Helmer E.H.,International Institute of Tropical Forestry |
Ruzycki T.S.,Colorado State University |
Wunderle J.M.,International Institute of Tropical Forestry |
Vogesser S.,Colorado State University |
And 4 more authors.
Remote Sensing of Environment | Year: 2010
Remote sensing of forest vertical structure is possible with lidar data, but lidar is not widely available. Here we map tropical dry forest height (RMSE=0.9m, R 2=0.84, range 0.6-7m), and we map foliage height profiles, with a time series of Landsat and Advanced Land Imager (ALI) imagery on the island of Eleuthera, The Bahamas, substituting time for vertical canopy space. We also simultaneously map forest disturbance type and age. We map these variables in the context of avian habitat studies, particularly for wintering habitat of an endangered Nearctic-Neotropical migrant bird, the Kirtland's Warbler (Dendroica kirtlandii). We also illustrate relationships between forest vertical structure, disturbance type and counts of forage species important to the Kirtland's Warbler. The ALI imagery and the Landsat time series are both critical to the result for forest height, which the strong relationship of forest height with disturbance type and age facilitates. Also unique to this study is that seven of the eight image time steps are cloud-cleared images: mosaics of the clear parts of several cloudy scenes. We created each cloud-cleared image, including a virtually seamless ALI image mosaic, with regression tree normalization. We also illustrate how viewing time series imagery as red-green-blue composites of tasseled cap wetness (RGB wetness composites) aids reference data collection for classifying tropical forest disturbance type and age. Our results strongly support current Landsat Program production of co-registered imagery, and they emphasize the value of seamless time series of cloud-cleared imagery. © 2010.
Wood T.E.,International Institute of Tropical Forestry |
Detto M.,Smithsonian Tropical Research Institute |
Silver W.L.,University of California at Berkeley
PLoS ONE | Year: 2013
Precipitation and temperature are important drivers of soil respiration. The role of moisture and temperature are generally explored at seasonal or inter-annual timescales; however, significant variability also occurs on hourly to daily time-scales. We used small (1.54 m2), throughfall exclusion shelters to evaluate the role soil moisture and temperature as temporal controls on soil CO2 efflux from a humid tropical forest in Puerto Rico. We measured hourly soil CO2 efflux, temperature and moisture in control and exclusion plots (n = 6) for 6-months. The variance of each time series was analyzed using orthonormal wavelet transformation and Haar-wavelet coherence. We found strong negative coherence between soil moisture and soil respiration in control plots corresponding to a two-day periodicity. Across all plots, there was a significant parabolic relationship between soil moisture and soil CO 2 efflux with peak soil respiration occurring at volumetric soil moisture of approximately 0.375 m3/m3. We additionally found a weak positive coherence between CO2 and temperature at longer time-scales and a significant positive relationship between soil temperature and CO2 efflux when the analysis was limited to the control plots. The coherence between CO2 and both temperature and soil moisture were reduced in exclusion plots. The reduced CO2 response to temperature in exclusion plots suggests that the positive effect of temperature on CO 2 is constrained by soil moisture availability. © 2013 Wood et al.
Fonseca da Silva J.,International Institute of Tropical Forestry |
Fonseca da Silva J.,University of Puerto Rico at San Juan
Ecology and Evolution | Year: 2015
Novel forests (NFs)-forests that contain a combination of introduced and native species-are a consequence of intense anthropogenic disturbances and the natural resilience of disturbed ecosystems. The extent to which NFs have similar forest function as comparable native secondary forests is a matter of debate in the scientific community. Little is known about the performance of individual species in those forests. This study focuses on the functional attributes of Castilla elastica NFs in Puerto Rico and on the differences between introduced and native species growing side by side in these forests. Rates of processes measured here were later compared with data from literature about NSFs. I hypothesize that juvenile plants of C. elastica in NFs have higher survival rate than those of native species and that C. elastica trees have faster biomass fluxes than native trees. To test the hypotheses, I measured survival rates of juvenile plants and tree growth and characterized the aboveground litter fluxes and storage. Although juvenile plants of native species displayed higher survival rates than those of C. elastica (53% vs. 28%), the latter was dominant in the understory (96%). Stand biomass growth rate was 2.0 ± 0.4 (average ± one standard deviation) Mg·ha-1·year-1 for the whole forest, and Guarea guidonia, a native species, exhibited the highest tree growth. Total litter fall was 9.6 ± 0.5 Mg·ha-1·year-1, and mean litter standing stock was 4.4 ± 0.1 Mg·ha-1. Castilla elastica litter fall decomposed twice as fast as that of native species (5.8 ± 1.1 vs. 3.03 ± 1 k·year-1). Literature comparisons show that the present NFs differ in some rates of processes from NSFs. This study brings unique and detailed supporting data about the ecological dynamics under mature novel forest stands. Further comprehensive studies about NFs are important to strengthen the body of knowledge about the wide range of variation of emerging tropical ecosystems. Due to the large increase in the area covered by NFs, greater attention is needed to understand their functioning, delivery of ecological services and management requirements. Differences between the introduced naturalized species in a complex and dynamic novel forest. Nature has incredible power to regenerate and rearrange, which may result in surprising novel ecosystems. © 2015 The Authors. Ecology and Evolution Published by John Wiley & Sons Ltd.
