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21.
Study on ecosystem service values (ESVs) is the bridge of understanding ecosystem and economic decision-making. To investigate the response of ESVs to ambient environment and their spatial scales is an urgent work in the process of ecological restoration and sustainable development in southwest China. Based on the previous research results, the remote images, and weather data of 31 years (1975-2005), the response of ESVs to ambient environment and their spatial scales in a typical karst area of northwest Guangxi, China were evaluated with the method of empirical mode decomposition (EMD) in this paper. The results showed that ESVs had obvious variations with changes in elevation, rocky types and soil types, and had corresponding characteristics of spatial scales. The ESVs in middle and low elevation areas were higher, but they decreased due to human activities such as deforestation. The ESVs in peak-cluster depression areas were lower, and they would increase as influenced by policies such as returning farmland to forestland. The ESVs were influenced by rocky types, showing lower values but an increasing trend in the typical karst regions while higher values but a decreasing trend in non-karst regions. The average ESVs in the west part of the study region, which is not only the main nature reserve for rare wildlife species in Guangxi, but also one of the best preserved natural vegetation regions in China, were more than 15,000 RMB Yuan ha-1,. Comparatively, the ESVs were less than 10,000 Yuan ha-1 in the middle part of the region attributed to low vegetation coverage, serious peak-cluster depression and karst rocky desertification. After about 20 years, that is from 1985 to 2005, the ecosystem conditions had been improved and the ESVs had increased in the middle and eastern part of this study region. On the contrary, in most western part, which was dominated by subtropical evergreen broad-leaved forest, they had been worsened, and the balance values of ESVs were negative. As for the relationships of ESVs with rocky types and soil types, lime soil and red soil were the two main soil types that contributed to ESVs (The total contribution was above 60%, and it is 63.77%,64.37%,64.56%,64.91% respectively in the four years of 1985, 1990, 2000 and 2005.). The variance contribution of intrinsic mode function (IMF) and trend (R) showed that there were obvious special sales for ESVs in this study area, and the main spatial scales were about 2.7 km, 5.5 km, and 11.6 km. The variance contribution ratio was 12.29%, 11.26%, 11.49% respectively, and the trend (R) was high (17.74%). In conclusion, this study indicated that ecosystem conditions in the typical karst area were improved owing to the application of rocky desertification control policies, such as ecological migration and returning farmland to forestland. Besides, the main spatial scales of ESVs in the study area were the interactions of terrain, physiognomy, land use / land cover and human activities.  相似文献   
22.
The new spider genus and species Trogloraptor marchingtoni Griswold, Audisio & Ledford is described as the type of the new family Trogloraptoridae. The oblique membranous division of the basal segment of the anterior lateral spinnerets of Trogloraptor suggests that this haplogyne family is the sister group of the other Dysderoidea (Dysderidae, Oonopidae, Orsolobidae and Segestriidae). Trogloraptor is known only from caves and old growth forest understory in the Klamath-Siskiyou region of Oregon and California.  相似文献   
23.
We present primers and amplification conditions for 15 microsatellite loci developed for the Cope's giant salamander (Dicamptodon copei), 14 of which are tetranucleotide repeats. Cross-species amplification revealed 10 of these loci to also be polymorphic in the Pacific giant salamander (Dicamptodon tenebrosus). Several loci produced nonoverlapping allelic ranges between the two species and may be useful in species identification. These polymorphic microsatellite loci are potentially useful for future studies of population genetics in dicamptodontid salamanders.  相似文献   
24.
