Assessment method & techniques forests & shrubland

Authors: Agostino Ferrara, Guiseppe Mancino, Luca Salvati, Michiel Curfs, Anton Imeson

Editor's note 10Sep12: Source D711-9.2. To be reviewed in the context of the articles. Eleni - the text of this category introduction cannot be edited from the front end. You need to copy and paste into a word document, make the corrections using track changes and email it to Jane.

Land and ecosystem degradation and desertification (LEDD) are complex socio-environmental phenomena that result from the interplay of biophysical and societal forces on and across spatial levels. In this ambit, according to the definition adopted in LEDDRA, responses to LEDD include all the actions taken in LEDD affected regions with the purpose either to directly and explicitly tackling a LEDD problem or of addressing other socio-economic problems (Briassoulis 2010).

The analysis of LEDD problems and responses to LEDD is based on the knowledge of their biophysical and socio-economic impacts that are assessed through the use of existing methodologies and the development of new approaches. Assessment methods and techniques used in LEDDRA are quantitative, qualitative or mixed, depending on the component of the SES under study. The main LEDD issues considered in forests/shrublands environments are: (a) forest productivity decline, (b) loss of biodiversity, (c) forest fragmentation, (d) water stress, (e) soil erosion, (f) land desertification.

Forest productivity decline is one of the most important LEDD phenomena in Mediterranean forests/shrublands. The loss of the ecosystem productive capacity is the result of a wide range of both human-induced and abiotic factors. This LEDD problem generally is the loss in the ability to retain nutrients and a decline in soil water storage capability by the ecosystem. An efficient model in estimating forest productivity is the process-based model 3-PG (Landsberg and Waring 1997) and its spatial version 3-PGS (Coops et al. 1998, 2001) to estimate forest productivity at ecosystem level, based on a simplified light-use efficiency (LUE) approach.

In forest ecosystems, loss in biodiversity implies not only the extinction of tree species, but also the destruction of habitats and ecosystems, with all other vegetal and animal organisms and species related to them. One technique to assess the loss in biodiversity at landscape level is to analyse changes in the γ diversity (Whittaker, 1972), representing the total richness in species over a large region. At forest level changes of the Diversity index as proposed by Shannon and Weaver (1949) can be also used.

Another important LEDD problem in forests/shrublands is forest fragmentation occurring when habitats, landscapes, and ecosystems are disconnected by human or non-human factors, including the short-term, non-sustainable exploitation of renewable or non-renewable natural resources. In forest ecosystems three spatial attributes of fragmentation are considered: core area, shape and isolation of forest fragments. The FFI (Forest Fragmentation index) is a composite index that measures forest fragmentation (Butler et al., 2004; Chatelain et al., 2010). The components selected to measure FFI are the percentage of non-forest cover, the percentage of edges and the interspersion. The fragmentation indices are mainly calculated on the basis of remote sensing images.

Water stress, especially in Mediterranean forests and shrublands, seems to be the major cause of forest productivity decline and of forest deterioration more generally. It is the direct consequence of severe climatic conditions and events such as continuous heat waves and drought periods. The water stress can be assessed using the Aridity Index proposed by UNEP (1992) as a proxy. The Aridity index is obtained from the equation: AIU = P/PET.

Soil erosion is an important LEDD issue in steep slope areas. In general, it is related to different processes linked to water, tillage, and wind erosion. In forests/shrublands environments soil erosion is mainly associated with water-induced erosion processes (water runoff, landslides, etc.) and, in this ambit, the PESERA (Pan - European Soil Erosion Risk Assessment) model has demonstrated its efficiency to estimate them (Kirkby, 1999; Kirkby et al., 2000; Kirkby et al. 2003).

Among the procedures aimed at assessing the level of land vulnerability to desertification that, besides the environmental and climatic factors take also into account the human activities, the Environmentally Sensitive Area (ESA) framework is the most widely applied in the Mediterranean basin and other arid and semi-arid environments. Recent studies (Ferrara et al., 2005; Sepehr et al., 2007; Ali and El Baroudy, 2008, Lavado Contador et al. 2009) have underlined the efficiency and the effectiveness of this key indicator system developed under the EU-funded MEDALUS III and DESERTLINKS projects (Kosmas et al., 1999; Kosmas et al., 2000; Basso et al., 2000; Brandt, 2005; Ferrara, 2005; Ferrara et al., 2005).

Methods and techniques to evaluate responses to LEDD in forests/shrublands include: (1) cost-benefit analysis, (2) cost-effectiveness analysis, (3) multicriteria analysis. Furthermore, valuation techniques that allow decision makers to evaluate tradeoffs between ecosystem management alternatives include: (1) direct market valuation approach, (2) stated preference approach, and (3) revealed preference approach (see LEDDRA deliverable D321).

NB: Each of the Articles below corresponds to one of the Task 3.2 deliverables.


2014-11-28 10:49:22