Mapping aboveground biomass by integrating geospatial and forest inventory data through a k-nearest neighbor strategy in North Central Mexico

As climate change negotiations progress,monitoring biomass and carbon stocks is becoming an important part of the current forest research.Therefore,national governments are interested in developing forest-monitoring strategies using geospatial technology.Among statistical methods for mapping biomass,there is a nonparametric approach called k-nearest neighbor(kNN).We compared four variations of distance metrics of the kNN for the spatially-explicit estimation of aboveground biomass in a portion of the Mexican north border of the intertropical zone.Satellite derived,climatic,and topographic predictor variables were combined with the Mexican National Forest Inventory(NFI)data to accomplish the purpose.Performance of distance metrics applied into the kNN algorithm was evaluated using a cross validation leave-one-out technique.The results indicate that the Most Similar Neighbor(MSN)approach maximizes the correlation between predictor and response variables(r=0.9).Our results are in agreement with those reported in the literature.These findings confirm the predictive potential of the MSN approach for mapping forest variables at pixel level under the policy of Reducing Emission from Deforestation and Forest Degradation(REDD+).     

Deforestation and forest restoration in Guanacaste,Costa Rica: Putting conservation policies in context

Traditionally Land Use Cover Change (LUCC) studies have focused on processes of negative land-cover change, primarily deforestation, partially because examples of positive land-cover change were not common. During the last two decades an outstanding tropical dry forest restoration process had taken place in the province of Guanacaste, Costa Rica, which has given us a unique opportunity to study how and why tropical dry forest regrowth occurs. The purpose of this paper is to undertake a retrospective analysis of the social dynamics of forest deforestation and restoration in Guanacaste from 1960 to 2005. Hence we investigate how structural drivers shape patterns of forest-cover change and examine how the role that Costa Rica's conservation policies had played in promoting forest restoration. Our study combined analyses of socioeconomic data and satellite images of forest cover. We showed that forest regrowth observed in Guanacaste after the 1980s was the result of multiple socioeconomic factors. Our results indicate that the degree of incentive provided by conservation policies such as Payment for Environmental Services are not enough to ensure that Guanacaste's forest will be protected against the potentially negative impacts of future socioeconomic changes. The findings from our analysis can assist decision-makers and managers in other regions to understand how social, economic and political dynamics impact the effectiveness of forest conservation efforts.     

Response of vascular epiphyte diversity to different land-use intensities in a neotropical montane wet forest

Although vascular epiphytes contribute substantially to the biodiversity of tropical montane forests, it is unclear how their diversity and community composition is affected by forest alteration. We studied the response of vascular epiphyte assemblages to different intensities of land-use in a montane wet forest of northeastern Ecuador: (1) unmanaged mature forest; (2) mature forest with mid- and understorey opened for cattle grazing; and (3) isolated remnant trees in cattle pastures. The numbers of individuals and species of epiphytes per host tree did not differ significantly between land-use types, neither did total epiphyte species richness (n = 30 trees). However, total species richness of pteridophytes was significantly lower on isolated remnant trees compared to unmanaged forest, whereas several taxa rich in xerotolerant species (Bromeliaceae, Orchidaceae, Piperaceae) exhibited the opposite trend. An analysis of floristic composition using ordination (NMS) and randomisation techniques (MRPP) showed that epiphyte assemblages on isolated remnant trees were significantly distinct from unmanaged forest while managed forest was intermediate between those two vegetation types. Ordination analysis further indicated reduced floristic heterogeneity in disturbed habitats. These results suggest considerable, rapid species turnover since land-use change 6 years prior to study, with pteridophytes being replaced by more xerotolerant taxa. We attribute this floristic turnover primarily to changes in microclimate towards higher levels of light and desiccation stress associated with forest disturbance. Our results support the notion that community composition offers a more sensitive indicator of human disturbance than species richness.     

