HOW IMPORTANT IS SEED PREDATION TO RECRUITMENT IN STABLE-POPULATIONS OF LONG-LIVED PERENNIALS
HOW IMPORTANT IS SEED PREDATION TO RECRUITMENT IN STABLE-POPULATIONS OF LONG-LIVED PERENNIALS
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DOI：
10.1007/bf00377076
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发表时间：
1989-01-01
期刊：
影响因子：
2.7
通讯作者：
ANDERSEN, AN
中科院分区：
文献类型：
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作者：
ANDERSEN, AN
为应对种子捕食而对种子生物学进行的许多进化修改并不一定意味着种子捕食者对种群招募有重要影响。这是因为，就种群而言，个体植物之间对稀有安全地点的竞争可能会导致种子供过于求。在任何时间点，种子损失对种群招募的重要性与安全地点的丰富程度有关(图1)：当没有安全地点时，损失为零；当安全地点稀少时，损失为零；当安全地点足够多，以致于招募受到种子供应的限制时，损失最大。在这里，我解释了严重的种子损失对四种长寿多年生植物(Eucalyptus Baxteri，Leptosperum juniperum，Casuarina pusilla和L.myrsinoides)种群招募的影响，从种群的总体种子动态来考虑这些损失。我的重点是种子供应和幼苗存活，作为目前安全地点丰富程度的衡量标准，以及种子库的维护，作为人口利用安全地点丰富程度未来变化的能力的衡量标准。在每种情况下，昆虫种子捕食者都破坏了大约95%的种子。然而，这些损失并不一定对种群招募产生重要影响，因为：(1)在大多数年份，招募似乎受到安全地点稀少的限制，而不是种子供应(高达43粒可萌发种子/平方米/年)；(2)损失并不妨碍建立大型种子库(从30粒到1100粒可存活种子/平方米)，这些种子库有可能利用有利于招募的临时条件。与许多一年生植物的情况相比，长寿多年生植物稳定种群的补充模式往往极其复杂，因此很难确定种子损失的重要性。
The many evolutionary modifications to seed biology in response to seed predation do not necessarily imply that seed predators have an important impact on population recruitment. This is because competition between individual plants for rare safe sites can cause an ''oversupply'' of seeds so far as a population is concerned. The importance of seed losses to population recruitment at any point in time is related to the abundance of safe sites (Fig. 1): it is zero when safe sites are absent, negligible when safe sites are rare, and greatest when safe sites are numerous enough for recruitment to be limited by seed supply. Here I interpret the impact of severe seed losses on population recruitment in four species of long-lived perennials (Eucalyptus baxteri, Leptospermum juniperinum, Casuarina pusilla and L. myrsinoides) by considering these losses in terms of the overall seed dynamics of the populations. I focus on seed supply and seedling survival, as a measure of the current abundance of safe sites, and the maintenance of seed banks, as a measure of the ability of populations to exploit any future changes in safe site abundance. Insect seed predators destroyed about 95% of total seeds in each case. However, these losses do not necessarily have an important impact on population recruitment, because: (i) in most years recruitment appears to be limited by a rarity of safe sites, and not be seed supply (which was as high as 43 germinable seeds/m2/yr); and (ii) the losses did not prevent the establishment of large seed banks (ranging from > 30 to > 1100 viable seeds/m2) potentially capable of exploiting temporary conditions favourable for recruitment. In contrast to the situation with many annual plants, patterns of recruitment in stable populations of long-lived perennials are often extremely complex, and the significance of seed losses therefore difficult to determine.