Nutrient use efficiency and biomass production of tree species for rotational woodlot systems in semi-arid Morogoro, Tanzania
Nutrient use efficiency and biomass production of tree species for rotational woodlot systems in semi-arid Morogoro, Tanzania
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DOI：
10.1007/s10457-007-9061-x
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发表时间：
2007-11-01
影响因子：
2.2
通讯作者：
Kimaro, Deborah A.
中科院分区：
文献类型：
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作者：
Kimaro, Anthony A.;Timmer, Vic R.;Kimaro, Deborah A.
在轮作林地系统收获木材和作物的同时，频繁的养分移走可能会导致土壤养分枯竭，导致立地生产力和可持续性下降。然而，在这个系统下，选择营养高效的树种可以很好地维持生产力。为了验证这一假设，采用完全随机区组试验，评价了5个树种对坦桑尼亚半干旱地区土壤养分状况、养分利用效率和木材产量的影响。轮作5年后，黑刺相思、多刺相思下的表层土壤。和马占相思Acacia mangium Wild.是最肥沃的，土壤有机碳和可交换性阳离子状态提高到接近自然土壤的水平。土壤无机氮和速效磷水平达到了可供后续玉米栽培的水平。休耕林地的木材生产力平均比Miombo林地高三倍，这表明林地系统提供薪材的潜力很大，从而缓解了天然林的采伐压力。厚果相思前本斯。产生最多的木材(51毫克公顷(-1))，营养“成本”低，这可能是由于高养分利用效率。该树种的木材产量分别比多棘木和尼罗罗提刺高42%和120%，但营养成分相对较少(磷、钾、钙低42%-60%)。灰葡萄和多棘豆在收获时通过砍伐归还了最多的营养物质。在所有受试树种中，厚果沙打旺表现出在轮作林地系统下维持木材生产的最大希望，因为它的生产力相对较高，收获时养分输出较少。
Frequent nutrient removals accompanying wood and crop harvests from rotational woodlot systems may contribute to declining site productivity and sustainability because of soil nutrient depletion. However, selecting for nutrient-efficient tree species may well sustain productivity under this system. To test this hypothesis, a randomized complete block experiment was adopted to assess effects of five tree species on soil nutrients status, nutrient use efficiency and wood yield in semi-arid Tanzania. After 5 years rotation, top soils under Gliricidia sepium (Jaqua), Acacia polyacantha Willd. and Acacia mangium Willd. were the most fertile with soil organic carbon and exchangeable cation status raised close to those in natural Miombo systems. Soil inorganic N and extractable P levels reached sufficiency levels for subsequent maize culture. Wood productivity in tree fallows averaged three times higher than that of Miombo woodlands indicating the high potential of the woodlot system to supply fuelwood, and consequently relieve harvesting pressures on the natural forests. Acacia crassicarpa A. Cunn. ex Benth. produced the most wood (51 Mg ha(-1)) at low nutrient "costs" presumably due to high nutrient use efficiency. Wood yield of this species was 42 and 120% greater than that of A. polyacantha and A. nilotica, respectively, but contained comparatively less nutrients (42-60% less for P, K, and Ca). Gliricidia sepium and A. polyacantha returned the largest amount of nutrients through slash at harvests. Of all test species, A. crassicarpa exhibited the most promise to sustain wood production under rotational woodlot systems due to relatively high productivity and low nutrient export at harvest.