Population-level dynamics are affected by temporal variation in individual vital rates of survival and reproduction, which are in turn influenced by habitat-specific processes. Variation in habitat quality within a population’s range can drive movement of individuals between different areas, and so there may be a relationship between variation in vital rates and spatial heterogeneity in population growth (λ). I investigated this relationship for the feral horses (Equus ferus caballus) of Sable Island, Nova Scotia, Canada, from 2008−2010. The horses (n = 484 in September 2010) form a closed population that is free from human interference and predation. I analyzed annual population growth using age-structured projection matrix models parameterized with survival and fertility data collected from almost every female (98.7% of females). I found some evidence of temporal variation in growth during the two years I studied the population (λ2008−2009 = 1.065, λ2009−2010 = 1.117). Age structure appears to have converged to a stable age distribution, suggesting this growth rate has been sustained in the years leading up to the end of my study. Variation in vital rates of adult fertility and foal survival made the largest contribution to annual variation in population growth. Future growth is predicted to be most influenced by proportional changes in adult survival, which remained relatively unchanged between 2008 and 2010. The population can be stratified into three spatially distinct subunits found across a west−east longitudinal gradient of water resources (access to permanent ponds vs. ephemeral water sources and holes dug in sand). I assessed the existence of source-sink dynamics to determine if individual movements between subunits could explain spatial heterogeneity in population growth. I found that spatial heterogeneity in growth appears to be most influenced by immigration and emigration events between subunits. Evidence suggests that current growth of the overall Sable Island horse population is made possible by individual emigration from more productive into less productive subunits; in particular, a source presented in the west of the island where permanent water ponds are located.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O extrativismo de Produtos Florestais não Madeireiros - PFNMs surge com a prerrogativa do uso dos produtos da biodiversidade com a manutenção da floresta em pé. No entanto, a coleta desses produtos pode afetar, em diferentes níveis, as taxas vitais dos indivíduos da espécie explorada e comprometer os parâmetros demográficos e genéticos das populações. Para garantir que o extrativismo seja uma atividade sustentável e gere desenvolvimento socioeconômico para os povos da floresta, é imprescindível agregar ao conhecimento tradicional informações sobre a ecologia das espécies e técnicas de manejo adequadas. A andiroba (Carapa guianesis Aublet.) é uma árvore de uso múltiplo, fornecendo um dos óleos medicinais mais utilizados na Amazônia e madeira de alta qualidade. Apesar do crescente interesse de mercado, informações sobre a biologia da espécie, aspectos econômicos e ecológicos da coleta das sementes para a extração do óleo e o processamento deste ainda são limitados. Nesse sentido, este estudo teve por objetivo avaliar o potencial produtivo de sementes e a dinâmica populacional de C. guianesis em uma população natural, no sul do Estado de Roraima. Em uma parcela de nove hectares, todos os indivíduos de C. guianensis com DAP &#8805; 10 cm foram classificados em estádios de desenvolvimento e tiveram a produção de sementes estimada durante um intervalo de seis anos. Indivíduos com DAP < 10 cm, denominados regenerantes, foram monitorados em 27 subparcelas de 25 x 25m (1,7 ha). Através de modelos matriciais foram avaliados a estrutura da população, estimada a taxa finita de crescimento populacional (&#955;) e identificado o parâmetro demográfico prioritário para a persistência populacional. Para propor recomendações de manejo, simulações de diferentes regimes de exploração da espécie foram realizadas. O diâmetro do caule das andirobeiras pode ser utilizado para identificar indivíduos produtivos, sendo as árvores com diâmetro acima de 35 cm as mais produtivas. A população estudada encontra-se estável e, se mantidas as condições atuais, não apresenta risco de declínio populacional. O parâmetro demográfico prioritário para a manutenção da população de C. guianensis foi a sobrevivência dos adultos II (DAP &#8805; 35 cm). Em simulações de manejo a remoção ou incremento de regenerantes, ou a retirada de adultos I (10 < DAP < 35 cm), não afetou a taxa de crescimento populacional. No entanto, a remoção de apenas dois adultos II, isto é, interferência inferior a 3% na sobrevivência dos indivíduos com maior potencial reprodutivo da população, a taxa de crescimento populacional decaiu (&#955; < 1). Assim, mantendo-se as condições atuais, a manutenção da taxa de crescimento da população estudada é compatível com o extrativismo de sementes. O manejo de uso múltiplo da espécie (madeira e sementes) deve evitar o corte de árvore nas classes mais produtivas (DAP &#8805; 35 cm) para não comprometer o equilíbrio populacional. / The harvest of non-timber forest products is a way of boosting income for poor people in the tropics, and encouraging forest conservation. However, harvesting of such products may changes ecological processes of the exploited species at different levels. These changes could affect vital rates of individuals and demographic and genetic parameters of the populations. To ensure that the harvesting is a sustainable activity and generate socio-economic development for the people of the forest, it is essential to add to traditional knowledge information about the ecology of the species and appropriate management techniques. The Andiroba (Carapa guianesis Aublet.) is a multipurpose tree, providing one of the most widely used medicinal oils in the Amazon, and high-quality wood. Despite markets growing interest, information on the species biology, economic, and ecological aspects of the seed harvesting and oil processing remain limited. This study aimed to evaluate seed production and population dynamics of C. guianesis in a natural stand in southern Roraima. In a nine-hectare plot, all individuals of C. guianensis with DBH &#8805; 10 cm were classified into developmental stages and tree individual seed production was estimated during a period of six years. Individuals with DBH <10 cm, named recruits, were monitored in 27 subplots of 25 x 25 m (1.7 ha). Matrix models were used to (i) evaluate population structure, (ii) estimate finite rate of increase (&#955;) and (iii) identify priority demographic parameter for population persistence. We used simulations to test different kinds of harvesting intensity to suggest management recommendations. Tree diameter can be used to identify productive individuals; trees with a diameter above 35 cm are the most productive. According to our simulations, the studied population is stable and, if current conditions remain unchanged, there is no risk of population decline. The main population parameter for the maintenance of C. guianensis population was the survival of adult II (DBH&#8805; 35 cm). Simulations of harvesting intensity, regeneration increase, or withdrawal of adults I (10 <DBH <35 cm), did not affect the rate of population growth. However, removal of only two adult II (or less than a 3% interference in the survival of individuals with higher reproductive potential of the population) results in a decrease of population growth rate (&#955; <1). Thus, maintaining current conditions, the growth rate of the population studied is consistent with seeds harvesting. Multiple uses of this species (wood and seeds) should avoid cutting trees in the most productive classes (DBH &#8805; 35 cm) to avoid compromising population growth.