Fires slow population declines of a long-lived prairie plant through multiple vital rates
Fires slow population declines of a long-lived prairie plant through multiple vital rates
复制标题
火灾通过多种生命率减缓了长寿草原植物的种群数量下降
DOI：
10.1007/s00442-021-04955-2
复制
发表时间：
2021
期刊：
影响因子：
2.7
通讯作者：
Wagenius, Stuart
中科院分区：
文献类型：
--
作者：
Nordstrom, Scott W.;Dykstra, Amy B.;Wagenius, Stuart
在全世界的草原上，改良的火循环正在加速草本物种的灭绝。火可以通过增加生存、繁殖或两者来避免种群下降。火灾后的生存和增长可以通过消除竞争对手或生物量和增加资源的可用性来促进。火灾刺激的繁殖也可能通过促进补充而促进人口增长。我们量化了火对北美高草草原多年生杂类草种群动态inEchinacea angustifolia的影响。我们首先使用了四个数据集，7-21年的时间，以估计火灾对生存，开花和招聘的影响。然后，我们使用矩阵投影模型来估计五个人群中几种烧伤频率的增长率，每个人群在15年内有一到四次烧伤。最后，我们估计了火灾引起的变化，在每个生命率的人口增长的变化的贡献。人口增长率通常随着燃烧而增加。这些增长的人口统计过程取决于青少年的生存。在高少年生存的人口，火灾引起的增加，在幼苗招聘和少年生存增强人口增长。然而，在幼年存活率低的种群中，成年存活率的微小变化驱动了生长率的变化。无论烧伤的频率，我们的模型表明，人口正在下降，招聘和青少年的生存严重影响人口对火灾的反应。然而，至关重要的是，只有当足够的新成员达到生殖成熟时，增加幼苗补充才会增加种群增长率。招募和幼年生存的重要性对于碎片化栖息地中的小种群尤其重要，这些栖息地受到雄性限制性Allee效应和近交衰退的影响，这分别减少了招募和生存。
In grasslands worldwide, modified fire cycles are accelerating herbaceous species extinctions. Fire may avert population declines by increasing survival, reproduction, or both. Survival and growth after fires may be promoted by removal of competitors or biomass and increasing resource availability. Fire-stimulated reproduction may also contribute to population growth through bolstered recruitment. We quantified these influences of fire on population dynamics inEchinacea angustifolia, a perennial forb in North American tallgrass prairie. We first used four datasets, 7–21 years long, to estimate fire’s influences on survival, flowering, and recruitment. We then used matrix projection models to estimate growth rates across several burn frequencies in five populations, each with one to four burns over 15 years. Finally, we estimated the contribution of fire-induced changes in each vital rate to changes in population growth. Population growth rates generally increased with burning. The demographic process underpinning these increases depended on juvenile survival. In populations with high juvenile survival, fire-induced increases in seedling recruitment and juvenile survival enhanced population growth. However, in populations with low juvenile survival, small changes in adult survival drove growth rate changes. Regardless of burn frequencies, our models suggest populations are declining and that recruitment and juvenile survival critically influence population response to fire. However, crucially, increased seedling recruitment only increases population growth rates when enough new recruits reach reproductive maturity. The importance of recruitment and juvenile survival is especially relevant for small populations in fragmented habitats subject to mate-limiting Allee effects and inbreeding depression, which reduce recruitment and survival, respectively.