Site location and background
The Dutch experimental site Oldebroek (52°24’N 5°55’E) is located at the Artillary Practice Ground (ASK) of the Dutch Army near the towns of ‘t Harde and Oldebroek. The site is part of a large heathland area called Oldebroekse heide.
The heathland vegetation found here is dominated by Calluna vulgaris, Deschampsia flexuosa and Molinia caerulea with some scattered Betula pendula and Pinus sylvestris trees and bushes of Juniperus. The plots are mainly covered with Calluna vulgaris plants of a maximum height of 75 cm.
The heathland is managed by regular sod-cutting to prevent grass encroachment. The soil is a well drained, sandy to loamy sand podzol, with a groundwater class of VII. The site is located at an elevation of 25 meter above sea level and is almost flat.
Oldebroek is one of the three northern heathland infrastructures, with Calluna vulgaris as dominant plant species. The most important distinction between this heathland and the others in Denmark and the UK is the relative high atmospheric nitrogen deposition. In addition, the heathland in the UK is a wet upland heath, while the sites in Denmark and the Netherlands are dry lowland heathlands.
The interesting scientific characteristic of the infrastructure is the high nitrate leaching measured in this site, which is even increased by only 0.5-1ºC warming. Because of the high N deposition, the growth of biota is limited by phosphorous. Remarkable as well is the strong plant response (production and chemistry) to warming and drought. Finally, climate change affects the overall water holding capacity of the soil leading to decreased moisture contents even in winter.
Climate change manipulations
At Oldebroek we have a total of 9 plots that have been under climatic manipulation since 1998. Each plot is 20 m2 and there are 3 replicates of each treatment plot; 3 control plots, 3 night time warming plots and 3 repeated summer drought plots. Automated, reflective aluminium curtains simulate night time warming and transparent, plastic curtains simulate summer drought. In 2009 half of all plots will be cut, allowing us to investigate the interaction between climate change and manipulation. A new experiment starting in May 2010 will involve a 50% increase of rainfall in young Calluna vegetation. This will result in 6 new plots; 3 precipitation plots and 3 control plots.
Research activities and research wanted
Research activities at the infrastructure cover several fields, including, plant phenology, primary productivity, ecophysiology, plant population biology, plant biodiversity, biodiversity of some animal groups (such as collembollas, aphids and soil nematodes), litter decomposition, N-mineralisation, soil respiration, water chemistry etc. New investigations will aim to address soil carbon dynamics and turnover at the bulk and molecular level, applying 13C tracer techniques. Geochemical studies will investigate the degradation and turnover of lignin. Microbial diversity and composition will also be assessed. A range of data has been collected at regular intervals at Oldebroek, providing us with a long term record of the effects of climatic manipulation. Research collaborations as part of the INCREASE transnational access may be applicable. We will give priority to projects addressing the following topics; microbial diversity, rhizosphere processes, phenology, lignin degradation and turnover, root turnover, NEE, carbon and nitrogen cycles, photosynthesis. For further information regarding transnational access please enquire via the contact address below.
Other facilities offered
Analytical instruments for nutrients, metals, organics, soil texture, GC/MS, PyGC/MS, LI-COR 6400XT, greenhouses, growth facilities and Respicon laboratory soil respiration can be offered.
The on-site team
The on-site team for Oldebroek includes Dr Albert Tietema, Post Doc Sharon Mason and PhD student Daan Asscheman.
For more information
Please contact, Sharon Mason – email: University of Amsterdam, Faculty of Science, Nieuwe Achtergracht 166, 1018 WV Amsterdam, NL.