Alvarez Ruiz M.,University of Puerto Rico at San Juan |
Lugo A.E.,International Institute of Tropical Forestry
Forest Ecology and Management | Year: 2012
We studied the structure and species composition of nine residual forest stands of Dacryodes excelsa (tabonuco), a dominant vegetation type in the moist and wet lower montane forests of the Caribbean. The stands were scattered over three different landscapes with different degrees of anthropogenic disturbance: forested, shade coffee, and tobacco. We compared our results with data from undisturbed stands inside a protected and forested landscape to see how the type of landscape that surrounded them affected the structure and species composition of the residual forest stands. In the process we sought conservation lessons that would help restore degraded tabonuco forests to original conditions. Tree density, basal area, and species density all increased with elevation. We found 98 tree species, including 50 of the 83 species that we identified as belonging to undisturbed tabonuco forests (including 13 of 18 endemic tree species), 41 tree species not reported for undisturbed tabonuco forests, eight primary forest species, and six introduced species. When ordered by species Importance Value by site, the stands in nine sites separated into three general groups corresponding to landscape type: (1) Heavily used for tobacco production. (2) Shade coffee, and (3) Forested. The importance of introduced species increased, and the abundance of tabonuco forest indicator species and endemic species decreased with increased anthropogenic disturbances. When restoring tabonuco forests, it is necessary to understand the landscape forces that influence the species composition of these forests. It appears that particular species combinations are natural outcomes of the level of anthropogenic activity in the landscape and reversing those tendencies might be impractical or too costly. © 2011.
Abelleira Martinez O.J.,International Institute of Tropical Forestry |
Abelleira Martinez O.J.,University of Puerto Rico at San Juan
Plant Ecology | Year: 2010
There is concern that secondary forests dominated by introduced species, known as novel forests, increase taxonomical similarity between localities and lead to biotic homogenization in human-dominated landscapes. In Puerto Rico, agricultural abandonment has given way to novel forests dominated by the introduced African tulip tree Spathodea campanulata Beauv. (Bignoniaceae). In this study, I characterized the tree species composition of S. campanulata forests in Puerto Rico as means to evaluate if biotic homogenization is occurring. Non-metric multidimensional scaling was used to examine what variables were related to the large (≥10 cm diameter at breast height [DBH]), small (≥2.5 to <10 cm DBH), and juvenile (<2.5 cm DBH) tree species composition of 20 sites. Species composition was strongly related to substrate properties, less related to land use history, and unrelated to spatial attributes. The introduced species component was low (mean = 17%, S. E. = 1.8) and compositional differences were mostly due to native tree species of secondary to old growth forests on equivalent substrates. Animals appear to disperse most species (86%) into these forests yet because of this some introduced species will persist. Although uncommon species were largely absent, recent species establishment is shaped by substrate properties making biotic homogenization in these forests unlikely. The S. campanulata forests of Puerto Rico facilitate native tree species establishment in lands where poor management practices extirpated the original forest. These results highlight the importance of remnant old growth forests or trees that act as seed dispersal sources and facilitate native species recovery in novel forests. © 2010 US Government Employee.
