Fire activity on drylands and floodplains in the southern Okavango Delta, Botswana

Heinl, Michael; Fröst, Peter; Vanderpost, Cornelis; Sliva, Jan

doi:10.1016/j.jaridenv.2005.10.023

Cited by 51 publications

(37 citation statements)

References 8 publications

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“…In swamps, burnings are not frequent, due to standing water, but can be a significant factor during droughts (Mitsch and Gosselink, 2000). For instance, in the Okavango delta, floodplains can have high frequency of fire (Heinl et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Effect of fire on a monodominant floating mat of Cyperus giganteus Vahl in a neotropical wetland

et al. 2015

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The rhizomatous Cyperus giganteus, abundant in the Pantanal wetland, can dominate extense floodable areas as monodominant communities. The Jacadigo lake has a large area of C. giganteus, where we performed an evaluation on community structure during two months in 2010, before it was hit by a wildfire which top-killed the vegetation, compared to ten months post-fire. We utilized 40 plots of 1m × 1m, along permanent trails, assessing two strata: the upper, near the inflorescence of adult plants, and the lower, close to the water level. Our results show that fire does not affect dominance of C. giganteus, as it maintained the same cover as before fire; species richness is not much altered either -28 before fire and 34 thereafter. Fire changed the floristic composition, due to the annual variation of species and the ability of some plants to colonize gaps and to regrow after fire from underground organs and seeds. The stratification of the vegetation with characteristic species of upper and lower strata was similar after fire.Keywords: Cyperaceae, floating meadow, diversity, Pantanal, plant succession. Efeito do fogo sobre uma comunidade monodominante de Cyperus giganteusVahl em uma área úmida neotropical ResumoA planta rizomatosa Cyperus giganteus, encontrada no Pantanal, pode dominar extensas áreas inundáveis, formando uma comunidade monodominante chamada localmente de pirizal. A lagoa do Jacadigo, situada na sub-região de Nabileque, possui uma extensa área de pirizal onde foi realizada uma avaliação na estrutura da vegetação durante dois meses no período de 2010, antes de ser atingida por um incêndio que causou perda da cobertura aérea da vegetação e foi comparada com 10 meses de avaliação pós-fogo. Com indicações na literatura de que o rizoma da planta pode favorecer a espécie através de rebrotamento após um incêndio, o objetivo deste trabalho foi avaliar as variações na estrutura da vegetação de pirizal após um evento de fogo. Foram utilizadas 40 parcelas não fixas de 1m × 1m e alocadas sistematicamente através de trilhas avaliando dois estratos: o superior, próximo a inflorescência dos adultos e o inferior, próximo a lâmina d'água. Nos dois meses logo após o fogo, devido ao tamanho reduzido nos indivíduos de C. giganteus foi avaliado apenas um estrato denominado total. Os resultados mostram que o fogo não afeta a dominância de C. giganteus, que se mantém na mesma faixa de cobertura do período anterior ao fogo; a riqueza de espécies não é alterada, 28 no período anterior ao fogo e 34 no período posterior. Após o incêndio, a estrutura da comunidade sofre alteração na composição florística, devido a mudança anual de espécies e a capacidade que certas plantas possuem em colonizar clareiras e rebrotar após o fogo por meio de órgãos subterrâneos e sementes. A estratificação da vegetação com espécies características de estrato superior e inferior se manteve após o fogo, porém com diferença menos acentuada entre as espécies.Palavras-chave: Cyperaceae, baceiro, diversidade, Pantanal, sucessão vegetal.

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Section: Introductionmentioning

confidence: 99%

Effect of fire on a monodominant floating mat of Cyperus giganteus Vahl in a neotropical wetland

et al. 2015

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“…Indeed, the roots and rhizomes of I. cylindrica have been reported to be remarkably resistant to fire (MacDonald 2004). A recent study on the fire history for southern Okavango Delta, using satellite imagery, identified the seasonal floodplains as the regions with the highest fire frequency and serving as a source of fires spreading into drylands (Heinl et al 2007). In addition, storage of a large fraction of nutrients, biomass and meristems underground protects savanna species also from herbivory (Archer et al 1996).…”

Section: Discussionmentioning

confidence: 99%

Seasonal and inter-annual photosynthetic response of representative C₄ species to soil water content and leaf nitrogen concentration across a tropical seasonal floodplain

et al. 2008

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We examined the seasonal and inter-annual variation of leaf-level photosynthetic characteristics of three C 4 perennial species, Cyperus articulatus, Panicum repens and Imperata cylindrica, and their response to environmental variables, to determine comparative physiological responses of plants representing particular microhabitats within a seasonal tropical floodplain in the Okavango River Delta, Botswana. Five measurement campaigns were carried out over a period of 2 y which covered two early rainy seasons, two late rainy seasons and one dry season. For all three species, light-saturated net photosynthetic rates (A sat ) and stomatal conductance (g sat ) decreased with decreasing soil water content with a seasonal range for A sat of approximately 5-45 μmol m −2 s −1 , and for g sat of 0.03-0.35 mol m −2 s −1 . The species representing the wettest microhabitat (Cyperus) had the highest g sat at low leaf-to-air vapour pressure deficits (D l ), the highest ratio of intercellular to ambient CO 2 concentration (C i /C a ), as well as the highest degree of variation in C i /C a from season to season. We interpret this as being indicative of its adaptation to a moist growth environment allowing for non-conservative water use strategies as soil moisture is usually abundant. For all three species there was significant variation in photosynthetic fluxes from one year to another that was related to variation in leaf nitrogen and phosphorus. This study shows that when assessing the role of savanna stands in large-scale carbon balance models, the remarkable inter-annual variation in leaf photosynthesis reported in this study should be taken into account.

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“…With distinctive wet and dry seasons, the floodplains of Okavango Delta are periodically burnt during the dry season and inundated during the wet season (Heinl et al, 2006). Compared to the upstream drylands, Okavango floodplains were identified as the center of fire activities with higher fire frequency (Heinl et al, 2007). Baker et al, 2011), compared to the information on forest, savanna and grassland ecosystems (e.g., Czimczik & Masiello, 2007;GonzalezPerez et al, 2004).…”

Section: Introductionmentioning

confidence: 90%

Environmental Dynamics of Dissolved Black Carbon in Aquatic Ecosystems

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Fire activity on drylands and floodplains in the southern Okavango Delta, Botswana

Cited by 51 publications

References 8 publications

Effect of fire on a monodominant floating mat of Cyperus giganteus Vahl in a neotropical wetland

Effect of fire on a monodominant floating mat of Cyperus giganteus Vahl in a neotropical wetland

Seasonal and inter-annual photosynthetic response of representative C₄ species to soil water content and leaf nitrogen concentration across a tropical seasonal floodplain

Environmental Dynamics of Dissolved Black Carbon in Aquatic Ecosystems

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Fire activity on drylands and floodplains in the southern Okavango Delta, Botswana

Cited by 51 publications

References 8 publications

Effect of fire on a monodominant floating mat of Cyperus giganteus Vahl in a neotropical wetland

Effect of fire on a monodominant floating mat of Cyperus giganteus Vahl in a neotropical wetland

Seasonal and inter-annual photosynthetic response of representative C4 species to soil water content and leaf nitrogen concentration across a tropical seasonal floodplain

Environmental Dynamics of Dissolved Black Carbon in Aquatic Ecosystems

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Seasonal and inter-annual photosynthetic response of representative C₄ species to soil water content and leaf nitrogen concentration across a tropical seasonal floodplain