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Forest stratification plays a crucial role in the interception of light and plants' photosynthetic activities. However, there is still a lack of information on the contribution of tropical forest stratification to its functioning, despite the increasing number of studies. Here, we analysed from a perspective of the whole tree community (WTC) and forest strata (i.e., large trees, understory trees, and small stems), the relationship between abiotic, biotic factors and aboveground Carbon (AGC). The abiotic factors-AGC relationships were positive for all strata and WTC. However, soil factors-AGC relationship was stronger for small stems and understorey, while topography factor-AGC relationship was stronger for large trees and WTC. Tree size inequality-AGC relationship was positive and much stronger for WTC, large trees and small stems. In addition, a species diversity-AGC relationship was found positive only for large trees and WTC. These results highlight the niche complementarity effect for driving positive relationships of species diversity and individual tree size variation with aboveground biomass at large tree strata and WTC. The lack of positive effect of species diversity on AGC for understorey and small stems strata might be attributable to the selection effect or resource complementarity among species.

Plant diversity conservation has become one of the most critical objectives of forest management in an ecologically sustainable way. However, biodiversity conservation and sustainable management issues are sometimes neglected in Cameroon's communal forests because their botanical importance, and high-priority species for conservation are poorly known. In the present study, done in the Doume Communal Forest (DCF) situated in eastern Cameroon, we explore its potential in terms of plant diversity as well as conservation value. Forest inventories done in thirty 1-ha plots were analysed using diversity indices, species and family importance values index as well as IUCN conservation status. A total of 22,064 stems with a diameter ≥ 1 cm were recorded within thirty 1-ha sampling plots, belonging to 307 species, 194 genera and 72 families. The DCF is particularly rich in members of the Malvaceae, Annonaceae, Meliaceae and Apocynaceae. The list of the plant species known from the DCF reaches 330 species, with 290 identified at the species level. It was found out that 49 species can be considered high-priority species for conservation and that these species include species that are rare and threatened in Cameroon, and even one species endemic to the country. This study highlights the botanical importance of communal forests in Cameroon and recommends that botanical assessments of these forests are performed to contribute to the sustainable management and conservation of their biodiversity.

Large-scale identification of land use and land cover change in a tropical forest is a challenge to landscape designers and forest ecologists. Here, Landsat images acquired during the years 2000, 2009, and 2018 were used to assess the spatial-dynamics of land use and land cover (LULC) during the last two decades (2000–2018). A classification system composed of six classes—dense forest with (high tree density and low tree density), swampy Raphia forest, swampy flooded forest and savanna were designed as LULC for this study. A maximum likelihood classification was used to classify Landsat images into thematic areas. Elsewhere, Landsat-based LULC mapping, post classification at the per-pixel scales and self-knowledge on the land cover change processes were combined to analyze LULC change, forest loss and change trajectories in Doume Communal Forest in eastern Cameroon. The results show that half of the study area changed in 2000–2009 and that the different types of LULC changes increased and involved more diverse and characteristic trajectories in 2009–2018 compared to 2000–2009. Degradation to a dense forest with low tree density and swampy Raphia forest was dominant, and the forest was mostly lost due to trajectories that involved conversion to agroforestry systems (10%), and a lesser extent due to trajectories that involved deforestation to grasslands (7%). The trajectory analyses did thus contribute to a more comprehensive analysis of LULC change and the drivers of forest loss and, therefore, is essential to improve the sustainable management and support spatial planning of the forest.

