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Land occupation and management systems have defined fire regimes and landscapes for millennia. The savanna biome is responsible for 86% of all fire events, contributes to 10% of the total carbon emissions annually and is home to 10% of the human population. European colonization has been associated with the implementation of fire suppression policies in many tropical savanna regions, markedly disrupting traditional fire management practices and transforming ecosystems. In this paper we assess savanna burning approaches from pre-colonial to contemporary eras in three regions: northern Australia, southern Africa and Brazil. In these regions, fire suppression policies have led to (i) conflicts between government authorities and local communities; (ii) frequent late dry season wildfires and/or (iii) woody encroachment. Such consequences are facilitating changes to fire management policies, including recognition and incorporation of traditional ecological knowledge in contemporary community-based adaptive savanna fire management. Such programs include implementation of prescribed early dry season fires and, in some regions, generating income opportunities for rural and traditional communities through the reduction of late dry season wildfires and associated greenhouse gas emissions. We present a brief history of fire management policies in these three important savanna regions, and identify ongoing challenges for implementation of culturally and ecologically sustainable fire management policies.

Land use changes affect the abundance of plants, and even when plants are spared in agroecosystems, they are further impacted by management practices. Knowing how populations are impacted and the factors affecting them in the landscape is a major challenge in ecosystems under intense land use conversion, an even more important task when the plant is important for livelihoods. To understand how anthropogenic and environmental factors affect plant abundance and the population structure of Annona crassiflora, an important wild fruit tree of Cerrado, we evaluated populations in a gradient of anthropogenic and environmental conditions. Our sampling ranged from well-preserved sites, in natural areas, to highly disturbed pastures in the agroecosystems, covering an extensive area of the Cerrado biome. Results indicate that vegetation thinning and the presence of cattle negatively affect the abundance of small plants. High frequency of thinning and large cattle herds prevent recruitment of small plants in pastures, which may drive populations to local extinction in these sites. Reducing the frequency and intensity of vegetation thinning and cattle herd size may allow the recruitment of small plants into higher life stages. Fruit harvesting, which is positively associated with plant abundance, can continue to be practiced.

O presente trabalho aborda a questão dos ecossistemas e o reflorestamento para a restauração ecológica e a preservação da biodiversidade.

The palm Syagrus coronata plays an important ecological role in the caatinga ecosystems and is a source of income and livelihood for rural communities in semiarid northeastern Brazil. Despite its ecological and socioeconomic importance, little is known about the environmental factors determining its geographic distribution. The main goals of this study were to investigate the influence of climatic and environmental factors on the geographic distribution of S. coronata and to evaluate the conservation status within its potential distribution area. We modeled the fundamental niche of S. coronata using the MaxEnt algorithm and assessed the degree of vulnerability of environmental suitability areas quantifying the representativeness of protected areas and the different land use and land cover classes. Results predicted that the distribution of S. coronata is determined mainly by seasonality of precipitation and precipitation of the coldest quarter of the year. The areas of suitability, despite their large geographical extent, showed a high degree of environmental vulnerability, mainly due to the high conversion rate of native vegetation areas into agriculture and livestock and the low representation of protected areas. The results indicate a low effectiveness of the system of conservation units to protect the species, with anthropogenic disturbances threatening the quality of habitats and the persistence of S. coronata populations. Results can be used to support actions for the conservation and management of S. coronata, as well as decision making on the design of protected areas.

