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21.
Ectomycorrhizal (ECM) fungal species, a "Symbiotic" relationship between tress and fungi in forest has a great ecological and economic importance. Here is an attempt to describe database named "EctomycorrhizalDB", addressing ECM diversity of Central Himalaya (Kumaun region), with special emphasis on their characterization, physical properties and morphological features along with specifications. This database would help the scientific community to draw a better understanding of the environmental factors that affects species diversity. AVAILABILITY: The database is available for free at http://www.kubic.nic.in/ectomychorhiza.  相似文献   
22.
辽东山区天然次生林雪/风灾害成因及分析   总被引:17,自引:1,他引:16  
对2003年春发生在辽东山区的森林雪/风灾害的成因、过程、受灾情况、造成的危害、与林分结构特征的关系以及对未来次生林生态系统的影响等进行了调查分析。结果表明,雪/风的发生是在一个大的降水天气过程基础上,由于气温的异常变化形成的,受灾严重区多分布于海拔高、坡度大,林型比较单一的桦树、柞树、色树、胡桃树和杨树等林分,林分密度和受灾率及土层厚度和受害株数均呈显著的线性负相关;受灾数量与径级和树高分别呈指数负相关和指数正相关,同时探讨了雪/风害对天然次生林生态系统内病虫害发生、林下植被、生境因子和建群种变化产生的可能影响。  相似文献   
23.
报道了原产地为西藏自治区白朗县马乡地区(海拔4500m以上)的藏雪鸡(Tetraogallus tibetanus)在人工条件下(在拉萨市区海拔3650m)为期4年的饲养繁殖情况,以及藏雪鸡在人工条件下所产的卵和野生卵的大小及重量的差异显著性分析结果。  相似文献   
24.
Aucuba japonica , an evergreen broad-leaved shrub. The model is based on the allometry of plant organs and incorporates the processes of flowering, branching, and allocation of biomass among different organs. Growth of model plants was simulated under different values of annual gross production per leaf area (LGP) for 15 years. The tree form was mainly determined by the critical shoot size for initiating flowering (SF), but the average increase of new shoot mass (INM) for two successive years had marked effects on the growth pattern of A. japonica in addition to SF. Under small LGP conditions, plants with larger SF did not flower or postponed the initiation of flowering. With increasing LGP, plants with larger SF had a greater advantage because of their high efficiency for vertical growth. A smaller SF was observed in A. japonica var. borealis, which is distributed in heavy snowfall areas, and resulted in precocious flowering with a higher reproductive rate. The small plant size and shoot size of var. borealis may be the result of selection for preventing the delay of the year in which reproduction starts under smaller LGP conditions. On the other hand, the large SF of A. japonica var. japonica, which is distributed in light snowfall areas, suppresses flowering under small LGP conditions, and flowering occurs only after achieving a certain amount of vertical growth. Received 8 July 1999/ Accepted in revised form 21 December 2000  相似文献   
25.
Each year severe winter storms (≈ice storms) damage trees throughout the southern USA. Arkansas and Oklahoma have a history of severe winter storms. To extend that history back beyond the reach of written records, a distinctive tree ring pattern or signature is needed. Storm-caused breakage, branch loss and bending stress provide that signature. We found a severe storm signature in shortleaf pine (Pinus echinata). We used three published site chronologies, a set of five new site chronologies from a growth-and-yield study conducted by Oklahoma State University and the unpublished Shortleaf Canyon chronology from a master’s thesis at the University of Arkansas. Our method is based on two ring width values for the first and second growing seasons after the storm standardized to the ring widths of the seven growing seasons after the storm. Concordance between storm years predicted by tree ring patterns and actual storm years was tested using Cohen’s Kappa. Concern about confounding of ice storm signals by droughts led us to test concordance between severe storms and drought in July, August and September; results were inconclusive but stand as a warning that these two phenomena cannot be distinguished with certainty in the tree ring record. Damaging severe storms occurred in about 2.8% of all years. Two out of three storms identified as “severe” produced glaze icing.  相似文献   
26.
Snow dominates the hydrology and climate of the United States’ central Pacific Coast, but because local measurements of snowpack and winter precipitation often extend back only a few decades, observations by themselves are not adequate to describe potential amplitude of wintertime conditions. Here we present a set of updated and extended mountain hemlock (Tsuga mertensiana [Bong.] Carr.) tree-ring width records from Crater Lake National Park, Oregon, and use these data to make inferences about snowpack prior to the start of instrumental monitoring. In July and August 2013, we collected cores from 228 trees at seven high-elevation hemlock stands that surround the crater’s rim. The oldest tree had an inner ring date of CE 1474, and the longest ring-width chronology maintained a satisfactory common signal back to the middle of the 16th century. The growth of high-elevation mountain hemlock is strongly and inversely related to cool-season precipitation, making these records some of the most southerly examples of a robust inverse cool-season moisture signal in North American tree rings. The growth of these snow-limited forests does not appear to have been affected by the substantial decline in spring snowpack observed in the past two decades across the broader Cascade Range, and we did not find any indication of changing relationships between tree growth and either monthly or seasonal winter precipitation since the early 1990s. The exceptional three-year sequence in Crater Lake tree rings between CE 1809 and 1811, which includes the narrowest ring since CE 1540 and anatomical abnormalities produced by cold weather, leads us to conclude that 1809–1810 was the most snowy and severe winter to affect south-central Oregon during the past four and a half centuries.  相似文献   
27.
