DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu
|ŠUMARSKI LIST 3-4/2013 str. 22 <-- 22 --> PDF|
In a society as demanding as the one we live in today, landscape reclamation projects should not only respect biological diversity, minimize resource dilapidation, preserve water and nutrient cycles, and maintain the quality of habitats, but also reinforce landscape character. This should be done taking into consideration the spirit of the place, integrating the pre-industrial existence in the new landscape, and promoting the creation of multifunctional resilient landscapes capable of incorporating change and enhancing quality of life. Degraded landscapes occur as a byproduct of economic, functional, spatial, and social transformation of cities and regions, and all this is accompanied by a temporary devaluation and abandonment of areas. Furthermore, it is extremely important that new redevelopments in degraded landscapes help people realize that reclaiming, restoring, and giving new uses to degraded landscapes are indispensable actions for maintaining landscape sustainability (Loures 2009). No single best method exists for assessing land degradation. Studies conducted at the global level are mainly based on expert opinion. Experimentally, field measurements, field observations, land users’ opinions, productivity changes, remote sensing, and modeling act as the backbone for many approaches used to assess land degradation (Kapalanga 2008). According to Gruenewald et al. (2007), the establishment of an agroforestry system can be a viable solution for degraded land. In this light, the yield potential and the sustainability of yields were studied for different clones of Populus spp., Salix viminalis, and Robinia pseudoacacia, considering different rotation periods (3-, 6-, and 9-year rotations). The highest yields of woody biomass were found for R. pseudoacacia. Special emphasis was given to the interaction between trees (R. pseudoacacia) and crops (Medicago sativa). R. pseudoacacia hedgerows have practically no negative influence on yields of M. sativa. Biomass plantations are useful tools for natural phytoextraction; namely, the ideal plant for trace element phytoextraction has to be highly productive in biomass and take up a significant part of the trace elements of concern (Vangronsveld et al. 2009). Klang-Westin and Eriksson (2003) estimated long-term Cd (Cadmium, heavy metals) removal by Salix using commercial Salix stands grown in different soil types. The net removal of Cd from the plough layer by Salix varied between 2.6 and 16.5 g Cd/ha/year using 8 t/ha as the highest Salix biomass value in the models. The authors concluded that Salix has a high potential for Cd removal from a long-term perspective (6–7 cutting cycles–approximately 25 years) and that it would be possible to extract theoretically a maximum of 413 g Cd/ha. With a higher yield of Salix biomass per ha, Cd phytoextraction would also be higher. Taškar (2009) carried out research on a fly ash landfill, where nine tree species were planted. The purpose was to determine which species would successfully adapt to the situation that prevailed in such degraded areas. From 2001 to 2008, the parameters (e.g., the growth of trees in height, development of roots, increment growth of trees) and ecological conditions were analyzed. The results showed only Ostrya carpinifolia and Betula pendula successfully adapted to the soil conditions. The arrival of animal species (e.g., birds, large game, insects, rodents) was noticed already within the first years of research. Birds also nested. Thus, it was confirmed that biodiversity increased when trees were planted in degraded areas. If managed in a sustainable way, agroforestry (silvopastoralism) can favorably affect biodiversity, landscape, and rural welfare issues that underpin agri-environment objectives through a number of attributes. These include efficient nutrient cycling, buffering against non-point source pollution, fulfilling animal welfare criteria, employment generation and income enhancement, reversal of rural abandonment and creation of viable rural communities (Mosquera-Losada et al. 2005, Rigueiro-Rodriguez et al. 2011). Interactions in silvopastoral systems generate economic, environmental, and social benefits (De Baets et al. 2007). Hislop and Claridge (2000) found that sheep spent more time in the shade and shelter of trees on hot, sunny days and cold, windy days than they did in the open. This could be considered a positive welfare benefit. Silvopastoralism requires less mechanical labor than alley cropping and is advantageous for reclaimed soils; therefore, silvopastoralism should be preferred (Eichler and Herzog 1997). A major role for agroforestry is also emerging in the domain of environmental services. Environmental services can be defined as "externalities," because they are not incurred by a party who did not agree to the action causing the cost or benefit. Throughout Europe, the aesthetics and representation of pastoral cultural heritage have been recognized as main benefits of agroforestry systems (Herzog 1998, Franco et al. 2003).
The scientific literature suggests different approaches for the assessment of agroforestry systems before major investments are decided (Alavalapati and Mercer 2004, Tojnko et al. 2011). Multi-criteria decision analysis (MCDA) is a useful methodological approach when the evaluation of several variables cannot be easily transformed into quantitative units and our goal is influenced by multiple competing criteria (Mendoza and Martins 2006). There has been significant growth in the environmental applications of MCDA over the last decade across all environmental application areas (Huang et al. 2011). The basic problem in research is developing the system in order to support decision-making in the selection of the most appropriate alternatives, with a combination of the technological-economic simulation model (cost-benefit analysis (CBA)) and analytical hierarchy process (AHP) multi-criteria decision analysis (Belton and Stewart 2002).