Ecología de la altiplanicie de la Gran Sabana (Guayana Venezolana) : Estructura, diversidad, crecimiento y adaptación en bosques de las subcuencas de los ríos Yuruaní y Alto Kukenán / editado por Lionel Hernández
[Show abstract][Hide abstract] ABSTRACT: Recent research on the ecology of fire has challenged the view that the use of fire by indigenous peoples is detrimental to
ecosystems and wildlife in protected areas. However, in Canaima National Park and World Heritage Site in southeastern Venezuela,
since 1981 managers have employed a costly fire control program to eliminate savanna burning by the Pemon indigenous people.
Here I present the results of the first study on Pemon perspectives of fire management in the park. I show that savanna burning
is an important tool in indigenous land management and plays a key role in preventing large catastrophic fires. Pemon knowledge
of fire also raises questions about conventional interpretations of environmental change in the park. Lastly, I recommend
a fire management policy that seeks to integrate local ecological knowledge. This will require: (a) greater openness from
scientists and resource managers to understanding Pemon rationale for the use of fire, (b) clarification among the Pemon themselves
of their own views of fire, and (c) research partnerships among scientists, resource managers and the Pemon in order to encourage
understanding of Pemon ecological knowledge of fire, and to assess its true impact in the Canaima National Park.
Human Ecology 01/2007; 35(3):331-343. · 1.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: P fractions and sorption processes were studied in samples taken from the organic surface layer and in the underlying mineral soil of a forest-savanna sequence consisting of: (1) tall primary forest (TPF), (2) tall secondary forest (MSF), (3) low secondary forest (LSF), and (4) open savanna (S) in la Gran Sabana, South Venezuela. The organic surface layer in the TPF and MSF showed the highest P concentrations in all analysed P fractions. P in this organic layer was mainly associated with inorganic forms, suggesting that this layer is an important source of bio-available P. The organic surface layer was not present in LSF and S probably because of the occurrence of recurrent surface fires. The conversion of forest to savanna influenced the distribution of the different forms of P in the soil. While non-occluded (resin-+NaOH-P extractable) and organic (NaHCO3-+NaOH-+HCl-Po) P declined from the forest to savanna, occluded (concentrated HCl-extractable+residual P) forms increased. The correlation between sorption maxima and soil organic C was not significant; however, organically bound forms of Al were the main component that explained the adsorption capacity of these soils. The above findings suggest that the organic surface layer and the soil organic matter are important for maintaining P fertility in the undisturbed and little disturbed forests. However, when the system is heavily perturbed by fire the organic surface layer, the main P source, disappears and the patterns of P cycling change.
Biology and Fertility of Soils 01/2004; 40(1):14-19. · 3.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The southern Gran Sabana (SE Venezuela) holds a particular type of neotropical savanna characterized by the local occurrence of morichales (Mauritia palm swamps), in a climate apparently more suitable for rain forests. We present a paleoecological analysis of the last millennia of Lake Chonita (4°39′N–61°0′W, 884 m elevation), based on biological and physico-chemical proxies. Savannas dominated the region during the last millennia, but a significant vegetation replacement occurred in recent times. The site was covered by a treeless savanna with nearby rainforests from 3640 to 2180 cal yr BP. Water levels were higher than today until about 2800 cal yr BP. Forests retreated since about 2180 cal yr BP onwards, likely influenced by a higher fire incidence that facilitated a dramatic expansion of morichales. The simultaneous appearance of charcoal particles and Mauritia pollen around 2000 cal yr BP supports the potential pyrophilous nature of this palm and the importance of fire for its recent expansion. The whole picture suggests human settlements similar to today – in which fire is an essential element – since around 2000 yr ago. Therefore, present-day southern Gran Sabana landscapes seem to have been the result of the synergy between biogeographical, climatic and anthropogenic factors, mostly fire.
Quaternary Research 01/2011; 76(3):335-344. · 2.58 Impact Factor
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