A model for small-scale seed bank and standing vegetation connection along time
A model for small-scale seed bank and standing vegetation connection along time
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DOI：
10.1111/j.1600-0706.2008.17138.x
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发表时间：
2008-12-01
期刊：
影响因子：
3.4
通讯作者：
Escudero, Adrian
中科院分区：
文献类型：
--
作者：
Caballero, Idoia;Olano, Jose M.;Escudero, Adrian
由于年际气候变化影响种子库和现存植被的组成和结构，预计它还会随着时间的推移在小尺度上影响两者之间的关系。我们假设，种子库和地上植被在小的空间和时间尺度上是紧密而有序的联系。我们进行了现场空间显式调查，以探索两个隔间之间的空间和时间关系。通过连续两个生长期(干、湿)的100个固定样地，分析了不同小尺度种子库和地上植被的丰富度、组成和空间结构。根据概念转换路径模型，我们分析了两个隔室之间组成和空间聚集的相关值随时间的变化，包括种子库的季节性变化。使用部分Mantel相关图评估空间结构的形状。对一年生和多年生植物的行会分别进行了研究。在多雨年，一年生植物的空间聚集度和盖度增加，而多年生植物则相反。在雨季之后的两个季节，两个行会的种子库密度和空间聚集度都有所增加，尤其是在一年中。瞬变种子库的丛生结构是现存植被空间结构和持久种子库共同作用的结果。一年生行会在枯水期持久种子库的表达较低。尽管群落具有很强的年际变异性，但群落仍保持着高度结构化的时空格局。促进这种稳定性的机制对于年度行会和常年行会是不同的。多年生植物的时间持久性主要取决于已建成植株的寿命，而一年生行会的持久性仅取决于种子库。这种紧凑的结构与群落中演替动态的存在是一致的，尽管持久的种子库可以减缓这种速度。为了充分理解这一过程，需要对种子库-立地植被动态进行更长期的研究。
Since inter-annual climatic variability influences composition and structure of seed bank and extant vegetation, it is expected that it also affects the relationship between both compartments at small scales along time. We hypothesize that seed bank and aboveground vegetation are closely and sequentially linked at small spatial and time scales. We conducted a field spatially explicit investigation to explore the spatial and temporal relationship between both compartments. Abundance, composition and spatial structure at different small-scales of seed bank and aboveground vegetation were analysed through 100 permanent plots during two consecutive (dry and wet) periods of growth. Following a conceptual transition path model, we analysed changes in correlation values in composition and spatial aggregation between both compartments along time including seasonal variations of seed bank. Shape of spatial structures were evaluated using partial Mantel correlograms. Annuals and perennials guilds were studied separately. During the wet year, annuals increased their aerial spatial aggregation and cover, whereas the opposite happened for perennials. Density and spatial aggregation of the seed bank increased for both guilds in the two seasons following the rain period, especially in annuals. The clumped structure of the transient seed bank is a consequence of the addition of spatial structure of extant vegetation and the persistent seed bank. Expression of the persistent seed bank is much lower during the dry period for the annual guild. In spite of the strong yearly variability, the community maintained a highly structured spatiotemporal pattern. The mechanisms promoting this stability differed for annual and perennial guilds. Temporal persistence in perennials relied mainly in established plants longevity, whereas annual guild persistence depended solely on seed bank. This tight structure was coherent with the existence of successional dynamics in the community, although persistent seed bank could moderate the pace. Longer term studies of seed bank-standing vegetation dynamics are required to fully understand this process.