Publications

Large tropical trees are rightly perceived as supporting a plethora of organisms. However, baseline data about the variety of taxa coexisting on single large tropical trees are lacking and prevent a full understanding of both the magnitude of biodiversity and the complexity of interactions among organisms in tropical rainforests. The two main aims of the research program “Life on Trees” (LOT) are (1) to establish baseline knowledge on the number ...

Tree stem respiration (R-S) is a substantial component of the forest carbon balance. The mass balance approach uses stem CO2 efflux and internal xylem fluxes to sum up R-S, while the oxygen-based method assumes O-2 influx as a proxy of R-S. So far, both approaches have yielded inconsistent results regarding the fate of respired CO2 in tree stems, a major challenge for quantifying forest carbon dynamics. We collected a data set of CO2 efflux, O-2 ...

Elevated atmospheric CO2 concentration (eCO2) commonly stimulates net leaf assimilation, decreases stomatal conductance and has no clear effect on leaf respiration. However, effects of eCO2 on whole-tree functioning and its seasonal dynamics remain far more uncertain. To evaluate temporal and spatial variability in eCO2 effects, one-year-old European aspen trees were grown in two treatment chambers under ambient (aCO2, 400ppm) and elevated ...

Individual tree segmentation from airborne laser scanning data is a longstanding and important challenge in forest remote sensing. Tree segmentation algorithms are widely available, but robust intercomparison studies are rare due to the difficulty of obtaining reliable reference data. Here we provide a benchmark data set for temperate and tropical broadleaf forests generated from labelled terrestrial laser scanning data. We compared the ...

In this article we propose a heuristic algorithm to explore search space trees associated with instances of combinatorial optimization problems. The algorithm is based on Monte Carlo tree search, a popular algorithm in game playing that is used to explore game trees and represents the state-of-the-art algorithm for a number of games. Several enhancements to Monte Carlo tree search are proposed that make the algorithm more suitable in a ...

Background and aims - Bitter and sweet African bush mango trees belong to the family Irvingiaceae and produce valuable non-timber forest products in humid lowland areas of West and Central Africa. The bitter and sweet types are treated as distinct taxa at the variety or species level. They have not been studied in the western part of their distribution range, and many aspects of their large-scale utilization remain unknown. In this study, we ...

BackgroundEnvironmental change has resulted in changes in forest growth in Europe during the last century. This has consequences for the products and services delivered by forest. Mixing tree species is often proposed as a strategy to deal with the consequences of climate change. Diversifying forests is believed to result in higher productivity and increased growth stability. Tree species diversity is therefore expected to affect long-term ...

Nitrogen (N) fixing trees including many species of Acacia are an important though variable component of savanna ecosystems. It is known that these trees enrich the soil with carbon (C) and N, but their effect on the combined C:N:P stoichiometry in soil is less well understood. Theory suggests that they might reduce available phosphorus (P), creating a shift from more N-limited conditions in grass-dominated to more P-limited conditions in ...

© 2017 Elsevier B.V. Vegetation can provide transpirative cooling in cities and is therefore being increasingly integrated as an essential part of Urban Heat Island (UHI) mitigation strategies. However, the behaviour of vegetation must be accurately understood to determine the effectiveness of vegetation based solutions. In this study, vegetation is modelled as a porous medium in a computational fluid dynamics model for flow of moist air, where ...