Search

This study investigates the relationships among seed dispersal, patterns of seedling recruitment and the spatial distribution of a pioneer tree (Hortia arborea, Rutaceae) in the Brazilian Atlantic forest. The study was carried out at Dois Irmaos Reserve, a 387.4 ha reserve in northeastern Brazil. Fruit shadow concentrated beneath parental trees (74.6 % < 6 m distant) and fruit removal averaged 5.6 % (0 - 25.5 %). Agoutis (Dasyprocta prymnolopha, Rodentia) ate fruits in the forest and in captivity and were the only vertebrates recorded feeding on Hortia fruits. Agoutis, however, destroyed 86.7 % of the seeds they ingested. In addition, only one seed from an expected number of 1980 germinated in a treefall gap after it passed through the digestive tract of agoutis. Both seed germination and seedling recruitment were restricted to gaps, and occurred among seeds manually released from the pulp or among those from fruits that naturally rotted in gaps. Moreover, exposed seedlings were taller than those covered by plants in a gap. H. arborea appears to self-maintain populations in the same patches of forest, which are delimited by a pool of old and newly created gaps. More specifically, there is successful recruitment in patches occupied by parents, resulting in dense clumps of H. arborea.

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼40,000 and ∼53,000, i.e. at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

In many human-modified tropical landscapes, biodiversity conservation and the provision of ecosystem services require large-scale restoration initiatives. Such initiatives must be able to augment the amount and the quality of remaining natural habitats. There is thus a growing need for long-term, multi-stakeholder and multi-purpose initiatives that result in multiple ecological and socioeconomic benefits at the biome scale. The Atlantic Forest Restoration Pact (AFRP) is a coalition of 260+ stakeholders, including governmental agencies, private sector, NGOs and research institutions, aimed at restoring 15 million ha of degraded and deforested lands by 2050. By articulating, and then integrating common interests, this initiative has allowed different sectors of society to implement an ambitious vision and create a forum for public and private concerns regarding forest restoration. The AFRP adopts a set of governance tools so multiple actors can implement key processes to achieve long-term and visionary restoration goals. Having overcome some initial challenges, AFRP now has to incorporate underrepresented stakeholders and enhance its efforts to make forest restoration more economically viable, including cases where restoration could be less expensive and profitable. The AFRP experience has resulted in many lessons learned, which can be shared to foster similar initiatives across tropical regions.

Amazonian rainforests sustain some of the richest tree communities on Earth, but their ecological and evolutionary responses to human threats remain poorly known. We used one of the largest experimental datasets currently available on tree dynamics in fragmented tropical forests and a recent phylogeny of angiosperms to test whether tree communities have lost phylogenetic diversity since their isolation about two decades previously. Our findings revealed an overall trend toward phylogenetic impoverishment across the experimentally fragmented landscape, irrespective of whether tree communities were in 1-ha, 10-ha, or 100-ha forest fragments, near forest edges, or in continuous forest. The magnitude of the phylogenetic diversity loss was low (

With the decreasing affordability of protecting large blocks of pristine tropical forests, ecologists have staked their hopes on the management of human-modified landscapes (HMLs) to conserve tropical biodiversity. Here, we examine key forces affecting the dynamics of HMLs, and propose a framework connecting human disturbances, land use, and prospects for both tropical biodiversity and ecosystem services. We question the forest transition as a worldwide source of new secondary forest; the role played by regenerating (secondary) forest for biodiversity conservation, and the resilience of HMLs. We then offer a conceptual model describing potential successional trajectories among four major landscape types (natural, conservation, functional, and degraded) and highlight the potential implications of our model in terms of research agendas and conservation planning.

