Caracterização e cartografia da vegetação da região do Chipindo Província da Huíla - Angola

Angola tem escassez de estudos de biodiversidade e a flora é mal conhecida. Neste trabalho estudou-se a vegetação no município de Chipindo, província da Huíla, sudoeste de Angola, inserido no bioma Sudano-Zambeziaco, coberto essencialmente por florestas ou florestas de Miombo. Foram realizados inventários de campo em 79 parcelas de 1.000 m2, distribuição aleatório-estratificada, pelo município de Chipindo em concordância com as manchas do mapa de vegetação. Calcularam-se índices de diversidade e, com análise de imagens de satélite, determinou-se a variação dos parâmetros fenológicos “Doy start green”, Amplitude, “Green duration” e Total Integral, ao longo do ano. A vegetação do Chipindo é bastante diversificada e apresenta três formações, todas do grupo Miombo: floresta aberta de Brachystegia floribunda, floresta de Brachystegia boehmii e floresta de Julbernardia paniculata e Brachystegia spiciformis. São formações jovens, com predominância de árvores com 30-80 cm de perímetro à altura do peito, que ocorrem em solos ferralíticos e paraferraliticos. Os principais fatores de degradação são a agricultura, fogo e aumento da população; Abstract: Characterization and cartography of vegetation in the Chipindo region of Huíla province - Angola Angola has a great lack of biodiversity studies and knowledge on vegetation is particularly scarce. In this work we studied the vegetation in the municipality of Chipindo, province of Huíla, southwest Angola, inserted in the Sudano-Zambeziaco biome, mainly covered by Miombo forests. Field surveys were carried out in 79 plots of 1,000 square meters, random-stratified distributed throughout the municipality of Chipindo in concordance with patches of vegetation map. Diversity indexes were calculated and, with satellite images, the variation of the phenological parameters "Doy start green", Amplitude, "Green duration" and Total Integral were determined throughout the year. Vegetation of Chipindo has great diversity and presents three formations, all of the group Miombo: open forest of Brachystegia floribunda, forest of Brachystegia boehmii and forest of Julbernardia paniculata. They are young formations, with predominance of trees with 30-80 cm of perimeter at breast height, that occur in ferralitic and paraferralitic soils. The main degradation threats are agriculture, fire and population increase

Structural diversity and tree density drives variation in the biodiversity-ecosystem function relationship of woodlands and savannas

Positive biodiversity-ecosystem function relationships (BEFRs) have been widely documented, but it is unclear if BEFRs should be expected in disturbance-driven systems. Disturbance may limit competition and niche differentiation, which are frequently posited to underlie BEFRs. We provide the first exploration of the relationship between tree species diversity and biomass, one measure of ecosystem function, across southern African woodlands and savannas, an ecological system rife with disturbance from fire, herbivores and humans. We used >1000 vegetation plots distributed across 10 southern African countries, and structural equation modelling, to determine the relationship between tree species diversity and aboveground woody biomass, accounting for interacting effects of resource availability, disturbance by fire, tree stem density and vegetation type. We found positive effects of tree species diversity on aboveground biomass, operating via increased structural diversity. The observed BEFR was highly dependent on organismal density, with a minimum threshold of c. 180 mature stems ha-1. We found that water availability mainly affects biomass indirectly, via increasing species diversity. The study underlines the close association between tree diversity, ecosystem structure, environment and function in highly disturbed savannas and woodlands. We suggest that tree diversity is an under-appreciated determinant of wooded ecosystem structure and function

Structural diversity and tree density drives variation in the biodiversity–ecosystem function relationship of woodlands and savannas

Positive biodiversity–ecosystem function relationships (BEFRs) have been widely documented, but it is unclear if BEFRs should be expected in disturbance-driven systems. Disturbance may limit competition and niche differentiation, which are frequently posited to underlie BEFRs. We provide the first exploration of the relationship between tree species diversity and biomass, one measure of ecosystem function, across southern African woodlands and savannas, an ecological system rife with disturbance from fire, herbivores and humans. We used > 1000 vegetation plots distributed across 10 southern African countries and structural equation modelling to determine the relationship between tree species diversity and above-ground woody biomass, accounting for interacting effects of resource availability, disturbance by fire, tree stem density and vegetation type. We found positive effects of tree species diversity on above-ground biomass, operating via increased structural diversity. The observed BEFR was highly dependent on organismal density, with a minimum threshold of c. 180 mature stems ha−1. We found that water availability mainly affects biomass indirectly, via increasing species diversity. The study underlines the close association between tree diversity, ecosystem structure, environment and function in highly disturbed savannas and woodlands. We suggest that tree diversity is an under-appreciated determinant of wooded ecosystem structure and function