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农户“困于土地”的原因探讨 被引量:1
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作者 蒲江 吴刚 杨启智 《天府新论》 2000年第2期7-11,共5页
农户接受合理而不合情的粮食低价、不合理也不合情的生猪低价 ,加之经济作物的种植利润被截留 ,农户收入偏低 ;而其家庭支出却日益增长 ,使得农户以土地为基础的农业经营事实上处于亏损状态。但是 ,由于规章限制 ,农户很难退出农业经营... 农户接受合理而不合情的粮食低价、不合理也不合情的生猪低价 ,加之经济作物的种植利润被截留 ,农户收入偏低 ;而其家庭支出却日益增长 ,使得农户以土地为基础的农业经营事实上处于亏损状态。但是 ,由于规章限制 ,农户很难退出农业经营。这也就形成了所谓农户“困于土地”的现象。 展开更多
关键词 粮价 退出限制 农业经营 农户 农业亏损
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Loss of preferred habitat and pollen limitation threatens reproduction in a rare mountain Paeonia delavayi 被引量:1
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作者 LI Wei PAN Wen-wen +1 位作者 TAN Rui WANG Juan 《Journal of Mountain Science》 SCIE CSCD 2016年第12期2147-2154,共8页
Paeonia delavayi is a wild tree peony species endemic to high-altitude regions in southwestern China.Recent agricultural land expansion,however,not only causes its dwindling population size,but also poses a severe thr... Paeonia delavayi is a wild tree peony species endemic to high-altitude regions in southwestern China.Recent agricultural land expansion,however,not only causes its dwindling population size,but also poses a severe threat to its long-term persistence.Since our knowledge of the reproductive biology of P.delavayi is very limited,and some management misconceptions have further exacerbated the already worrisome situation,the aim of the present study is to provide some scientific evidence regarding habitat preference and breeding system of P.delavayi,and to help correct some management misconceptions.Specifically,morphological traits of P.delavayi populations growing in two different habitats(i.e.,the open area versus forest understory),including basal stem diameter,plant height and flower numbers per plant,were measured and compared with each other.A range of floral manipulation experiments was further conducted to study the extent of self-compatibility and pollen limitation.The results showed that P.delavayi preferred the open habitat over forest understory as it generally grew bigger with thickerstems,and produced a higher number of flowers in the former habitat.Therefore,the open habitat should receive immediate priority for conservation action instead of being converted to agricultural land;also,P.delavayi is pollen limited,as evidenced by the fact that experimental flowers receiving supplemental non-self pollen generally displayed elevated seed production than flowers subjected to other treatments(e.g.,non-supplemental self pollen,non-supplemental non-self pollen and supplemental self pollen),which is consistent with reported observations that alpine plants are more likely to be pollen-limited than lowland plants.We suggest that human intervention might be necessary to guarantee the long-term persistence of P.delavayi as harsh alpine environment,intense competition for pollinators and different anthropogenic perturbations co-limit its reproductive success. 展开更多
关键词 Paeonia delavayi Peony Alpine ecosystems Habitats Breeding system Pollen limitation
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