For the successful conservation of a species, habitat loss and fragmentation must be controlled through a protected area network that adequately covers its habitat. Here the suitable habitats of all ...of Trinidad and Tobago’s endemic plant species are determined and used to perform a gap analysis of a proposed protected area network. Data from a recently completed botanical survey, the WorldClim 2 environmental parameters, and a range of other sources were used to determine the habitat of each species using the species distribution model MaxEnt. Modelled habitat suitability for each species was combined and used to create maps showing endemic richness, weighted endemism and corrected weighted endemism, and to rank areas by conservation value using Zonation. The coverage of the proposed protected area network and a land use map were overlaid on these modelled distributions. We identified data limitations which meant that more than half of the 66 endemic species could not be modelled with confidence. For the remaining species, we found that the proposed protected area network contains just 13 ± 7% of the total modelled habitat of the endemic species. For eight endemic species > 25% of the suitable habitat is degraded. Model analysis indicated that elevation and temperature seasonality are the most important drivers of endemism. Based on a gap analysis the inclusion of high elevation areas of Trinidad’s Northern Range in the proposed protected area network would expand the coverage to include > 25% of the total modelled habitat of the endemic species, thus greatly increasing the long-term sustainability of the endemic species populations.
Abstract
Many tropical species live close to their thermal limits within a narrow niche. Here, we investigate the ecophysiological limits of the tropical tree Podocarpus trinitensis, which is endemic ...to Trinidad and Tobago where most populations exist as isolated stands on hilltops. Five wild stands from a range of elevations were compared in the field with measurements of leaf temperature, canopy cover, stomatal conductance (gs), chlorophyll content and several chlorophyll fluorescence parameters. A parallel greenhouse experiment was used to acclimate seedlings to ‘CONTROL’ and ‘HEAT’ treatments (with mid-day air temperatures of 34.5 and 37 °C respectively), after which the above parameters were measured along with photosynthetic light and temperature response curves, leaf morphology and in vitro Fv/Fm thermostability.
There was a positive association between improved physiological performance and elevation. In the high elevation sites, leaf temperatures were significantly lower while most of the physiological parameters were higher (gs, chlorophyll content, ɸ PSII, ETRmax and Isat90). In the greenhouse, HEAT and CONTROL plants were similar for most parameters, except leaf temperature (which was coupled with air temperature) and leaf mass per unit area (which was higher in HEAT plants). Temperature response curves showed an optimum temperature for photosynthesis of 30 ± 0.5 °C (TOpt) and in vitro Fv/Fm indicated a critical temperature of 47.4 ± 0.38 °C for HEAT and 48.2 ± 0.24 °C for CONTROL (T50), with no indication of heat acclimation. Podocarpus trinitensis was found to be shade tolerant. In the field, seedlings established under a close canopy (>95% canopy cover) and had a low light saturation point (LCP). In the greenhouse, where more light was available, seedlings retained a low light compensation point, light saturation point (LSP) and maximum photosynthetic rate (Amax). The results suggest that P. trinitensis is moderately heat tolerant with the higher elevation sites being more habitable, but stands are also able to survive near sea level under a closed canopy. The narrow niche, along with the 30 ± 0.5 °C optimum temperature for photosynthesis and the lack of thermal plasticity in critical temperature, suggests that P. trinitensis has little room to acclimate to temperatures higher than those currently experienced.
Plant functional traits are thought to drive biomass production and biogeochemical cycling in tropical forests, but it remains unclear how nitrogen (N)‐fixing legumes influence the functional traits ...of neighbouring trees and forest‐wide biomass dynamics. Further, the degree to which effects of N‐fixers are density‐dependent and may depend on stem size and spatial scale remains largely unknown.
Here, we examine 30 years of stem demography data for ~20,000 trees in a lowland tropical forest in Trinidad that span a wide range of functional traits thought to drive above‐ground biomass (AGB) dynamics.
These forests show positive but decreasing long‐term net AGB accumulation resulting from constant average productivity but increasing mortality of non‐fixing trees over time. We find that high abundance of N‐fixing trees is associated with compositional shifts in non‐fixer functional traits that confer lower competitive performance and biomass accumulation. Across tree size classes, most interactions between N‐fixers and non‐fixers were negative, density‐dependent, and strongest at smaller spatial scales.
Synthesis. Overall, our findings suggest that local trait‐based interactions between N‐fixing and non‐fixing trees can influence long‐term carbon accumulation in tropical forests.
Plant functional traits are thought to drive biomass production and biogeochemical cycling in tropical forests, but it remains unclear how nitrogen‐fixing legumes influence the functional traits of neighbouring trees and forest biomass dynamics. Using long‐term forest demographic data from Trinidad, we show that local trait‐based interactions between N‐fixing and non‐fixing trees can negatively influence long‐term carbon accumulation in tropical forests.
