Liverworts and mosses are a major component of the epiphyte flora of tropical montane forest ecosystems. Canopy access was used to analyse the distribution and vertical stratification of bryophyte epiphytes within tree crowns at nine forest sites across a 3400 m elevational gradient in Peru, from the Amazonian basin to the high Andes. The stable isotope compositions of bryophyte organic material ( 13 C/ 12 C and 18 O/ 16 O) are associated with surface water diffusive limitations and, along with C/N content, provide a generic index for the extent of cloud immersion. From lowland to cloud forest δ 13 C increased from −33‰ to −27‰, while δ 18 O increased from 16.3‰ to 18.0‰. Epiphytic bryophyte and associated canopy soil biomass in the cloud immersion zone was estimated at up to 45 t dry mass ha −1 , and overall water holding capacity was equivalent to a 20 mm precipitation event. The study emphasizes the importance of diverse bryophyte communities in sequestering carbon in threatened habitats, with stable isotope analysis allowing future elevational shifts in the cloud base associated with changes in climate to be tracked.
Human activities increasingly result in disturbance of wild animal populations. Behavioral responses vary according to the type, duration, frequency and intensity of disturbance. Exposure to disturbance, for example, arising from ecotourism, may promote tolerance of humans and drive a decrease in vigilance and avoidance behaviors, whereas disturbance resulting from extractive activities is typically more intense and is likely to be perceived as a threat. To understand how animals cope with land transformation and human presence, it is imperative to study their responses under different disturbance regimes. We performed behavioral sampling of groups of the giant otter, a charismatic top carnivore, exposed to ecotourism, extractive activities (mining and fishing) and control sites without disturbance to compare their responses. Foraging efficiency was impacted by fish abundance and thus was reduced in mined and fished areas. Giant otters in lakes with managed ecotourism did not show avoidance of research vessels and demonstrated reduced rates of defensive behavior compared to control lakes. Groups from lakes with fishing and gold mining showed increased avoidance, suggesting that these types of disturbance may involve more direct conflict. Our findings suggest that noninvasive disturbance such as ecotourism may promote giant otter tolerance to the presence of humans, whereas extractive activities may be perceived as riskier. Current protected area conservation strategies of strict ecotourism regulation and the maintenance of no-access oxbow lakes may ensure the maintenance of behavioral flexibility in giant otter populations. However, resource depletion and more intense human-giant otter interactions in disturbed areas may not be sustainable. Further studies are necessary to determine whether distinct disturbance regimes drive longer-term demographic effects.
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