Human impact of wild firewood species in the Rural Andes community of Apillapampa, Bolivia

Firewood is the basic fuel source in rural Bolivia. A study was conducted in an Andean village of subsistence farmers to investigate human impact on wild firewood species. A total of 114 different fuel species was inventoried during fieldtrips and transect sampling. Specific data on abundance and growth height of wild firewood species were collected in thirty-six transects of 50 x2 m(2). Information on fuel uses of plants was obtained from 13 local Quechua key participants. To appraise the impact of fuel harvest, the extraction impact value (EIV) index was developed. This index takes into account local participants' appreciation of (1) decreasing plant abundance; (2) regeneration capacity of plants; (3) impact of root harvesting; and (4) quality of firewood. Results suggest that several (sub-)woody plant species are negatively affected by firewood harvesting. We found that anthropogenic pressure, expressed as EIV, covaried with density of firewood species, which could entail higher human pressure on more abundant and/or more accessible species. The apparent negative impact of anthropogenic pressure on populations of wild fuel species is corroborated by our finding that, in addition to altitude, several anthropogenic variables (i.e. site accessibility, cultivation of exotics and burning practices) explain part of the variation in height of firewood species in the surroundings of Apillapampa

Vulnerabilities of Tropical Forests to Climate Change: The Significance of Resident Epiphytes

Abstract. Predictions about the impacts of climate change on tropical forests require information on the relative vulnerabilities and roles of the biological components of these unusually complex systems. Central to the structure and function of any ecosystem – and the subject of this paper – is its flora, the energetic base for co-occurring heterotrophs. Much data indicate that arboreal flora (the epiphytes), those plants anchored in the forest canopy without access to the ground, occupy unusually climate-defined ecospace compared with co-occurring types such as the supporting trees. This report also describes how the epiphytes influence adjacent biota and whole-system processes, specifically those concerned with energetics, hydrology, and mineral cycling. Second, a mechanistic explanation for the exceptionally climate-sensitive nature of arboreal flora is provided. Finally, points one and two are used to make the case that arboreal flora represent a weak link in the integrity of certain types of forest, especially cloud forest and other types at lower elevations well known for their extraordinarily diverse biota. These plants, more than most, should provide early indications of floristic response to climate change throughout much of the tropics, but particularly in montane regions. 1

No differences in soil carbon stocks across the tree line in the Peruvian Andes

Reliable soil organic carbon (SOC) stock measurements of all major ecosystems are essential for predicting the influence of global warming on global soil carbon pools, but hardly any detailed soil survey data are available for tropical montane cloud forests (TMCF) and adjacent high elevation grasslands above (puna). TMCF are among the most threatened of ecosystems under current predicted global warming scenarios. We conducted an intensive soil sampling campaign extending 40 km along the tree line in the Peruvian Andes between 2994 and 3860 m asl to quantify SOC stocks of TMCF, puna grassland, and shrubland sites in the transition zone between the two habitats. SOC stocks from the soil surface down to the bedrock averaged (±standard error SE) 11.8 (±1.5, N = 24) kg C/m2 in TMCF, 14.7 (±1.4, N = 9) kg C/m2 in the shrublands and 11.9 (±0.8, N = 35) kg C/m2 in the grasslands and were not significantly different (P > 0.05 for all comparisons). However, soil profile analysis revealed distinct differences, with TMCF profiles showing a uniform SOC distribution with depth, shrublands a linear decrease, and puna sites an exponential decrease in SOC densities with soil depth. Organic soil layer thickness reached a maximum (~70 cm) at the upper limit of the TMCF and declined with increasing altitude toward puna sites. Within TMCF, no significant increase in SOC stocks with increasing altitude was observed, probably because of the large variations among SOC stocks at different sites, which in turn were correlated with spatial variation in soil depth