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Variability in survival and mortality of Acacia drepanolobium Sjøstedt following prescribed burning at Olpejeta Conservancy, Kenya
Author(s) -
Wahungu Geoffrey M.,
Mureu Lucy K.,
Macharia Paul G.
Publication year - 2010
Publication title -
african journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.499
H-Index - 54
eISSN - 1365-2028
pISSN - 0141-6707
DOI - 10.1111/j.1365-2028.2009.01172.x
Subject(s) - seedling , acacia , biology , agronomy , biomass (ecology) , predation , horticulture , forestry , botany , ecology , geography
Mortalities to Acacia drepanolobium , a main item in the diet of the eastern black rhino (Diceros bicornis Michaeli) in Olpejeta conservancy, Kenya, are caused by three main factors: drought, browsers and fire. The effect of controlled fires on A. drepanolobium was examined by monitoring survival and growth in experimental plots before and after fire episodes between 2003 and 2007. Density, survival and growth in A. drepanolobium trees were compared eighteen months before and after burning. Tall trees were more likely to die from fire compared to short trees ( R 2 = 0.575; df = 6; P = 0.048), while seedling densities increased after fire ( χ 2 = 36.57; df = 1; P = 0.001). Even with increased seedling densities, burned areas attracted large numbers of seedling predators, lowering the possibility of seedling recruitment into adult, as mean seedling heights reduced significantly (ANOVA, F = 204.42; df = 1; P = 0.036). Fires also significantly lowered flowering ( F = 346; df = 1; P < 0.05) in A. drepanolobium , thereby affecting fruit production. Although fires caused mortalities to adult A. drepanolobium , the most significant effect was tree reversals into seedling height class as trees resprouted. Although fire may increase browse biomass of A. drepanolobium available for black rhino, it is not an appropriate black rhino habitat management tool because burnt areas attract many seedling predators that lower seedling recruitment into adult trees.