Loss of tropical forests and changes in land-use/land-cover are of growing concern worldwide. of forest cover occurred mainly in areas characterized by insecure property rights, while areas with well-defined property rights showed either regenerating or stable forest cover. The results thus corroborate our hypothesis. The large-scale spontaneous regeneration dominated by native endemic species appears to be a result of a combination of changes in precipitation, migration and decreased human population and livestock grazing pressure, but under conditions of maintained and well-defined property rights. Our study emphasizes the large capacity of a semi-arid system to spontaneously regenerate, brought on by decreased pressures, but where existing interpersonal institutions mitigate other drivers of deforestation and option land-use. Introduction Loss of tropical forests and changes in land-use/land-cover affect climate and environmental change at global scales and are of growing concern worldwide [e.g. 1], [2]. However, estimates of tropical DPC4 forest loss and changes in land-cover are still uncertain and 2062-84-2 IC50 a 50% margin of error appears possible [1], [3]. Not only are rates of deforestation uncertain, but there is also little knowledge about tropical forest regeneration rates [3]. Achard et al. [1] estimated that at a global level, the annual regrowth area of humid tropical forest is usually 1 million ha compared with the annual forest loss of 5.8 million ha. In other words, annual regeneration may correspond to roughly 20% of the total area of deforestation in the humid tropics. In spite of this, surprisingly little is known about regeneration in terms of functional aspects of biodiversity and generation of ecosystem services for local and regional human consumption and use [e.g. 4], [5]. The local interpersonal institutional context is usually increasingly emphasized in analyses of drivers of forest cover change [6]C[9], with stable forest cover (i.e. effective protection) often found to be a function of strength and enforcement of local social institutions [9]. Although we have some knowledge about the institutional context in which tropical forest loss is usually embedded [2], [6], [10], little is known about the role of social institutions (sensu Ostrom [11]) in influencing rates of tropical forest regeneration, especially at the local scale [12]. In Madagascar, the rate of total deforestation has been estimated to be high and thought to be a result of a rapidly growing human population and the use of fire as a farming practice [13]. Recent research has, however, challenged both the dramatic deforestation scenarios [e.g. 14], [15] as well as the conventional view that blames farmers for mismanaging natural resources [e.g. 6], [16]. Current estimates of the remaining wet and moist forest cover are significantly higher than estimates published in the 1980’s and recent analyses suggest that the island was only partly covered with forest in pre-human occasions [13]. Further, recent studies reveal a temporally as well as spatially much more complex relationship between human population densities and forest loss than was previously assumed [13], [16]. The dry forest of the semi-arid south and southwest of Madagascar harbors the highest level of herb endemism in Madagascar with 48% of the genera and 95% of the species endemic [17], [18]. The area is also listed as one of the 200 most important ecological regions in the world [19]. Arid conditions have resulted in a historically less intensive slash and burn agriculture and natural fires are infrequent in this system [17]. Since the early 1970’s, the dry forest cover has been reported as declining, principally due to clearing for agriculture, cattle herding, timber harvest and charcoal production [20], [21]. Despite global recognition of the value of the southern dry forest, there have been surprisingly few studies on forest cover changes or effects of anthropogenic impacts [22]. 2062-84-2 IC50 Furthermore, and in contrast to other types of forests in Madagascar there are only a few, small areas of dry forest formally 2062-84-2 IC50 under protection [23]. Informal institutions are, however, playing an important role in southern Madagascar to protect these forest ecosystems [24]. In the present study we used Landsat images from southern Madagascar from three different years.