Mercado-Diaz J.A.,International Institute of Tropical Forestry |
Lucking R.,University of Illinois at Chicago |
Parnmen S.,Ministry of Public Health
Phytotaxa | Year: 2014
Two new genera and twelve new species of Graphidaceae are described from Puerto Rico. The two new genera, Borinquenotrema and Paratopeliopsis, are based on a combination of molecular sequence data and phenotype characters. Borinquenotrema, with the single new species B. soredicarpum, features rounded ascomata developing beneath and persistently covered with soralia and with an internal anatomy reminescent of Carbacanthographis; it is close to the tribe Ocellularieae. Paratopeliopsis, including the single new species P. caraibica, resembles a miniature Topeliopsis but differs in the distinctly farinose thallus and the small, brown ascospores; it is not closely related to the latter genus but belongs in tribe Thelotremateae. The other ten new species belong in the genera Acanthotrema, Clandestinotrema, Compositrema, Fissurina, Ocellularia, and Thalloloma. Acanthotrema alboisidiatum is closely related to A. brasilianum but differs in the short, white isidia resembling insect eggs. Clandestinotrema portoricense has a unique ascospore type with a longitudinal septum only in the proximal cell. Compositrema borinquense resembles a species of Stegobolus but belongs in Compositrema based on sequence data, and is characterized by ascomata with a unique columella composed of thick, irregularly radiating strands. The second new species in this genus, C. isidiofarinosum, differs by its ecorticate, farinose thallus with scattered, corticate isidia and by its small ascomata with inconspicuous columella. The three new species of Fissurina all have 3-septate ascospores and are otherwise characterized by an isidiate thallus and stellate, orange-yellow lirellae (F. aurantiacostellata), a verrucose thallus strongly encrusted with calcium oxalate crystals and white, irregularly branched lirellae (F. crystallifera), and myriotremoid ascomata arranged in short lines (F. monilifera). Ocellularia portoricensis belongs in the core group of Ocellularia and differs from O. cavata in the white medulla and the larger ascospores becoming brown, whereas O. vulcanisorediata produces prominent soralia and immersed ascomata with apically carbonized excipulum and columella and small, transversely septate, hyaline ascospores; it is closely related to O. conformalis. Finally, Thalloloma rubromarginatum resembles T. haemographum in the brownish lirellae with bright red margin but differs from that and other species in the corticate thallus and the norstictic acid chemistry. The new combination Ampliotrema rimosum (Hale) Mercado-Díaz, Lücking & Parnmen is also proposed. Considering the current biodiversity knowledge on this family, the high level of endemism observed in other groups of organisms in the island, and the relatively high number of Graphidaceae described, it is highly likely that at least some of these new taxa are endemic to the island. This view is further supported by the unique features of several of the new species, representing novel characters in the corresponding genera. © 2014 Magnolia Press.
Munoz-Erickson T.A.,International Institute of Tropical Forestry
Ecology and Society | Year: 2014
I examined the multiple visions of the future of the city that can emerge when city actors and organizations reconfigure themselves to address sustainability. In various cities worldwide, novel ideas, initiatives, and networks are emerging in governance to address social and ecological conditions in urban areas. However, cities can be contested spaces, bringing a plurality of actors, network configurations, preferences, and knowledge that shape the politics over desirable pathways for future development. I used the knowledge-action systems analysis (KASA) approach to examine the frames and knowledge systems influencing how different actors involved in the land governance network of the city of San Juan constructed visions for the future of the city. Results revealed four visions for the city coexisting in San Juan. Although sustainability is a goal that cuts across all four visions, they each optimized distinct dimensions of the concept. The contrasts in visions can be explained in part by competing frames of the urban social-ecological system and power asymmetries in the multiple knowledge systems coexisting in the city. I discussed the theoretical, methodological, and practical implications of the politics of sustainability for adaptive urban governance research and practice. The KASA approach can serve as a window into the adaptive capacity of the city by disentangling the competing ways that actors ‘see’ and ‘know’ the urban social-ecological systems. Most importantly, this approach offers a way of appraising sustainable pathways by revealing either the extent to which dominant social structures and cognitive patterns are being reinforced, or whether opportunities for innovative and transformative approaches are emerging in the city. © 2014 by the author(s).
Colon S.M.,University of Puerto Rico at San Juan |
Lugo A.E.,International Institute of Tropical Forestry |
Ramos Gonzalez O.M.,International Institute of Tropical Forestry
Forest Ecology and Management | Year: 2011
We report results of new research on (1) community composition of novel subtropical dry forests developing on abandoned pastures and agricultural fields in both private and protected public lands and (2) seed germination and growth rates of plantings of native tree species on degraded soils. We found that novel dry forests were dominated by introduced species, which accounted for 59 percent of the Importance Value (IV) of stands. These forests had high species dominance, with the most dominant species averaging 51 percent of the IV but reaching values as high as 92 percent. The floristic similarity between novel and mature native forests was low (5.6 percent) compared with the similarity among novel forest stands (26 percent). Collectively, the emerging novel forests had relatively high species richness (39 species/1.2. ha). After 45-60 years of growth and development, novel forests lagged mature native forests in basal area, tree density, and species richness, and lagged stands of similar age and past land use inside a protected area. Novel forest stands inside the protected Guánica Forest had higher species richness than those located outside in private lands. Most regeneration was from seed (67 percent of the new stems were single stems). The results from the germination and planting experiment show that seeds of 17 of 21 native tree species germinated in the laboratory and grew successfully in abandoned pastures when planted and watered for a period of 13 months. Our research shows that after the initial invasion and dominance of introduced species on degraded sites, the stands diversify with native species thus evolving towards new forest types with novel species combinations. © 2011.
