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FP5

NAT-MAN Report Summary

Project ID: QLK5-CT-1999-01349
Funded under: FP5-LIFE QUALITY
Country: Denmark

GAP - integrated experiments

The objectives of the research were to investigate microclimatic conditions, biogeochemical processes and mycorrhizal abundance in gaps of different sizes in natural forest ecosystems as well as managed forest stands where nature-based forestry was applied. Changes and interactions were examined, with focus on differences between processes within the open gap and under the closed canopy. The specific objectives were:

- To determine the influence of gap-size on nutrient cycling and soil water in European beech forests;

- To determine the mycorrhizal activity/abundance in different regeneration gaps in European beech forests.

The research provides results on temperature regimes, soil water, nutrient cycling and mycorrhizal abundance in and around gaps in different beech forests in Denmark, Slovenia and Hungary. Findings indicate that:

- The main influence of gaps on soil processes at stand level seems related to gap area per ha forest stand rather than the size of individual gaps;

- Soil temperatures were only slightly higher in gaps than under closed canopy in natural forests with abundant advanced regeneration, and the difference between gap and surrounding forest gradually disappeared as seedlings were released;

- N mineralization rates tended to be higher in gaps than in the surrounding forest, but extreme increases did not occur after gap formation;

- Gap formation led to significant changes in soil moisture during the growing season;

- Concentrations of nitrate were significantly higher in gaps than in the surrounding forest and in longer periods exceeded the threshold value for nitrate in drinking water (11.3 mg NO3-N l-1);

- Due to higher nitrate concentration in soil solution and higher water fluxes, leaching of N from gaps was higher than from under closed canopy;

- Gap size appeared mainly to affect soil temperatures;

- In recently established gaps there were lower numbers of ectomycorrhizae types, vital ectomycorrhizal roots, old and non-viable-mycorrhizal roots, and lower species diversity than under closed canopy and the edge of the gap.

The research has contributed substantially to the European knowledge base on biogeochemistry in natural forests and forests regenerated in gap formations. A fairly large number of natural and man-made gaps were studied with variable intensity in beech forests of Denmark, Hungary and Slovenia. Such a large number of gaps have not previously been included in studies of water and nutrient dynamics. Results should thus help obtain a better understanding of natural forest ecosystems and to provide a reference for nature-based forestry.

Related information

Contact

Karsten Raulund RASMUSSEN, (Head of department)
Tel.: +45-352-81666
Fax: +45-352-81517
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