18 research outputs found
Dataset from: On the importance of root traits in seedlings of tropical tree species
No full textData from: On the importance of root traits in seedlings of tropical tree species
Here, we discuss biomass allocation of tropical tree species at the seedling stage, and how they differ between species originating from different vegetation types. We discuss how extreme stressors (drought and fire) can alter biomass allocation patterns as expected under the functional equilibrium hypothesis. Specifically, we tested whether above- and below-ground traits of tropical tree seedlings could explain observed occurrence along gradients of resources (light, water) and defoliation(fire, herbivory).
We selected species from the following taxa: Meliaceae, Leguminosae, and Combretaceae, found on the following ecosystems: dry savanna, wet savanna, moist savanna, transition zone, dry forest, wet forest, moist forest. The seedlings grew for 6 months in a greenhouse. The experiment started in June 2015. We measured the following traits: starch concentration; specific root length; mean rooting depth; root mass fraction; leaf area ratio; specific leaf area; leaf size; stem mass fraction; leaf mass fraction; plant weight. The root data was analyzed with WinRHIIZO software.
This dataset contains information on all traits for all species included in the experiment (mean and standard deviation values)
Shifts in ecosystem equilibria following trophic rewilding
No full textAim: Trophic rewilding is proposed as an approach to tackle biodiversity loss by restoring ecosystem dynamics through the reintroduction of keystone species. Currently, evidence on the ecological consequences of reintroduction programmes is sparse and difficult to generalize. To better understand the ecological consequences of trophic rewilding, we simulated the extinction and reintroduction of large-bodied mammals under different environmental conditions.
Location: Europe.
Methods: We selected four locations varying in productivity and seasonality in Europe and used a general ecosystem model called Madingley to run simulations. We initialized the model using body mass limits of a European Holocene baseline; we then removed large mammals and let the model converge to a new equilibrium. Next, we reintroduced the previously removed groups to assess whether the equilibrium would shift back to the initial condition. We tested three different reintroduction scenarios, in order to disentangle the importance of the different large mammal groups.
Results: The removal of large-bodied mammals led to cascading effects, mainly resulting in increases in smaller-bodied herbivores and the release of mesopredators. Post-reintroduction, the system's new equilibrium state was closer to the initial equilibrium for stable and productive locations compared to highly seasonal and low-productive locations. The maximum trait space volume of the initial state and the post-reintro-duction state varied by 9.1% on average over all locations, with an average decrease in trait combinations of 6.6%. The body mass distribution differed by 28%, comparing the initial state to the post-reintroduction state.
Main Conclusions: Our simulation results suggest that reintroducing locally extinct large-bodied mammals can broadly restore shifts in ecosystem structure, roughly resembling the baseline ecosystem conditions. However, the extent to which the ecosystem's state resembles the original ecosystem is largely dependent on the reintroduction strategy (only herbivores and omnivores vs. also carnivores) and timing, as well as local environmental conditions
Wetland plant development overrides nitrogen effects on initial methane emissions after peat rewetting
No full textGrowing productive wetland species on rewetted peatland (paludiculture) is a promising solution to offset carbon loss from drained peatlands. The inlet of nitrogen (N) rich surface water, a proposed method to improve productivity of vegetation, may affect methane (CH4) emissions. This study aims to compare initial CH4 emissions from newly rewetted peat with different types of vegetation and N loading simulating diffuse N inlet. Diffusive CH4 emissions were measured in peat mesocosms during one growing season. Peat cores were either planted with Typha latifolia or Phragmites australis or they were left bare. Mesocosms received 0, 50, 150 or 450 kg ha−1 year−1 N. Plants affected CH4 emissions from rewetted peat soil, leading to stable fluxes over time of 133 mg m−2 day−1 CH4 at 20 °C. Biomass harvesting lead to a 153% increase of CH4 emissions. With increasing N load, CH4 emissions from mesocosms with Typha and Phragmites decreased up to a load of 150 kg ha−1 N, but this was only significant for the Phragmites treatment. Emissions of unvegetated mesocosms increased with increasing N load but not significantly. In conclusion, our mesocosm study suggests that vegetation can reduce or prevent an increase in CH4 emissions from rewetted peatlands compared to only rewetting, possibly due to an increased oxygenation of the sediments by macrophyte roots preventing excessive CH4 formation, while added N does not provoke great changes in emissions at N concentrations up to 150 kg ha−1.</p
Trait-based projections of climate change effects on global biome distributions
No full textAim: Climate change will likely modify the global distribution of biomes, but the magnitude
of change is debated. Here, we followed a trait-based,
statistical approach to
model the influence of climate change on the global distribution of biomes.
Location: Global.
Methods: We predicted the global distribution of plant community mean specific leaf
area (SLA), height and wood density as a function of climate and soil characteristics
using an ensemble of statistical models. Then, we predicted the probability of occurrence
of biomes as a function of the three traits with a classification model. Finally,
we projected changes in plant community mean traits and corresponding changes in
biome distributions to 2070 for low (RCP 2.6; +1.2°C) and extreme (RCP 8.5; +3.5°C)
future climate change scenarios.
Results: We estimated that under the low climate change scenario (sub)tropical biomes
will expand (forest by 18%–22%,
grassland by 9%–14%
and xeric shrubland by
5%–8%),
whereas tundra and temperate broadleaved and mixed forests contract by
30%–34%
and 16%–21%,
respectively. Our results also indicate that over 70%–75%
of the current distribution of temperate broadleaved and mixed forests and temperate
grasslands is projected to shift northwards. These changes become amplified
under the extreme climate change scenario in which tundra is projected to lose more
than half of its current extent.
