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991.
简要介绍赴美人工林经营技术培训考察基本情况 ,着重介绍了美国人工林经营中的林木育种、苗木生产、集约经营和产学研结合等情况 ,并结合我国人工林经营管理现状 ,提出提高我国人工林经营水平的 6点建议 相似文献
992.
指出了金平县是一个典型的山区林业大县,山区面积占全县总面积的98.7%.林业产业是同时兼有生态、经济和社会三大效益的特殊产业,在促进经济社会可持续发展中,具有其它行业不可替代的重要作用.近年来随着财政投入的增大和各族群众意识的增强,鼓励发展经济林、野生观赏苗木、用材林、商品林(杉木)和林下经济作物等林业产业,充分开发利用荒山荒地资源,发展绿色无公害林业产业,不仅可以增加农民经济收入,还可有效维持金平山绿水清,山有多高水有多清的天然资源环境.因此,发展林业产业,对全县经济建设和生态文明建设具有重要的双重意义. 相似文献
993.
994.
Jian Zhang Zhanqing Hao I. -Fang Sun Bo Song Ji Ye Buhang Li Xugao Wang 《Annals of Forest Science》2009,66(2):204-204
995.
The pattern of species co-occurrence is instrumental for understanding community assembly rules. In this paper, we analyzed the co-occurrence of tree species in a 25-ha old-growth temperate forest plot in Northeastern China. The analysis was conducted at seven scales from 5 m × 5 m up to 100 m × 100 m in order to determine the patterns of co-occurrence at different spatial scales. Our analyses were conducted for all species, species with larger abundances, species with larger sizes, and five phylogenetic-based species groups. Our results showed that at smaller scales, the co-occurrence patterns of all species, species with larger abundances, and species with larger sizes were significantly higher than expected by chance, suggesting that strong interspecies competition exists in the community. At larger scales, there was no significant difference compared to randomized matrices. The result indicated that plant assembly rules are only found at small spatial scales. However, when co-occurrence metrics were restricted to phylogenetic groups, we could not find any clear evidence of interspecific competition within these groups. In conclusion, we found that competition is an important assembly rule at small scales in governing tree communities of our temperate forest, although it is not the only process involved. The importance of other processes should also be taken into account to explain species co-occurrence patterns. 相似文献
996.
Monthly variation in litterfall and the amount of nutrients in an Aleurites montana plantation 总被引:2,自引:0,他引:2
Han Lin Tao Hong Cheng-zhen Wu Hui Chen Can Chen Jian Li Yong-ming Lin Hai-lan Fan 《中国林学(英文版)》2012,14(1):30-35
In this study,the dynamics of monthly variation in litterfall and the amount of nutrients,i.e.,organic C,N,P and K,in an Aleurites montana plantation were analyzed,based on a field study and experiments over one year.The results show that the litterfall mass of A.montana collected generally presents an ascending trend with maximum defoliation occurring in the autumn and winter (October-December),accounting for 75.67% of the total amount of annual litterfall.The sequence in the amount of nutrients in A.montana litter was as follows:organic C > N > K > P;their monthly amounts show various dynamic curves.Similar to the dynamics of the mass of monthly litterfall,the monthly returns of C,N,P and K generally show an ascending trend with their peak values all occurring in December.The mass of A.montana litterfall and the dynamics of its monthly nutrient return provide,to a certain degree,a scientific reference for planting and fertilizing A.montana. 相似文献
997.
998.
999.
Tree-ring width chronologies of Larix chinensis were developed from the northern and southern slopes of the Qinling Mountains in Shaanxi Province,and climatic factors affecting the tree-ring widths of L.chinensis were examined.Correlation analysis showed that similar correlations between tree-ring width chronologies and climatic factors demonstrated that radial growth responded to climate change on both slopes.The radial growth of L.chinensis was mainly limited by temperature,especially the growing season.In contrast,both chronologies were negatively correlated with precipitation in May of the previous year and April of the current year.Spatial climate-correlation analyses with gridded land-surface climate data revealed that our tree-ring width chronologies contained a strong regional temperature signal over much of northcentral and eastern China.Spatial correlation with seasurface temperature fields highlights the influence of the Pacific Ocean,Indian Ocean,and North Atlantic Ocean.Wavelet coherence analysis indicated the existence of some decadal and interannual cycles in the two tree-ring width chronologies.This may suggest the influences of El Nin˜o-Southern Oscillation and solar activity on tree growth in the Qinling Mountains.These findings will help us understand the growth response of L.chinensis to climate change in the Qinling region,and they provide critical information for future climate reconstructions based on this species in semi-humid regions. 相似文献
1000.
兰州市高校校园绿地群落物种组成及多样性分析 总被引:1,自引:0,他引:1
初步尝试采用天然群落样带调查法对兰州市几所具有代表性高校校园绿地群落进行调查,分析其物种组成、重要值及多样性等特征,为城市生态学研究及校园绿化建设提供理论根据。调查结果表明:5所院校绿化树种中被子植物种类数量均占绝对优势,裸子植物偏少,以蔷薇科、杨柳科、蝶形花科植物为主,显示出北方地域植被的特点;除甘肃农业大学外,其它4所院校绿化树种中的乡土种比例均高于栽培和外来种;甘肃省委党校校园物种种类丰富,均匀度指数较大,多样性较高;其它4所院校绿地群落多样性水平均不高。5所院校校园乔木层、灌木层Shannon-Weiner指数(H’)和Simpon指数的统计结果基本一致。 相似文献