Background Litterfall input and associated nutrient flux are critically important in the restoration of soil in degraded landscapes through exclosures. This study was conducted to evaluate the effects of exclosure on seasonal litterfall production and nutrient content, and estimate annual C and N inputs to the soil in an age sequence at Kewet district, central lowland of Ethiopia. Leaf litterfall production was recorded by a 0.25 m 2 litter trap from a systematically laid line transects from 5, 15, and 20 years old exclosures and adjacent grazing land. Results Leaf litterfall input in the exclosures ranged from 37 g m −2 in January (at the old exclosure) to 7.33 g m −2 (at the young exclosure), and 3 g m −2 in March at the grazing land. Litterfall input showed seasonal variation and peaked in the dry months. Mean monthly leaf litterfall production was significantly ( p <0.05) higher (22 g m −2 ) in the old exclosure than the adjacent grazing land (9 g m −2 ). Total annual leaf litterfall ranged from 1073 kg ha −1 (grazing land) to 2662 kg ha −1 (old exclosure). There were no significant differences in leaf litterfall nutrients i.e., N, P, K, Ca, and Mg concentrations, except for C. The annual leaf litterfall associated C and N input ranged from 412 (grazing land) to 1025 (old exclosure) and 27 (middle age exclosure) to 68 kg ha −1 (old exclosure), respectively. The positive change recorded in leaf litterfall production and associated C and N return is associated with restoration of vegetation. Conclusions Through well-managed area exclosure, leaf litterfall production in the degraded landscapes can reach the level of tropical dry lowland forest in about a decade. Further research on the contribution of dominant tree species in litter production along the age of exclosure is recommended to improve the effectiveness of rehabilitation of degraded lands.

中文翻译：

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埃塞俄比亚中部低地 Kewet 区沿围墙时间序列的凋落物产量和相关碳和氮通量

背景 凋落物输入和相关的养分通量对于通过围栏恢复退化景观中的土壤至关重要。本研究旨在评估围栏对季节性凋落物产量和养分含量的影响，并估计埃塞俄比亚中部低地 Kewet 地区按年龄序列对土壤的年度 C 和 N 输入。从 5、15 和 20 年历史的围栏和邻近的牧场的系统铺设的线断面中，通过一个 0.25 m 2 的凋落物陷阱记录了落叶量的产生。结果 围栏的落叶量输入范围从 1 月份的 37 g m -2 （在旧围栏）到 7.33 g m -2 （在新围栏），以及 3 月在牧场的 3 g m -2 。凋落物输入呈现季节性变化，并在干旱月份达到峰值。旧围场的平均每月凋落物产量（22 g m -2 ）显着（p <0.05）高于相邻牧场（9 g m -2 ）。年落叶总量从 1073 kg ha -1（牧场）到 2662 kg ha -1（旧围栏）不等。除了 C 外，枯叶落叶的营养物质（即 N、P、K、Ca 和 Mg 浓度）没有显着差异。 一年生枯叶落叶相关的 C 和 N 输入范围从 412（牧场）到 1025（旧围栏）和分别为 27（中年围栏）至 68 kg ha -1（旧围栏）。落叶量产生和相关的 C 和 N 返回记录的积极变化与植被恢复有关。结论 通过管理良好的区域围护，退化景观中的落叶产量可在大约十年内达到热带干旱低地森林的水平。建议进一步研究沿开垦年龄优势树种在凋落物生产中的贡献，以提高退化土地恢复的有效性。