In this study, we review the current available information on the social-ecological context of Brazilian tropical dry forests (TDFs), a vegetation type that covers approximately 3% of the country territory. For this purpose, we conducted a comparative analysis of two case studies, one study in the north of Minas Gerais state and the other in Parana River Basin, situated in southeastern and central Brazil, respectively. We compiled published bibliographical and census-based data for the two regions, concerning the historical human occupation and land use and the environmental and development policies affecting TDF management and sustainable use. Brazilian TDFs usually occur in semi-arid climates, and have been intensely converted mainly to extensive pasturelands in large farms, thus leading to high income concentration in those areas. Our case studies involve less-developed regions that support populations with very low human development indices, which is the norm for Brazilian TDFs. Many of these are traditional populations, such as indigenous and slave descendents, with peculiar cultural practices only recently considered in government policies proposed for the forest management. Though the two regions have similar land use histories, current social-ecological scenarios are very different. In the north of Minas Gerais, TDF conversion policies were debated intensely for the last 15 years, recently resulting in a state law specifically generated to regulate TDF use. Also, this region has 20 conservation units (CUs), some of them delimited inside the territories of the several traditional populations that inhabit TDF areas. This process caused enduring conflicts that can affect both CUs' effectiveness and the sustenance of these populations. In the Parana River Basin, there is no specific policy towards TDFs, whose use is regulated by the 43-year-old Brazilian Federal Forest Code. There are only four CUs in this region, and most traditional populations were expelled from their original territories and consequently lost their cultural identity. Government sustainability strategies are limited to the establishment of CUs, a response that may disregard social demands and cultural practices, depending on the local context. Given the uniqueness and threat level to TDFs, specific and more diversified policies towards land use should be established for these ecosystems in order to stimulate low-impact activities that maintain ecosystem services and improve the livelihoods of TDF inhabitants.

We examined the following hypotheses: (i) seeds of dry forest trees have high pre- and post-germination mortality by desiccation due to the time between seed dispersal and germination and to irregular rains at the onset of the rainy season; (ii) seedlings from seeds dispersed in the dry season which survive the dry spells are larger at the end of the first rainy season than those dispersed in the rainy season because the former have more time to grow. We evaluated the possible trade-off between few large seedlings (resulting from natural dispersal) × many small seedlings (resulting from delayed dispersal) on seedling survival during the dry season. We sowed eight tree species in a greenhouse in September, simulating the natural dispersal timing (before the rains), and in November, when rains are more constant. Because shading can counteract the effects of desiccation, we applied three levels of shade (10%, 40% and 72% of PPFD). From September 2005 to December 2006, we provided the daily precipitation of a median year from a major patch of dry forest in Central Brazil. At the end of the rainy season, a subset of seedlings was collected for growth measurements (dry mass) and the remainder was left to follow the dry season survivorship. The lower germination expected for seeds dispersed in the dry season and in full sun was not confirmed for species that had some dormancy. The delayed dispersal was advantageous for the initial establishment of fast germinating species, but it was irrelevant or even disadvantageous for others. Also, the greenhouse weather was certainly milder than the natural environment, reducing the potential for mortality by desiccation. The growth of the four species of higher dormancy were not affected by timing of seed dispersal, while three out of four fast germinating species had higher root biomass when dispersed in the dry season. The growth during the rainy season did not affect seedling survival during the dry season. Keeping seeds to sow when rain is constant might be a good strategy to increase the establishment of fast-germinating tree species.

We assessed seed fate of six tree species in a seasonally deciduous forest of Central Brazil. Seed germination, predation, removal and death caused by pathogens or dessication were followed in an undisturbed forest site, a logged forest site, and an active pasture. In both forest types we sowed seeds under patches of liana tangles (Low Forest habitat) and under patches of mature forest (High Forest habitat). Seeds were monitored weekly for up to 8 months. Overall, small-seeded species ( Astronium fraxinifolium and Tabebuia impetiginosa ) had high germination, although germination was lower in the pasture due to insect predation. The hard-coated seeds of Erythrina sp. had higher germination rates in the pasture. The large-seeded Cavanillesia arborea and Swartzia multijuga had high seed removal (ca. 90%) in the pasture and under High Forest, but only 23–34% under Low Forest in the logged site. Lower removal of large seeds in Low Forest suggests that this habitat conceals the seeds and constrains the movement of large mammals. Both species were favored in Low Forest, suggesting that caution should be used when managing lianas. When protected from predation, seeds with a soft coat and high water content, such as the seeds of Eugenia dysenterica and S. multijuga , died from desiccation in the pasture. Restoration efforts must take into consideration high mortality caused by desiccation or insect predation in abandoned pastures of dry forests.