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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.

Die Erkenntnisse und die Werke Alexander von Humboldts sind aus den Pflanzenwissenschaften nicht wegzudenken. Dennoch wären viele überrascht, würde man Humboldt hauptsächlich als Botaniker bezeichnen. Schließlich hat er interdisziplinär gearbeitet und sich sowohl zahlreichen Naturwissenschaften als auch kultur- und sozialwissenschaftlichen Themenbereichen gewidmet. Besonders die Zusammenhänge zwischen verschiedenen Disziplinen haben ihn interessiert. Zusammenhänge zu verstehen, setzt ein fachübergreifendes Interesse und Verständnis voraus, das Humboldt mitbrachte und das ihn (unter anderem) zum «Vater der Pflanzengeographie» machte. Dies gelang vermutlich gerade deshalb, weil er neben seinen außerordentlichen Kenntnissen und seinem großen Interesse an anderen Disziplinen eine ausgeprägte Leidenschaft für die Botanik hatte. Dies erlaubte ihm, die Botanik mit anderen Disziplinen zu verknüpfen. Fest steht, dass er von der Botanik nachhaltig geprägt wurde und seinerseits die Botanik nachhaltig prägte.

Die Rolle von Botanischen Gärten geht weit über die gezeigten Pflanzensammlungen hinaus. Sie sind Orte der Bildung, Forschung, Kultur, Erholung und wichtige Akteure bei der Erhaltung gefährdeter Pflanzenarten. Der Botanische Garten der Universität Bern (BOGA) ist eine grüne Oase mitten in der Stadt. Er beherbergt nicht nur eine grosse Vielfalt an Pflanzen, sondern bietet auch Lebensraum, Nahrungsquelle, Unterschlupf- und Nistmöglichkeiten für eine Vielzahl von wildlebenden Organismen. Doch wie hoch genau ist die Biodiversität auf dem 2.5 ha grossen Gelände? Wie viele Pflanzenarten auf dem BOGA-Gebiet kultiviert werden, war bereits bekannt: rund 5500 Arten aus aller Welt. Auch zu einigen wild lebenden Tiergruppen, wie Vögeln oder Wildbienen, wurden über die Jahre bereits Artenlisten zusammengetragen. Um das Potenzial des Botanischen Gartens als Lebensraum für weitere wild lebende Bewohner zu erforschen, führte der BOGA zusammen mit rund 30 Expert*innen im Frühjahr 2019 eine Bestandsaufnahme durch. Insgesamt wurden 14 Taxa von Tieren, Pflanzen und Pilzen untersucht (Weichtiere, Spinnen, Käfer, Libellen, Tagfalter, Reptilien, Amphibien, Vögel, Fledermäuse, Kleinsäuger, Pilze, Flechten, Moose, Gefässpflanzen). Bisher wurden auf dem BOGA-Gelände 1139 Arten identifiziert, von denen etwa je ein Drittel Pilze, wild wachsende Pflanzen und wirbellose Tiere sind. Da zahlreiche Organismengruppen noch nicht untersucht wurden oder eine andere Jahreszeit bevorzugen, ist zu erwarten, dass die Artengemeinschaft im BOGA sogar noch deutlich grösser ist und es auch weiterhin viel zu entdecken gibt. Zu den Highlights der Bestandsaufnahme zählen z.B. der Erstnachweis der Spinnenart Triaeris stenaspis in der Schweiz oder der Pilz Scirrhia osmundicola, welcher zum ersten Mal seit seiner Erstbeschreibung 1959 gesichtet wurde. Zudem sind einige Gruppen erstaunlich gut vertreten, so wurden 34 der Schweizer Vogelarten im BOGA gesichtet und dies auf gerade mal 0.00005 der Landesfläche. Diese Bestandsaufnahme zeigt eindrücklich, wie wertvoll die hohe Pflanzenartenvielfalt und der vielfältige Lebensraum des BOGA für die gesamte Biodiversität mitten in der Stadt ist.

The rapid conversion of Southeast Asian lowland rainforests into monocultures calls for the development of rapid methods for species identification to support ecological research and sustainable land-use management. Here, we investigated the utilization of DNA barcodes for identifying flowering plants from Sumatra, Indonesia. A total of 1,207 matK barcodes (441 species) and 2,376 rbcL barcodes (750 species) were successfully generated. The barcode effectiveness is assessed using four approaches: (a) comparison between morphological and molecular identification results, (b) best-close match analysis with TaxonDNA, (c) barcoding gap analysis, and (d) formation of monophyletic groups. Results show that rbcL has a much higher level of sequence recoverability than matK (95% and 66%). The comparison between morphological and molecular identifications revealed that matK and rbcL worked best assigning a plant specimen to the genus level. Estimates of identification success using best-close match analysis showed that >70% of the investigated species were correctly identified when using single barcode. The use of two-loci barcodes was able to increase the identification success up to 80%. The barcoding gap analysis revealed that neither matK nor rbcL succeeded to create a clear gap between the intraspecific and interspecific divergences. However, these two barcodes were able to discriminate at least 70% of the species from each other. Fifteen genera and twenty-one species were found to be nonmonophyletic with both markers. The two-loci barcodes were sufficient to reconstruct evolutionary relationships among the plant taxa in the study area that are congruent with the broadly accepted APG III phylogeny. Open-Access-Publikationsfonds 2019 peerReviewed