The genus Capricornis (Caprinae, Bovidae) includes six species, i.e., Capriconis sumatraensis, Capricornis swinhoei, Capricornis crispus, Capricornis rubidus, Capricornis milneedwardsii and Capricornis thar. Based on morphological, anatomical and physiological evidence, the Himalayan serow (C. thar), which is distributed in the mountain regions of the Tibetan Plateau and adjacent areas, is generally classified as a species of the genus Capricornis. However, considering the lack of molecular phylogenetic evidence, a heated controversy still exists over the taxonomic position of the Himalayan serow. To determine the phylogenetic status of C. thar, we sequenced the complete mitochondrial genome (mtDNA) of one Himalayan serow using the polymerase chain reaction (PCR) technique. Then, we constructed a molecular phylogenetic tree of the genus Capricornis and its related species in the Caprinae subfamily based on maximum likelihood and Bayesian interference methods. The results reflect that the structural characteristics, nucleotide content and codon usage bias of the mitochondrial genome of the Himalayan serow were similar to those of other serows. A phylogenetic analysis using two rRNA genes and 12 encoded protein-coding genes indicated that C. thar is clustered within the C. milneedwardsii clade, which is a sister group of C. sumatraensis. The present study provides useful information about the evolution of the Himalayan serow, which will be essential for conservation genetic studies.  相似文献   
28.
29.
新疆雪豹调查中的痕迹分析   总被引:6,自引:0,他引:6  
雪豹(Unciauncia)属于中亚高山高度濒危动物,夜行性,极其罕见。新疆雪豹研究小组2004年9~11月,在新疆的北塔山、阿尔泰山东部、天山东部和托木尔峰地区大约9个地点,对雪豹的痕迹进行了全面调查。共计完成67个样线,总长度47776m,其中发现遗留痕迹的样线有27条,痕迹数118个,平均为2.47个/km。记录到的痕迹有粪团、嗅痕(气味标记)、足迹、刨痕、卧迹、爪印、毛发、尿迹、血迹、剩余食物(动物尸体)和吼声等。同步还完成了200余份问卷调查表,充分了解雪豹与当地居民的冲突。最后,通过痕迹学的分析,初步掌握雪豹的栖息地选择、领域范围、分布规律和相对密度。这对于种群数量估计和物种的保护管理具有重要意义。  相似文献   
30.
Polygonatum verticillatum (L.) All. is an important medicinal herb that belongs to the family Asparagaceae. The rhizome of the species is used in Chyavanprash preparation and several other ayurvedic formulations. Numerous active constituents like saponins, alkaloids, phytohormones, flavonoids, antioxidants, lysine, serine, aspartic acid, diosgenin, β-sitosterol, etc. have been reported from this species. In this study, morphological, phytochemical, antioxidant and genetic variations of 11 distant populations of P. verticillatum were measured. Considerably (P < 0.05) higher variations were recorded among different populations of P. verticillatum using morphological, phytochemical and genetic diversity parameters. AGFW (above ground fresh weights); flavonols, FRAP (Ferric ion reducing antioxidant power) and NO (Nitric Oxide scavenging activity) were recorded maximum in Kafni population. Similarly, a significantly higher above and below ground dry weight was recorded in Mayawati and Surmoli populations respectively. Maximum phenolic content, tannins, and DPPH (2,2-diphenyl-1-picrylhydrazyl) activity were recorded in Milam population. A total of 165 individuals from 11 populations were assessed for genetic diversity using inter-simple sequence repeats (ISSR) marker. High genetic diversity (He = 0.35) was recorded in Himkhola and Surmoli populations while it was observed minimum (0.28) in the Mayawati population. Altitude showed a significant positive correlation with tannins (r = 0.674; P < 005) and DPPH (r = 0.820; P < 0.01). Phenol content exhibited a considerably positive relationship with He (r = 0.606; P < 0.05) and BGFW (r = 0.620; P < 0.05), flavonol displayed a positive correlation with Pp% (r = 0.606; P < 0.05). The population structure of P. verticillatum, exhibited that the optimal value of the K was 3 for its populations as determined by the ΔK statistic structure. Among populations, the amount of gene flow is higher (Nm = 1.717) among all sites. Hence, it can be concluded that P. verticillatum populations possess considerable variability in the collected populations. Likewise, the populations from Kafni, Satbunga and Himkhola with higher morphological, phytochemicals and genetic variability were prioritized and therefore recommended for cultivation and mass multiplication to meet the industrial demand for target species.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-01044-9.  相似文献   
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