Completed Projects
2020
- Anthropogenic disturbances and regeneration of semiarid Caatinga - the role of key organisms and their interactions with soil
The Caatinga Biome in Northeastern Brasil is severely threatened by climate change and chronic anthropogenic disturbance. In this project, we examine how key organisms respond to chronic anthropogenic disturbance and agricultural land use, the effect of disturbance-induced reactions of key organisms on the regeneration dynamic of the Caatinga, and the consequences for ecosystem function and services.
[Details] - The role of nutrients for the variability of drought effects on community composition and productivity across land use gradients in grasslands: a trait-based approach
Land use and precipitation are important drivers for shaping community diversity, and ecosystem function in grasslands worldwide, and are two of the main global change drivers. The main aim of this project is to improve our capability of predicting consequences of global change for grasslands through assessing the combined effects of nutrients and drought at the trait and whole plant performance level and integrating them with drought effects on community composition and productivity across land-use gradients in grasslands.
A project within the Biodiversity Exploratories, DFG Priority Programme 1374
[Details] - Drought and grazing impacts in semi-arid rangelands: Testing a novel trait-based conceptual framework
Drought and land use are among the most important global change drivers, particularly for dryland ecosystems. Species and communities in dry areas are assumed to be resistant to both grazing and drought (Generalized Grazing model). However, the generality of this model has been called into question in semiarid rangelands dominated by winter annuals, which exhibit a substantially different strategy to cope with drought than perennials. To test a novel trait-based framework that can resolve the apparent inconsistencies, we use a steep rainfall gradient in the Eastern Mediterranean as a model system, and explicitly link traits, whole plant performance, long-term community responses, and distribution patterns.
[Details]
2019
- Spatial and temporal variation of soil moisture in tropical forests - effects on seedling dynamics and distribution
Local tree species distributions in tropical forests correlate strongly with soil moisture availability. However, it is unclear how soil moisture influences seedling demography, how species responses to water and light are related to each other, and how that, in turn, affects tree species distributions and coexistence. In this project, we quantify the spatial and temporal variation of soil water potentials in a long-term forest dynamics plot in Panama and address the consequences for seedling dynamics and distributions.
[Details]
2018
- Intraspecific variation in drought responses of tropical tree seedlings - consequences for species distributions under climate change
Phenotypic variation within species can significantly influence ecological dynamics and may affect species’ responses to climate change. In tropical forests, which are predicted to experience pronounced changes in rainfall patterns, the existence and extent of intraspecific variation in species’ environmental tolerances remain virtually unexplored. To further our understanding into the extent of intraspecific variation in tropical tree species’ responses to water availability and the underlying processes we employ an interdisciplinary approach, combining tools from classical quantitative genetics, plant physiology, and community ecology to assess intraspecific variation in a range of species, using a steep natural rainfall gradient in central Panama as a model system.
at Smithsonian Tropical Research Institute
[Details] - RAPID: The effect of an extreme El Nino event on tropical forest seedling regeneration
Tropical forests are among the most diverse terrestrial ecosystems and they play a vital role in the global carbon and water cycle. How tropical forest species and communities will respond to global climate change remains a great source of uncertainty. Over much of the moist and wet tropics, anomalous yet periodic El Niño Southern Oscillation events are associated with reduced cloud cover, decreased rainfall, and severe drought. The seedling stage is a critical stage in the population dynamics and regeneration of trees, and is most sensitive to drought. We study the effects of one of the strongest El Niño events on record on tree seedling regeneration in tropical forests that span a pronounced rainfall gradient in central in Panama.
at Smithsonian Tropical Research Institute
[Details]
2017
- Anthropogenic disturbance and key organisms of the regeneration dynamics in semiarid Caatinga - Brazil's threatened dry forest landscape
The goal of this German-Brazilian research cooperation is to understand how anthropogenic disturbance (including decreases of rainfall through Global Change) influence biological communities and ecological interactions. Toward this aim, we examine three key organism groups: plants, soil crusts, and leaf-cutting ants and their interactions along gradients of anthropogenic disturbance and rainfall in the Caatinga, one of the most threatened biomes of South America.
[Details] - Variation of plant drought tolerance in grasslands: effects on community assembly and ecosystem resilience
Under conditions of climate change, water availability in temperate grasslands is projected to decrease, and extreme events – including droughts - to increase. A thorough understanding of species responses to drought, of the traits governing drought responses, and how they affect community assembly and ecosystem function is necessary for projections of consequences of climate change for the future. In this study, we comparatively assess whole-plant drought tolerance of 38 grassland species, and identify the key traits for differential drought responses, through directly linking physiological, anatomical and morphological traits that influence species water relations to the species’ drought tolerance.
A project within the Biodiversity Exploratories, DFG Priority Programme 1374.
[Details]
2016
- Differential drought sensitivity of tropical trees: a key for understanding the consequences of global change in the Brazilian Caatinga ecosystem
The Caatinga Biome is a mosaic of seasonal tropical dry forests in the northeast of Brazil. It covers about 800,000 km2 and more than 23 million people live in the region. Caatingas have been heavily modified and at the same time, they experience extreme climatic conditions with very low rainfall, which is predicted to further decrease with climate change. Mechanisms that lead to the death of trees during drought remain poorly understood worldwide and are a research priority in view of widespread forest dieback.
This project will provide the first insights into the differential susceptibility of tree species to drought in the Caatinga.Funded by BayLAT.
[Details] - Quantifying tropical seedling responses to key resources
Bettina Engelbrecht, Jim Dalling [Details]
2015
- Natural enemies, climate, and the maintenance of tropical tree diversity
[Details]
2014
- Regional distribution patterns in tropical forest: direct and indirect consequences of drought periods
Julian Gaviria, Delicia Pino Garay, Bettina Engelbrecht [Details]
2013
- How, why and where will tree species survive increasing pressure? Providing diagnosis and decision-making tools to attenuate the effect of global change on biodiversity in the Congo Basin forests
[Details]