Main conclusions: Our results indicate considerable imminent alterations in the
global distribution of biomes, with possibly major consequences for life on Earth. The
level of accuracy of our model given the limited input data and the insights on how
trait–environment
relationships can influence biome distributions suggest that trait-based
correlative approaches are a promising tool to forecast vegetation change and
to provide an independent, complementary line of evidence next to process-based
vegetation modelsPeer reviewe
Tree cover homogenization in semi-open ecosystems worldwide and implications for ecosystem stability and conservation
No full textSemi-open ecosystems, such as savannas and open woodlands, are biodiversity hotspots due largely to their heterogeneous tree cover (TC), which supports diverse habitats. However, increasing woody encroachment is altering TC heterogeneity, with unclear consequences for ecosystem stability. Using global satellite-based TC estimates (2000–2020), we reveal widespread TC homogenization (24.1%) in semi-open ecosystems, predominantly in temperate and boreal bioclimates undergoing substantial warming. Contrary to the assumption that vegetation heterogeneity promotes ecosystem stability, we find that TC homogenization has mixed correlations with ecosystem functional stability. Notably, positive relations dominate in water-abundant areas with increasing TC, while negative correlations prevail in water-constrained regions with stable or decreasing TC. Protected areas exhibit lower homogenization and greater stability than surrounding landscapes, underscoring their conservation value. Our findings highlight the need for nuanced land management strategies that balance biodiversity conservation, carbon sequestration, and ecosystem stability under global reforestation and restoration initiatives.</p
Plant functional and taxonomic diversity in European grasslands along climatic gradients
No full textAim: European grassland communities are highly diverse, but patterns and drivers of their continental-scale diversity remain elusive. This study analyses taxonomic and functional richness in European grasslands along continental-scale temperature and precipitation gradients.
Location: Europe.
Methods: We quantified functional and taxonomic richness of 55,748 vegetation plots. Six plant traits, related to resource acquisition and conservation, were analysed to describe plant community functional composition. Using a null-model approach we derived functional richness effect sizes that indicate higher or lower diversity than expected given the taxonomic richness. We assessed the variation in absolute functional and taxonomic richness and in functional richness effect sizes along gradients of minimum temperature, temperature range, annual precipitation, and precipitation seasonality using a multiple general additive modelling approach.
Results: Functional and taxonomic richness was high at intermediate minimum temperatures and wide temperature ranges. Functional and taxonomic richness was low in correspondence with low minimum temperatures or narrow temperature ranges. Functional richness increased and taxonomic richness decreased at higher minimum temperatures and wide annual temperature ranges. Both functional and taxonomic richness decreased with increasing precipitation seasonality and showed a small increase at intermediate annual precipitation. Overall, effect sizes of functional richness were small. However, effect sizes indicated trait divergence at extremely low minimum temperatures and at low annual precipitation with extreme precipitation seasonality.
Conclusions: Functional and taxonomic richness of European grassland communities vary considerably over temperature and precipitation gradients. Overall, they follow similar patterns over the climate gradients, except at high minimum temperatures and wide temperature ranges, where functional richness increases and taxonomic richness decreases. This contrasting pattern may trigger new ideas for studies that target specific hypotheses focused on community assembly processes. And though effect sizes were small, they indicate that it may be important to consider climate seasonality in plant diversity studies
CO<sub>2</sub> emissions of drained coastal peatlands in the Netherlands and potential emission reduction by water infiltration systems
No full text<jats:p>Abstract. Worldwide, the drainage of peatlands has turned these systems from CO2 sinks into sources. In the Netherlands, where ∼7 % of the land surface consists of peatlands, drained peat soils contribute &gt;90 % and ∼3 % to the country's soil-derived and total CO2 emissions, respectively. Hence, the Dutch National Climate Agreement has set targets to cut these emissions. One potential mitigation measure is the application of subsurface water infiltration systems (WISs) consisting of subsurface pipes connected to ditchwater. WISs aim to raise the water table depth (WTD) in dry periods to limit peat oxidation while maintaining current land-use practices. Here, we used automated transparent chambers in 12 peat pasture plots across the Netherlands to measure CO2 fluxes at high frequency and assess (1) the relationship between WTD and CO2 emissions for Dutch peatlands and (2) the effectiveness of WISs in mitigating emissions. Net ecosystem carbon balances (NECBs) (up to 4 years per site, 2020–2023) averaged 3.77 and 2.66 tCO2-Cha-1yr-1 for control and WIS sites, respectively. The magnitude of NECBs and the slope of the WTD–NECB relationship fall within the range of observations of earlier studies in Europe, though they were notably lower than those based on campaign-wise, closed-chamber measurements. The relationship between annual exposed carbon (C; defined as the total amount of carbon within the soil above the average annual WTD) and NECB explained more variance than the WTD–NECB relationship. The magnitude of the NECB represented 1.0 % of the annual exposed C on average, with a maximum of 2.4 %. We found strong evidence for a reducing effect of WISs on CO2 emissions, reducing emissions by 2.1 (95 % confidence interval 1.2–3.0) tCO2-Cha-1yr-1, and no evidence for an effect of WISs on the WTD–NECB and annual exposed carbon–NECB relationships. This means that relationships between either WTD or exposed carbon and NECB can be used to estimate the emission reduction for a given WIS-induced increase in WTD or exposed carbon. High year-to-year variation in NECBs calls for multi-year measurements and sufficient representative measurement years per site as demonstrated in this study with 35 site-year observations.
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Assessing the reliability of predicted plant trait distributions at the global scale
No full textContains fulltext :
218118.pdf (Publisher’s version ) (Open Access
On the importance of root traits in seedlings of tropical tree species
No full textContains fulltext :
216600pub.pdf (Publisher’s version ) (Open Access