Although the Northwest currently has the least proportion of non-native invasive plant species relative to other regions of North America, invasions continue to increase into the mountainous areas of the region. Landscape structure, such as the variation found along the complex gradients of the Northwest mountain ecoregions, affects the expansion of invasive plant species and the invasibility of plant communities. Also, the history of land use and current use patterns affect the expansion of invasive plants, and many of the deteriorated environments in the region's mountains may invite and stabilize plant invasions. We examined the patterns of invasive plant diversity in Northwest mountain ecoregions, as derived from literature sources, to analyze which factors influence plant invasions. Our analysis found altered riparian systems and disturbed forests to be especially vulnerable to plant invasion. Conversely, alpine and wilderness areas are still relatively unaffected by invasive plants. Both riparian and alpine communities, while making up a relatively small area across Northwest mountain ecoregions, have significant ecological importance and deserve special protection from invasive plant introductions. Human settlement at low elevations and intense land use of upland forests will likely continue to enhance invasive plant introductions into Northwest mountain ecosystems. Knowledge of the relationships between biological and environmental factors, disturbance, and human land use will be critical for future management strategies that proactively locate, prevent, or contain plant invasions in the mountains of the Northwest.  相似文献   
25.
Riparian zones associated with alluvial rivers are spatially dynamic, forming distinct vegetative mosaics that exhibit sharp contrasts in structure and processes related to the underlying biophysical template. The productivity of riparian plants, especially trees, influences streamside community characteristics as well as the forms and fluxes of organic matter to adjacent streams – thereby strongly impacting patterns of channel morphology, water flow, sedimentation, and habitat in rivers. As part of a comprehensive investigation of riparian dynamics in coastal rain forest rivers of the Pacific Northwest (USA), we examined riparian tree abundance (density, basal area, and biomass) and rates of production (basal area growth [BAI] and bole wood biomass increase [P]) of seven common species – red alder (Alnus rubra), Sitka spruce (Picea sitchensis), bigleaf maple (Acer macrophyllum), western hemlock (Tsuga heterophylla), black cottonwood (Populus trichocarpa), vine maple (Acer circinatum) and willow (Salix spp.) – in the lowland floodplain of the Queets River (Olympic National Park), Washington. Measurements were made annually for three years (1999 – 2001) in 16 permanent plots on three biophysical templates that formed a toposequence – active floodplain, young terrace and mature terrace. Stem density was highest in the active floodplain (∼27,000 stems/ ha), decreasing in the young terrace (∼2,700 stems /ha) and the mature terrace (∼500 stems/ha). Basal area and total stem biomass were lowest in the active floodplain (∼16 m2/ha and ∼18 Mg dry weight/ha, respectively) and higher on the young terrace (∼32 m2/ha and ∼134 Mg dry weight/ha) and on the mature terrace (∼69 m2/ha and ∼540 Mg dry weight /ha). Total plot-scale BAI was not significantly different among the physical templates with mean values ranging from approximately 1.4 (low terrace) to approximately 2.8 m2/ha/y (active floodplain). In contrast, P was significantly higher on the mature terrace (10.3 Mg/ha) than the active floodplain (3.2 Mg/ha) but there was no significant difference between young terrace (6.5 Mg/ha) and mature terrace. For the entire Queets River floodplain (57 km2 over 77 km of river length), the mature terrace contributed 81% of the total annual production (28,764 Mg) whereas the active floodplain and young terrace accounted only for 5 and 14%, respectively. Overall, we show that riparian trees grow quickly in this coastal Pacific Northwest system and that the older riparian forests on mature terraces are the main contributors to stem production at the plot and floodplain scales for at least 350 years after stand initiation. This suggests that, in combination with the rapid lateral migrations of many alluvial rivers, the older riparian forests on those terraces are important and sustained sources of organic matter (especially large woody debris, LWD) that, over decades to centuries, shape the character of coastal rivers in the Pacific Northwest.  相似文献   
26.
生态经济区划研究——以西北6省为例   总被引:17,自引:1,他引:16  
汇集西北6省区近300个气象站点的多年气象数据,400多个县市的土地利用和社会经济统计数据,提取降水、气温、湿度、土地利用类型、人口、GDP、矿产资源、产业结构(三次产业)等要素,设计了水热状况、人类活动强度、工业化程度、城镇化程度等指标,借助GIS工具,通过要素指标的空间分异特征研究,构筑指标体系,进行了以县域尺度为最小空间单元的生态经济区划研究。根据西北地区县域尺度上的生态环境状况和人类活动状况,将西北划分为3级27个生态经济区。  相似文献   
27.
