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首页> 外文期刊>Conservation Biology >Effect of habitat deterioration on population dynamics and extinction risks in a previously common perennial
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Effect of habitat deterioration on population dynamics and extinction risks in a previously common perennial

机译：在以前常见的多年生植物中，栖息地恶化对种群动态和灭绝风险的影响

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Habitat deterioration affects population viability and persistence,of both plant and animal species. For plants the effect of changes in environmental conditions on population dynamics and extinction risks largely depends on the life span of the species. We used transition matrix models, a life-table response experiment, and stochastic simulations to investigate the overall effects of nitrogen enrichment (9, 6,3, and 0 g N/m(2)/year) and grassland management (mowing and grazing) on vital rates, population growth rate (X), and extinction risks of a previously common perennial herb (Primula veris [L.]). We experimentally manipulated 32 permanent plots that were monitored during a 5-year period. To study the effects of nitrogen addition and management on recruitment in more detail and to evaluate the role of seed availability, we experimentally sowed seeds at different densities. Nitrogen addition always resulted in negative population growth rates (range: 0.998 to 0.700), whereas mean population growth rates in the control situation were > 1. Interaction effects indicated that the negative effect of increasing nitrogen addition decreased population growth rate more strongly when the vegetation was mown compared with grazing. Besides significantly increased mortality rates, especially in the youngest life stages, decreased population growth rates under nitrogen enrichment were mainly the result of reduced flowering probabilities, seed production rates per plant, recruitment, and establishment of seedlings. Mowing, however, encouraged growth of vegetative adults into a flowering stage and decreased germination and seedling establishment, whereas the reverse was observed under grazing. Under the highest nitrogen levels, mean times to extinction were much shorter than would be expected based on the longevity of the species, especially under mowing. These results demonstrate that even long-lived and formerly common perennial species may quickly respond to habitat deterioration, especially when the deterioration takes place over a short period of time.
机译：生境的恶化会影响动植物物种的生存能力和持久性。对于植物而言，环境条件的变化对种群动态和灭绝风险的影响在很大程度上取决于物种的寿命。我们使用过渡矩阵模型，寿命表响应实验和随机模拟研究了氮富集（9、6,3和0 g N / m（2）/年）和草地管理（割草和放牧）的总体影响）上以前常见的多年生草本植物（Primula veris [L.]）的生命率，种群增长率（X）和灭绝风险。我们通过实验操作了32个永久性地块，并在5年内对其进行了监控。为了更详细地研究氮素的添加和管理对募集的影响并评估种子可用性的作用，我们以实验方式播种了不同密度的种子。氮添加总是导致种群增长率为负（范围：0.998至0.700），而对照情况下的平均种群增长率为>1。交互作用表明，当植被生长时，增加氮添加的负效应会更强烈地降低种群增长率。与放牧相比被割。除了显着提高死亡率（尤其是在最年轻的生命阶段）外，在富氮条件下种群生长速率下降的主要原因是开花概率降低，单株种子生产率，招募和幼苗生长。但是，割草可以促进无营养成年植物的生长，使其进入开花期，并减少发芽和幼苗的生长，而放牧则相反。在最高氮含量下，平均灭绝时间比根据物种的寿命，特别是在割草时的寿命所期望的要短得多。这些结果表明，即使是长期存在且以前很常见的多年生物种也可能对栖息地的退化做出快速反应，特别是当退化在短时间内发生时。

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