Conversion of rainforest into agricultural land affects multiple facets of tropical plant diversity. While the effects of tropical land use change and intensification on species diversity are comparatively well studied, the effects on phylogenetic diversity (PD) and structure of plant communities are largely unknown. Furthermore, it is not clear how the loss of native species and addition of alien species collectively affect PD and structure. We investigated the PD and structure of understorey plants; a diverse and ecologically important, yet poorly studied group. We studied four prominent land use systems (tropical lowland rainforest, jungle rubber agroforest, rubber plantations, and oil palm plantations) in the lowlands of Sumatra (Indonesia), a region experiencing dramatic land use changes. Across the four systems, we investigated differences in four metrics of phylogenetic community structure (PD, mean pairwise distance, mean nearest taxon distance, and their abundance‐weighted variants). Our analyses were based on a comprehensive vegetation survey consisting of 32 plots, 1,197 species of vascular plants, and 146,599 plant individuals. Our results showed that forest conversion into agricultural systems leads to a pronounced loss of PD. Furthermore, the standardized effect size of mean pairwise distance indicated a gradual change from clustered to overdispersed phylogenetic community structure with increasing land use intensity from forest over jungle rubber to the monoculture plantations. In most land use systems, the presence or absence of alien plant species did not affect phylogenetic structure. Only in oil palm plantations, removing alien species from the data led to a more overdispersed structure. In conclusion, conserving the PD and structure requires efficient protection of the last remaining rainforests. Synthesis and applications. Forest conversion into agricultural areas negatively affects phylogenetic understorey plant diversity and leads to a shift from clustered to overdispersed phylogenetic community structure. These trends are partly driven by alien species particularly in oil palm plantations. Protecting the remaining rainforests and considering multispecies agroforestry systems in favour of intensive monoculture plantations are thus imperative to conserve phylogenetic plant diversity and community structure.

Land-use transitions can enhance the livelihoods of smallholder farmers but potential economic-ecological trade-offs remain poorly understood. Here, we present an interdisciplinary study of the environmental, social and economic consequences of land-use transitions in a tropical smallholder landscape on Sumatra, Indonesia. We find widespread biodiversity-profit trade-offs resulting from land-use transitions from forest and agroforestry systems to rubber and oil palm monocultures, for 26,894 aboveground and belowground species and whole-ecosystem multidiversity. Despite variation between ecosystem functions, profit gains come at the expense of ecosystem multifunctionality, indicating far-reaching ecosystem deterioration. We identify landscape compositions that can mitigate trade-offs under optimal land-use allocation but also show that intensive monocultures always lead to higher profits. These findings suggest that, to reduce losses in biodiversity and ecosystem functioning, changes in economic incentive structures through well-designed policies are urgently needed.

The rapid conversion of Southeast Asian lowland rainforests into monocultures calls for the development of rapid methods for species identification to support ecological research and sustainable land-use management. Here, we investigated the utilization of DNA barcodes for identifying flowering plants from Sumatra, Indonesia. A total of 1,207 matK barcodes (441 species) and 2,376 rbcL barcodes (750 species) were successfully generated. The barcode effectiveness is assessed using four approaches: (a) comparison between morphological and molecular identification results, (b) best-close match analysis with TaxonDNA, (c) barcoding gap analysis, and (d) formation of monophyletic groups. Results show that rbcL has a much higher level of sequence recoverability than matK (95% and 66%). The comparison between morphological and molecular identifications revealed that matK and rbcL worked best assigning a plant specimen to the genus level. Estimates of identification success using best-close match analysis showed that >70% of the investigated species were correctly identified when using single barcode. The use of two-loci barcodes was able to increase the identification success up to 80%. The barcoding gap analysis revealed that neither matK nor rbcL succeeded to create a clear gap between the intraspecific and interspecific divergences. However, these two barcodes were able to discriminate at least 70% of the species from each other. Fifteen genera and twenty-one species were found to be nonmonophyletic with both markers. The two-loci barcodes were sufficient to reconstruct evolutionary relationships among the plant taxa in the study area that are congruent with the broadly accepted APG III phylogeny.

