In the project ClimaDyst-RainFor, we are investigating the relationships between climate and forest structure and composition in the Colchic temperate rainforests of the Lesser Caucasus in NE Turkey and the Republic of Georgia. We are conducting an integrated study combining multi-century climate reconstructions, forest disturbance histories, and forest succession models along environmental gradients in these temperate forests.
A distinct characteristic of these forests is the dominance of well-developed broadleaf evergreen understory bushes that can reach over 5 m in height. Several species of Rhododendron dominate this stratum, but other species such as Prunus laurocerasus, Ilex or Ruscus are also present. In contrast, the only evergreen dominant canopy trees are conifers (Abies and Picea). These forests have a high degree of endemism and are seriously endangered by global change and anthropogenic disturbances (see the WWF page).
In this project, we address issues of historical forest dynamics at landscape and plot level, by reconstructing canopy disturbance events and tree recruitment and mortality through dendrochronological methods across a network of forest plots on altitudinal and precipitation gradients. We also used a forest succession model (ForClim) for simulating past and future forest dynamics and understanding the involved processes driving forest development including climate variability. Because simulations of past forest dynamics require information of past climatic conditions, we are also working on reconstructing precipitation and temperature variability for the last several centuries.
The combination of paleoecological and modelling approaches allow for investigating multiple climate effects on the ecology of these forests under changing environmental conditions. A deeper understanding of ecological processes under a combination of complex disturbances provides critical and long-term perspectives on the role of climate variability in causing vegetation changes in these ecosystems where global change is expected to lead to more frequent and intense droughts.
Preliminary analysis of the data collected across our tree-ring plot network show a diversity of species sensitivity to climate for broadleaf and conifer species. Drought sensitivity for certain species and locations have allowed us to reconstruct spring-summer precipitation over the last 250 years and show that climate observations during the recent period might underestimate the real occurrence of drought in this otherwise wet region (Martin-Benito et al. 2016).
Our investigations also have lead to the discovery and inventory of several large patches of well preserved old-growth forest dominated by trees >300 years old. These forests, however, may be endangered by logging and road development.
- Martin-Benito, D., Ummenhofer C.C., Köse, N., Güner, H.T., Pederson, N. 2016. Tree-ring reconstructed May-June precipitation in the Caucasus since 1752 CE. Climate Dynamics 1:17. PDF [Supplementary material]
[Updated August 17, 2016]