We review strategies of sexual and asexual reproduction and persistence in plants of flood-prone Central Amazonia. Adaptations in response to the strong instability of these environments are highlighted together with the importance of river connectivity for species dispersal and persistence.
This review presents the current knowledge regarding South American wetlands and summarizes major outcomes of the implementation of the Ramsar Convention on Wetlands of International Importance for the South American continent. South America is the wettest continent on Earth, with wetlands accounting for ∼20% of its area. Wetlands harbor an exceptional rich biodiversity also including many endemic plant and animal species. They provide numerous ecosystem services in terms of provisioning material goods, regulating biogeochemical cycles, providing habitat, sustaining cultural practices, and importantly, contributing to the maintenance and generation of regional biodiversity. Major threats to wetlands include agroindustrial expansion, deforestation, soil erosion, mining, pollution, inadequate resource use, and large infrastructural projects such as reservoir construction for hydropower. South American countries were slow in adopting definitions, delineations, and classifications of their wetlands and in inventorying wetlands according to their extent and ecological characteristics. However, Ramsar sites are increasing continuously in both numbers and extent, covering 113 sites, totaling an area of ∼373,000 km 2. Threats to wetlands and Ramsar sites are ongoing, mainly because of the lack of specific national wetland policies, limited financial and human resources, general lack of infrastructure, and limited monitoring capacity. The process of changing perceptions on the value of wetlands and their ecosystem services is improving, but it could be hastened by improved infrastructure and cooperation between Ramsar sites, wetland scientists, and local stakeholders. Outreach to raise awareness of societies, administrators, and governments of the critical importance of wetlands continues to be a major challenge for the conservation of South American wetlands.
No abstract
Wetlands harbor an important compliment of regional plant diversity, but in many regions data on wetland diversity and composition is still lacking, thus hindering our understanding of the processes that control it. While patterns of broad-scale terrestrial diversity and composition typically correlate with contemporary climate it is not clear to what extent patterns in wetlands are complimentary, or conflicting. To elucidate this, we consolidate data from wetland forest inventories in Brazil and examine patterns of diversity and composition along temperature and rainfall gradients spanning five biomes. We collated 196 floristic inventories covering an area >220 ha and including >260,000 woody individuals. We detected a total of 2,453 tree species, with the Amazon alone accounting for nearly half. Compositional patterns indicated differences in freshwater wetland floras among Brazilian biomes, although biomes with drier, more seasonal climates tended to have a larger proportion of more widely distributed species. Maximal alpha diversity increased with annual temperature, rainfall, and decreasing seasonality, patterns broadly consistent with upland vegetation communities. However, alpha diversity-climate relationships were only revealed at higher diversity values associated with the uppermost quantiles, and in most sites diversity varied irrespective of climate. Likewise, mean biome-level differences in alpha-diversity were unexpectedly modest, even in comparisons of savanna-area wetlands to those of nearby forested regions. We describe attenuated wetland climate-diversity relationships as a shifting balance of local and regional effects on species recruitment. Locally, excessive waterlogging strongly filters species able to colonize from regional pools. On the other hand, increased water availability can accommodate a rich community of drought-sensitive immigrant species that are able to track buffered wetland microclimates. We argue that environmental conditions in many wetlands are not homogeneous with respect to regional climate, and that responses of wetland tree communities to future climate change may lag behind that of non-wetland, terrestrial habitat.
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