Distribution of plants in a California serpentine grassland: are rocky hummocks spatial refuges for native species?
Distribution of plants in a California serpentine grassland: are rocky hummocks spatial refuges for native species?
复制标题
加州蛇纹草原上的植物分布：岩石丘陵是本地物种的空间避难所吗？
DOI：
10.1023/b:vege.0000026332.57007.7b
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发表时间：
2004
期刊：
影响因子：
1.7
通讯作者：
R. S. Burton
中科院分区：
文献类型：
--
作者：
W. Gram;E. Borer;K. L. Cottingham;E. Seabloom;V. Boucher;L. Goldwasser;F. Micheli;B. Kendall;R. S. Burton
非本地物种的入侵可能对本地物种造成严重后果。在严重入侵的中部加州的蛇纹草草原，许多本地物种似乎被限制在孤立的浅蛇纹土露头，或“丘”，虽然在何种程度上，这些丘功能作为避难所的本地植被从来没有被量化。我们测试了本地植物物种是否仅限于在一个蜿蜒的草地在大学的加州塞奇威克保护区附近的圣巴巴拉，加州通过采样物种沿着丘草地梯度的丘。我们还研究了土壤参数，丘面积，接近其他丘，在这个网站上的16个丘的物种组成和空间位置的影响。丘和周围的草地有高镁，低钙，低钙镁比典型的蛇纹岩系统。丘似乎是更紧张的环境，因为他们的土壤较浅，较低的阳离子交换能力，和更大的百分比砂。在沿着丘草地样带取样的27种最常见的植物中，我们确定了8个丘专家，7个边缘专家，8个矩阵专家和4个通才。重要的是，无论是丘和矩阵专家组包括本地物种。植物群落组成与沙丘的空间位置和土壤Ca、Na、K和N相关。物种数量增加，群落组成的变化与增加丘面积。物种组成是最相似的驼峰在彼此接近，并随着驼峰之间的距离增加而下降。我们的研究结果表明，蛇形草地的群落结构是空间上复杂的，有效的管理或恢复计划必须解决这种复杂性。
Invasions by non-native taxa can have severe consequences for native species. In the heavily invaded serpentine grasslands of central California, many native species appear to be restricted to isolated outcrops of shallow serpentine soil, or “hummocks,” although the extent to which these hummocks function as refuges for native vegetation has never been quantified. We tested whether native plant species were restricted to hummocks within a serpentine grassland at the University of California Sedgwick Reserve near Santa Barbara, California by sampling species along hummock-grassland gradients. We also examined the influence of soil parameters, hummock area, proximity to other hummocks, and spatial location on species composition across 16 hummocks at this site. Both the hummocks and the surrounding grassland had high Mg, low Ca, and low Ca to Mg ratios typical of serpentine systems. Hummocks appeared to be more stressful environments because of their shallower soils, lower cation exchange capacity, and greater percent sand. Of the 27 most common plant species sampled along hummock-grassland transects, we identified 8 hummock specialists, 7 edge specialists, 8 matrix specialists, and 4 generalists. Importantly, both the hummock and matrix specialist groups included native species. Plant community composition was correlated with spatial positioning of the hummocks and with soil Ca, Na, K, and N. The number of species increased and community composition changed with increasing hummock area. Species composition was most similar among hummocks in close proximity to each other, and decreased with increasing distance between hummocks. Our results suggest that the community structure of serpentine grasslands is spatially complex and an effective management or restoration plan must address this complexity.