Grazing effects on patchy dryland vegetation in northern Patagonia

被引:202
作者
Bisigato, AJ
Bertiller, MB
机构
[1] Ctro. Nac. Patagonico (CONICET), 9120, Puerto Madryn, Chubut, Boulevard Brown s/n
关键词
patch patterns; patch dynamics; recolonization; fragmentation;
D O I
10.1006/jare.1996.0247
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
In this study the spatial patterns and dynamics of vegetation patches along a grazing gradient in the steppe of Larrea divaricata and Stipa spp. in NE Patagonia (Argentina) are described. A general effect of grazing is the reduction of total plant cover resulting from the decrease in cover of perennial grasses (Stipa speciosa, Poa ligularis, Stipa tenuis) and some tall shrubs (Chuquiraga hystrix, Bougainvillea spinosa, Lycium chilense). Dwarf shrubs (Nassauvia fueguiana and Junellia seriphioides) increase their cover under medium and/or high grazing pressures. Plant species are spatially grouped into patches which alternate with areas of bare soil. Eleven types of vegetation patch differing in the dominant plant functional type or species, floristic richness and size were identified with different relative frequency along the grazing gradient. Based on these results, it is postulated that grazing forces the replacement of large patches dominated by tall shrubs with high species richness, by Larrea divaricata patches or small dwarf shrub patches with low species richness and the extinction of grass patches. This results from: (1) disruption of local balances of species deletions and additions; (2) fragmentation of large patches; and (3) formation of new vegetation patches. These changes lead to differing plant spatial organization and heterogeneity along the grazing gradient which may be described by characteristic arrays of vegetation patches. (C) 1997 Academic Press Limited.
引用
收藏
页码:639 / 653
页数:15
相关论文
共 48 条
[1]   COMPETITION, FACILITATION, SEED DISTRIBUTION AND THE ORIGIN OF PATCHES IN A PATAGONIAN STEPPE [J].
AGUIAR, MR ;
SALA, OE .
OIKOS, 1994, 70 (01) :26-34
[2]  
[Anonymous], [No title captured]
[3]   HISTORIC VEGETATION CHANGE, MESQUITE INCREASES, AND CLIMATE IN SOUTHEASTERN ARIZONA [J].
BAHRE, CJ ;
SHELTON, ML .
JOURNAL OF BIOGEOGRAPHY, 1993, 20 (05) :489-504
[4]  
BARROS V, 1982, MAPAS PROBABILIDAD P, V54
[5]   ECOSYSTEM CHANGES ASSOCIATED WITH GRAZING INTENSITY ON THE PUNTA-NINFAS RANGELANDS OF PATAGONIA, ARGENTINA [J].
BEESKOW, AM ;
ELISSALDE, NO ;
ROSTAGNO, CM .
JOURNAL OF RANGE MANAGEMENT, 1995, 48 (06) :517-522
[6]   DOES HERBIVORY BENEFIT PLANTS - A REVIEW OF THE EVIDENCE [J].
BELSKY, AJ .
AMERICAN NATURALIST, 1986, 127 (06) :870-892
[7]   SEASONAL-VARIATION IN THE SEED BANK OF A PATAGONIAN GRASSLAND IN RELATION TO GRAZING AND TOPOGRAPHY [J].
BERTILLER, MB .
JOURNAL OF VEGETATION SCIENCE, 1992, 3 (01) :47-54
[8]   Grazing effects on sustainable semiarid rangelands in Patagonia: The state and dynamics of the soil seed bank [J].
Bertiller, MB .
ENVIRONMENTAL MANAGEMENT, 1996, 20 (01) :123-132
[9]  
BERTILLER MB, 1991, J ARID ENVIRON, V21, P1
[10]   COVER OF PERENNIAL GRASSES IN SOUTHEASTERN ARIZONA IN RELATION TO LIVESTOCK GRAZING [J].
BOCK, CE ;
BOCK, JH .
CONSERVATION BIOLOGY, 1993, 7 (02) :371-377