Measurements of transient seedbanks mediated by shrub effects in the Mojave and San Joaquin Deserts

The biodiversity of annual plants in deserts are stored in seedbank waiting on precipitation events. Previous research has examined how shrubs interfere with seed flow in deserts, however, less examined are the indirect effects on seedbank densities. Shrubs facilitate plant densities within their canopy that can inhibit seed movement or that can produce greater seed rain. Herein, we chose two distinct desert ecosystems and established plots in shrub and open microsites to test how shrubs can facilitate seedbank densities. We included treatments that manipulated annual plant cover and persistent seedbank densities over two years (2013 and 2014). Four treatments were established in shrub and open microsites at three neighbouring sites at each of these deserts. No experiment was set up in Mojave Desert in 2014 because of extreme drought for that area. Ten replicates were used.沙漠一年生植物的生物多样性以种子库（seedbank）的形式储存，静待降水事件的触发。既往研究已探讨了灌木如何干扰沙漠中的种子流，但针对其对种子库密度的间接影响的相关研究仍较为匮乏。灌木可提升其冠层内的植物种群密度，这类植物既会抑制种子移动，也能产生更多的种子雨。本研究选取两类截然不同的沙漠生态系统，在灌木覆盖微生境与开阔微生境中设置样地，以探究灌木对种子库密度的提升作用。实验设置了调控一年生植物盖度与持久种子库密度的处理组，实验周期为2013年与2014年两年。针对这两个沙漠生态系统，分别在每个沙漠的3处邻近样地的灌木覆盖与开阔微生境中，各设置4种处理方案。由于莫哈韦沙漠（Mojave Desert）2014年遭遇极端干旱，当年未在该区域开展实验。本实验共设置10次生物学重复。