Work package 5: Plant response climate stress
Competition between seedlings of beech and ash (two key species in oceanic base-rich beech forests) grown under various real-to-life conditions will be studied. Different densities of the two species (both separately and mixed) will be grown in pots of different sizes (to simulate low to high competition) and in different temperature (to simulate different European regions) and light regimes (to simulate different gap-sizes). Seedlings will be allowed to compete for resources below (water and nutrients) and above ground (light, evaporative gradient). Eight closed-top chambers with one replicate per temperature and CO2 treatment will be used. Reference chambers track outdoor temperature and CO2; another set of chambers track outdoor temperature at elevated CO2 (ambient + 350 ppm), and two sets of chambers track outdoor temperature +3C with ambient CO2 or ambient CO2 + 350 ppm CO2. Each chamber simulates a forest gap in which light is either at the high end (15-20% of open field light flux) or at the low end (3-5% of open field light flux). Two outdoor plots serve as controls to the chambers. The experiment requires new durable equipment (light sensors, CO2-dossage, cables, datalogger, CIRAS autochamber, valves and stationary IRGA). Consumerables to run the experiment includes (CO2, pumps, valves, plants, pots, soil, fertilizer and misc. spareparts).
Closed-top chambers experimental design. The experiment includes 8 climate controlled 15 m2 chambers with an air circulation of one air change per minute. The air stream is cooled and heated to balance outdoor temperature, or to increase/decrease it as seemed fit for a given experiment. All 8 chambers will be used fully for the Nat-Man competition study. Competition is a question of both competition for space above ground (mainly competition for light) and space below ground (mainly competition for water and nutrients, and possible also regarding allelopathy and symbionts). We have designed, therefore, two sets of pots. Small pots with one seedling in each for aerial competition, and larger pots with 2-4 seedlings in each for soil-space + aerial competition. The small pots are approx. 250 ml (5 cm diameter, 20 cm tall), while the large pots are 1 liter (or larger).
The total number of plants will be 4.608 experimental plants (totally 9.504+ plants, including frame and buffer plants). We plan to measure stem diameter, height, leaf area and biomass on leaf, stem and root fractions on each plant. Other possible measurements will be taken on fractions of the experimental material. The statistical analysis of an experiment with 5 variables: light, temperature, CO2, species density, etc. is quite complex, which is the reason why the research team includes an statistician.
The study will complement an existing experiment on the physiology and growth of beech and ash seedlings grown under different light, temperature, nutrients and drought regimes. It will reveal the role of light and climate conditions on the regenerative competitiveness of two key species in base-rich beech forests. Reporting will focus on the relevance to gap-phase regeneration in beech forests.
Work-package leader:
Henrik Saxe, The Royal Veterinary and Agricultural University (KVL)
Unit of Forestry, Rolighedsvej 23, DK-1958 Frederiksberg C, DENMARK, Fax: (+45) 35282671, phone: (+45) 35283632, e-mail:
Jens Emborg, - last update:8 March 2012