Paquet Matthieu, Arlt Debora, Knape Jonas, Low Matthew, Forslund Pär, Pärt Tomas
Department of Ecology Swedish University of Agricultural Sciences Uppsala Sweden.
Ecol Evol. 2019 Feb 5;9(2):868-879. doi: 10.1002/ece3.4766. eCollection 2019 Jan.
Land use is likely to be a key driver of population dynamics of species inhabiting anthropogenic landscapes, such as farmlands. Understanding the relationships between land use and variation in population growth rates is therefore critical for the management of many farmland species. Using 24 years of data of a declining farmland bird in an integrated population model, we examined how spatiotemporal variation in land use (defined as habitats with "Short" and "Tall" ground vegetation during the breeding season) and habitat-specific demographic parameters relates to variation in population growth taking into account individual movements between habitats. We also evaluated contributions to population growth using transient life table response experiments which gives information on contribution of past variation of parameters and real-time elasticities which suggests future scenarios to change growth rates. LTRE analyses revealed a clear contribution of Short habitats to the annual variation in population growth rate that was mostly due to fledgling recruitment, whereas there was no evidence for a contribution of Tall habitats. Only 18% of the variation in population growth was explained by the modeled local demography, the remaining variation being explained by apparent immigration (i.e., the residual variation). We discuss potential biological and methodological reasons for high contributions of apparent immigration in open populations. In line with LTRE analysis, real-time elasticity analysis revealed that demographic parameters linked to Short habitats had a stronger potential to influence population growth rate than those of Tall habitats. Most particularly, an increase of the proportion of Short sites occupied by Old breeders could have a distinct positive impact on population growth. High-quality Short habitats such as grazed pastures have been declining in southern Sweden. Converting low-quality to high-quality habitats could therefore change the present negative population trend of this, and other species with similar habitat requirements.
土地利用很可能是栖息在人为景观（如农田）中的物种种群动态的关键驱动因素。因此，了解土地利用与种群增长率变化之间的关系对于许多农田物种的管理至关重要。利用一个综合种群模型中关于一种数量下降的农田鸟类的24年数据，我们研究了土地利用的时空变化（定义为繁殖季节具有“矮”和“高”地面植被的栖息地）以及特定栖息地的人口统计学参数如何与考虑到栖息地之间个体移动的种群增长变化相关。我们还使用瞬态生命表响应实验评估了对种群增长的贡献，该实验提供了关于参数过去变化的贡献信息，以及实时弹性，实时弹性表明了未来改变增长率的情景。长期响应估计（LTRE）分析表明矮栖息地对种群增长率的年度变化有明显贡献，这主要是由于雏鸟补充，而没有证据表明高栖息地有贡献。种群增长变化中只有18%由模拟的当地人口统计学解释，其余变化由明显的迁入（即剩余变化）解释。我们讨论了开放种群中明显迁入贡献高的潜在生物学和方法学原因。与LTRE分析一致，实时弹性分析表明，与矮栖息地相关的人口统计学参数比高栖息地的参数对种群增长率有更强的影响潜力。最特别的是，老年繁殖者占据的矮栖息地比例增加可能对种群增长有明显的积极影响。瑞典南部高质量的矮栖息地（如放牧牧场）一直在减少。因此，将低质量栖息地转变为高质量栖息地可能会改变这种以及其他具有类似栖息地需求的物种目前的负种群趋势。