Tropical forests play an important role in biodiversity conservation and ecosystem functioning. Few studies have teased apart the independent effects of biotic and abiotic factors on aboveground carbon across tree size groups and the whole tree community level in a tropical semi-deciduous rainforest. This study aims to analyze the relative and independent effects of abiotic (topography, soil fertility/texture and disturbance) and biotic factors on carbon stocks across tree size groups, as well as at the whole tree community in semi-deciduous plots, including logged plots.We used data from 30 1-ha plots and 22,064 trees distributed in a semi-deciduous tropical rainforest of Cameroon. For each plot, we quantified disturbance, topography and eleven soil conditions. Besides, we quantified three taxonomic richness and diversity Gini index. We used structural equation models to test the hypothesis that all drivers have independent, positive effects on aboveground carbon stocks across tree-sized groups and the whole tree community.The logging disturbance decreased aboveground carbon stocks for the whole tree community and trees size groups across our site except for large trees. Topographical factors (i.e., slope and elevation) increased aboveground carbon (AGC) of the whole tree community and the large trees. In contrast, soil nitrogen (Nsoil) and clay proportion increased AGC of the small stems and understorey trees groups. This study found that biotics factors have some indirect and direct effects on AGC. Taxonomic diversity through niche complementarity had a positive relationship with aboveground carbon stocks across the trees size groups and the whole tree community, while diversity Gini index had strongest relationships with aboveground carbon stocks.The significant effects of structural diversity on aboveground carbon stocks of the whole tree community, large trees, and understory trees highlight the importance of maintaining a layered structure and tall trees in the forest.

In Ethiopia, recurrent droughts were associated with El Nino phenomenon, particularly in the study area where the majority of smallholder farmers depend on rain-fed agriculture. The aim of this study was to model the spatio-temporal meteorological drought onset, offset, duration, magnitude, intensity, frequency, severity and spatial extent in Raya and its environs, Northern Ethiopia. Both the ground meteorological stations and TAMSAT (tropical applications of meteorology using satellite and ground-based observations) monthly rainfall data were gathered from the National Meteorological Agency of Ethiopia for the period 1983–2015. The Inverse Distance Weighting (IDW), a type of the deterministic interpolation method was applied to quantify the amount of seasonal rainfall by producing surface rainfall map. A Standardized Precipitation Index (SPI) at 3-month timescale was used to evaluate seasonal rainfall deficit and characterize meteorological drought. The results revealed that all sites obtained minimal and irregular rainfall, hence led to catastrophic droughts. Also, the findings showed that there was high rainfall variability across the study area that ranged from 28.14 to 42.32%. As a result, mild-to-severe meteorological drought phenomena were observed once in every 2–3 years. This incidence was found to be high in terms of spatial and temporal coverage during the last three decades. Therefore, this study may help to offer better insight for policymakers to establish drought mitigation and adaptation strategies.

The aim of this study was to model the relationship between Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI), Vegetation Condition Index (VCI), Temperature Condition Index (TCI), Vegetation Health Index (VHI), and Standardized Precipitation Index (SPI) at 3-month timescale in Raya and its environs, Northern Ethiopia. This study answered how NDVI and LST, VCI and TCI, SPI and VHI are related. It also explained better drought indices for meteorological and agricultural drought monitoring. MOD11A2 LST Terra, eMODIS NDVI, and monthly rainfall data of the tropical applications of meteorology using satellite and ground-based observations (TAMSAT) were used. The data were analyzed using a simple linear regression model. The results revealed that the mean LST was high (i.e., between 39.6 and 41.29 °C), while NDVI was poor and unhealthy (i.e., below 0.27) in the lowland area due to unfavorable moisture condition than the mid and highland areas. The regression result indicated that NDVI and LST have a relatively strong negative and significant relationship (R2/P = 0.40/0.01 to R2/P = 0.62/0.00) in all districts of the study area. This study also reported that there is a positive and significant relationship between VCI and TCI (R2/P = 0.38/0.02 to R2/P = 0.63/0.00) in all districts of the study area. Furthermore, this study found that the relationship between SPI and VHI is positive and significant (R2/P = 0.36/0.02 to R2/P = 0.60/0.00) in all districts of the study area. The SPI and VHI indices are suitable for monitoring the incidence of meteorological and agricultural drought. This study may help to improve the understanding of both meteorological and agricultural drought indices relationships.