Cavaleri M.A.,Michigan Technological University |
Reed S.C.,U.S. Geological Survey |
Smith W.K.,University of Montana |
Wood T.E.,International Institute of Tropical Forestry
Global Change Biology | Year: 2015
Although tropical forests account for only a fraction of the planet's terrestrial surface, they exchange more carbon dioxide with the atmosphere than any other biome on Earth, and thus play a disproportionate role in the global climate. In the next 20 years, the tropics will experience unprecedented warming, yet there is exceedingly high uncertainty about their potential responses to this imminent climatic change. Here, we prioritize research approaches given both funding and logistical constraints in order to resolve major uncertainties about how tropical forests function and also to improve predictive capacity of earth system models. We investigate overall model uncertainty of tropical latitudes and explore the scientific benefits and inevitable trade-offs inherent in large-scale manipulative field experiments. With a Coupled Model Intercomparison Project Phase 5 analysis, we found that model variability in projected net ecosystem production was nearly 3 times greater in the tropics than for any other latitude. Through a review of the most current literature, we concluded that manipulative warming experiments are vital to accurately predict future tropical forest carbon balance, and we further recommend the establishment of a network of comparable studies spanning gradients of precipitation, edaphic qualities, plant types, and/or land use change. We provide arguments for long-term, single-factor warming experiments that incorporate warming of the most biogeochemically active ecosystem components (i.e. leaves, roots, soil microbes). Hypothesis testing of underlying mechanisms should be a priority, along with improving model parameterization and constraints. No single tropical forest is representative of all tropical forests; therefore logistical feasibility should be the most important consideration for locating large-scale manipulative experiments. Above all, we advocate for multi-faceted research programs, and we offer arguments for what we consider the most powerful and urgent way forward in order to improve our understanding of tropical forest responses to climate change. © 2015 John Wiley & Sons Ltd.
Gonzalez G.,International Institute of Tropical Forestry |
Lodge D.J.,Center for Forest Mycology Research |
Richardson B.A.,165 Braid Road |
Richardson M.J.,165 Braid Road
Forest Ecology and Management | Year: 2014
In this study, we used a replicated factorial design to separate the individual and interacting effects of two main components of a severe hurricane - canopy opening and green debris deposition on leaf litter decay in the tabonuco forest in the Luquillo Mountains of Puerto Rico. We quantify changes in percent mass remaining (PMR), the concentration and absolute amounts of various chemical elements using fresh (green) and senesced leaf litter contained in litterbags of two different mesh sizes. Mass loss was significantly slowed by canopy trimming. There was no significant effect of debris treatment on the PMR of the litter. Canopy trimming increased the percent of initial N, Al, Ca, Fe, and Mg remaining and decreased the percent of initial Mn remaining compared with not trimmed plots. Debris addition increased the percent of initial N and P remaining and decreased the percent of initial Al, and Fe remaining in the decomposing litter compared to no debris added plots. Of the elements studied, only Al and Fe accumulated above 100% of initial. Accumulation of Al and Fe in the canopy trimmed and no debris plots. is most likely dominated by the adsorption of these ions onto the surfaces of the decaying litter. Overall, P showed a rapid initial loss during the first 0.2. yr followed by steady loss. Nitrogen was lost steadily from leaf litter. The PMR of fresh and senesced litter was significantly affected by mesh size, with a higher mass remaining in small mesh bags. Fresh litter decayed faster than senesced litter; following patterns of initial N and P concentrations (higher in the former litter type). We found a significantly negative correlation between the Margalef index of diversity for the litter arthropods contained in the litterbags and the PMR, suggesting functional complexity is an important determinant of decay in this forest. Our results imply hurricanes can differentially impact litter decomposition and associated nutrient release via canopy opening and litter inputs. © 2014.