Symbiotic nitrogen (N) fixation has been shown to support carbon storage in young regenerating tropical forests, but N-fixing trees can also be strong competitors with non-fixing trees, making it ...unclear which mechanism drives long term patterns in biomass accretion. Many tropical forests have excess N, but factors such as rising atmospheric CO
or selective cutting practices might induce additional N demand. Here we combine decades of stem inventory data, in-situ measures of symbiotic N fixation, and simulations of N demand to evaluate demographic and biogeochemical controls on biomass dynamics in legume-rich lowland forests of Trinidad. We document sustained net biomass accumulation and high rates of N fixation in these forests, regardless of the timing of selective timber harvests, including an old growth stand. The biomass accumulation was explained by growth of non-fixing trees, not N-fixing trees, but the total amount of symbiotic N fixation was sufficient to account for most of net above ground N demands, suggesting that N-fixers could contribute to the long-term C sink in these forests via fertilizing non-fixers.
Studies of small-scale spatial genetic structure are crucial to the implementation of successful conservation and management plans as they enhance our capacity to predict a population’s ability to ...respond to changing environments. This is especially true in the tropics, where high rates of fragmentation and land-use change create potential barriers to genetic exchanges. We examined the genetic diversity of wild populations of the economically important palm, Mauritia flexuosa (Arecaceae) in and around the Aripo Savannas Scientific Reserve on the island of Trinidad. In a small collection area of roughly 10 km² we found both spatial and inter-generational, or temporal, genetic differentiation and high levels of nearest-neighbor mating. We suggest that these spatial and temporal genetic patterns reflect recent and drastic anthropogenic changes to the landscape of the study sites, which we hypothesize have created barriers to gene flow through animal-mediated seed dispersal and pollination.
Moriche palm (Mauritia flexuosa Linn f. Arecaceae) is a dominant species in the savanna margins of the Caribbean island of Trinidad. The savanna margins are frequently subjected to fires and the ...moriche palm, like many palm species, is adapted to cope with a degree of fire damage. These palms also frequently host large termite nests that tend to burn during fires, which causes further damage to the palm stems. This paper explores the possibility that the combination of termite nests and frequent fires can increase tree mortality. Two post-fire surveys were conducted to record, evidence of fire exposure, fire damage to termite nests and fire damage to palm stems. In both surveys, the majority of palms with termite nests suffered fire damage to their stems, while none of the termite-free palms showed damage. Furthermore, a comparison of nest size and damage to the bark showed stems with larger nests had significantly more damage than those with smaller or no nests. The results suggest that the presence of termite nests increases the extent of fire damage to palm trunks by providing a point of combustion that focuses flames on the already compromised stem tissue. Long-term studies are warranted to investigate the impact of repeated fires on wild arborescent palm populations.
Botanists have been urged to help assess the conservation status of all known plant species. For resource-poor and biodiversity-rich countries such assessments are scarce because of a lack of, and ...access to, information. However, the wide range of biodiversity and geographical resources that are now freely available on the internet, together with local herbarium data, can provide sufficient information to assess the conservation status of plants. Such resources were used to review the vascular plant species endemic to Trinidad and Tobago and to assess their conservation status. Fifty-nine species were found to be endemic, much lower than previously stated. Using the IUCN Red List criteria 18 endemic species were assessed as Critically Endangered, 16 as Endangered, 15 as Vulnerable, three as Near Threatened, and three as Data Deficient (i.e. insufficient data are available to assess their conservation status). Although such rapid assessments cannot replace in depth research, they provide essential baseline information to target research and conservation priorities and identify specific conservation actions.
Research conducted in the Archive and Library of Fairchild Tropical Botanic Garden, the U.S. National Archives, and the U.S. National Herbarium allowed us to reconstruct field work performed by David ...Fairchild (1869–1954) in the islands of Beata, Saona, Tobago, Tortola, and Trinidad in 1932. This was part of a larger expedition to the Caribbean Islands, Suriname and Guyana by the United States Department of Agriculture between December 1931 and April 1932. During the collection endeavor to these five islands, 261 photographs were taken, 82 herbarium collections (75 species) were made, and 185 germplasm accessions (148 species) were added to the USDA germplasm repositories. In total, plant material for 185 species (224 collections) was collected. A major highlight of the trip were the herbarium collections that led to the description of the Beata endemic genus Armouria (Malvaceae). However, more recent taxonomic studies place this genus within the tropical genus Thespesia (~13 species). Thirteen distinguished naturalists or high ranking government officers were met in Trinidad (12) and Tortola (1). Collections of cotton (6 accessions) and palms (25 accessions) were relevant to the expedition objectives; however no samples of Sea-Island Cotton were obtained, despite this being a major germplasm objective. Exploring the Botanic Garden of Trinidad was another main highlight of the trip. Documents, photos, and research results are made available online at: www.archive.org. The project is framed within an undergraduate research program on botanical history that is being performed in partnership with botanists from national and foreign institutions. Part of the collected material was introduced into the Jardín Botánico de Cienfuegos, Cuba shortly after the expedition ended.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The floristic affinities of the dry forest of Little Tobago, a continental island off northern South America, were assessed. Surveys found a total of 103 native species in the vegetation community of ...Little Tobago Island. Floristic affinities were strongest with northern South American countries but were also heavily influenced by Antillean elements indicating that Little Tobago lay in a transition zone between continental South American dry forests and Antillean dry forests. Poor protection of dry forests in the areas with which Little Tobago has the highest floristic affinities make the island important for conservation purposes.
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