Convergent structural responses of tropical forests to diverse disturbance regimes

Author:

Kellner, James R., Asner, Gregory P.

Title:

Convergent structural responses of tropical forests to diverse disturbance regimes

Periodical:

Ecology Letters

Year:

2009

Volume:

12

Pages:

887-897

Subject:

Costa Rica Ohia dieback Hawaii Island Rain forest ecology Hawaii Island Ohia-lehua Metrosideros polymorpha

Summary:

While size frequency distributions of canopy gaps are a distinguishing characteristic of forest dynamics, it is unknown whether legacies of forest disturbance are affecting the vertical size structure of landscapes, and for how long, or whether these patterns are expressed in the space-filling properties of the forests. The main reason for this is because precise measurements of structure and geometry within forest canopies have not been available for sufficiently large areas, or with large enough sampling to facilitate comparative analysis across forest types. As a result, data from LiDAR remote sensing were used to determine the distributions of canopy height, and sizes of canopy gaps, in five tropical rain forest landscapes in Costa Rica and Hawaii. These sites represented a wide range of variation in structure and natural disturbance history. It consisted of canopy gap dynamics in lowland Costa Rica and Hawaii to stages and types of stand-level dieback that are located in the upper elevations of Mauna Kea and the Kohala mountains that are located on the island of Hawaii. These five tropical rain forest landscapes were characterized by large differences in vertical canopy structure -- some of which were related to known disturbance events. While there were quantitative differences in the values of scaling exponents within and among sites, size frequency distributions of canopy gaps followed power laws at all sites and in all canopy height classes. Scaling relationships in gap size at different heights in the canopy were qualitatively similar at all sites. This revealed a striking similarity despite clearly defined differences in species composition and modes of prevalent disturbance. These findings indicate that power-law gap-size frequency distributions are omnipresent features of these five tropical rain forest landscapes. It also suggests that mechanisms of forest disturbance may be secondary to other modes that may be used in an effort to determine the vertical and horizontal size structure in canopies.

Label:

Ecology - Rain Forests

URL:

http://cletus.uhh.hawaii.edu:2074/10.1111/j.1461-0248.2009.01345.x

Collection:

Periodicals