Regional‐scale above‐ground biomass (AGB) estimates of tropical savannas and woodlands are highly uncertain, despite their global importance for ecosystems services and as carbon stores. In response, we collated field inventory data from 253 plots at four study sites in Cameroon, Uganda and Mozambique, and examined the relationships between field‐measured AGB and cross‐polarized radar backscatter values derived from ALOS PALSAR, an L‐band satellite sensor. The relationships were highly significant, similar among sites, and displayed high prediction accuracies up to 150 Mg ha−1 (±∼20%). AGB predictions for any given site obtained using equations derived from data from only the other three sites generated only small increases in error. The results suggest that a widely applicable general relationship exists between AGB and L‐band backscatter for lower‐biomass tropical woody vegetation. This relationship allows regional‐scale AGB estimation, required for example by planned REDD (Reducing Emissions from Deforestation and Degradation) schemes.

Summary1. In many countries, areas delineated for conservation purposes can only achieve their objectives if effective law enforcement occurs within them. However, there is no method currently available to allocate law enforcement effort in a way that protects species and habitats in a cost-effective manner. Law enforcement is expensive and effort is usually concentrated near the locations of patrol stations where rangers are based. This hampers effective conservation, particularly in large protected areas, or regions with limited enforcement capacity. 2. Using the spatial planning tool Marxan, we demonstrate a method for prioritizing law enforcement in a globally important conservation landscape (the Greater Virunga Landscape, GVL, in central Africa) using data on the spatial distribution of illegal activities and conservation features within the landscape. 3. Our analysis of current patrol data shows that law enforcement activity is inadequate with only 22% of the landscape being effectively patrolled and most of this activity occurring within 3 km of a patrol post. We show that the current patrol effort does not deter illegal activities beyond this distance. 4. We discover that when we account for the costs of effective patrolling and set targets for covering key species populations and habitats, we can reduce the costs of meeting all conservation targets in the landscape by 63%, to $2Á2-3Á0 million USD, relative to the cost of patrolling the entire landscape. This cost is well within the current expenditure of approximately $5Á9 million USD for the GVL but would better target effort from both patrol posts and mobile patrol units in the landscape. 5. Synthesis and applications. Our results demonstrate a method that can be used to plan enforcement patrolling, resulting in more cost-efficient prevention of illegal activities in a way that is targeted at halting declines in species of conservation concern.

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Abstract. Forest-woodland-savannah mosaics are a common feature in the East African landscape. For the conservation of the woody species that occur in such landscapes, the species patterns and the factors that maintain it need to be understood. We studied the woody species distribution in a forest-woodland-savannah mosaic in Budongo Forest Reserve, Uganda. The existing vegetation gradients were analyzed using data from a total of 591 plots of 400 or 500 m 2 each. Remotely sensed data was used to explore current vegetation cover and the gradients there in for the whole area. A clear species gradient exists in the study area ranging from forest, where there is least disturbance, to wooded grassland, where frequent fire disturbance occurs. Most species are not limited to a specific part of the gradient although many show a maximum abundance at some point along the gradient. Fire and accessibility to the protected area were closely related to variation in species composition along the ordination axis with species like Cynometra alexandri and Uvariopsis congensis occurring at one end of the gradient and Combretum guenzi and Lonchocarpus laxiflorus at the other. The vegetation cover classes identified in the area differed in diversity, density and, especially, basal area. All vegetation cover classes, except open woodland, had indicator species. Diospyros abyssinica, Uvariopsis congensis, Holoptelea grandis and all Celtis species were the indicator species for the forest class, Terminalia velutina and Albizia grandbracteata for closed woodland, Grewia mollis and Combretum mole for very open woodland and Lonchocarpus laxiflorus, Grewia bicolor and Combretum guenzi for the wooded grassland class. Eleven of the species occurred in all cover classes and most of the species that occurred in more than one vegetation cover class showed peak abundance in a specific cover class. Species composition in the study area changes gradually from forest to savannah. Along the gradient, the cover classes are distinguishable in terms of species composition and vegetation structure. These classes are, however, interrelated in species composition. For conservation of the full range of the species within this East African landscape, the mosaic has to be managed as an integrated whole. Burning should be varied over the area with the forest not being burnt at all and the wooded grassland burnt regularly. The different vegetation types that occur between these two extremes should be maintained using a varied fire regime.