Background Droughts cause serious effects on the agricultural and agro-pastoral sector due to its heavy dependence on rainfall. Several studies on agricultural drought monitoring have been conducted in Africa in general and Ethiopia in particular. However , these studies were carried out using the limited capacity of drought indices such as Normalized Difference Vegetation Index (NDVI), Vegetation Condition Index (VCI), and Deviation of Normalized Difference Vegetation Index (DevNDVI) only. To overcome this challenge, the present study aims to analyze the long-term agricultural drought onset, cessation, duration, frequency, severity and its spatial extents based on remote sensing data using the Vegetation Health Index (VHI) 3-month time-scale in Raya and its surrounding area, Northern Ethiopia. Both the MOD11A2 Terra Land Surface Temperature (LST) and eMODIS NDVI at 250 by 250 m spatial resolution and hybrid TAMSAT monthly rainfall data were used. A simple linear regression model was also applied to examine how the agricultural drought responds to the rainfall variability. Results Extremely low mean NDVI value ranged from 0.23 to 0.27 was observed in the lowland area than mid and highlands. NDVI coverage during the main rainy season decreased by 3–4% in all districts of the study area, while LST shows a significant increase by 0.52–1.08 °C. VHI and rainfall value was significantly decreased during the main rainy season. Agricultural drought responded positively to seasonal rainfall (R2 = 0.357 to R2 = 0.651) at p

There are very few scientific studies on the predictions of future drought hazard and its effects on economic, social, and environmental under the existing global climate change scenarios. This study, aims to predict the future meteorological drought hazard (2016–2070) under the representative concentration path 4.5 climate change scenarios in Raya and its environs, Northern Ethiopia. The study also investigates the onset, end set, duration, magnitude, intensity, frequency, severity and spatial coverage of future drought occurrences. Monthly tropical applications of meteorology using satellite data and ground–based observations and daily AgMERRA daily climatic data were used from 19 meteorological stations. A robust interpolation technique called Inverse distance weighted was also applied to assess the spatial–temporal distribution of rainfall. Then, the temporal seasonal rainfall variability was analyzed using the coefficient of variation. A standardized precipitation index at 3 months time scale was applied to measure the precipitation deficit and characterize drought properties. The results reveal an increasing and worsening drought event in the future than the last three decades. Hence, the study area will be stricken for about 30–39 times with mild to extreme droughts. The rate of drought recurrence will also be once in every 1.8–2.3 years. The duration (1–5 years) of drought will be similar in all districts, but the magnitude and intensity will vary due to the level of precipitation deficit. It is, therefore, recommended that policy or decision makers and smallholder farmers should improve the existing water management and agricultural practices to cope up with the climate extremes and boost agricultural productivity.

Little is known about the future land use and land cover (LULC) type in some parts of Ethiopia, but not in the study area. This study aims to predict and analyze the future scenarios of LULC (2015–2033) using cellular automata and Markov Chain model (CA_Markov) by taking into consideration the physical and socio-economic drivers of LULC dynamics. The historical LULC change data of 1984–1995, 1995–2015, and 1984–2015 were used as a baseline. Both transition rules and transition area matrix for the period 1984–1995, 1995–2015, and 1984–2015 were produced quantitatively using the Markov chain model. After that, the physical and socio-economic factors were standardized using fuzzy and then Multi-Criteria Evaluation (MCE) was used to produce the transition suitability image. The CA_Markov model was then applied as a standard contiguity filter of 5 × 5 to predict the 2033 LULC condition using the TerrSet Geospatial Modeling and Monitoring System software. The result indicated that forestland are predicted to increase by 108 sq km (44.5%), shrub/bush lands 710 sq km (20%), built-up area 286.2 sq km (48.3%), and grasslands 31 sq km (15%), respectively. However, significant reductions (losses) in a water body (Wb) 5.2 sq km (11.2%), croplands (Cl) 78.9 sq km (1.3%), barren lands (Bl) 800 sq km (27.4%), and floodplain area (Fp) 251.68 sq km (33.7%), respectively. Furthermore, the Pearson correlation result between the historical and predicted LULC type indicated that there are positive, strongly correlated, and are statistically significant relationships (r = 0.981, p = 0.000). The increase in forest land and reduction in barren and flood plain may benefit the study area. However, the decrease in the water body may contribute to the severity of drought in the area. This study may help to use as useful information to foster better decisions and improve policies in land use within the framework of sustainable land use planning system.

