College of Nature Conservation, Beijing Forestry University, Beijing, China.
PLoS One. 2010 Oct 26;5(10):e13631. doi: 10.1371/journal.pone.0013631.
The ability of small clonal fragments to establish and grow after disturbance is an important ecological advantage of clonal growth in plants and a major factor in the invasiveness of some introduced, clonal species. We hypothesized that orientation in the horizontal position (typical for stoloniferous plants) can increase the survival and growth of dispersed clonal fragments, and that this effect of orientation can be stronger when fragments are smaller and thus have fewer reserves to support initial growth.
METHODOLOGY/PRINCIPAL FINDINGS: To test these hypotheses, we compared performance of single-node pieces of stolon fragments of Alternanthera philoxeroides planted at angles of 0, 45 or 90° away from the horizontal position, with either the distal or the proximal end of the fragment up and with either 1 or 3 cm of stolon left attached both distal and proximal to the ramet. As expected, survival and growth were greatest when fragments were positioned horizontally. Contrary to expectations, some of these effects of orientation were stronger when attached stolons were longer. Orientation had smaller effects than stolon length on the performance of fragments; survival of fragments was about 60% with shorter stolons and 90% with longer stolons.
CONCLUSIONS/SIGNIFICANCE: Results supported the hypothesis that orientation can affect establishment of small clonal fragments, suggested that effects of orientation can be stronger in larger rather than smaller fragments, and indicated that orientation may have less effect on establishment than amount of stored resources.
小克隆片段在受到干扰后能够建立和生长的能力是植物克隆生长的一个重要生态优势，也是一些外来克隆物种具有入侵性的主要因素。我们假设，在水平位置上的定向（典型的匍匐植物）可以增加分散的克隆片段的生存和生长，而这种定向的效果在片段较小且初始生长所需储备较少时可能更强。
方法/主要发现：为了检验这些假设，我们比较了在与水平位置成 0、45 或 90 度角种植的、具有单个节点的匍匐片段的单节点片段的性能，片段的远侧或近侧端向上，并且在片段的远侧和近侧都有 1 或 3 厘米的匍匐茎附着。正如预期的那样，当片段处于水平位置时，生存和生长最大。与预期相反，当附着的匍匐茎较长时，一些定向效应更强。定向对片段性能的影响小于匍匐茎长度；短匍匐茎的片段存活率约为 60%，长匍匐茎的片段存活率约为 90%。
结论/意义：结果支持了定向可以影响小克隆片段建立的假设，表明定向的影响在较大片段中可能比在较小片段中更强，并表明定向对建立的影响可能小于存储资源的数量。
