Stand Structure, Diversity and Regeneration Status of Woody Species in Open and Exclosed Dry Woodland Sites around <i>Molapo</i> Farming Areas of the Okavango Delta, Northeastern Botswana

Abstract

Stand structure, diversity and regeneration status of woody species were investigated in open and exclosed dry woodland sites in Island Safari, Shorobe and Xobe, northeastern Botswana. A total of 105, 111 and 130 quadrats, measuring 20 × 20 m each, were laid down along parallel line transects in the three sites, respectively, to collect data. A total of 47 species, representing 16 families and 24 genera, were recorded in the study sites. Of these, 33 species representing 13 families and 20 genera, 41 species representing 15 families and 23 genera and 27 species representing 10 families and 14 genera were encountered in Island Safari, Shorobe and Xobe, respectively. The most diverse family was Fabaceae followed by Combretaceae and Tiliaceae at all the three sites. The most diverse genus was Acacia, followed by Combretum and Grewia. The diversity of woody species in the study sites were 2.18, 2.15 and 1. sii and A. luederitzii in Xobe. The alarming result was the fact that 71%, 80% and 85% of the woody species recorded in Island Safari, Shorobe and Xobe, respectively, exhibited hampered regeneration and, thus, unhealthy population structures. Therefore, there is an urgent need to address the observed unhealthy population structures of the woody species through investigation of the major causes of their hampered regeneration, and also designing measures that will facilitate natural and artificial regeneration of these species at the three study sites.

Modelagem Da Distribuição Diamétrica De Florestas Tropicais

“…O treinamento e aplicação das redes ao conjunto de validação foram realizados com 10 repetições, onde no início de cada treinamento eram utilizados pesos iniciais aleatórios nas conexões dos neurônios da rede. RESULTADOS E DISCUSSÃO A distribuição média da probabilidade observada por classe de diâmetro apresentou forma exponencial negativa (J invertido), sendo as classes de menores diâmetros com maior probabilidade de ocorrência dos indivíduos, típica de florestas inequiâneas (NEELO et al, 2015;JIMENEZ et al, 2016). Conforme esperado, as classes diamétricas inferiores apresentaram maior amplitude de valores de probabilidade em relação às classes superiores, no entanto, quando é feita a razão pela média da classe, nota-se maior variação nestas últimas (Figura 2).…”

Tree Species Diversity and Composition of Miombo Woodlands in South-Central Angola: A Chronosequence of Forest Recovery after Shifting Cultivation

“…The selected areas were then grouped into four categories, according to fallow age: young fallows (range 7-8 yrs), medium-aged fallows (range [10][11][12][13][14] were divided into ten 100 m 2 subplots [33]. A total of forty plots were surveyed, corresponding to ten mature stands and ten in each of the fallow stages.…”

“…The rapid growth of human population in rural areas of Africa and increasing needs for food production have caused the shortening of fallow periods of abandoned fields and people to encroach into new areas that have not been subjected to agriculture before [12]. The increasing demands of the rapidly growing human population have led to land scarcity, and the remaining forests are being increasingly over utilized, far beyond their capacity for regeneration [13]. This process, as a whole, seriously impacts forest biodiversity patterns, for example, species richness and composition [14].…”

“…In order to manage disturbed and undisturbed stands and to understand the provision of nontimber ecosystem services, it is imperative to describe patterns of species composition [13]. Additionally, data on woody species composition serve as baseline information for projecting changes in vegetation over time, which is fundamental to understand regeneration processes, such as tree growth, tree mortality, understory development, and the spread of disturbances [18].…”

Diversity, stand structure and regeneration status of woody species, and spatial cover of herbaceous species in Mokolodi Nature Reserve, Southeastern Botswana

“…The species, family and genera richness values of woody species (44 spp., 17 families and 26 genera) recorded in this study were higher than those reported from studies in Shorobe (41 spp., 15 families and 23 genera), Maun (area exclosure in Island Safari Lodge, 33 spp., 13 families and 20 genera) and Xobe (27 spp., 10 families and 24 genera) villages (Neelo et al, 2013;Neelo et al, 2015) as well as in an area exclosure of more than 10 years (32 spp., 12 familes and 19 genera) and open area adjacent the area exclosure (24 spp., 10 familes and 15 genera) in Maun (Teketay et al, 2016) in northern Botswana, and in Shekole (18 spp.) and Guba (23 spp.)…”