Land-use change modifies the spatial structure of tropical landscapes, shaping global biodiversity patterns. Yet, it remains unknown how key ecological processes, such as seed dispersal, can be affected by changes in landscape patterns, and whether such effects differ among regions with different climate and disturbance intensity. We assessed the effect of five landscape metrics (forest cover, matrix openness, forest edge density, forest fragmentation, and interpatch distance) on the seed rain recorded in two Mexican fragmented regions (20 forest sites per region): the more deforested, defaunated, and windy Los Tuxtlas rainforest (LTX), and the better-preserved Lacandona rainforest (LAC). We quantified the proportions of dispersed tree species and their seeds, separately evaluating wind- and animal-dispersed species. Our findings support the hypothesis that forest loss is more important than fragmentation per se, negatively impacting the seed rain in both regions. As expected, landscape patterns were comparatively more important for wind-dispersed seeds in LTX, probably because of stronger wind events in this region. Specifically, proportions of wind-dispersed seeds and species decreased with increasing edge density, suggesting that forest edges prevent dispersal of wind-dispersed species, which may occur if edges create physical barriers that limit wind flow. This pattern can also be caused by source limitation in landscapes with more forest edges, as tree mortality rates usually increase at forest edges. The wind-dispersed seed rain was also positively related to matrix openness, especially in LTX, where wind flow can be favored by the dominance of treeless anthropogenic matrices. Surprisingly, the proportion of animal-dispersed seeds in LTX was positively related to matrix openness and patch isolation, suggesting that seed dispersers in more deforested regions may be forced to concentrate in isolated patches and use the available habitat more intensively. Yet, as expected, patch isolation limited wind-dispersed seeds in LAC. Therefore, dispersal (and potentially regeneration) of wind-dispersed trees is favored in regions exposed to stronger wind events, especially in landscapes dominated by regularly shaped patches surrounded by open areas. Conversely, animal-dispersed seeds are primarily favored by increasing forest cover. Preventing forest loss is therefore critical to promote animal seed dispersal and forest recovery in human-modified rainforests.

中文翻译：

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区域背景和传播方式驱动景观结构对种子传播的影响。

土地用途的变化改变了热带景观的空间结构，塑造了全球生物多样性格局。然而，仍然未知的是，景观格局的变化如何影响关键的生态过程（例如种子传播），以及这种影响在气候和干扰强度不同的地区之间是否有所不同。我们评估了五个景观指标（森林覆盖率，基质开放度，森林边缘密度，森林破碎度和插片间距离）对两个墨西哥破碎区域（每个区域20个森林站点）记录的种子雨的影响：和多风的Los Tuxtlas雨林（LTX），以及保存得更好的Lacandona雨林（LAC）。我们量化了分散的树种及其种子的比例，分别评估了风和动物分散的树种。我们的发现支持以下假设：森林流失本身比破碎本身更为重要，这对两个地区的种子雨都产生了负面影响。不出所料，景观模式对LTX中风散种子的影响相对更重要，这可能是因为该地区的强风事件。具体而言，随边缘密度的增加，风散种子和物种的比例降低，这表明森林边缘阻止了风散物种的扩散，如果边缘形成限制风速的物理屏障，则可能发生这种情况。这种模式也可能是由于森林边缘较多的景观中的源限制所致，因为树木死亡率通常在森林边缘处增加。风散种子雨也与基质开放度呈正相关，特别是在LTX中，无树的人为矩阵的优势可能有利于风的流动。令人惊讶的是，LTX中动物分散种子的比例与基质开放度和斑块隔离成正相关，这表明森林面积更大的地区的种子分散剂可能被迫集中在孤立的斑块上，并更密集地利用可利用的栖息地。但是，正如预期的那样，补丁隔离限制了LAC中风散的种子。因此，在暴露于强风事件的地区，特别是在以规则形状的斑块为中心，被开放区域包围的景观中，散布（并可能再生）风散布的树木是有利的。相反，主要通过分散森林覆盖率来有利于分散动物的种子。