Accessibility predicts structural variation of Andean Polylepis forests

Abstract

High Andean mountain forests, formed almost purely by trees of the genus Polylepis, occur nowadays as scattered remnant patches of a more continuous past distribution. Apparently, the destruction of Polylepis forests has mainly been caused by millennia of human disturbance, although forest distribution may also have fluctuated according to prevailing climatic conditions. Nowadays, the remaining Polylepis forest stands are still threatened by anthropogenic disturbance, which gradually degrades the forests. The aim of our study was to test if the structural variation of Polylepis forest patches, as an indication of forest degradation, can be predicted by accessibility to humans. The study was carried out in the Cordilleras Vilcanota and Vilcabamba, Cuzco, Peru. We used indices of forest biomass and proportion of vegetative regeneration as forest structural variables. First we examined the dependence of these variables on elevation with linear regressions. We did this separately for different Polylepis species and combining the species within humid and dry areas. Thereafter, we used the residual forest structural variation to assess possible relationships with accessibility, quantified as geographical distance to the nearest village, road or market centre. We found several significant relationships between the structural variables and accessibility, which may reflect different landscape related preferences in forest use. The results suggest accessibility can be used for rapid spatial prediction of Polylepis forest degradation, which facilitates identifying Polylepis forests that are potentially the most degraded and therefore in the most urgent need of restoration or conservation activities.

The role of root buds in the regeneration of Casearia sylvestris Swartz (Salicaceae) in the cerrado, São Carlos, São Paulo state, Brazil

“…Imatomi et al (2009) observed that 77.8 % of C. sylvestris seeds were subjected to predation or aborted (unviable) and only 20% of the viable seeds sown in a greenhouse emerged. On the other hand, young root sprouts ensure the maintenance of the population, likely due to greater resistance to physical damage by root sprouts than by seedlings (Toivonen et al 2011) and to rapid development, because their resources are drawn from the main trunk which is already established.…”

Elevational Shifts in the Topographic Position of Polylepis Forest Stands in the Andes of Southern Peru

“…The study area was selected based on the availability of high-resolution and cloud-free remote sensing data and extensive field surveys for ground truthing carried out in the area since 2006 [23]. The climate in the study area is a semi-arid tropical alpine climate, with mean annual growing season air and soil temperatures at 4450 m of 3.9 • C and 4.6 • C, respectively [6], and with low annual but high diurnal variations in temperature [15].…”

“…Both accessibility and recovery capacity are topography dependent, but only the latter is related to the ecology of the trees, whereas the former is more related to the ecology of humans and livestock. The mentioned bias is likely strongest at lower elevation due to higher anthropogenic influence [23]. However, these highly impacted areas were excluded from this study, as we focused only on treeline-forming P. subsericans stands, which are mostly of difficult access.…”

Influence of Landscape Features on Forest Maturity: the Case of a Fragmented Landscape in the erra do Mar Coastal Forest in Brazil

“…Landscape features have been related to vegetation characteristics to support diagnostics on maturity or degradation of forest fragments (Teixeira et al 2009;Pütz et al 2011;Toivonen et al 2011). Particularly in human modified landscapes, acessibility and land use may represent relevant landscape features to explain maturity of forest fragments (Gardner et al 2010;Toivonen et al 2011).…”

“…Particularly in human modified landscapes, acessibility and land use may represent relevant landscape features to explain maturity of forest fragments (Gardner et al 2010;Toivonen et al 2011). Conservation strategies include preserve or manage tropical forests, even forest fragments located in human modified landscapes, to improve connectivity, increase avaliable habitat and biodiversity (Ribeiro et al 2009;Gardner et al 2010).…”