Departamento de Biología Vegetal I, Universidad Complutense de Madrid, Madrid, Spain.
PLoS One. 2011;6(8):e23004. doi: 10.1371/journal.pone.0023004. Epub 2011 Aug 2.
In the Peruvian Coastal Desert, an archipelago of fog oases, locally called lomas, are centers of biodiversity and of past human activity. Fog interception by a tree canopy, dominated by the legume tree tara (Caesalpinia spinosa), enables the occurrence in the Atiquipa lomas (southern Peru) of an environmental island with a diverse flora and high productivity. Although this forest provides essential services to the local population, it has suffered 90% anthropogenic reduction in area. Restoration efforts are now getting under way, including discussion as to the most appropriate reference ecosystem to use.
METHODOLOGY/PRINCIPAL FINDINGS: Genetic diversity of tara was studied in the Atiquipa population and over a wide geographical and ecological range. Neither exclusive plastid haplotypes to loma formations nor clear geographical structuring of the genetic diversity was found. Photosynthetic performance and growth of seedlings naturally recruited in remnant patches of loma forest were compared with those of seedlings recruited or planted in the adjacent deforested area. Despite the greater water and nitrogen availability under tree canopy, growth of forest seedlings did not differ from that of those recruited into the deforested area, and was lower than that of planted seedlings. Tara seedlings exhibited tight stomatal control of photosynthesis, and a structural photoprotection by leaflet closure. These drought-avoiding mechanisms did not optimize seedling performance under the conditions produced by forest interception of fog moisture.
CONCLUSIONS/SIGNIFICANCE: Both weak geographic partitioning of genetic variation and lack of physiological specialization of seedlings to the forest water regime strongly suggest that tara was introduced to lomas by humans. Therefore, the most diverse fragment of lomas is the result of landscape management and resource use by pre-Columbian cultures. We argue that an appropriate reference ecosystem for ecological restoration of lomas should include sustainable agroforestry practices that emulate the outcomes of ancient uses.
在秘鲁沿海沙漠，有一个雾绿洲群岛，当地称为洛马斯，这里是生物多样性和过去人类活动的中心。树冠截留雾，由豆科树塔拉（Caesalpinia spinosa）主导，使得在阿蒂基帕洛马斯（秘鲁南部）出现了一个环境岛屿，这里植物种类多样，生产力高。尽管这片森林为当地居民提供了重要的服务，但它的面积已经减少了 90%。现在正在进行恢复工作，包括讨论使用最合适的参考生态系统。
方法/主要发现：在阿蒂基帕地区和广泛的地理和生态范围内研究了塔拉的遗传多样性。既没有发现与洛马斯形成有关的特有质体单倍型，也没有发现遗传多样性的明显地理结构。比较了自然招募到洛马斯森林残余斑块中的幼苗和在相邻森林砍伐区中招募或种植的幼苗的光合作用性能和生长情况。尽管树冠下的水分和氮素供应更多，但森林幼苗的生长与在森林砍伐区中招募的幼苗没有区别，而且低于种植的幼苗。塔拉幼苗表现出对光合作用的紧密气孔控制，以及通过小叶闭合实现的结构性光保护。这些避免干旱的机制并没有优化幼苗在雾水分被森林截留产生的条件下的性能。
结论/意义：遗传变异的地理分割较弱，以及幼苗对森林水分条件的生理特化缺乏，这两个因素都强烈表明，塔拉是由人类引入洛马斯的。因此，洛马斯最具多样性的片段是前哥伦布文化进行景观管理和资源利用的结果。我们认为，用于洛马斯生态恢复的适当参考生态系统应包括模仿古代用途的可持续农林复合经营实践。
