Habitat-specific demography across dune fixation stages in a semi-arid sandland: understanding the expansion, stabilization and decline of a dominant shrub
Habitat-specific demography across dune fixation stages in a semi-arid sandland: understanding the expansion, stabilization and decline of a dominant shrub
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DOI：
10.1111/j.1365-2745.2010.01777.x
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发表时间：
2011-03-01
影响因子：
5.5
通讯作者：
Zuidema, Pieter A.
中科院分区：
文献类型：
--
作者：
Li, Shou-Li;Yu, Fei-Hai;Zuidema, Pieter A.
1. 在不同的生境中维持有活力的种群需要植物的生理、形态和人口适应。在沙丘固定过程中，植物的生长条件发生了较大的变化，前期沙的流动性较大，后期植被覆盖较密。研究了优势灌木油蒿（Artemisia ordosica）在半固定沙丘、固定沙丘和被微生物结皮覆盖的固定沙丘3个固定阶段的人口统计学变化。利用三次年度人口普查的人口数据进行参数化积分投影模型（IPMs）的比较人口分析。随着沙丘变得更加固定，植物的生长和繁殖明显减少。植物高度的收缩非常频繁，特别是在有微生物结皮的固定沙丘中。3 .随着沙丘的固定，种群增长率（lambda）大幅下降：从半固定沙丘的快速扩张（lambda = 1.35-1.09）到有微生物结皮的固定沙丘的适度下降（lambda = 0.94-0.89）。弹性分析表明，在所有生境中，存活率是种群增长的关键因素。在半固定生境中，生长和繁殖力的重要性高于其他两个生境，其中收缩成为决定lambda的重要因素。在半固定沙丘生境中，幼苗和小型植物对种群增长至关重要，而在其他生境中，中型至大型植物对种群增长最为重要。生命表响应试验结果表明，固沙过程中λ的显著下降主要是由于繁殖力的降低，但植物生长的减少和收缩的增加也有重要的贡献。因此，在半固定的沙丘上，由于繁殖力比在其他生境中高得多，种群能够迅速扩大。合成。在沙丘固定过程中，油蒿采用不同的生活史策略。半固定沙丘的快速扩张是由于种子产量高和有效的补充，而沙丘固定后期的种群则是通过频繁的植物收缩来维持的。积分投影模型是分析这类生活史变化的非常适当的工具，因为它们是基于各生境的生命率的统计比较。
1. Maintaining viable populations in different habitats requires physiological, morphological and demographic adaptations of plants. In sandland environments, plants experience substantial variation in growing conditions during the dune fixation process, with high sand mobility in early stages and denser vegetation cover in later stages.2. We studied the changes in demography of a dominant shrub, Artemisia ordosica, at three stages of dune fixation: semi-fixed dunes, fixed dunes and fixed dunes covered with microbiotic crust. Demographic data from three annual censuses were used to parameterize integral projection models (IPMs) to conduct comparative demographic analyses.3. Plant growth and reproduction decreased strongly as dunes became more fixed. Shrinkage in plant height occurred very frequently, particularly in the fixed dunes with microbiotic crust. Population growth rate (lambda) declined substantially with dune fixation: from rapid expansion in semi-fixed dunes (lambda = 1.35-1.09) to moderate decline in fixed dunes with microbiotic crust (lambda = 0.94-0.89).4. Elasticity analysis revealed that survival was a key vital rate for population growth in all habitats. Growth and fecundity were of higher importance in the semi-fixed habitat than in the other two habitats where shrinkage became an important factor determining lambda. Seedlings and small plants were critical for population growth in semi-fixed dunes, whereas moderate to large-sized plants were most important in the other habitats.5. Results of life table response experiments showed that the observed strong decrease in lambda during dune fixation was mainly caused by reduction in fecundity, but with additional and considerable contributions from reduced plant growth and increased occurrence of shrinkage. Thus, populations in semi-fixed dunes are able to expand rapidly due to a much higher fecundity compared to those in other habitats.6. Synthesis. Artemisia ordosica adopts different life history strategies along the dune fixation process. Fast expansion in semi-fixed dunes is enabled by high seed production and effective recruitment, while populations at later dune fixation stages are maintained through frequent plant shrinkage. Integral projection models are highly appropriate tools for analysing such life history changes as they are based on statistical comparisons of vital rates across habitats.