Overview of the current research projects
This site is still under construction and information on additional ongoing projects (Mexico, Costa Rica, The Netherlands, Siberia and Brazil) will be added in the near future.
Hydrology and biogeochemistry of heath forest of contrasting stature in Central Kalimantan, Indonesia.
Heath forest (HF) is a distinctive lowland rain forest type occurring on acid podzol soils developed in siliceous sandy substrates, mostly in the Amazon and Borneo. HF is poorer in species (but high in endemism), simpler in structure, and of lesser biomass than lowland evergreen rain forest (LERF) on clay soils. Also, HFs are particularly vulnerable to disturbance. There has been a long-standing debate whether the distinctive features of HF are due mainly to nutrient deficiency (notably N and P), water stress (be it drought or persistent waterlogging), or a combination of both. The evidence supporting the drought hypothesis is both scattered and contradictory whereas analysis of the organic topsoils of HF suggests that these are not poorer than those of taller LERF on clay soils. Concentrations of N in HF leaves and litter are distinctly low, however, suggesting N may be in short supply although bioassays with HF soils using local crops have failed to produce a response after adding nutrients unless the soils were limed. This, together with the very high H/Al ratios found in HF soils suggest that toxicity due to excess acidity may be the prime cause of the poor development of HF although high phenols or silicon levels may be important as well. This WOTRO funded PhD project (W76-217) carried out by Ronald Vernimmen, aims to elucidate the importance of the respective factors / mechanisms controlling forest stature in a series of forests at Barito Ulu, Central Kalimantan, ranging from tall LERF through HFs of increasingly shorter stature. Preliminary results suggest that neither excess nor shortage of water causes reduced forest stature in the study area.
Impact of natural regrowth on erosion and the sediment transport of the Dragonja River, Slovenia.
The Dragonja River area in Slovenia has seen natural forest regrowth since the end of the second world war, when people abandoned their agricultural fields and moved to cities and rural areas in Italy. The regrowth of forest lead to increased evaporation, leading to a gradual decline of the river discharge. This in turn has lead to changes in the geomorphology of the channel area and changes in sediment deposition rates in the floodplain. The present study aims to enhance our knowledge on the subject of reforestation in the Mediterranean and is carried out by Mrs. Saskia Keesstra. The project is presently in its final year.
The TCOS Project: Carbon cycling research in Siberian Tundra and Taiga
The department of Hydrology and Geo-Environmental Sciences participates in the TCOS - Siberia project that is part of CarboEurope and funded by the EU. TCOS's objectives are to quantify the carbon balance of the Siberian part of Asia. This is important because it is often assumed that the vast Siberian forests are a sink of anthropogenic carbon, but the sink strength is as yet unknown. Furthermore, little is known about the sensitivity of the sink strength to climate change (e.g. global warming, changes in precipitation regime, thawing of the permafrost). Almost 20 research groups from many countries in Europe and the Russian Federatoion are participating in TCOS - Siberia. The department of GeoEnvironmental Sciences is cooperating with the Institute of Biological Problems of the Cryolithozone, Russian Academy of Sciences in Yakutsk.
Resilience of Amazonian ecosystems to reduced rainfall in relation to small-scale topographic variation in the carbon cycling (WOTRO Integrated Programme)
The WOTRO integrated programme consists of 5 projects and is co-ordinated by Bart Kruijt from Alterra. The first project in the programme is the responsability of the VU University Amsterdam, in collaboration with the INPA research institute in Manaus, Brazil. In view of predicted decreases in rainfall over the Amazon Basin, we will study the effect of drought on transpiration, carbon and nitrogen cycling in different parts of the landscape (i.e. well-drained and poorly drained soils) and for different vegetation types associated to soil type and drainage status (tall terra firme forest, wetland forest and campina forest). The research within this project will be carried out by Mr. Fabricio Zanchi (PhD student). The study has started in February 2005 and will continue until January 2009.
Impact of topography on natural reforestation and evaporation (VU funded project)
Christaan van der Tol has started in 2002 with a PhD study on the impact of topography on the growth, species composition and hydrology of natural forests in the Dragonja River area in Slovenia. Measurements included sapflow rates, photosynthetic activity, meteorological parameters, leaf area indices and soil moisture in four different plots (wet versus dry and North versus South facing plots. The project is carried out in collaboration with the University of Ljubljana. Preliminary results show that the topography and aspect does influence the forest development to a significant extend.
How does spatial variation in carbon uptake and release of Amazonian rain forest affect eddy correlation carbon budget estimates?
Comparison of micrometeorological and ecological studies indicate that there is considerable uncertainty about whether undisturbed Amazonian rainforest presently acts as a sink for carbon. We suspect that in terrain with varying topography, such as at our research catchment in Central Amazonia, spatial variation in carbon emissions and storages and local nighttime circulations (carbon dioxide "drainage" from plateau to valley), perhaps caused by differences in soil temperature, may cause a flow of carbon dioxide out of the area through the valleys that may not be detected by the tower setup on the plateau. To check this, we intend to do footprint analyses of the plateau tower flux data to see if the fluxes are wind direction dependent. In addition, a second flux tower will be placed in the valley to study the carbon exchange of the water logged forest. Spatial variations in nighttime carbon dioxide storage within the canopy will be studied from profile measurements at various topographic locations, whereas above canopy profiles will be obtained from balloon studies. The outcome of this study should provide answers on the spatial variation in nightime carbon storage and the importance of nighttime circulations and processes for the determination of the carbon balance using eddy covariance methods in non-heterogenous terrain. This study is carried out by Alessandro Araujo in collaboration with the INPA research institute in Manaus.
