Produção primária líquida em área queimada e não queimada de campo sujo de cerrado (Planaltina - DF)

Abstract

RESUMO -Foi estimada a produção primária líquida aérea de duas áreas de campo sujo de cerrado em Planaltina (DF), sendo uma preservada e outra queimada no início do experimento. A produção foi estimada através das diferenças entre o peso seco da fitomassa herbácea aérea coletada quinzenalmente. O estudo foi realizado de outubro de 1980 a abril de 1981, que corresponde ao período das chuvas no DF. A produção primária líquida aérea do estrato herbáceo da área queimada (176 :!: 33 g m-2 ) foi maior que a observada na área que não sofreu queima (108 :!: 26 g m-Z). A eficiência da conversão de energia solar para matéria seca foi de 0,19 :!: 0,04% para a área queimada e 0,:;'2 :!: 0,03% na área preservada. A produção quinzenal apresentou correlação significativa com a precipitação e água no solo, demonstrando ser a água um fator limitante da produtividade do estrato herbáceo em área de campo sujo de cerrado.Palavras-chave: produção primária, fogo, cerrado, campo sujo. ABSTRACf -The above-ground net primary production was estimated for two areas of campo sujo of cerrado, one unburnt and the other initially burnt. Production was estimated by using diferences in the above-ground biomass which was sampled at quarterly intervals. The study was planned to coincide with the wet season, between oclober 1980 and april 1981. The aboVe-ground net primary production of lhe herbaceous layer in the burnt area (176 :!: 33 g m-2 ) was higher than in the unburnt area (108 :!: 26 g m-Z). The efficiency of the conversion of solar energy into dry matter was 0,12 :!: 0,0,03% for the unburnt campo sujo and 0,19 :!: 0,04% for the burnt campo sujo. The quartely production figures had significative correlation with precipitation and soil water, showing that the water is a limiting factor to the herbaceous layer primary production in campo sujo of cerrado.

A simple graphical model of small mammal succession after fire in the Brazilian cerrado / Un modèle graphique simple de repeuplement par les petits mammifères du cerrado brésilen après brûlis

“…This result is consistent with the fact that grass ground cover shows a high increase immediately after fire (Meirelles and Henriques 1992). Over time, this cover decreases and shrub and tree cover increases after fire (Moreira 2000).…”

“…The pattern of species replacement over time depends critically on how quickly the habitat gradient trajectory changes. Previous studies showed that initially after fire, the rate of increase in herbaceous cover is higher than for woody cover (Meirelles and Henriques 1992). In our model we assumed that the rate of change is higher in the initial stages of succession and decreases with time ( Figure 3B).…”

Potential impacts of climate change on biogeochemical functioning of Cerrado ecosystems

“…The dead standing herbaceous layer is a usually underestimated component of litter. In typical cerrado areas the dead standing herbaceous achieved 4.7 Mg ha -1 (Meirelles and Henriques, 1992). The reduction by 22% in the fine litter production one year after fire (Nardoto et al, 2006) can be related to the higher mortality rates of woody species after successive fire events (Sato and Miranda, 1996;Sato et al, 1998).…”

Belowground biomass seasonal variation in two Neotropical savannahs (Brazilian Cerrados) with different fire histories

“…ANCOVA ( primary production [21], as well as the mortality of the aboveground parts of the majority of the herb layer are accompanied by a decrease in the belowground biomass present in the upper soil layers which are submitted to a severe drought [31].…”