Improving Planting Stocks for the Brazilian Atlantic Forest Restoration through Community-Based Seed Harvesting Strategies

High-diversity reforestation can help jumpstart tropical forest restoration, but obtaining viable seedlings is a major constraint: if nurseries do not offer them, it is hard to plant all the species one would like. From 2007 to 2009, we investigated five different seed acquisition strategies employed by a well-established tree nursery in southeastern Brazil, namely (1) in-house seed harvesters; (2) hiring a professional harvester; (3) amateur seed harvesters; or (4) a seed production cooperative, as well as (5) participating in a seed exchange program. In addition, we evaluated two strategies not dependent on seeds: harvesting seedlings from native tree species found regenerating under Eucalyptus plantations, and in a native forest remnant. A total of 344 native tree and shrub species were collected as seeds or seedlings, including 2,465 seed lots. Among these, a subset of 120 species was obtained through seed harvesting in each year. Overall, combining several strategies for obtaining planting stocks was an effective way to increase species richness, representation of some functional groups (dispersal syndromes, planting group, and shade tolerance), and genetic diversity of seedlings produced in forest tree nurseries. Such outcomes are greatly desirable to support high-diversity reforestation as part of tropical forest restoration. In addition, community-based seed harvesting strategies fostered greater socioeconomic integration of traditional communities in restoration projects and programs, which is an important bottleneck for the advance of ecological restoration, especially in developing countries. Finally, we discuss some of the limitations of the various strategies for obtaining planting stocks and the way forward for their improvement.

Responses of transplanted native tree species to invasive alien grass removals in an abandoned cattle pasture in the Lacandon region, Mexico

We tested the early performance of 16 native early-, mid-, and late-successional tree species in response to four intensities of grass removal in an abandoned cattle pasture dominated by the introduced, invasive African grass, Cynodon plectostachyus, within the Lacandon rainforest region, southeast Mexico. The increase in grass removals significantly improved the performance of many species, especially of early-and mid-successional species, while performance of late-successional species was relatively poor and did not differ significantly among treatments. Good site preparation and at least one additional grass removal four months after seedling transplant were found to be essential; additional grass removals led to improved significantly performance of saplings in most cases. In order to evaluate the potential of transplanting tree seedlings successfully in abandoned tropical pastures, we developed a "planting risk index", combining field performance measurements and plantation cost estimations. Our results showed a great potential for establishing restoration plantings with many early-and mid-successional species. Although planting risk of late-successional species was considered high, certain species showed some possibilities of acclimation after 18 months and should be considered in future plantation arrangements in view of their long-term contributions to biodiversity maintenance and also to human welfare through delivery of ecosystem services. Conducting a planting risk analysis can help avoid failure of restoration strategies involving simultaneous planting of early-, mid-, and late-successional tree species. This in turn will improve cost-effectiveness of initial interventions in large-scale, long-term restoration programs.

Testing the Performance of Fourteen Native Tropical Tree Species in Two Abandoned Pastures of the Lacandon Rainforest Region of Chiapas, Mexico

The rainforest of Mexico has been degraded and severely fragmented, and urgently require restoration. However, the practice of restoration has been limited by the lack of species-specific data on survival and growth responses to local environmental variation. This study explores the differential performance of 14 wet tropical early-, mid- or late-successional tree species that were grown in two abandoned pastures with contrasting land-use histories. After 18 months, seedling survival and growth of at least 7 of the 14 tree species studied were significantly higher in the site with a much longer history of land use (site 2). Saplings of the three early-successional species showed exceptional growth rates. However, differences in performance were noted in relation to the differential soil properties between the experimental sites. Mid-successional species generally showed slow growth rates but high seedling survival, whereas late-successional species exhibited poor seedling survival at both the study sites. Stepwise linear regressions revealed that the species integrated response index combining survivorship and growth measurements, was influenced mostly by differences in soil pH between the two abandoned pastures. Our results suggest that local environmental variation among abandoned pastures of contrasting land-use histories influences sapling survival and growth. Furthermore, the similarity of responses among species with the same successional status allowed us to make some preliminary site and species-specific silvicultural recommendations. Future field experiments should extend the number of species and the range of environmental conditions to identify site generalists or more narrowly adapted species, that we would call sensitive.

Tree species richness, does it play a key role on a forest restoration plantation?

The Brazilian Atlantic forest is considered one of the world's biodiversity conservation hotspot. Today there is less than ten percent remaining. Therefore it is necessary to restore these ecosystems. There are many ways of achieving restoration's main goals, but there is a lack of ecological studies that analyzes tree species richness as a variable. Thus, this study's goal is to investigate if there is a difference between a forest restoration in a gradient of tree species richness that varies from 20, 60 to 120 species, by using the litterfall as an indicator. Every month, for one year the forest litter was collected from litter traps that were previously installed. Results revealed that stands produced litterfall by the increasing gradient of species was of 5,370, 5,909 and 6,432 kg ha(-1) yr(-1). The statistical analyses revealed no significant difference among them. Therefore this six-year-old forest restoration plantation shows no difference on the litter production by the tree species richness.