Coupled transport processes in groundwater and osmosis in clayes sediments in The Netherlands
This project deals with chemical osmosis in clayey sediments. The objective of the PhD research conducted by Ana Maria Garavito Rojas is to provide evidence for, and to quantify the membrane properties of clayey sediments and their role in transport of solutes and water in groundwater systems in The Netherlands. She is performing in-situ osmosis experiments in combination with numerical modeling. The project is in its final year.
The eco-hydrological significance of fog in the eastern Sierra Madre, Central Veracruz, Mexico
Project details
Field researcher: Dr Friso Holwerda. Duration and funding agency: 30 months starting 1 March 2005; The Netherlands Foundation for the Advancement of Tropical Research (WOTRO). Collaborating institutions: Institute of Ecology, Xalapa, Veracruz, Mexico; Iowa State University, Ames IA, USA; UNAM, Mexico City, Mexico; ETH Zentrum LFW/Institute of Plant Sciences, Zurich, Switzerland; King's College, University of London, UK; University of Agricultural Sciences, Vienna, Austria.
Summary
Despite the great significance attached to montane cloud forest (MCF) in eastern Mexico for the safeguarding of water supplies and biodiversity, much MCF has been converted to pasture and coffee plantations in recent decades. Virtually nothing is known of the hydrological functioning of these unique forests, including the role of cloud water interception and soil water uptake in determining forest productivity and distribution. Yet, such information is vital to forest restoration and conservation efforts. This project is the first to quantify cloud water interception and sources of plant water uptake in undisturbed and regenerating Mexican MCF (using partly novel and complementary techniques) along an altitudinal gradient. The present work constitutes an essential element within a larger framework consisting of several separately funded complementary projects with the ultimate aim of assessing the hydrological effects of montane forest disturbance and regeneration, and the development of a soundly based payment for environmental services scheme in Eastern Mexico.
Hydrological impacts of converting tropical montane cloud forest to pasture with initial reference to northern Costa Rica
Project details
Field researchers: Arnoud Frumau MSc, Dr Conrado Tobon-Marin. Duration and funding agency: 1 February 2001 - 30 June 2005; Forestry Research Programme of the UK Department for International Development. Collaborating institutions: Faculty of Forestry, Technological Institute of Costa Rica (ITCR), Cartago, Costa Rica; Universidad Nacional de Costa Rica (UNCR), Heredia, Costa Rica; King’s College, University of London; University of Alabama, Huntsville AL, USA; Institute of Geography, University of Bern, Bern, Switzerland; CLUWRR, University of Newcastle, Newcastle, UK.
Summary
Declining streamflows in Central America constitute a major problem for rural and urban water supplies and potentially hamper agricultural production and hydropower generation during the dry season. The causes may include the clearing of montane cloud forest (mostly for pasture) and regional climatic change induced by large-scale deforestation in the lowlands. This project aims to quantify the impact of cloud forest conversion to pasture on streamflow in the Tiláran Range of northern Costa Rica using hydrological process research and modelling. A measuring protocol will be developed for use at other locations in the region as well as a physically-based catchment-scale hydrological model (FIESTA) to assess the basic hydrological impacts of (cloud) forest conversion. The latter is a conditio sine qua non for designing realistic ‘payment for environmental services’ schemes compensating uplanders for sustainable land stewardship. The socio-economic (sustainable livelihood) aspects of this developmental problem will be addressed by a specifically designed twin project (also funded by DFID, R 8174).
Preview of cloud forest project documentary (Apple)
Preview of cloud forest project documentary (Windows)
Cloud forest project web site
Integrated observations and modelling of greenhouse gas budgets at the ecosystem level in the Netherlands: changing environment and management practices in peat meadows
This project aims to asses the effects of changing environment and management practices on greenhouse gas fluxes (CO2, CH4 and N2) from peat meadow areas. It is part of the Dutch BSIK ME1 Research Programme. The research site in the Horstermeer is included in the CarboEurope network of flux measurement sites. The project may help to resolve the question of longer term effects of land use change on the GHG fluxes. The Horstermeer site is a good example of a peat meadow and is located on former agricultural land in a drained natural lake. The research site has been taken out of agricultural production more than 10 years ago, and has developed into semi-natural grassland. The soil consists of peat, overlain with organic-rich lake deposits. The area is subject to strong groundwater seepage from surrounding lake areas and Pleistocene ice pushed ridges. After the site has been taken out of agricultural production, the ditch water table has been raised to approximately 10 cm below the land surface. We want to understand the controlling mechanisms of GHG fluxes emissions in fen meadows and to asses the possibility of water level manipulation as a management tool for GHG fluxes. Furthermore we have the objective to improve the estimates of the contribution of the fen meadow areas to overall land use GHG emissions from the Netherlands. The PhD student working on this project is Dimmie Hendrix.
Measurement and modelling of L-band forest emission for future soil moisture retrieval from SMOS signatures
The Bray 2004 experiment is conducted for the SMOS satellite, planned for launch in 2007. A high percentage of SMOS pixels is infected with fractional forest, whereas our knowledge of L-band forest radiative transfer properties is limited. Jennifer Grant is conducting a detailed study of angular and polarization characteristics of forests, that will be essential for solving the problem of heterogeneity. An experimental campaign was conducted with INRA in the coniferous forest of Les Landes near Bordeaux, France. We used a multi-angular and polarimetric L-band (1.4 GHz) radiometer mounted on top of a 40 m mast to provide long-term measurements over a forest canopy. The time series allowed data to be obtained for a variety of surface conditions in terms of interception and moisture content of soil and litter. The project improves our knowledge of forest emission, effects of litter and understory and data assimilation through coupling with forest functioning models.
