Fourteen years of protection against grazing and human impacts of the coastal lowland vegetation in Eastern Saudi Arabia (an experimental site in the vicinity of A1-Hassa region) has led to an increase of 68 % in the total cover, 33 % in species richness and 32% in species relative evenness. Many of
Effects of grazing on the abundance and diversity of annual plants in Chihuahuan desert scrub habitat
โ Scribed by Douglas A. Kelt; Thomas J. Valone
- Publisher
- Springer-Verlag
- Year
- 1995
- Tongue
- English
- Weight
- 545 KB
- Volume
- 103
- Category
- Article
- ISSN
- 0029-8549
No coin nor oath required. For personal study only.
โฆ Synopsis
We assess the impact of release from cattle grazing on the abundance and diversity of both winter and summer annual plant communities at an upper Chihuahuan Desert scrub site in south-eastern Arizona. In contrast to previous studies, we found that removal of herbivores (cattle) had little impact on ephemeral plant assemblages at our site. The total number of summer annual individuals per quadrat did not differ significantly, but there were significantly more winter annual plants on ungrazed quadrats. The number of species per quadrat, however, did not differ significantly between sites exposed to, or protected from, grazing in either season. Of 79 annual species recorded (34 in winter, 45 in summer), only 2 species, 1 in each season, responded significantly to the removal of cattle: Stephanomeria exigua and Polygala tweedyi were more abundant on ungrazed plots. Three additional species, Eriastrum diffusum and Cryptantha micrantha in winter, and Mollugo cerviana (summer), approached statistical significance. Differences in the effect of cattle grazing on annual plants between our results and those at other sites in the arid southwest most likely reflect differences in the speed of response by annuals in different areas. Comparisons of this with other studies underscores recent calls for studies at broader spatial and greater temporal scales.
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