Wednesday, August 5, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Background/Question/Methods Gap hypothesis remains one of the non-equilibrium theories explaining the maintenance of high diversity in tropical forests. Treefall is the key form of disturbance event that create small gaps to large forest clearings. That notwithstanding, these single- to several-tree canopy gaps are yet to be fully characterized as a driving force and foci for regeneration and succession in tropical forests. All gaps within the 20m x 20m quadrats in the 50 ha forest dynamic plot in Korup National Park were mapped, measured and their causal factors evaluated visually. Gap size was estimated using a unified approach based on shape and classified into small, medium and large gaps. Species identities were extracted from the plot enumeration database based on the tag numbers recorded in the field.
Results/Conclusions Gaps make up 0.1% of the plot’s forest cover. Medium sized gaps (100 – 400 m2) were more frequent (53%) while large gaps (>400m2) were rare (2%). Gap formation was not random and followed a topographic gradient with 40% of the gaps occurring in the highly elevated section of the plot (slopes ≥ 15̊.) 40.6% of the gaps were as a result of snapping and their resultant domino effects. Protomegabaria stapfiana (Beille) Hutch (Euphorbiaceae), Oubanguia alata Bak. F. (Syctopetalaceae) and Dichostema glaucescens Gürke were the species most prone to gap formation.
Given the historical importance of gap hypothesis the parameters investigated provides sound basis for the predictability of gap formations and the evaluation of the impact of gaps across broad environmental gradient, giving empirical support in testing their role in the provision of regeneration niches.
Results/Conclusions Gaps make up 0.1% of the plot’s forest cover. Medium sized gaps (100 – 400 m2) were more frequent (53%) while large gaps (>400m2) were rare (2%). Gap formation was not random and followed a topographic gradient with 40% of the gaps occurring in the highly elevated section of the plot (slopes ≥ 15̊.) 40.6% of the gaps were as a result of snapping and their resultant domino effects. Protomegabaria stapfiana (Beille) Hutch (Euphorbiaceae), Oubanguia alata Bak. F. (Syctopetalaceae) and Dichostema glaucescens Gürke were the species most prone to gap formation.
Given the historical importance of gap hypothesis the parameters investigated provides sound basis for the predictability of gap formations and the evaluation of the impact of gaps across broad environmental gradient, giving empirical support in testing their role in the provision of regeneration niches.
