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Land-use change and intensification in tropical rainforest regions is generally linked to a loss in species diversity that especially affects forest-dependent species. Indonesia is currently the country with the highest deforestation rates worldwide with potentially devastating effects on its diverse and highly endemic flora and fauna. Here we present a comprehensive assessment of the varied effects of forest conversion and land-use intensification on vascular plant diversity across the four dominant land-use systems in the lowlands of Sumatra: rainforest, jungle rubber agroforest, rubber plantations, and oil palm plantations. We conducted plot-based species inventories in Jambi Province and assessed a total of 156,006 individuals and 1382 plant species. Forest had the highest levels of alpha, beta, and gamma diversity, followed by jungle rubber. Plant communities in oil palm plantations were characterized by a high density of herbaceous weeds, but low species numbers and low beta diversity. Species numbers were comparable in oil palm and rubber plantations, but the latter showed slightly higher beta diversity. Forest had a clearly distinct floristic composition while the floristic composition of the other systems - and especially the two plantation systems - converged. Alien species were almost completely absent from forest, but the number and relative abundance of alien species increased with increasing land-use intensity and was highest in oil palm plantations where 25% of the species and 62% of the individuals belonged to alien species. Our results represent a first quantitative baseline for how forest conversion in Southeast Asia causes loss in species richness, changes in floristic composition and vegetation structure, as well as a shift from native to alien-dominated plant communities. [ABSTRACT FROM AUTHOR]

• We studied tropical forest regeneration along an elevation and disturbance gradient. • We recorded and identified all saplings of woody plants in 65 plots of 100 m2 each. • Natural regeneration was shown in all vegetation zones and disturbance levels. • Sapling diversity and abundance was strongly driven by climate and land-use. • Our data serve as baseline for future monitoring of disturbance and climate change. The continuous decline and degradation of tropical rainforests is currently mainly driven by land-use change. Over the long term, climate change will further exacerbate the situation for the remaining forests. To develop sustainable conservation strategies, we need to understand the natural forest-recovery potential after disturbance and the impact of climate on forest recovery. So far, little is known about regeneration of woody species in tropical landscapes, especially in tropical Africa. We investigated the regeneration of woody plant species in six natural and seven anthropogenically disturbed habitat types along a 3.6 km elevational gradient from savanna woodland to afro-alpine vegetation at Mt. Kilimanjaro, Tanzania. We recorded and identified all saplings of woody plants in a total of 65 plots, each measuring 100 m2. The total number of recorded sapling individuals amounts to 4,738 saplings from 110 species of 50 families. Along the elevational gradient, sapling numbers in natural plots showed a hump-shaped distribution peaking at mid elevation, where rainfall and overall woody biomass were highest, while species number and diversity of saplings were continuously decreasing with increasing elevation. The sapling layer in the savanna zone had three times as many species as the layer of adult trees and shrubs in the same plots, but the species composition of saplings differed strongly from the one of trees and shrubs, indicating strong spatial or temporal heterogeneity. Active agricultural plots at lower elevations also showed natural regeneration of woody species, even though numbers of sapling individuals and species were much lower than in natural low-elevation plots. Forests formerly disturbed by fire and logging showed either comparable or even increased numbers of sapling individuals and species than natural plots at the same elevation, indicating ongoing succession. Finding regeneration of woody species in all disturbed habitat types, even in agriculturally managed habitats, strongly suggests that natural regeneration is a very powerful tool to recover forest diversity after disturbances. Furthermore, our sapling dataset provides an important baseline for future monitoring of the consequences of climate and land-use change on regeneration. [ABSTRACT FROM AUTHOR]

Land-use change is the main driver of biodiversity loss in the tropics worldwide. Lowland rainforest regions in Southeast Asia are experiencing particularly high rates of large-scale conversion of forests and agroforests into monocultural tree plantations including oil palm and rubber with devastating effects on forest-dependent species. Canopy-dwelling organisms such as epiphytes are expected to be particularly susceptible to changes in land use, vegetation structure, and microclimate but the consequences of these changes are only poorly known for this plant group in Southeast Asia. We investigated the diversity of vascular epiphytes in four major land-use systems in Jambi Province (Sumatra, Indonesia). Epiphyte communities were sampled in 120 20 × 20 m plots in Bukit Duabelas National Park (lowland rainforest) and in surrounding jungle rubber agroforests as well as in rubber and oil palm plantations owned by smallholders. At plot level, lowland rainforest, jungle rubber, and oil palm were statistically indistinguishable in terms of richness, diversity, and evenness but had significantly higher values than rubber. Oil palm plantations had the highest epiphyte abundance, but lowest total species number of all systems. Furthermore, oil palm had distinct, fern-dominated epiphyte communities that differed significantly from the other systems. In conclusion, the value of monocultural tree plantations of oil palms and rubber trees for epiphyte conservation is very low. Jungle rubber, an extensively managed yet vanishing system, represents a refuge for epiphytes and could play a vital role in conserving epiphyte diversity, especially of ferns and orchids. Non-orchid angiosperms, however, mainly occurred in forest and are thus most threatened by forest conversion. [ABSTRACT FROM AUTHOR]

Sound recordings obtained from passive acoustic monitoring systems are increasingly used to sample animal biodiversity. However, sound recorders sample variable detection spaces, so that data may not be comparable between sampling sites and recording setups. Focusing on terrestrial systems, we measured understory vegetation, tree structure, sound transmission, ambient sound pressure level, and derived sound detection spaces of 38 plots in lowland rainforest, jungle rubber, and oil palm and rubber plantations, using different combinations of sound frequency (0.05 to 40 kHz) and source height (0 to 5 m). We show that simple vegetation structure measures poorly predict sound transmission, so that direct sound transmission measurements are indispensable. We depict highly variable sound detection spaces in different land-use types. Finally we estimated species richness of exemplary animal groups and found considerable differences between land-use types on the basis of variable detection space areas alone. Sound detection spaces respond non-linearly to sound frequency and source height, and they need to be quantified in acoustic surveys to avoid substantial bias in biodiversity estimates between sampling sites. Detection spaces also determine species detection probabilities and allow comparing data between recording setups. We provide guidelines and computer scripts for measuring sound transmission and ambient sound level using consumer audio equipment, and for computing detection spaces. Appreciating the effective sampling area of acoustic recorders closes a gap between acoustic and traditional animal survey methods. Species richness estimates can now be reported for measured sampling areas, and animal population variables such as abundance, density, and activity can be compared at equal areas. [ABSTRACT FROM AUTHOR]