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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Forest and landscape restoration at Pontal do Paranapanema: ecological attributes of forest restoration in a coffee agroforestry system / Restauração da paisagem florestal no Pontal do Paranapanema: indicadores ecológicos em sistemas agroflorestais com café sombreado

Badari, Carolina Giudice 12 February 2019 (has links)
A direct consequence of disorganized human population growth and the indiscriminate use of natural resources are the reduction of area and the fragmentation of native ecosystems, as they transform into agricultural areas. In this scenario, agroforestry systems (AFS) may be an alternative to reconcile restoration, conservation and local agricultural production. However, there is a diversity of AFS, and its use as a forest restoration strategy is still uncertain, mainly because we lack evaluations based on ecological indicators from those systems. Thus, we compared ecological indicators measured in a coffee agroforestry system in the Pontal do Paranapanema with those inform conventional restoration plantings of the same age and with regional reference ecosystems. We measured natural regeneration density and richness; canopy cover by native species and aboveground biomass and compared among sites using an ANOVA, followed by Tukey\'s test for mean comparison. Aiming to understand the factors influencing the ecological indicators of forest restoration in coffee AFS, we performed generalized linear models (GLM) using density of coffee and native trees, biomass, percentage of animal-dispersed trees, distance to the nearest forest remnant and richness of tree species as predictor variables and percentage of canopy cover and density and richness of natural regeneration as response variables. The reference forests had the highest values for forest structure indicators, followed by AFS and finally by the conventional restoration plantings. However, we found a greater diversity of tree species planted in the AFS and a natural regeneration similar to that found in the reference ecosystems. Despite coffee density in the AFS negatively influencing natural regeneration, the coffee AFS had greater ecological performance than the conventional restoration, being a viable alternative for forest restoration. We conclude that AFS with coffee and native tree species play an important ecological role in the FLR in Pontal do Paranapanema, reconciling productivity with forest restoration. / Um reflexo direto do crescimento desordenado da população humana e das atividades antrópicas é a diminuição e a fragmentação da área ocupada por ecossistemas nativos e sua substituição por áreas agrícolas. Neste cenário, os sistemas agroflorestais (SAF) podem ser uma alternativa para conciliar restauração, conservação e produção agrícola local. No entanto, tendo em vista a diversidade de SAFs, sua adoção como estratégia de restauração florestal ainda carece de estudos que avaliem os níveis de indicadores ecológicos de cada sistema. Neste sentido, comparamos os indicadores ecológicos de sistemas agroflorestais com café e espécies arbóreas nativas no Pontal do Paranapanema, com os de plantios convencionais de restauração florestal de mesma idade (12-15 anos) e ecossistemas de referência regionais. Medimos a densidade e a riqueza da regeneração natural, a cobertura do solo por espécies nativas e a biomassa acima do solo e as comparamos entre as áreas pela análise de variância ANOVA seguida da comparação de médias pelo teste de Tukey. Buscando compreender os fatores que influenciam os indicadores ecológicos da restauração florestal no SAF, analisamos modelos lineares generalizados, tendo biomassa, porcentagem de árvores zoocóricas, distância do remanescente florestal mais próximo, densidades de café, riqueza e densidade de árvores nativas como variáveis preditoras, e porcentagem de cobertura do dossel, densidade e riqueza da regeneração natural como variáveis respostas. As florestas de referência tiveram os maiores valores para indicadores de estrutura florestal, seguidas pelos SAFs e pelos plantios convencionais de restauração florestal. Entretanto, encontramos elevada diversidade de espécies arbóreas nos SAFs e valores próximos aos das florestas de referência para a diversidade da regeneração natural. Embora a densidade de plantas de café influencie negativamente a regeneração natural, os SAFs apresentaram um melhor desempenho ecológico que as áreas de restauração convencional, correspondendo à uma alternativa viável para restauração florestal. Desta forma, concluímos que os sistemas agroflorestais estudados desempenham um papel ecológico importante na restauração da paisagem florestal no Pontal do Paranapanema, conciliando produção com restauração florestal.
2

Intraspecific Trait Plasticity in Coffee Agroforestry Systems of Costa Rica

Gagliardi, Stephanie 18 March 2014 (has links)
Although a common plant response to environmental gradients, leaf trait plasticity is often uncharted in agroforestry systems. The objective of this study was to examine the effect of a i) local-scale gradient (light, nutrients) induced by shade tree diversity and ii) large-scale gradient (climato-edaphic) induced by altitude on coffee plant response on multiple agroforestry research farms in Costa Rica. Results show large variability of coffee traits: leaf photosynthetic rates, specific leaf area (SLA) and number of fruiting nodes deviate along both gradients. Mean SLA increased with increasing shade tree diversity. However, with increasing altitude, full sun coffee photosynthesized at higher rates than shaded coffee. Concurrently, other coffee leaf physiological and morphological traits differentiated between full sun and shaded coffee with increasing altitude. Results suggest soil moisture and light availability dominate environmental correlates to intraspecific coffee trait plasticity, providing insight to sources of coffee performance variability in monoculture and agroforestry systems.
3

Intraspecific Trait Plasticity in Coffee Agroforestry Systems of Costa Rica

Gagliardi, Stephanie 18 March 2014 (has links)
Although a common plant response to environmental gradients, leaf trait plasticity is often uncharted in agroforestry systems. The objective of this study was to examine the effect of a i) local-scale gradient (light, nutrients) induced by shade tree diversity and ii) large-scale gradient (climato-edaphic) induced by altitude on coffee plant response on multiple agroforestry research farms in Costa Rica. Results show large variability of coffee traits: leaf photosynthetic rates, specific leaf area (SLA) and number of fruiting nodes deviate along both gradients. Mean SLA increased with increasing shade tree diversity. However, with increasing altitude, full sun coffee photosynthesized at higher rates than shaded coffee. Concurrently, other coffee leaf physiological and morphological traits differentiated between full sun and shaded coffee with increasing altitude. Results suggest soil moisture and light availability dominate environmental correlates to intraspecific coffee trait plasticity, providing insight to sources of coffee performance variability in monoculture and agroforestry systems.

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