Aims

We studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits of rainfall and temperature. Two hypotheses were established: (1) regeneration of Quercus species is strongly favored by the presence of tree cover; and (2) growth of Q. suber is driven by the climatic variables that represent the lower ecological limit of its leading distribution edge.

Methods

We selected woodlands and old fields with and without tree remnants (n = 3 per type), and analyzed stand structure, soil parameters and tree growth.

Results

Succession was arrested in old fields without tree remnants. By contrast, remnant trees were accelerators of forest recovery in old fields. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation that mitigate the effects of summer drought on seedlings. Also, tree cover improved soil parameters (e.g., organic matter) that are important factors for understanding differences in regeneration. Winter/spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September.

Conclusions

Regeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover.

中文翻译：

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分布前沿的破碎景观中的再生动态：作为研究案例的栎属林地

宗旨

我们研究了在雨量和温度下限以栎属植物为主的景观中林地和废弃旧田的再生动态。建立了两个假设：（1）树木覆盖的存在强烈有利于栎属物种的再生；(2) Q. suber 的增长是由代表其前沿分布边缘的生态下限的气候变量驱动的。

方法

我们选择了有和没有树木残余物的林地和旧田（ 每种类型n = 3），并分析了林分结构、土壤参数和树木生长情况。

结果

继承被逮捕在没有树木残余的旧田里。相比之下，残树是旧田森林恢复的加速器。在整个种子传播和促进过程中，树木覆盖在Quercus招募中发挥了重要作用，可减轻夏季干旱对幼苗的影响。此外，树木覆盖改善了土壤参数（例如有机质），这些参数是了解再生差异的重要因素。冬季/春季降水对树木生长以及冬季/春季和 9 月的温度产生了积极影响。

结论

再生动态通过Q. suber分布区域的寒冷和干燥边缘的树木覆盖密度建模，其中Q. ilex丰度增加。尽管温度对Q. suber的树木生长有积极影响，但考虑到人口统计过程时，可用水量的减少可能在Q. ilex募集中发挥关键作用。这反过来会改变优势等级，特别是在树木覆盖很少或没有的废弃区域。