 |
| Titel |
Origin of the Hawaiian rainforest and its transition states in long-term primary succession |
| VerfasserIn |
D. Mueller-Dombois, H. J. Boehmer |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 7 ; Nr. 10, no. 7 (2013-07-30), S.5171-5182 |
| Datensatznummer |
250018369
|
| Publikation (Nr.) |
 copernicus.org/bg-10-5171-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| This paper addresses the question of transition states in
the Hawaiian rainforest ecosystem with emphasis on their initial
developments. Born among volcanoes in the north central Pacific about 4
million years ago, the Hawaiian rainforest became assembled from spores of
algae, fungi, lichens, bryophytes, ferns and from seeds of about 275
flowering plants that over the millennia evolved into ca. 1000 endemic
species. Outstanding among the forest builders were the tree ferns
(Cibotium spp.) and the 'ōhi'a lehua trees (Metrosideros spp.), which still dominate the
Hawaiian rainforest ecosystem today. The structure of this forest is simple.
The canopy in closed mature rainforests is dominated by cohorts of
Metrosideros polymorpha and the undergrowth by tree fern species of Cibotium. When a new lava flow cuts
through this forest, kipuka are formed, i.e., islands of remnant vegetation.
On the new volcanic substrate, the assemblage of plant life forms is similar
to the assemblage during the evolution of this system. In open juvenile forests, a
mat-forming fern, the uluhe fern (Dicranopteris linearis), becomes established. It inhibits further
regeneration of the dominant 'ōhi'a tree, thereby reinforcing the cohort
structure of the canopy guild. In the later part of its life cycle, the
canopy guild breaks down often in synchrony. The trigger is hypothesized to
be a climatic perturbation. After the disturbance, the forest becomes
reestablished in about 30–40 yr. As the volcanic surfaces age, they go
from a mesotrophic to a eutrophic phase, reaching a biophilic nutrient
climax by about 1–25 K yr. Thereafter, a regressive oligotrophic phase
follows; the soils become exhausted of nutrients. The shield volcanoes break
down. Marginally, forest habitats change into bogs and stream ecosystems.
The broader 'ōhi'a rainforest redeveloping in the more dissected
landscapes of the older islands loses stature, often forming large gaps
that are invaded by the aluminum tolerant uluhe fern. The 'ōhi'a trees
still thrive on soils rejuvenated from landslides and from Asian dust on the
oldest (5 million years old) island Kaua'i but their stature and living
biomass is greatly diminished. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|