Impacts of precipitation variability on the dynamics of a dry tropical montane forest
Tropical forests are of crucial importance for global biodiversity and carbon budgets. However, they are highly sensitive to changes in precipitation amount and seasonal precipitaiton distribution. One example in the sub-humid tropics is the Munessa-Shashemene Forest in south-east Ethiopia (Fig. 1), where changes in precipitation have been observed and are predicted for the future.
Research questions:
1. How resilient is the forest stand structure and species composition to variations in annual precipitation?
2. What is the influence of intra-annual precipitation variability on the aboveground biomass production?
Figure 1: Climate diagram covering the years 2001-2011 for the study site in the Munessa-Shashemene Forest in south-east Ethiopia. It is showing semi-humid conditions with a long dry season (LD) from November to March and a long rainy season (LR) from July to October. Changes in precipitation have been observed, mainly during the very variable, short rainy season (SR)
To answer our research questions, we combine two different methodological approaches:
1. Forest growth modelling by using the simulation model Formind, which is:
- Process-based, and individual-oriented
- Includes dynamic soil water and precipitation modules
2. Dendrochronology by using multi-year tree-ring dating and dendrometer measurements
- To derive species-specific stem diameter increment rates for site-fitting the forest model Formind
Our way of proceeding:
1. Model fitting by means of field observation data
2. Development of scenarios for different precipitation conditions by adjusting:
- Frequency distribution of precipitation events
- Amount of rainfall per precipitation event
In the future:
We will evaluate the effects of different management strategies on forest growth dynamics by implementing a management module to the existing forest simulation model. This will allow the development of management strategies that maximize forest yield in consideration of optimum carbon sink.
Publication:
Hiltner, U., Bräuning, A., Gebrekristos, A., Huth, A., Fischer, R., 2016: Impacts of precipitation variability on the dynamics of a dry tropical montane forest. Ecol. Modell. 320, 92-101. http://www.sciencedirect.com/science/article/pii/S0304380015004524