Accessible habitat: an improved measure of the effects of habitat loss and roads on wildlife populations

Habitat loss is known to be the main cause of the current global decline in biodiversity, and roads are thought to affect the persistence of many species by restricting movement between habitat patches. However, measuring the effects of roads and habitat loss separately means that the configuration of habitat relative to roads is not considered. We present a new measure of the combined effects of roads and habitat amount: accessible habitat. We define accessible habitat as the amount of habitat that can be reached from a focal habitat patch without crossing a road, and make available a GIS tool to calculate accessible habitat. We hypothesize that accessible habitat will be the best predictor of the effects of habitat loss and roads for any species for which roads are a major barrier to movement. We conducted a case study of the utility of the accessible habitat concept using a data set of anuran species richness from 27 ponds near a motorway. We defined habitat as forest in this example. We found that accessible habitat was not only a better predictor of species richness than total habitat in the landscape or distance to the motorway, but also that by failing to consider accessible habitat we would have incorrectly concluded that there was no effect of habitat amount on species richness.     

埃塞俄比亚土壤侵蚀状况分析其治理对策

埃塞俄比亚土壤保持与提高农业生产息息相关。因此,土壤侵蚀监测与土地地力分类至关重要。本文论述了埃塞俄比亚土地退化状况,分析森林砍伐、过度放牧、生态退化等与土壤退化的关系。通过分析土地退化状况监测手段,提出改善了土地退化的策略与方法。     

A multi-region assessment of tropical forest biodiversity in a human-modified world

The fate of much of the world’s terrestrial biodiversity is linked to the management of human-modified forest landscapes in the humid tropics. This Special Issue presents the first pan-tropical synthesis of research on the prospects for biodiversity in such systems, with eight individual regional summaries covering Mesoamerica, Amazonia, Atlantic forest of South America, West Africa, Madagascar, Western Ghats, Southeast Asia and Oceania. Two additional papers compare the state of conservation science in tropical forests with both temperate forests and savannah systems. This overview paper provides a comparative analysis of the threats and opportunities facing tropical forest biodiversity, thereby helping to identify the most pressing areas of future research and region-specific factors that contribute towards the effectiveness of individual conservation initiatives. While many of the threats facing tropical forest biodiversity are commonplace they vary markedly in their relative importance across different regions. There is a critical lack of comparable data to understand scale dependent processes, or the relative importance of varying geographic and historical contexts in determining present-day patterns. Conservation science has a key role to play in safeguarding the future of tropical forest biodiversity, but needs to become more effectively embedded in the context of real-world conservation challenges and opportunities. Significant progress can be achieved by improving the cost-effectiveness of research as well as the exchange of ideas and data amongst scientists working in different, often isolated parts of the world. We hope this special issue goes some way top achieving this exchange of knowledge.     

Habitat fragmentation and the desiccation of forest canopies: A case study from eastern Amazonia

Across the deforestation frontier in eastern Amazonia, we examined the relationship between edge-related forest desiccation and deforestation patterns using remote-sensing techniques. Canopy-moisture levels were estimated over an eight-year period in three study sites that encompassed ∼100,000 km² in area. We found four main effects of deforestation on dry-season canopy desiccation. First, intact forests showed no detectable change in canopy water content whereas forests adjacent to clearings showed significant water loss. Second, the distance to which edge-related desiccation penetrated into forest interiors varied among landscapes with differing forest loss and fragmentation. In moderately fragmented landscapes (with 65% and 51% remaining forest cover), canopy desiccation extended 1-1.5 km into forest interiors, whereas in heavily fragmented landscapes (20% forest cover) desiccation penetrated up to 2.7 km into forests. Third, the magnitude of edge-related desiccation varied among landscapes with differing fragmentation. Moderately fragmented landscapes exhibited a greater magnitude of change in canopy-water loss over the first 1 km from an edge than did heavily fragmented landscapes. Finally, forest desiccation penetrated further into forests over time in the moderately fragmented landscapes, but not in the heavily fragmented landscape, where edge-related desiccation had evidently ‘saturated’ remaining forests. We conclude that protracted dry seasons will have far more serious effects on fragmented than intact rainforests, with the former becoming highly vulnerable to destructive fires. With ∼30,000 km of new forest edge being created annually in Brazilian Amazonia, these finding have serious implications for forest conservation.     