This study models the spatio-temporal dynamics, patterns, and evolution of land use and land cover (LULC) (1984–2015) using remote sensing and GIS supported by in-suit measurements in Raya, Northern Ethiopia. Landsat thematic mapper (TM), and operational land imager (OLI) path 168/169 and row 051/52 were acquired from the United States Geological Survey Landsat archive. All necessary image pre-processing techniques were applied to remove the distortions due to sensors. Eight major LULC types based on a supervised image classification and maximum likelihood decision rule were identified. Post-classification change detection method was also applied to detect the dynamics in LULC. Significant change in forestland, shrub/bush land, built-up area, grassland, cropland, barren land, and floodplain areas were observed over the period 1984–2015. Considerable losses were observed in grasslands (36.9%), water body (8.7%), and floodplain areas (74.4%), while other LULC types increased. This explains why the study area is frequently affected by drought and other related disasters. An overall accuracy of 88.5, 86.5 and 90.5% were observed for the 1984, 1995 and 2015 LULC, respectively. The overall Kappa coefficient of 0.87, 0.85, and 0.90 were also observed for the same periods. Besides, the Pearson pairwise correlation matrix among the 1984–1995, 1995–2015 and 1984–2015 LULC shows positive and strong correlation (r = 0.916, r = 0.908, r = 0.914) at p

Arid and semi-arid areas worldwide face challenges of over utilization of rangelands, with a possibility of declining into degraded lands. Overgrazing by livestock and persistent deforestation of woodlands has been reported in the rangelands of Boteti Sub- District of Botswana. This study focuses on depicting changing patterns of land use that have come about as a result of a forcing from natural phenomenon. Periodic droughts and the drying up of the Boteti river which has been a source of livelihood for a long time has manifested on land utilization trends around the villages of Boteti District. New patterns of land use have since emerged as an adaptation strategy against the drier environment. The study mapped land use and land cover around two ‘river village settlements’. Land degradation indicators were identified within the various land cover categories. Results show that communities have shifted from flood recession farming to dry-land farming with emphasis on livestock. The latter are ironically pr...

Tropical forests contribute to climate change mitigation by absorbing carbon from the atmosphere and storing this in biomass and soil organic matter. However, there is still considerable uncertainty about the above- and belowground quantity and distribution of carbon stocks in African forests. Here, we evaluate how different carbon pools (aboveground live biomass, aboveground dead biomass, belowground biomass) contribute to total carbon stocks, and how different carbon components (e.g. large trees, understorey trees, coarse woody debris, roots, soil organic carbon etc.) contribute to carbon pools and total carbon stocks. We evaluated data of extensive inventories within 30 1-ha plots spanning the terra-firme semi-deciduous forest in eastern Cameroon. Hence, the plots were placed at a mean distance of 1 km from the nearest plot and we analyzed the data using variation partitioning, linear regressions and correlation tests. We found that the terra-firme semi-deciduous forests store 283.97 ± 51.42 Mg C ha−1. The aboveground biomass pool, with a carbon stock of 180.99 ± 25.8 Mg C ha−1, mostly explained variation in total carbon stocks (R2 = 0.79). From all aboveground biomass components, carbon in large trees was most strongly correlated with total carbon stocks. The second most important carbon pool was belowground carbon (on average 85.06 ± 16.86 Mg C ha−1; R2 = 0.78), mainly explained by coarse root carbon. Carbon in dead biomass had only a small contribution to total carbon stocks (R2 = 0.04). Hence, our results indicate that aboveground live biomass is a good predictor for variation in total carbon storage within this semi-deciduous terra-firme forest. However, aboveground live carbon and belowground carbon and their interactions explained most of the variation in total carbon stock, indicating that a whole-ecosystem approach is necessary for a full understanding of the carbon cycle.