Rainforests are undergoing severe deforestation and fragmentation worldwide. A huge amount of small forest patches are being created, but their value in conserving biodiversity and forest structure is still controversial. Here, we demonstrate that in a species-rich and moderately-managed Mexican tropical landscape small rainforest patches (

In human-modified tropical landscapes, biodiversity is threatened by a myriad of forces, including habitat loss and fragmentation, land degradation, overexploitation of forest resources, and biological invasions. Ecological restoration offers a promising way to enhance biodiversity persistence and the delivery of ecosystem services by: 1) establishing structural elements in the landscape to enhance connectivity, 2) providing additional forest cover, 3) restoring degraded forest remnants through protection from human-mediated disturbances and reestablishment of successional trajectory, and 4) supporting sustainable socio-economic development in marginalized rural communities, where the lack of job opportunities drives deforestation, forest degradation, and overexploitation. Due to biodiversity requirements, however, this potential will only be realized if restoration is carried out on very large spatial scales. Although conservation biologists have historically doubted the potential of ecological restoration to reverse ecosystem degradation and mitigate species loss, we argue that conservation policies and programs should include restoration among the strategies adopted to mitigate extinction debts and support the creation of biodiversity friendly-landscapes. Otherwise, we will likely continue to describe a slow and irreversible loss of our biological heritage in isolated protected areas in human-modified tropical landscapes.

In this study we assessed the seedling assemblages of a large fragment of the Atlantic forest to test 2 hypotheses: (1) seedling abundance and richness are lower in the forest edge (0–200 m) than in the forest interior (>250 m); and (2) large-seeded seedlings (seeds >1.5 cm) are the main group affected by edge creation. The study was car ried out at the Coimbra forest, an old, 3500-ha fragment surrounded by sugar cane plantations in northeast Brazil. The seedling survey was based on 200-m-long transects along which 420 plots of 1-m2 were set up per habitat and per season (dry and rainy). Within the plots, all shrub, tree, palm, and liana species seedlings ≤ 50 cm tall were counted and classified to morphospecies level. A total of 13 208 seedlings were recorded in the whole survey. At plot level, forest edge and interior showed similar scores for both average seedling density (4.7–11.2 seedlings·m−2) and richness (2.8–5.1 species·m−2) irrespective of season. At community level, however, scores for...

Globally, human populations are rapidly converting large blocks of tropical old-growth forests into ragged quilts of small forest patches, embedded within human-modified landscapes, consisting mostly of agricultural fields and pasture lands (Chazdon et al. 2009). Such landscapes impose a myriad of threats to native biodiversity, including those related to habitat loss and fragmentation, overexploitation of forest resources and matrix-mediated perturbations (Gardner et al. 2009). As human-modified landscapes exhibit increasing levels of biotic impoverishment and homogenization (Lobo et al. 2011), scientists, environmentalists, and policy makers are looking for a modus vivendi between conservation and ongoing human demands for land (Phalan et al. 2011).

Here we describe the seed shadow, seedling recruitment, ontogenetic structure and spatial distribution of Buchenavia capitata (an emergent canopy tree) in a 380-ha fragment of the Atlantic forest in northeast Brazil. In particular, we examine seed distribution around 10 parental trees and both seedling recruitment and mortality, during an 18 month period beneath and around parental trees. Moreover, we describe: (1) B. capitata occurrence within treefall gaps; (2) population structure in terms of ontogenetic stages for the whole site; and (3) spatial distribution of adults within an area of 51 hectares. 99% of seeds were found beneath parent crowns (n = 4,236) and seed density reached 14.6 ± 29.9 seeds/m² (0-140 seeds/m²). 49% of all seeds germinated but seedling mortality reached 100% after an 18 month period. In addition, saplings of B. capitata were not found in forest understory and within 30 treefall gaps (94-2,350 m²). The adults showed an average DBH of 69.3 ± 22.1 cm, were 19.2 ± 2.9 m tall and presented a clumped spatial distribution. B. capitata matched some of the features presented by shade intolerant trees or large-gap specialists, and we hypothesize that low rates or even lack of long distance seed dispersal events may be reducing the probability of B. capitata seeds reaching suitable habitats for successful seedling recruitment and growth. Because of that (1) seedlings face high levels of early mortality; (2) there is no sapling recruitment at the study site; and (3) local population faces senility and it is threatened by local extinction.