Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, USA.
PLoS One. 2013 Aug 13;8(8):e71446. doi: 10.1371/journal.pone.0071446. eCollection 2013.
The rate of new exotic recruitment following removal of adult invaders (reinvasion pressure) influences restoration outcomes and costs but is highly variable and poorly understood. We hypothesize that broad variation in average reinvasion pressure of Triadica sebifera (Chinese tallow tree, a major invader) arises from differences among habitats in spatiotemporal availability of realized recruitment windows. These windows are periods of variable duration long enough to permit establishment given local environmental conditions. We tested this hypothesis via a greenhouse mesocosm experiment that quantified how the duration of favorable moisture conditions prior to flood or drought stress (window duration), competition and nutrient availability influenced Triadica success in high stress environments. Window duration influenced pre-stress seedling abundance and size, growth during stress and final abundance; it interacted with other factors to affect final biomass and germination during stress. Stress type and competition impacted final size and biomass, plus germination, mortality and changes in size during stress. Final abundance also depended on competition and the interaction of window duration, stress type and competition. Fertilization interacted with competition and stress to influence biomass and changes in height, respectively, but did not affect Triadica abundance. Overall, longer window durations promoted Triadica establishment, competition and drought (relative to flood) suppressed establishment, and fertilization had weak effects. Interactions among factors frequently produced different effects in specific contexts. Results support our 'outgrow the stress' hypothesis and show that temporal availability of abiotic windows and factors that influence growth rates govern Triadica recruitment in stressful environments. These findings suggest that native seed addition can effectively suppress superior competitors in stressful environments. We also describe environmental scenarios where specific management methods may be more or less effective. Our results enable better niche-based estimates of local reinvasion pressure, which can improve restoration efficacy and efficiency by informing site selection and optimal management.
外来种入侵后新个体的入侵速率（再入侵压力）会影响生态恢复的结果和成本，但入侵速率的变化幅度大且难以预测。我们假设，光叶楮（Triadica sebifera）的平均再入侵压力存在广泛差异，其原因在于不同生境中潜在繁殖窗口的时空可利用性存在差异。繁殖窗口是指在当地环境条件下，植物建立种群所需的持续时间长短不定的时间段。为了验证这一假说，我们开展了一个温室中尺度模拟实验，量化了洪水或干旱胁迫前（窗口持续时间）有利水分条件的持续时间、竞争和养分供应如何影响光叶楮在高胁迫环境下的生存状况。窗口持续时间影响了胁迫前幼苗的丰度和大小、胁迫期间的生长以及最终的丰度；它与其他因素相互作用，影响胁迫期间的最终生物量和种子发芽率。胁迫类型和竞争影响最终的大小和生物量，以及胁迫期间的发芽率、死亡率和大小变化。最终丰度还取决于竞争以及窗口持续时间、胁迫类型和竞争的相互作用。施肥分别与竞争和胁迫相互作用，影响生物量和高度变化，但不影响光叶楮的丰度。总的来说，较长的窗口持续时间促进了光叶楮的建立，竞争和干旱（相对于洪水）抑制了其建立，施肥的影响较弱。各因素之间的相互作用在特定背景下会产生不同的影响。研究结果支持我们的“逆境中生长”假说，并表明非生物窗口的时间可用性以及影响生长速率的因素决定了光叶楮在胁迫环境中的繁殖。这些发现表明，在胁迫环境中，添加本地种子可以有效地抑制优势种的生长。我们还描述了特定管理方法在不同环境下可能更有效或更无效的情况。我们的研究结果可以更好地基于生态位来估计本地再入侵压力，从而通过选择合适的地点和优化管理来提高生态恢复的效果和效率。
