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机械化玉米生产新体系的经济效益分析
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作者 李立辉 杨印生 赵耀 《农业技术经济》 北大核心 1998年第3期60-62,共3页
本文论述了在干旱半干旱地区研制和推广玉米生产新体系的意义。建立了玉米生产新体系经济效益评估指标体系和评估模型。
关键词 干旱 半干旱地区 松树市 玉米生产 机械化
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Study on Tending Operations to Control over Harm of Pine Scale in Urban Park
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作者 HUANGJinshui KEYuzhu +2 位作者 TANGQiliang ZHONGJinghui YEJianxiong 《Chinese Forestry Science and Technology》 2004年第4期96-100,共5页
The change of pine scale (Hemiberlesia pitysophila Takagi) population density on pine forest in urban park between treatment (tending operations) and CK (no tending operations) was researched in this paper. The result... The change of pine scale (Hemiberlesia pitysophila Takagi) population density on pine forest in urban park between treatment (tending operations) and CK (no tending operations) was researched in this paper. The results were shown as follows: population density declined to 0.63 head per bundle from 2.61 heads per bundle when crown density of pine in urban park had become 0.5 or so by means of cultivation activities such as felling, pruning and thinning and so on, and drop got to 75.86 percent. The pinewoods would soon get revived once using these cultivation activities, so tending operations was main measures controlling over harm of pine scale in urban park; At the same time, population density of pine scale on pinewoods in the sunny slope was more than that in the somber slope and it had become less and less from sunny slope to somber slope. Therefore, tree species must be chosen in the planning and design of urban park for preventing harm and happening of pine scale. 展开更多
关键词 pine scale (Hemiberlesia pitysophi) urban park tending operation effect PINE Pinus massonianaa
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