Forest ecosystem physiology and forest management

Objectives of our research

a) Description and interpretation of the changes in carbon sequestration of forest stands of different ages. Understanding the ecosystem roles of natural and man-made disturbances; development of tools for the integration of forest carbon budgets at the landscape scale;

b) Understanding the biology of aging and development of forest trees. As trees age, their physiology changes substantially; however, whether these changes can be entirely attributed to environmental changes, entirely to changes in gene expression or to a combination of the two is unclear;

c) Understanding the effects of global change on the carbon balance of Mediterranean ecosystems, particularly with respect to tree water relations and soil carbon dioxide efflux.

d) Understanding the links between faunal and vegetation diversity and carbon sequestration in restored mangrove forests in Gazi Bay, south of Mombasa (Kenya).

e) using ¹³C and ¹⁸O stable isotopes as tracers of gross photosynthetic activity and respiratory fluxes in ecosystems.

f) Constructing a new sensor for measuring phloem flow in trees.

g) Using network theory, and particularly percolation theory, to derive estimates of hydraulic conductance in wood xylem.

Achievements and discoveries.

We have developed a theoretical framework and provided the empirical evidence to demonstrate the consequences of stature on plant physiological ecology. We have demonstrated that age-related declines in net primary productivity in Scots pine were linked to concurrent declines in the capacity to deliver water and nutrients to the top of tall trees. We have also demonstrated that significant hydraulic and biomass costs can be shown to occur for all plant species, as one moves from small ferns and herbaceous species, up to woody shrubs and majestic trees. We have now clarified that these changes are inherently a function of tree size, not age (i.e., not senescence).

People involved

Maurizio Mencuccini, Lisa Wingate, Jordi Martinez-Vilalta, Lasse Loepfe, Carole Helfter, Evi Korakaki, H. A. Hamid, Dirk Venderklein, Rafael Pojol

Collaboration with other institutions, countries, etc.

a) Institute of Forest Ecology of the University of Florence (Italy); b) Kenya Marine and Fisheries Research Institute (Gazi, Kenya) ; c) Department of Physics at Heriot-Watt University; d) Complex System Science (CSIRO, Australia); e) CREAF (Centre for Ecological Research and Forestry Applications, Barcelona, Spain); e) Forestry Commission (UK); f) MontClair University(NJ, USA).