Oak Regeneration: Ecological Dynamics and Restoration Techniques
Oak Regeneration: Ecological Dynamics and Restoration Techniques
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橡木再生：生态动力学和恢复技术
DOI：
10.1007/978-94-007-6707-2_5
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发表时间：
2013
影响因子：
3.2
通讯作者：
T. Plieninger
中科院分区：
文献类型：
--
作者：
F. Pulido;D. McCreary;I. Cañellas;M. McClaran;T. Plieninger
加利福尼亚州和西班牙的橡树林面积有所减少，特别是在二十世纪。目前，西班牙大多数幸存的林分都遭受橡木再生失败的困扰，并且在加利福尼亚州的许多林分中也已注意到这一问题。缺乏将橡子转移到安全（阴凉）地点的分散者是德赫萨斯的主要招募限制，那里的灌木侵占通常会导致更高的橡树招募率。在加利福尼亚州，招聘失败是由多种因素造成的。引进的地中海一年生植物、大量牲畜放牧、灭火以及本地和非本地野生动物对橡子和幼苗的捕食都会产生影响，具体取决于地点和时间段。植树造林一直是解决再生问题的主要手段，特别是在西班牙。局部规模的自然更新受到灌木的青睐，但也通过保护幼苗和改变环境来支持，以便年轻的橡树能够生长到安全的高度。在加利福尼亚州，完全排除牲畜的价值有限，因为啮齿动物密度增加会阻碍幼苗的建立。然而，在德赫萨斯，自然更新只能发生在季节性放牧或完全未放牧的地方，尽管依赖牲畜的土地所有者通常不愿意采取这些措施。
The acreage of oak woodlands has decreased in California and Spain, especially in the twentieth century. Currently, most surviving stands in Spain suffer from oak regeneration failure and it has been noted as a problem in many stands in California. A lack of dispersers transferring acorns to safe (shaded) sites is the main recruitment limitation in dehesas, where shrub encroachment generally results in higher oak recruitment rates. In California, recruitment failure is due to a combination of factors. The effects of introduced Mediterranean annuals, heavy livestock grazing, fire suppression, and predation by native and non-native wildlife on acorns and seedlings are all implicated, depending on locale and time period. Afforestation has been the main instrument for addressing the regeneration problem, especially in Spain. Natural regeneration at local scales is favored by shrubs, but also supported by protecting seedlings and by modifying the environment so young oaks can grow to a safe height. Complete livestock exclusion is of limited value in California as it hampers seedling establishment due to increasing rodent density. In dehesas, however, natural regeneration can only occur in seasonally grazed or wholly ungrazed sites, though livestock-dependent landowners are generally reluctant to carry out these measures.