Oil palm plantations are intensively managed agricultural systems that increasingly dominate certain tropical regions. Oil palm monocultures have been criticized because of their reduced biodiversity compared to the forests they historically replaced, and because of their negative impact on soils, water, and climate. We experimentally test whether less intensive management schemes may enhance biodiversity and lessen detrimental effects on the environment while maintaining high yields. We compare reduced vs. conventional fertilization, as well as mechanical vs. chemical weed control (with herbicides) in a long-term, full-factorial, multidisciplinary experiment. We conducted the experiment in an oil palm company estate in Sumatra, Indonesia, and report the results of the first 2 years. We measured soil nutrients and functions, surveyed above- and below-ground organisms, tracked oil palm condition and productivity, and calculated plantation gross margins. Plants, aboveground arthropods, and belowground animals were positively affected by mechanical vs. chemical weed control, but we could not detect effects on birds and bats. There were no detectable negative effects of reduced fertilization or mechanical weeding on oil palm yields, fine roots, or leaf area index. Also, we could not detect detrimental effects of the reduced fertilization and mechanical weeding on soil nutrients and functions (mineral nitrogen, bulk density, and litter decomposition), but water infiltration and base saturation tended to be higher under mechanical weeding, while soil moisture, and microbial biomass varied with treatment. Economic performance, measured as gross margins, was higher under reduced fertilization. There might be a delayed response of oil palm to the different management schemes applied, so results of future years may confirm whether this is a sustainable management strategy. Nevertheless, the initial effects of the experiment are encouraging to consider less intensive management practices as economically and ecologically viable options for oil palm plantations.

Following large-scale conversion of rainforest, rubber and oil palm plantations dominate lowland Sumatra (Indonesia) and other parts of South East Asia today, with potentially far-reaching ecohydrological consequences. We assessed how such land-use change affects plant transpiration by sap flux measurements at 42 sites in selectively logged rainforests, agroforests and rubber and oil palm monoculture plantations in the lowlands of Sumatra. Site-to-site variability in stand-scale transpiration and tree-level water use were explained by stand structure, productivity, soil properties and plantation age. Along a land-use change trajectory forest-rubber-oil palm, time-averaged transpiration decreases by 43 ± 11% from forest to rubber monoculture plantations, but rebounds with conversion to smallholder oil palm plantations. We uncovered that particularly commercial, intensive oil palm cultivation leads to high transpiration (827 ± 77 mm yr−1), substantially surpassing rates at our forest sites (589 ± 52 mm yr−1). Compared to smallholder oil palm, land-use intensification leads to 1.7-times higher transpiration in commercial plantations. Combined with severe soil degradation, the high transpiration may cause periodical water scarcity for humans in oil palm-dominated landscapes. As oil palm is projected to further expand, severe shifts in water cycling after land-cover change and water scarcity due to land-use intensification may become more widespread.

1. The high biodiversity and biomass of soil communities is crucial for litter decomposition in terrestrial ecosystems such as tropical forests. However, the leaf litter that these communities consume is of particularly poor quality as indicated by elemental stoichiometry. The impact of resource quantity, quality, and other habitat parameters on species richness and biomass of consumer communities is often studied in isolation, although much can be learned from simultaneously studying both community characteristics. 2. Using a data set of 780 macro-invertebrate consumer species across 32 sites in tropical lowland rainforest and agricultural systems on Sumatra, Indonesia, we investigated the effects of basal resource stoichiometry (C:X ratios of N, P, K, Ca, Mg, Na, S in local leaf litter), litter mass (basal resource quantity and habitat space), plant species richness (surrogate for litter habitat heterogeneity), and soil pH (acidity) on consumer species richness and biomass across different consumer groups (i.e., three feeding guilds and ten selected taxonomic groups). 3. In order to distinguish the most important predictors of consumer species richness and biomass, we applied a standardised model averaging approach investigating the effects of basal resource stoichiometry, litter mass, plant species richness, and soil pH on both consumer community characteristics. This standardised approach enabled us to identify differences and similarities in the magnitude and importance of such effects on consumer species richness and biomass. 4. Across consumer groups, we found litter mass to be the most important predictor of both species richness and biomass. Resource stoichiometry had a more pronounced impact on consumer species richness than on their biomass. As expected, taxonomic groups differed in which resource and habitat parameters (basal resource stoichiometry, litter mass, plant species richness, and pH) were most important for modulating their community characteristics. 5. The importance of litter mass for both species richness and biomass indicates that these tropical consumers strongly depend on habitat space and resource availability. Our study supports previous theoretical work indicating that consumer species richness is jointly influenced by resource availability and the balanced supply of multiple chemical elements in their resources.