Evaluation and selection of indicators for land degradation and desertification monitoring: types of degradation, causes, and implications for management

Indicator-based approaches are often used to monitor land degradation and desertification from the global to the very local scale. However, there is still little agreement on which indicators may best reflect both status and trends of these phenomena. In this study, various processes of land degradation and desertification have been analyzed in 17 study sites around the world using a wide set of biophysical and socioeconomic indicators. The database described earlier in this issue by Kosmas and others (Environ Manage, 2013) for defining desertification risk was further analyzed to define the most important indicators related to the following degradation processes: water erosion in various land uses, tillage erosion, soil salinization, water stress, forest fires, and overgrazing. A correlation analysis was applied to the selected indicators in order to identify the most important variables contributing to each land degradation process. The analysis indicates that the most important indicators are: (i) rain seasonality affecting water erosion, water stress, and forest fires, (ii) slope gradient affecting water erosion, tillage erosion and water stress, and (iii) water scarcity soil salinization, water stress, and forest fires. Implementation of existing regulations or policies concerned with resources development and environmental sustainability was identified as the most important indicator of land protection.

Evaluation and selection of indicators for land degradation and desertification monitoring: methodological approach

An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment, socio-economic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score to desertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient, plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation.

Changes in matrix metalloproteinases during the evolution of interstitial renal fibrosis in a rat experimental model

The aim of the present study was to analyze the matrix metalloproteinase (MMP) activity during the evolution of interstitial renal fibrosis in a rat experimental model of unilateral ureteral obstruction. The interstitial type I collagenase and the gelatinolytic activities were analyzed by radiolabeled substrate degradation. Interstitial collagenase activity was low at all times while gelatinolytic activity increased on day 6 of evolution, with a decrease in activity from this point. The use of organomercurials revealed the presence of latent enzyme in all cases. Normal kidney samples contained MMP-9 in both active and proenzyme forms as revealed by zymography. On day 3 MMP-9 dimers appeared, and increased activity was observed until day 6. A decrease in the gelatinolytic activity was detected from days 9-15 of evolution. This observation was confirmed by Western blot analysis that revealed the presence of proMMP-9 mainly from days 6-12. Tissue inhibitor of metalloproteinase-1 (TIMP-1) was also detected alone and in combination with proMMP-1 and MMP-1, particularly from days 6-15 of evolution. The presence of MMP-9 and MMP-1 was detected in the cytoplasm of cortical tubular cells by immunohistochemistry, with no difference between the experimental and the normal kidneys. There was also an increase in collagen concentration from day 3 after surgery that increased during the entire evolution of the experimental model. This work reveals that the decrease in the MMP-9 and MMP-1 enzymatic activity, due to their interaction with TIMP-1 and to the lack of activation of the latent forms, may participate in the excessive collagen deposit during the evolution of experimental interstitial renal fibrosis.