Frugivory and seed dispersal by foxes in relation to mammalian prey abundance in a semiarid thornscrub
Frugivory and seed dispersal by foxes in relation to mammalian prey abundance in a semiarid thornscrub
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DOI：
10.1111/j.1442-9993.2005.01449.x
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发表时间：
2005-11
期刊：
影响因子：
1.5
通讯作者：
Sergio Silva;F. Bozinovic;Fabian M Jaksic
中科院分区：
文献类型：
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作者：
Sergio Silva;F. Bozinovic;Fabian M Jaksic
我们研究了在智利半干旱的荆棘灌木丛中，本地狐狸作为果食者和种子传播者的角色。我们在两年的时间里(1998年1月至2000年2月)对其饮食中的水果和动物成分与田间水果和小型哺乳动物的可获得性进行了量化。我们通过量化通过狐狸肠道的种子的活力和发芽率与从植物中采摘的种子的百分比来测试狐狸作为分散剂的合法性和有效性。我们还研究了它们作为分散器的效率，监测田间放置的粪便中种子的命运。当小型哺乳动物猎物的丰度为每公顷6只时，狐狸消耗水果的频率最高，无论田野中的水果丰度如何。因此，狐狸把水果作为一种补充食物来源。根据326个粪便，在两年的研究期间，消耗的水果总数约为34000个，来自外来灌木Schinus molle的水果占总数的98%，本土的仙人掌远远排在第二位。处理后的辣椒种子发芽率和生活力分别比对照降低了66%和48%。与之相比，发芽率提高了50%，对生活力无明显影响。关于狐狸，狐狸是合法的(它们排出可存活的种子)，但无效(粪便中的种子发芽率低于直接从亲本植物中获取的种子，并且在田间没有幼苗建立)和低效的传播者(粪便中的种子被存放在不利于种子萌发和幼苗建立的微生境上)。然而，对于S.molle，狐狸是合法的、有效的(粪便中的种子比直接从亲本植物中获取的种子萌发得更高；在田间有萌发但没有建立)，并且是有效的传播者(超过41%的种子被存放在安全的微型站点上)。因此，一只本地狐狸可能促成了外来灌木的传播，拉拢了现有的社区进程。
We examine the role of the native fox, Pseudalopex culpaeus, as a frugivore and seed disperser in a semiarid thornscrub of Chile. We quantified the fruit and animal components in its diet versus the availability of fruits and small mammals in the field over a 2-year period (January 1998 through February 2000). We tested the legitimacy and effectiveness of foxes as dispersers by quantifying the percentages of seed viability and of germination of seeds that passed through fox gut versus those picked from plants. We also studied their efficiency as dispersers, monitoring the fate of seeds in faeces placed in the field. The highest frequencies of fruit consumption by foxes were observed when abundances of small mammal prey were <6 individuals per hectare, regardless of fruit abundance in the field. Thus, foxes consumed fruits as a supplementary food resource. Based on 326 faeces, the total number of fruits consumed was about 34 000 over the 2-year study period, and fruits from the alien shrub Schinus molle represented 98% of that total, with the native Porlieria chilensis a distant second. Germination and viability of defecated seeds of P. chilensis were reduced by 66% and 48%, respectively, in comparison to controls. In contrast, germination of seeds of S. molle increased by 50% and no effect on viability was observed. With regard to P. chilensis, foxes were legitimate (they defecated viable seeds), but ineffective (seeds in faeces had lower germination than those taken directly from parental plants and there was no seedling establishment in the field) and inefficient dispersers (seeds in faeces were deposited on microhabitats hostile to seed germination and seedling establishment). However, with regard to S. molle, foxes were legitimate, effective (seeds in faeces had higher germination than those taken directly from parental plants; there was germination but no establishment in the field), and efficient dispersers (over 41% of seeds were deposited on safe microsites). Thus, a native fox may be contributing to the spread of an alien shrub, co-opting existing community processes.