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内蒙古自治区自然保护区的发展历程 被引量:2
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作者 娜日苏 《内蒙古农业大学学报(自然科学版)》 CAS 2008年第2期209-212,共4页
本文分析了内蒙古自治区自然保护区的发展历程特点及其原因。结果表明:改革开放前,内蒙古没有建立起自然保护区,1979年~1995年内蒙古的自然保护区数量少,保护区面积比例大大落后于全国平均水平,原因在于国家对保护对象的认识不全面;地... 本文分析了内蒙古自治区自然保护区的发展历程特点及其原因。结果表明:改革开放前,内蒙古没有建立起自然保护区,1979年~1995年内蒙古的自然保护区数量少,保护区面积比例大大落后于全国平均水平,原因在于国家对保护对象的认识不全面;地方经济落后;保护区管理封闭,视保护与利用为对立;地方建立保护区的积极性不高等。1996年~2003年自然保护区数量和面积快速增加,这是由于国家加强了保护区建设力度的同时,保护区管理开放,认识到以建立保护区发展经济,从而地方建立保护区的积极性提高,但具有功利性;还有些地方为了提高政绩,片面追求保护区数量和面积。2004年以来,保护区数量增加,但面积缩小,其原因复杂,需进一步研究。 展开更多
关键词 内蒙古自治区 自然保护区 保护区数量 保护区面积
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A Study of Fructification Quantitative Characteristics of Spartina alterniflora Lossel in Mangroves 被引量:7
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作者 覃盈盈 梁士楚 《Agricultural Science & Technology》 CAS 2009年第1期101-104,共4页
[Objective] The countermeasure on the number of fructification of Spartina alterniflora in the period of sexual reproduction and the component of seed yielding construction was explored.[Method] The Spartina altemiflo... [Objective] The countermeasure on the number of fructification of Spartina alterniflora in the period of sexual reproduction and the component of seed yielding construction was explored.[Method] The Spartina altemiflora in Mangroves conservation zone located at Hepu of Guangxi being taken as experimental material, its morphological and quantitative characteristics, as well as the weight of 100 full seeds at maturity stage in three different growth conditions( clay, loam and sand) were studied. [ Results] The results showed that Spartina alterniflora had the best growth pattern in the loam. The morphological factors of fructification of S. altemiflora grown in sand were larger then in others. In the three growth conditions the order of quantitative characteristics of fructification of S. alterniflora was clay 〉 sand 〉 loam and the seeds in spikelet at top position were more maturity than those at the button position. [ Conclusion] In good condition, the Spartina altemiflora growth was vigor but the ratio of seed-setting was low. 展开更多
关键词 Spartina altemiflora Different habitat FRUCTIFICATION Quantitative characteristics
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Characteristics of natural Japanese yew population in Muling Nature Reserve of Heilongjiang Province,China 被引量:1
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作者 刘彤 周志强 《Journal of Forestry Research》 SCIE CAS CSCD 2006年第2期132-134,共3页
The scalar of Japanese yew (Taxus cuspidata) population and the relationship between individual distribution and site factors were analyzed according to investigating data in 74 sample belts with a total sampled are... The scalar of Japanese yew (Taxus cuspidata) population and the relationship between individual distribution and site factors were analyzed according to investigating data in 74 sample belts with a total sampled area of 436.872 hm2 in Muling Nature Reserve. The result showed that the distribution rules of Japanese yew population were correlated to elevation, slope position, slope aspect and slope gradient. The optimal distribution range in elevation for the natural Japanese yew population is at the attitudes of 700-800 m. The amounts of Japanese yew individuals on shady slope were more than those on sunny slope. On top slope and mid-slope, the individual amounts of Japanese yew are more than those on toe slope. Most of Japanese yew individuals occurred on slope gradient of less than 15. The scalar of the population was decreased with the slope gradient increasing. 展开更多
关键词 Japanese yew Taxus cuspidate Muling Nature Reserve POPULATION
