Impact of Climate Change on Life in Africa

An article from the World Wide Fund for Nature (WWF)url:www.panda.org/climat

Development of a MIOMBO woodland dynamics model in Zambezian Africa using Malawi as a case study

A path model was developed to characterize the effects of climate on succession of miombo dry forests of Zambezian Africa using Malawi as a case study. The model, called MIOMBO, is based on the FORSKA Version I gap model of forest succession by Prentice and Leemans (1990). The FORSKA model was modified to include the effects of moisture and fire; and how these affect processes of establishment, survival, growth and development. The impacts that four different GCM scenarios for a CO2 doubling might have on dynamics of a number of miombo species were analyzed. Preliminary results show a gradual increase in the basal area of the more mesic species. This result is consistent with what might be expected with increased precipitation. Tree growth and development data with associated detailed climatic data are lacking and severely limit the ability to define quantitatively how species are influenced by given levels of environmental factors (such as climate and nutrient factors), and how they might respond to seasonal changes in climate variability

Impact of Climate Change on Life in Africa

Climate change will have significant impacts on biodiversity and food security in Africa. Therefore, substantial reductions of heat-trapping gas emissions in developed countries and adaptation strategies are crucial. For example, biodiversity must be managed to ensure that ensure that conservation is occurring both inside and outside of parks and reserves, and that adequate habitat is preserved to enable species—plants, animals and humans—to migrate

Ecological implications of projected climate change scenarios in forest ecosystems in northern Michigan, USA

Changes in seasonal temperature and precipitation, as predicted by several global climate models, were utilized together with a stochastic daily weather stimulation model to evaluate the ecological impacts of projected global climate change scenarios on temperate forest ecosystems in northern Michigan, USA. The model simulated the impacts of these projected changes on ecologically significant weather variables, such as the length of the frost-free period, average growing season temperature, average growing season degree days (4.4° C basis), summer precipitation, potential evaporation during the growing season, and the ratio of precipitation to potential evaporation during July and August. The results indicate that even the lower range of predicted climate changes could lead to ecologically and commercially significant changes in the composition and productivity of these forests. Of particular concern is the possibility of climatically induced regional decline episodes for a number of important commercial species in the northern temperate forests of central North America

MIOMBO - a vegetation dynamics model for the miombo woodlands on Zambezian Africa

The gap model FORSKA was modified to develop MIOMBO, a model to simulate productivity and succession in the miombo tropical dry woodlands of Central Africa. A few measured parameters of the miombo were used to establish suitable ranges of the rest of the parameters in the model by simulation to form a \u27base case\u27. This base case does not represent any specific site, however, deviations from the base case under hypothesized fire and drought regimes can be used to study the response of the miombo to fire and drought in a general way. The MIOMBO model can be used as a starting point for more detailed parameterization for specific sites. In this paper, we emphasize the changes made to FORSKA. © 1994

Ecological implications of projected climate change scenarios in forest ecosystems of central North America

Climate change scenarios in central North America were projected for selected weather stations using a stochastic daily weather simulation model. The projections were conditioned on changes in seasonal temperature and precipitation as predicted by several global climate models. The impacts of these projected changes on temperate forest ecosystems were evaluated through projected changes in such variables as average annual temperature, average growing season temperature, and the ratio of potential evaporation to precipitation during July and August. Even the mildest climate change scenario examined indicated that ecologically significant changes could occur in the composition and productivity of these forests. The possibility also exists that climatically induced regional decline episodes for a number of important commercial species could occur in the northern temperate forests of central North America. © 1994

Evaluating forest stress factors using various forest growth modeling approaches

This paper examines in detail the relative merits of several modeling approaches to evaluating forest site, physical, chemical and climatic stresses. The modeling approaches considered are (i) empirical growth and yield (management) models (STEMS and FOREST); (ii) successional models (JABOWA/FORET gap-phase simulation models and FORSKA); (iii) forest process models (FOREST-BGC). The models were analyzed in terms of their assumptions, formulation, and predictive ability. The analysis incorporated intensive measurements of tree growth and weather conditions taken over 7 years in two stands of northern hardwoods located in Upper Michigan (USA). The process model was very detailed and required many input variables. All models performed poorly when pridictions were compared with the observed data making accurate site-specific predictions impossible without local calibrations. © 1994

