; reference ecosystem) and cattle pastures (degraded ecosystem) in southern Mexico. We also described microclimate, microhabitat heterogeneity, woody vegetation structure and diversity for each type of land use, and their relationship to amphibian species and functional diversity. Compared to TMCF, restoration areas had similar environmental conditions. However, amphibian species richness was similar in the three types of land use and abundance was lower in the restoration areas. In TMCF, the amphibian assemblage was dominated by forest-specialist species, the pastures by generalist species, and the restoration areas by a combination of both species types. Interestingly, functional richness, functional evenness and functional divergence did not vary with land use, though the number of functional groups in restoration areas and TMCF was slightly higher. Overall, the results suggest that after seven years, active restoration provided habitat heterogeneity and recovered woody vegetation capable of maintaining amphibian species and functional groups similar to those inhabiting TMCF. Forest fragments adjacent to restoration areas seem to facilitate fauna recolonization and this emphasizes the importance of the conservation of the reference ecosystems to achieving restoration success.

Value of Riparian Vegetation Remnants for Leaf-Litter Ants (Hymenoptera: Formicidae) in a Human-Dominated Landscape in Central Veracruz, Mexico

ABSTRACT Riparian remnants are linear strips of vegetation immediately adjacent to rivers that may act as refuges for biodiversity, depending on their habitat quality. In this study, we evaluated the role of riparian remnants in contributing to the diversity of leaf-litter ants by determining the relationship between ant diversity and several riparian habitat characteristics within a human-dominated landscape in Veracruz, Mexico. Sampling was carried out in 2012 during both dry and rainy seasons at 12 transects 100 m in length, where 10 leaf-litter samples were collected along each transect and processed with Berlese-Tullgren funnels and Winkler sacks. A total of 8,684 individuals belonging to 53 species, 22 genera, and seven subfamilies were collected. The observed mean alpha diversity accounted for 34.4% of the total species recorded and beta diversity for 65.6%. Species richness and composition were significantly related to litter-layer depth and soil compaction, which could limit the distribution of ant species depending on their nesting, feeding, and foraging habits. Riparian remnants can contribute toward the conservation of ant assemblages and likely other invertebrate communities that are threatened by anthropogenic pressures. In human-dominated landscapes where remnants of riparian vegetation give refuge to a diverse array of myrmecofauna, the protection of the few remaining and well-preserved riparian sites is essential for the long-term maintenance of biodiversity.

The surrounding landscape influences the diversity of leaf-litter ants in riparian cloud forest remnants

Riparian vegetation is a distinctive and ecologically important element of landscapes worldwide. However, the relative influence of the surrounding landscape on the conservation of the biodiversity of riparian remnants in human-modified tropical landscapes is poorly understood. We studied the surrounding landscape to evaluate its influence on leaf-litter-ant alpha and beta diversity in riparian remnants in the tropical montane cloud forest region of central Veracruz, Mexico. Sampling was carried out in 12 sites with riparian vegetation during both rainy (2011) and dry (2012) seasons. Ten leaf-litter samples were collected along a 100-m transect per site and processed with Berlese-Tullgren funnels and Winkler sacks. Using remotely-sensed and ground-collected data, we characterized the landscape around each site according to nine land cover types and computed metrics of landscape composition and configuration. We collected a total of 8,684 ant individuals belonging to 53 species, 22 genera, 11 tribes, and 7 subfamilies. Species richness and the diversity of Shannon and Simpson increased significantly in remnants immersed in landscapes with a high percentage of riparian land cover and a low percentage of land covers with areas reforested with Pinus, cattle pastures, and human settlements and infrastructure. The composition of ant assemblages was a function of the percentage of riparian land cover in the landscape. This study found evidence that leaf-litter ants, a highly specialized guild of arthropods, are mainly impacted by landscape composition and the configuration of the focal remnant. Maintaining or improving the surrounding landscape quality of riparian vegetation remnants can stimulate the movement of biodiversity among forest and riparian remnants and foster the provision of ecosystem services by these ecosystems. Effective outcomes may be achieved by considering scientific knowledge during the early stages of riparian policy formulation, in addition to integrating riparian management strategies with broader environmental planning instruments.