This paper aims at delineating and rationalising the spatial processes that characterise peri-urbanisation in sub-Saharan Africa, using Lobatse, Botswana, as a case study. The research techniques employed included the sourcing of: archival documents; available and simulated time series data; social survey data; field observations as well as spatial data derived from aerial photographs for 1966–2006 and integrated in a geographical information systems framework. The exercise resulted in: (1) the production of temporal-spatial model maps, (2) the systematic description and explanation of the spatial growth patterns of the study area, (3) the modelling of its rationalised growth pattern, and (4) an analysis of the environmental and socioeconomic implications of this spatial growth pattern. The study further confirmed the relevance of certain underlying principles of urban morphology and morphogenesis. Among the key recommendations, we suggest that, to move towards sustainable development, the national Enviro...

The aim of this paper is to discuss the role of existing policies, programmes and legislation in promoting sustainable land management and livelihoods in mid-central Botswana. The paper is based on data from the survey of relevant literature, analysis of policy and legal documents, field observations and a series of stakeholder workshops held in the villages of Mopipi, Mokobaxane and Rakops in Boteti Sub-District between 2008 and 2009. The study's findings indicate that formal land use and rangeland management institutions have influenced the process of environmental change in the study area, mostly in a negative way. Institutional failure and support to the expansion of the livestock sector have promoted overstocking; arable production support has encouraged land clearance in a drought-prone and windy area; whereas protectionist wildlife management has been in conflict with, rather than complementary to, traditional uses of the communal rangelands. The environmental outcomes of all this have been the shrinkage of the Boteti commons, overgrazing, deforestation and wind erosion. The study recommends adoption of a community-based natural resource management strategy, which could simultaneously secure livelihoods and conserve the commons. © 2013 John Wiley & Sons, Ltd.

Mopane woodland are a source of valuable resources that contribute substantially to rural economies and nutrition across Southern Africa. However, a number of factors have, of late, brought the sustainability of the mopane woodland resources into question. One of such factors is the difficulty in monitoring of defoliation process within the woodland. In this study we set out to discriminate the levels of change in forest canopy cover detectable after insect defoliation using ground based hyperspectral measurements in mopane woodland. Canopy spectral measurements were taken from three levels of defoliation: Undefoliated (UD), Partly defoliated (PD) and Refoliating plants (R) using ASD FieldSpec HandHeld 2. A pre-filtering approach (ANOVA) was compared with random forest independent variable selector in selecting the significant wavelengths for classification. Furthermore, a backward feature elimination method was used to select optimal wavelengths for discriminating the different levels of defoliation in mopane woodland. Results show that optimal wavelengths located at 707 nm, 710 nm, 711 nm, 712 nm, 713 nm, 714 nm, 727 nm, and 1066 nm were able to discriminate between the three levels of defoliation. The results further show that there was no significant difference in the overall accuracy of classification when random forest variable selector was used 82.42% (Kappa = 0.64) and the pre-filtering approach (ANOVA) 81.21% (Kappa = 0.68) used before building the classification. Overall, the study clearly demonstrated that the dynamic process of defoliation in mopane woodland can be assessed and detected using hyperspectral dataset and effective algorithm for discrimination.

