Center for Conservation and Sustainable Development, Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110, U.S.A.
Division of Biostatistics, Washington University, St. Louis, MO, 63110, U.S.A.
Conserv Biol. 2019 Jun;33(3):601-611. doi: 10.1111/cobi.13255. Epub 2019 Jan 4.
Reintroductions are important components of conservation and recovery programs for rare plant species, but their long-term success rates are poorly understood. Previous reviews of plant reintroductions focused on short-term (e.g., ≤3 years) survival and flowering of founder individuals rather than on benchmarks of intergenerational persistence, such as seedling recruitment. However, short-term metrics may obscure outcomes because the unique demographic properties of reintroductions, including small size and unstable stage structure, could create lags in population growth. We used time-to-event analysis on a database of unusually well-monitored and long-term (4-28 years) reintroductions of 27 rare plant species to test whether life-history traits and population characteristics of reintroductions create time-lagged responses in seedling recruitment (i.e., recruitment time lags [RTLs]), an important benchmark of success and indicator of persistence in reintroduced populations. Recruitment time lags were highly variable among reintroductions, ranging from <1 to 17 years after installation. Recruitment patterns matched predictions from life-history theory with short-lived species (fast species) exhibiting consistently shorter and less variable RTLs than long-lived species (slow species). Long RTLs occurred in long-lived herbs, especially in grasslands, whereas short RTLs occurred in short-lived subtropical woody plants and annual herbs. Across plant life histories, as reproductive adult abundance increased, RTLs decreased. Highly variable RTLs were observed in species with multiple reintroduction events, suggesting local processes are just as important as life-history strategy in determining reintroduction outcomes. Time lags in restoration outcomes highlight the need to scale success benchmarks in reintroduction monitoring programs with plant life-history strategies and the unique demographic properties of restored populations. Drawing conclusions on the long-term success of plant reintroduction programs is premature given that demographic processes in species with slow life-histories take decades to unfold.
再引入是稀有植物物种保护和恢复计划的重要组成部分，但长期成功率却知之甚少。以前对植物再引入的研究主要集中在短期（例如，≤3 年）的创始个体的存活和开花上，而不是代际持续存在的基准，如幼苗的补充。然而，短期指标可能会掩盖结果，因为再引入的独特人口特征，包括规模小和不稳定的阶段结构，可能会导致种群增长滞后。我们使用事件时间分析方法，对 27 种稀有植物物种的异常监测和长期（4-28 年）再引入数据库进行了分析，以检验再引入的生活史特征和种群特征是否会导致幼苗补充（即补充时间滞后[RTL]）的时间滞后反应，这是成功的重要基准，也是再引入种群中持久性的指标。再引入之间的补充时间滞后差异很大，从安装后<1 年到 17 年不等。补充模式与生活史理论的预测相符，即短命物种（快速物种）的 RTL 始终短于长寿物种（慢速物种），且变化较小。长寿物种的 RTL 出现在长寿草本植物中，尤其是在草原中，而短寿命的 RTL 出现在短命的亚热带木本植物和一年生草本植物中。在整个植物生活史中，随着繁殖成年个体数量的增加，RTL 减少。在具有多次再引入事件的物种中观察到高度可变的 RTL，这表明局部过程与生活史策略一样，是决定再引入结果的重要因素。再引入结果的时间滞后突出表明，需要根据植物生活史策略和恢复种群的独特人口特征，调整再引入监测计划中的成功基准。考虑到具有缓慢生活史的物种的人口过程需要几十年才能显现，因此过早地对植物再引入计划的长期成功得出结论是不成熟的。
