ON THE REPLACEMENT OF THE RED SQUIRREL IN BRITAIN - A PHYTOTOXIC EXPLANATION
ON THE REPLACEMENT OF THE RED SQUIRREL IN BRITAIN - A PHYTOTOXIC EXPLANATION
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DOI：
10.1098/rspb.1993.0028
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发表时间：
1993-03-22
影响因子：
4.7
通讯作者：
HOLM, JL
中科院分区：
文献类型：
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作者：
KENWARD, RE;HOLM, JL
扩散模型表明，保守的人口特征与觅食竞争相结合可以解释红松鼠被灰松鼠取代的原因。我们使用了橡榛树林和欧洲赤松中七个独立的红松鼠和灰松鼠种群的现场数据，以驳斥红松鼠密度和繁殖本质上比灰松鼠差的假设。在橡榛树林中，灰松鼠的觅食、密度和生产力与橡树和橡子的丰度有关。相比之下，红松鼠则在榛树丰富的地方觅食。它们相对较低的密度和繁殖成功与丰富的榛子有关。红松鼠未能利用优质的橡子作物，尽管橡子比榛子丰富，但赤松的密度和繁殖成功率与落叶林中的灰松鼠一样高。圈养的灰松鼠靠吃橡子而茁壮成长，但红松鼠的相对消化效率仅为 59%，显然是因为它们中和橡子多酚的能力远不如灰松鼠。秋季榛树作物（在橡子作物生长之前就被灰松鼠吃掉）的简单竞争模型表明，在橡树冠层超过 14% 的树林中，红松鼠不太可能与灰松鼠一起生存。由于大多数英国落叶林中的橡树为灰松鼠提供了红松鼠无法利用的食物避难所，因此红松鼠的替代可以仅通过喂养竞争来解释，而战后小林榛树的减少加剧了这种竞争。
Diffusion modelling has shown that conservative demographic traits combined with feeding competition could explain red squirrel replacement by grey squirrels. We used field data from seven separate red and grey squirrel populations, in oak-hazel woods and Scots pines, to reject the hypothesis that red squirrel density and breeding is intrinsically poorer than that of grey squirrels. In oak-hazel woods, grey squirrel foraging, density and productivity were related to oak and acorn abundance. In contrast, red squirrels foraged where hazels were abundant; their relatively low density and breeding success were related to the abundance of hazel nuts. Red squirrels failed to exploit good acorn crops, although acorns were more abundant than hazels, but in Scots pines had densities and breeding success as high as grey squirrels in deciduous woods. Captive grey squirrels thrived on a diet of acorns, but red squirrels had a comparative digestive efficiency of only 59%, apparently because they were much less able than grey squirrels to neutralize acorn polyphenols. A model with simple competition for the autumn hazel crop, which was eaten by grey squirrels before the acorn crop, shows that red squirrels are unlikely to persist with grey squirrels in woods with more than 14% oak canopy. With oaks in most British deciduous woods giving grey squirrels a food refuge which red squirrels fail to exploit, replacement of red squirrels can be explained by feeding competition alone, exacerbated by the post-war decline in coppiced hazel.