Skip J. Van Bloem Department of Agronomy PO Box 9030 UPR Mayaguez Mayaguez, Puerto Rico 00680 787 832-4040, x 2118, x 2442 svanbloem@uprm.edu
Ariel E. Lugo International Institute of Tropical Forestry USDA Forest Service 1201 Ceiba Street Jardin Botanico Sur Rio Piedras, Puerto Rico 00926-1119 787 766-5335 alugo@fs.fed.us
This RFI provides the scientific rationale for the selection of sites within the Atlantic Neotropical (NeoNEON) domain (Fig. 1). All of our proposed sites are part of one or more continental-level RFI’s - specifically hurricanes, sea level raise, urbanization, climate change, drought, and invasive species. As indicated in the ISEP, global change is leading to changes in ecosystem function, hydroecological relationships, the distribution of plant and animal species, and the structure and composition of ecosystems. The future distribution and performance of organisms and ecosystems will be determined by the range and seasonality of temperature and precipitation, the intensity and frequency of large, infrequent disturbances such as hurricanes, and human alteration of ecosystems. These are factors that we are particularly well situated to assess. While our sites function as part of continental scale questions, they also provide opportunities to address additional NEON-level hypotheses within the NeoNEON domain. The main question that we address with these sites is: What is the nature of the synergy between natural and anthropogenic disturbances and what effects do these disturbances have on the biota, ecosystem function, and landscape of Neotropical islands? We address this question with the Domain and Continental toolboxes to test the following hypotheses:
H1. Climate and land use change will have large effects on ecosystem function, particularly in the pulsing and patchiness of nutrient availability and increasing the patchiness of species distribution. This will cause short term “leakiness” in systems. In the long term, species composition will adjust to return ecosystem function to a dynamic equilibrium, but this state will most likely be reached by a combination of native and introduced species. The resulting species community and ecosystem function are likely to exhibit characteristics that are unfamiliar to humans using or relying on the ecosystem.
H2. Increased rainfall variability and night temperatures will determine coupling, intensity, and frequency of nutrient availability to plants, phenological patterns, and plant-animal interactions.
H3. Land-use changes will have greater influence than climate change alone on decadal scales for biogeochemical processes and changes in species composition.
H4. Spatial and temporal variability in physical factors associated with climate change (i.e., temperature, ET) and biological responses to these factors (i.e., nutrient cycling, productivity, etc.) will increase as land use intensity increases.
H5. Severity of natural disturbance (e.g., hurricane, disease outbreaks) effects will increase as land use intensity increases. More wild systems will be more resistant and resilient to disturbance.
H6. Following large-scale, intensive disturbances, non-native species will increase their dispersal and coexist with native species.
H7. Highly variable discharges increase the rates of dispersal of non-native riparian and aquatic species that will alter spatial distributions of native species.
Collectively, these hypotheses address all seven NEON grand challenges as follows:. biodiversity (H1, H4, H6, H7), biogeochemical cycles (H1, H2, H4), climate change (H1, H2, H3, H4), hydroecology (H3, H7), infectious disease (H1, H5), invasive species (H1, H6, H7), and land use (H1, H3, H5).