Long-term livestock exclosure did not affect soil carbon in southern Ethiopian rangelands
Long-term livestock exclosure did not affect soil carbon in southern Ethiopian rangelands
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DOI：
10.1016/j.geoderma.2017.07.030
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发表时间：
2017-12-01
期刊：
影响因子：
6.1
通讯作者：
Shepherd, Keith
中科院分区：
文献类型：
--
作者：
Aynekulu, Ermias;Mekuria, Wolde;Shepherd, Keith
控制放牧管理被认为是提高土壤固碳的有效策略，但经验证据很少。特别是，在非洲干旱和半干旱的大草原上，与土壤固碳有关的牲畜排斥的作用还没有得到很好的理解。我们调查了长期(14-36年)封育在埃塞俄比亚南部半干旱稀树草原提高土壤碳含量的有效性。我们测试了封育和邻近的露地牧场之间土壤碳含量的差异，同时考虑了封育的年龄和土壤深度的影响。我们从12个围栏和邻近的露天放牧场的96个样地采集了两个土壤深度(0-20 cm和20-50 cm)的土壤样品。我们发现封育和邻近的露地牧场在两种土壤深度的土壤碳含量没有显著差异(P>；0.05)。年龄时间序列进一步表明，随着封育时间的延长，土壤碳含量的增加存在微弱的非线性趋势。因此，这些结果挑战了控制放牧提高半干旱稀树草原土壤固碳能力的观点。然而，我们仍然对这些调查结果的结论性持谨慎态度，因为缺乏关于其他混杂因素的信息，这些因素可能会解开围栏的影响，最重要的是，在围栏之前缺乏土壤数据。
Controlled grazing management is considered as an effective strategy to enhance soil carbon sequestration, but empirical evidences are scarce. Particularly, the role of livestock exclusion related to soil carbon sequestration is not well understood in arid and semiarid savannas of Africa. We investigated the effectiveness of long-term (14-36 years old) exclosures in enhancing soil carbon in the semiarid savanna, southern Ethiopia. We tested for differences in soil carbon content between exclosures and adjacent open-grazed rangelands, while accounting for effects of age of exclosures and soil depths. We collected soil samples at two soil depths (0-20 cm and 20-50 cm depths) from 96 plots from 12 exclosure and adjacent open grazing sites. We found no significant differences (P > 0.05) between exclosures and adjacent open-grazed rangelands in soil carbon content in both soil depths. The age chronosequence further suggested a weak non-linear trend in increasing soil carbon content with increasing duration of exclosures. These results thus challenge the opinion that controlled grazing enhances soil carbon sequestration in semiarid savannas. However, we remain cautious in regard to the conclusiveness of these findings given the paucity of information regarding other confounding factors which may disentangle the effects of the exclosure, and most importantly in the absence of soil data prior to exclosures.