Biodiversity conservation in human-modified Amazonian forest landscapes

Amazonia (sensu lato) is by far the largest tropical forest region, but has succumbed to the highest absolute rates of tropical deforestation and forest degradation, driven by rapid frontier expansion, road-building, and spontaneous or government-subsidized migration. The large area-through-time and paleo-climatic stability of Amazonian forests may help explain the high regional to local scale plant and animal species diversity of true forest specialists and high ecological sensitivity to contemporary land-use change. We describe the prevailing forms of anthropogenic disturbance that affect forest organisms in the context of the geographic and evolutionary background that has shaped the degree to which forest species may be resilient to environmental change. The fate of Amazonian biodiversity will partly depend upon the interaction between land-use and climate change, and the extent to which seasonally-dry forests can retain immunity against catastrophic recurrent wildfires. This review illustrates the importance of considering interactions between different forms of forest disturbance to develop effective conservation policy. We conclude with some considerations of the policy agenda necessary to protect forest cover and forest biodiversity at a meaningful scale across the Amazonian biome.     

Burning biodiversity: Woody biomass use by commercial and subsistence groups in western Uganda’s forests

Woodfuels are the most heavily used energy source in sub-Saharan Africa. We analyzed the ecological impacts and modes of access of five user groups (domestic consumers, gin distillers, brick manufacturers, charcoal producers, and tea companies) drawing biomass energy from natural forests in western Uganda. While domestic consumers use the most species for fuelwood (>50), their consumption is likely sustainable because they generally harvest fast-growing species from fallows on their own land or their neighbors’. Charcoal producers prefer old-growth hardwood species and are responsible for the greatest loss of natural forests. They access forests by finding landholders who, either willingly or through coercion, allow trees on their lands to be cleared. The impact of charcoal production is exacerbated by a license system that undervalues natural forests and rewards rapid harvests across large areas. The tea industry consumes mainly eucalyptus wood (Eucalyptus spp.) from corporate plantations, but they indirectly create pressure on natural forests by hiring immigrants who subsequently settle in and clear forest remnants. If such practices continue, forest remnants will soon be exhausted, leaving Kibale National Park as the last natural forest in the region. Forest remnants are a vital source of water, medicinal plants, and energy for local citizens and to protect them from over-exploitation, policy makers should target the charcoal and tea industry for reform. Support for local land management institutions governing access to fallows and successional forests will inevitably enhance the policy interventions.     

Deforestation and forest degradation monitoring and assessment of biomass and carbon stock of lowland rainforest in the Analanjirofo region, Madagascar

Madagascar is currently developing a policy and strategies to enhance the sustainable management of its natural resources, encouraged by United Nations Framework Convention on Climate Change (UNFCCC) and REDD. To set up a sustainable financing scheme methodologies have to be provided that estimate, prevent and mitigate leakage, develop national and regional baselines, and estimate carbon benefits. With this research study this challenge was tried to be addressed by analysing a lowland rainforest in the Analanjirofo region in the district of Soanierana Ivongo, North East of Madagascar. For two distinguished forest degradation stages: “low degraded forest” and “degraded forest” aboveground biomass and carbon stock was assessed. The corresponding rates of carbon within those two classes were calculated and linked to a multi-temporal set of SPOT satellite data acquired in 1991, 2004 and 2009. Deforestation and particularly degradation and the related carbon stock developments were analysed. With the assessed data for the 3 years 1991, 2004 and 2009 it was possible to model a baseline and to develop a forest prediction for 2020 for Analanjirofo region in the district of Soanierana Ivongo. These results, developed applying robust methods, may provide important spatial information regarding the priorities in planning and implementation of future REDD+ activities in the area.