Secondary forests of central Panama increase in similarity to old-growth forest over time in shade tolerance but not species composition
Secondary forests of central Panama increase in similarity to old-growth forest over time in shade tolerance but not species composition
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DOI：
10.1111/j.1654-1103.2012.01482.x
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发表时间：
2013-05-01
影响因子：
2.8
通讯作者：
Denslow, Julie S.
中科院分区：
文献类型：
--
作者：
Dent, Daisy H.;DeWalt, Saara J.;Denslow, Julie S.
问题：热带次生林的物种和功能组成是否更紧密地遵循确定性或随机性的演替模式？地点巴拿马中部的巴罗科罗拉多自然纪念碑（BCNM）。BCNM包括巴罗科罗拉多岛（BCI）和五个相邻的大陆半岛，是一个镶嵌的热带原始林（OG）和次生林（SF）。方法以20 ~ 100年生的SF林分和2个OG林分为对照，研究了其幼苗、幼树和成年树群落的种类和功能组成。功能成分是指不同耐荫程度的植物的代表性。我们还研究了物种多样性和优势的模式，以更好地了解驱动组成变化的过程。结果物种多样性迅速恢复，到20年，物种丰富度的所有大小级是相当的，如果不是更高的SF相比，OG。幼苗的物种多样性低于幼树或成树，物种优势度高于幼树或成树。实生林、幼树和成树树种组成与OG的相似性随林龄的增加没有明显增加。相反，林分之间物种组成的差异反映了特定物种优势的变化。光需求的物种变得不那么常见，耐荫的物种更常见的林分年龄，与功能组成的老次生林收敛的OG。幼苗和幼树社区的时序组成的耐荫的子集，这些物种中发现的立场作为成年人。结论本研究结果表明，SF的幼苗群落的招聘是由可预测的（如耐荫物种的选择）和不可预测的因素（如物种特异性繁殖事件和扩散限制）。树苗和树木群落的招募反映了对耐荫物种的更强且潜在的复合选择。因此，在这方面的再生森林的物种组成的变化似乎是不可预测的，即使功能组成遵循一个更确定性和可预测的轨迹，随着时间的推移，在OG收敛。
Question Does species and functional composition of secondary tropical forests more closely follow a deterministic or a stochastic model of succession? Location The Barro Colorado Nature Monument (BCNM), central Panama. The BCNM comprises Barro Colorado Island (BCI) and five adjacent mainland peninsulas and is a mosaic of tropical old-growth (OG) and secondary forests (SF). Methods We studied the species and functional composition of seedling, sapling and adult tree communities in a chronosequence of SF stands ranging in age from 20 to 100yrs since abandonment, as well as two OG stands for comparison. Functional composition was defined as the representation of species with different degrees of shade tolerance. We also examined patterns of species diversity and dominance to better understand processes driving compositional changes. Results Species diversity recovered rapidly, and, by 20yrs, species richness for all size classes was equivalent if not higher in SF compared to OG. Species diversity tended to be lower and species dominance higher for seedlings than saplings or adults. Seedling, sapling and adult tree species composition did not clearly increase in similarity to OG with forest age. Instead, differences in species composition among stands reflected variation in dominance by particular species. Light-demanding species became less common and shade-tolerant species more common over stand age, with the functional composition of older secondary forests converging on that of OG. The seedling and sapling communities across the chronosequence were composed of a shade-tolerant subset of those species found in the stands as adults. Conclusion Our results suggest that recruitment into the seedling community of SF is determined by both predictable (e.g. selection for shade-tolerant species) and unpredictable factors (e.g. species-specific reproduction events and dispersal limitation). Recruitment into the sapling and tree communities reflects stronger, and potentially compounded, selection for shade-tolerant species. Therefore, changes in the species composition of regenerating forests in this area appear to be unpredictable, even though the functional composition follows a more deterministic and predictable trajectory with convergence on OG over time.