Africa has experienced unprecedented rates of urban growth, at above 3% annually. This growth was accompanied not only by agglomeration economies and spread effects but negative externalities that impinge on the inhabitants and the natural resource base in the rural–urban transition zone. Already, cities occupy large geographical areas that are continually expanding. Botswana’s population is small with a recent urbanization history. However, it has recorded one of the highest urbanization levels (61%) and annual urban growth rates (2.5%). Unlike in most developed countries, the dynamics of peri-urbanization in Gaborone reflect a strong interplay of market and institutional factors. Actual population growth and demand for space has always defied projected forecasts. The country presents unique prospects for investigating patterns and processes that characterize urban growth and their intersecting environmental and policy implications for sustainable urbanization. The study utilizes a developmental approach based on spatial data to describe, interpret and analyse patterns and processes that determined the growth of Gaborone. It is evident that certain developments within the urban shadow of the city have been unregulated. In spite of the apparent ecological footprints resultant from the geographical manifestation of urban growth, legislative mitigation measures have rarely been implemented to promote sustainable urbanization.

For land degradation monitoring and assessment (M&A) to be accurate and for sustainable land management (SLM) to be effective, it is necessary to incorporate multiple knowledges using a variety of methods and scales, and this must include the (potentially conflicting) perspectives of those who use the land. This paper presents a hybrid methodological framework that builds on approaches developed by UN Food & Agriculture Organisation's land degradation Assessment in Drylands (LADA), the World Conservation Approaches and Technologies (WOCAT) programme and the Dryland Development Paradigm (DDP), and is being applied internationally through the EU-funded DESIRE project. The framework suggests that M&A should determine the progress of SLM towards meeting sustainability goals, with results continually and iteratively enhancing SLM decisions. The framework is divided into four generic themes: (i) establishing land degradation and SLM context and sustainability goals; (ii) identifying, evaluating and selecting SLM strategies; (iii) selecting land degradation and SLM indicators and (iv) applying SLM options and monitoring land degradation and progress towards sustainability goals. This approach incorporates multiple knowledge sources and types (including land manager perspectives) from local to national and international scales. In doing so, it aims to provide outputs for policy-makers and land managers that have the potential to enhance the sustainability of land management in drylands, from the field scale to the region, and to national and international levels. The paper draws on operational experience from across the DESIRE project to break the four themes into a series of methodological steps, and provides examples of the range of tools and methods that can be used to operationalise each of these steps. Refereed/Peer-reviewed

The Okavango wetlands in north western Botswana are the mostfire-proneenvironmentinBotswana.Mostofthesefires are anthropogenic. The fires in this environment are thoughttoimpacttheenvironmentnegativelyandtherefore practices that are associated with extensive use of fire have been strongly criticized. Despite this, there has been little work done to understand how these fires impact the wetlands environment and its dynamics, especially the vegetation resources that are used by the local communities in the wetlands. The objective of the study was to identify fire spatial and temporal trends in relation to settlement distribution, through the use of remote sensing, socio-economic and phytosociological surveys. The fire history results show that geographically there has not been any significant change in vegetation structure and that in fact fires may have promoted biodiversity. The results of analysis show an

This paper explores an approach to problem-oriented, interdisciplinary field-based courses devised by university consortia in southern Africa and Denmark. The SLUSE (Sustainable Land Use and Natural Resource Management) model has been applied on six three-week field courses within southern Africa and trained over 200 students. Student groups composed of individuals from different academic disciplines that investigated problems specifically devised to integrate social and natural science approaches set the stage for an interdisciplinary approach. The field locations are in rural areas that have a legacy of marginalization, poverty and reliance on natural resources for at least part of their livelihoods thus allowing for environmental and natural resource issues to be investigated. Course evaluations show that students feel they gain invaluable exposure to the innovative field-based learning environment created by the SLUSE approach. The main benefit perceived by hosting local communities was an increase in...

