ISSN:
1573-5052
Schlagwort(e):
Competition
;
Cyclic succession
;
Facilitation
;
Patagonian arid steppe
;
Resource utilization
;
Shrub-grass association
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Two patch types were recognized in the Occidental District of the Patagonian arid steppe: i) shrubs encircled by a ring of tussock grasses, and ii) tracts of scattered tussocks. Completeness of the ring of grasses around the three dominant shrubs was a function of shrub size. Average completeness was 62, 71 and 83%, respectively for the three dominant shrubs (Senecio filaginoides, Mulinum spinosum and Adesmia campestris). A model for the cyclic dynamics of the two patch types was proposed. It includes a building phase (grass ring construction), a mature phase (maximum ring completeness) and a degenerate phase. In this last phase, triggered by shrub death, completeness of the ring progressively decreases until remnant grasses become undistinguishable from the scattered tussocks patch type. Ring formation occurred independently of shrub species. Grass species were differentially associated to the two patch types and to rings of different shrub species. Cyclical patch dynamics influenced the pattern of resource utilization, since the shrub-ring patch, with a share of only 18% of cover, contributed 44% of the total primary productivity.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00040332
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