International Geosphere-Biosphere Programme (IGBP) Report 41

This report describes the strategy for the Miombo Network Initiative, developed at an International Geosphere-Biosphere Programme (IGBP) intercore-project workshop in Malawi in December 1995 and further refined during the Land Use and Cover Change (LUCC) Open Science Meeting in January, 1996 and through consultation and review by the LUCC Scientific Steering Committee (SSC). The Miombo Network comprises of an international network of researchers working in concert on a 'community' research agenda developed to address the critical global change research questions for the miombo woodland ecosystems. The network also addresses capacity building and training needs in the Central, Eastern and Southern Africa (SAF) region, of the Global Change System for Analysis Research and Training (START). The research strategy described here provides the basis for a proposed IGBP Terrestrial Transect study of land cover and land use changes in the miombo ecosystems of Central Africa. It therefore resides administratively within the LUCC programme with linkages to other Programme Elements of the IGBP such as Global Change and Terrestrial Ecosystems (GCTE). The report provides the framework for research activities aimed at understanding how land use is affecting land cover and associated ecosystem processes; assessing what contribution these changes are making to global change; and predicting what effects global change in turn could have on land use dynamics and ecosystem structure and function. The key issues identified are: patterns, causes and rates of change in land cover in relation to land use; consequences of land-use and land-cover changes on regional climate, natural resources, hydrology, carbon storage and trace gas emissions; determinants of the distribution of species and ecosystems in miombo; and fundamental questions of miombo ecosystem structure and function

Modeling canopy structure and heterogeneity across scales: From crowns to canopy

Canopy studies have been limited in ecological investigations due to problems of canopy accessibility, and the lack of efficient sampling and modeling methods. The primary objective of this study was to develop an efficient modeling approach to describe the 3-dimensional, hierarchical structure of individual crown shells within stands and corresponding canopy patches. Crown shells were modeled based on crown ratio, maximum cardinal radius, vertical position, and shape, Canopies were represented by adding unique crowns to simulated point patterns of trees of known aggregation as measured by Pielou\u27s index of nonrandomness. Canopy patches were delineated at multiple horizontal and vertical scales using the ARC/INFO geographic infomation system (GIS). The patterns of canopy patches are clearly variable and scale dependent. Canopy patterns become more diverse at broader horizontal scales, and change greatly from the lower to the upper canopies. The modeling approach used in this study has general utility in characterizing 3-dimensional canopies of many types of forests

A comparison of forest gap models: Model structure and behaviour

Forest gap models share a common structure for simulating tree population dynamics, and many models contain the same or quite similar ecological factors. However, a wide variety of formulations are being used to implement this general structure. The comparison of models incorporating different formulations is important for model validation, for assessing the reliability of model projections obtained under scenarios of climatic change, and for the development of models with a wide range of applicability. This paper reviews qualitative and quantitative comparisons of the structure and behaviour of forest gap models. As examples of qualitative model comparisons, the different formulations used for the height-diameter relationship, for the maximum growth equation, and for the effects of temperature and drought on tree growth are reviewed. The variety of formulations currently in use has the potential to influence simulation results considerably, but we conclude that little is known on the sensitivity of the models in this respect. The quantitative model comparisons performed so far allow us to draw the following conclusions: (1) Gap models are quite sensitive to the formulation of climate-dependent processes under current climate, and this sensitivity is even more pronounced under a changed climate. (2) Adaptations of forest gap models to specific regions have required detailed sub-models of species life history, thus complicating model comparison. (3) Some of the complex models developed for region-specific applications can be simplified without hampering the realism with which they simulate species composition. (4) Attempts to apply the models without modification beyond the area for which they were developed have produced controversial results. It is concluded that the sensitivity of forest gap models to the exact process formulations should be examined carefully, and that more systematic comparisons of model behaviour at a range of test sites would be desirable. Such studies could improve our understanding of forest dynamics considerably, and they would help to focus future research activities with gap models