Thought to be endemic to the Commonwealth of Puerto Rico, Ruehssia woodburyana (Apocynaceae) was recently discovered at a single location on Norman Island in the British Virgin Islands. Despite an increase in the extent of occurrence and area of occupancy, this species meta-population is very limited with a total of 37 individuals known in the wild. The largest subpopulation, on Mona Island, has only 26 individuals. The species suitable habitat is experiencing a continuing decline due to urban development, grazing by feral ungulates and human-induced forest fires. Conservation action is urgently needed and should be directed towards establishing genetically representative ex situ collections, such as seed for long term storage and live material for propagation. This species is evaluated as Critically Endangered (CR), based on Criteria C2a(i)+D, according to the IUCN Red List Categories and Criteria (version 3.1) and guidelines (Subcommittee IUCN Standards and Petitions 2016). Extensive and regular surveys to the region enable the discovery of new plant records for different countries and islands. In this paper, we record a new island record for Ruehssia woodburyana on Norman Island, in the British Virgin Islands and discuss the species conservation status. Marsdenia woodburyana is transferred to the genus Ruehssia to reflect the resurrection of that genus for species of Marsdenia native to the New World.
Question: Hurricanes are a major factor influencing forest structure and have been linked to higher incidences of multiple-stemmed trees in Caribbean dry forests relative to the continent. In Sept 1998, category 3 Hurricane Georges passed over Mona Island. This island, unlike others in the Caribbean, has had feral goats for five centuries. In this study we addressed the following questions: (i) what are the short-term (4 mo) and long-term (10 yr) responses of Mona Island's dry forests to hurricane disturbance in terms of forest structure and tree mortality; and (ii) is there any effect of goat exclusion on the recovery process and forest structure after the hurricane?Location: Dry forest of Mona Island, Puerto Rico.Methods: Permanent fenced and unfenced plots established in 1997 and monitored annually until 2008 were used to evaluate the interplay between goat herbivory and hurricane effects on structural dynamics of the tree community. Within these plots, vegetation data collected include species identity, DBH, successional status and hurricane-related tree mortality. Results:We found that vegetation responses to hurricane disturbances may have been influenced by the presence of feral goats through at least two mechanisms. First, goats may have led to changes in forest structure and composition that feed back into the recovery dynamics that follow hurricane events. Second, goat herbivory limits the production of multiple stems, a trait that could be an adaptive response in hurricane-prone areas. Feral goats may lead to alternate successional pathways by keeping this dry forest at early-successional stages much longer than expected, and shifting vegetation communities to an alternate state where smaller, shrubbier and perhaps less palatable species dominate.Conclusions: Differences in structure between Mona Island's dry forest and other tropical dry forests are related to changes in species composition that may have been triggered by introduced goats. Our results highlight the potential complexities that may arise when setting management goals within the context of novel ecosystems. Ultimately, implementation of management goals requires knowing what changes are linked to the ecological integrity of the ecosystem and what cultural values are placed on the current state of the tree community vs its historical condition.
The Puerto Rican Plain Pigeon (Columba inornata wetmorei) was listed as endangered in 1970. Transect-survey and nest-monitoring data were collected to estimate reproductive parameters and to assess effects of weather, food, predation, and habitat. We monitored 377 of 423 nests found in east-central Puerto Rico during February-September 1986-2000. The largest sampling effort was conducted in May-June 1998, and 131 nests were found along 8,460 m, resulting in a nest density (D̂) of 5.26 per hectare or 356 nesting pairs (N̂) in the surveyed area (a = 67.7 ha). Nest spatial distribution was highly clumped (b̂ = 3.2) and transect surveys were highly variable (CV = 40%). Thus, 34,000 m needed to be surveyed for a desired coefficient of variation (CV[D̂]) of 20%. Nest density varied widely during May-June 1986–2000. With a CV about the trend line of 121%, from 18 to 28 years of data would be needed to detect an increase or a decrease (r) of 5–10% in log-transformed nest density estimates through linear regression analysis (alpha = 0.15 and power = 0.80). Whereas food abundance had positive and significant relationships with nest density and number of fledglings produced, predator density had negative and significant relationships with nesting success and the number of fledglings produced. Predation accounted for 79% of nest losses (n = 183). Mayfield's estimates of nesting success averaged 40% and an average of 0.5 fledglings were produced per nesting pair. Because Plain Pigeons are able to produce fledglings from three or more broods per year and have extended nesting seasons (with a nest density peak usually occurring in May-June), we hypothesized that hatch-year and after-hatch-year survival rates of 50–65% and a yearly productivity of 1.4–2.0 fledglings per nesting pair were enough to offset mortality. Our optimism is tempered by the fact that Plain Pigeons have not been reported nesting outside east-central Puerto Rico, where rapid destruction and fragmentation of second-growth forests, catastrophic weather, food availability, nest predation, illegal hunting and poaching of nestlings may interact and cause an irreversible population decline. Managers should focus on conserving and restoring second-growth forest fragments to provide food and cover throughout the year. Additional recommendations are given based on the results of our study, which was part of a larger study of factors affecting the reproduction of columbids on Puerto Rico and its territories.
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