The spatial distribution of a tree species, Colophospermum mopane is mapped at its southern limits in eastern Botswana. Its relationship with soil type distribution is also investigated. Methods applied in the exercise used the possibilities of integrated applications of geographic information systems and remote sensing to detect and delineate spectral classes of C. mopane and of soils. Landsat TM data for the wet and dry seasons were analysed and interpreted for soil and vegetation classification. Supervised classification of the wet season (19/04/93) image was carried out using land use/cover classes derived from Colour infrared (CIR) aerial photographs, flown during the wet season (April, 1996) over the study area. Classification of the dry season (19/10/84) image on the other hand was based on the existing Food and Agricultural Organisation (FAO) soil maps of the same area. Results show that CIR photographs can be reliably used in selecting training areas for the classification of Landsat TM imagery. Secondly, results also indicate that Landsat TM can be used to map the distribution pattern of mopane. The methods applied in this study and the tools used prove that the much needed inventorying of vegetation in Botswana can be carried out using remote sensing. Lastly, the study shows that spectral classes of soil and vegetation have a positive relationship.

The abandonment of land is a global problem with environmental and socioeconomic implications. An approach to assess the relationship between land abandonment and a large set of indicators was illustrated in the present study by using data collected in the framework of the European Union DESIRE research project from 808 field sites located in 10 study sites in the Mediterranean region, Eastern Europe, Latin America, Africa and Asia. A total of 48 indicators provided information for biophysical conditions and socioeconomic characteristics measured at the plot level. The selected indicators refer to farm characteristics (family status, land tenure, present and previous types of land-use, soil depth, slope gradient, tillage operations) and to site-specific characteristics including annual rainfall, rainfall seasonality and water availability. Classes were designated for each indicator and a sensitivity score was assigned to each class based on existing research or empirically assessing the importance of each indicator to the land abandonment issue. Questionnaires for each process of land degradation were prepared and data were collected at field site level in collaboration with land users. Based on correlation statistics and multivariate analyses more than ten indicators out of 48 resulted as significant in affecting land abandonment in the studied field sites. Among them, the most important were rainfall seasonality, elderly index, land fragmentation, farm size, selected soil properties, and the level of policy implementation. Results contribute to the development of appropriate tools for assessing the effectiveness of land management practices for contrasting land abandonment.

Delineation of stands of Colophospermum mopane is carried out on aerial photographs for the area around Palapye, Botswana. The purpose of this study was to evaluate aerial photos as ground truth material for satellite image classification, and to assess the quality of an existing vegetation map around the study area. Colophospermum mopane can be accurately mapped using colour infrared (CIR) photographs. The study shows that CIR photography can be used for accurately mapping the distribution of mopane. This material can therefore, be used as a reliable tool for ground truthing vegetation classification of satellite images, as well as for monitoring the distribution of the species. The only pre-existing vegetation map over the study area is checked against a visually interpreted map for consistency of the level of detail. A close-up view of pictures of scanned CIR air photos are used to study tree shadow characteristics of Savannah vegetation. Results from this investigation are used to explain the concept of the darkening effect, prevalent on Savannah environments. A model is presented to show the effect of tree shadows on brightness values and on NDVI measured by satellites.

International audience; 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 , socioeconomic 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 todesertification 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.

It is increasingly recognised that tackling land degradation through more sustainable land management depends on incorporating multiple perspectives by using a variety of methods at multiple scales, including the perspectives of those who manage and/or use the land. This paper reports experience implementing a previously proposed methodological framework that is designed to facilitate knowledge sharing between researchers and stakeholders about land degradation severity and extent, and sustainable land management options. Empirical findings are presented from the Botswana site of the EU-funded Desertification Mitigation and Remediation of Land project. The paper reflects upon the challenges and benefits of the proposed framework and identifies a number of benefits, notably related to insights arising from the integration of local and scientific knowledge, and the ownership of the sustainable land management strategies that emerged from the process. However, implementing the framework was not without challenges, and levels of poverty and formal education may limit the implementation of the framework in some developing world contexts