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Effect of Environmental Gradients on the Quantity and Quality of Fallen Logs in Tsuga longibracteata Forest in Tianbaoyan National Nature Reserve, Fujian Province,China 被引量:16
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作者 YOU Hui-ming HE Dong-jin +2 位作者 YOU Wei-bin LIU Jin-shan CAI Chang-tang 《Journal of Mountain Science》 SCIE CSCD 2013年第6期1118-1124,共7页
We investigated the quantity and quality 0f fallen l0gs in different Tsuga l0ngibracteata f0rest c0mmunities in the Tianba0yan Nati0nal Nature Reserve. We used redundancy analysis t0 determine the spatial distributi0n... We investigated the quantity and quality 0f fallen l0gs in different Tsuga l0ngibracteata f0rest c0mmunities in the Tianba0yan Nati0nal Nature Reserve. We used redundancy analysis t0 determine the spatial distributi0n 0f fallen l0gs in the different f0rest c0mmunities and t0 analyze the relati0nships am0ng stand structure, t0p0graphic fact0rs and human disturbance. The v0lume, c0vered area, mean l0g length and number 0f fallen l0gs differed significantly am0ng f0rest types (P 〈 0.05), but mean diameter at breast height sh0wed n0 significant difference (P 〉 0.05). The l0g v0lume and c0vered area in different f0rest types sh0wed the f0ll0wing trend: T. l0ngibracteata pure f0rest 〈 T. l0ngibracteata + Olig0staehyum scabrifl0rur 〈 T. l0ngibraeteata + hardw00d 〈 Rh0d0dendr0n simiarum + T. l0ngibraeteata 〈 T. l0ngibraeteata + Phyll0stachys heter0cycla pubescens. The spatial distributi0n patterns 0f l0gs quantity and quality indicated that l0g v0lume and c0vered area were str0ngly affected by envir0nmental fact0rs in the f0ll0wing 0rder: human disturbance 〉 elevati0n 〉 sl0pe p0siti0n 〉 b0le height 〉 tree height 〉 sl0pe aspect 〉 density 〉 basal area 〉 sl0pe gradient. The relative c0ntributi0n 0f envir0nmental variables 0n the t0tal variance was t0p0graphy (76%) 〉 disturbance (42%) 〉 stand structure (35%). T0p0graphy and disturbance c0mbined explained 8.2% 0f the variance. Fallen l0~s auantitv and aualitvwere negatively related t0 elevati0n and sl0pe p0siti0n, and p0sitively ass0ciated t0 human disturbance. The l0g v0lume decreased fr0m n0rthern t0 s0uthern sl0pes. Envir0nmental fact0rs had the highest impact 0n class I (slightly decayed), and l0west impact 0n class V (highly decayed). 展开更多
关键词 Fallen logs Distribution patterns TOPOGRAPHY Human disturbance TianbaoyanNational Nature Reserve
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Double Charm Decays of B Mesons in mSUGRA Model
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作者 吕林霞 肖振军 +1 位作者 王帅伟 李文君 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第7期125-133,共9页
Based on the low energy effective Hamiltonian with naive factorization, we calculate the branching ratios (BRs) and CP asymmetries (CPAs) for the twenty three double charm decays B/B8 → D(*)D(*) in both the... Based on the low energy effective Hamiltonian with naive factorization, we calculate the branching ratios (BRs) and CP asymmetries (CPAs) for the twenty three double charm decays B/B8 → D(*)D(*) in both the standard (s) (s) model (SM) and the minimal supergravity (mSUGRA) model. Within the considered parameter space, we find that (a) the theoretical predictions for the BRs, CPAs and the polarization fractions in the SM and the mSUGRA model are all consistent with the currently available data within ±2σ errors; (b) For all the considered decays, the supersymmetric contributions in the mSUGRA model are very small, less than 7% numerically. It may be difficult to observe so small SUSY contributions even at LHC. 展开更多
关键词 charm decay minimal supergravity model branching ratio CP asymmetry
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