赣西北食(药)用菌的种质资源   总被引:2,自引:0,他引:2  
陈晔  罗敏  许祖国  李军  方亮 《菌物研究》2004,2(2):31-37
报道了赣西北地区的食 (药 )用真菌 12 4种 ,其中 7种为江西的新记录种。为本地区大型野生真菌资源的开发与利用提供可靠依据。  相似文献   
28.
滇西北野生观赏花卉调查   总被引:5,自引:0,他引:5  
依据野外调查结果和有关文献资料,运用统计和比较的方法,对滇西北地区野生花卉的多样性进行了研究。结果表明,滇西北野生花卉有83科324属2206种。其中草本花卉1,163种,木本花卉。743种,滇西北特有野生花卉751种,珍稀濒危花卉35种。本文对滇西北地区野生花卉植物的种类、分布、观赏类型、花色、花期、受威胁状况以及特有现象进行了详细地统计分析。发现滇西北地区花卉植物的丰富度依次为丽江、中甸、贡山、德钦、维西、鹤庆、福贡、洱源、大理、兰坪。从垂直分布上看,海拔2400~3000m以及海拔3500m以上的地段花卉植物较为丰富,且特有和珍稀濒危野生花卉植物也较多地集中在这两个地段。按花色紫蓝、橙黄、红、白四大类型分类,则以紫蓝花种类最为丰富(约400种)、橙黄花次之(约230种)、红花较少(约170种)、白花最少(约140种)。  相似文献   
29.
西北地区志留纪温洛克世晚期-罗德洛世早期的一些笔石   总被引:1,自引:0,他引:1  
记述西北地区志留纪温洛克世晚期-罗德洛世早期笔石5属,11种,进一步肯定罗德洛世早期nilssoni带的地层在陕西紫阳,甘肃迭部和内蒙古额济纳旗的存在,首次确认陕西紫阳和内蒙古额济纳旗发育温洛克世侯默中晚期含笔石地层,大致为parvus带或稍高。  相似文献   
30.
中国西北地区蚂蚁区系特征   总被引:12,自引:0,他引:12  
长有德  贺达汉 《动物学报》2002,48(3):322-332
于1997-2000年对宁夏、甘肃、青海及内蒙古西北部地区进行了系统的蚁类标本采集,获得标本1000余号,并对其进行了系统的分类鉴定,获得蚂蚁3亚科16属79种。本调查区蚁类区系组成呈现以下特征:古北界分布的有15属,代表属为蚁属、红蚁属、毛蚁属、原蚁属、箭蚁属、收获蚁属等;东洋界分布的有9属,代表属为火蚁属、细胸蚁属、酸臭蚁属、光胸臭蚁属和弓背蚁属等;在种级水平上,古北界分布的有79种,东洋界分布的仅17种。蒙新区分布的成分有15属,其中以铺道蚁属、原蚁属及箭蚁属为主体,蚁属和心结蚁属次之;区分布的成分有4属,以蚁属和毛蚁属为主体;东北区分布的成分有5属,蚁属和毛蚁属为主体;华北区分布的成分有15属,其中以蚁属、红蚁属和毛蚁属为主体,仅心结蚁属无分布;华中区、华南区和西南区分布的成分均不明显。在种级水平,华北区和蒙新区分布的成分为主体,分别占51和49种,其次为华中区、青藏区和东北区的成分,分别占17、15和15种,华南区和西南区的成分最少,分别为8和5种。在区系分类的基础上,根据优势种、特有种,并结合植被、地形、地貌将调查区划分为6个蚁类区:黄土高原蚁类区、荒漠蚁类区(其下设4个蚁类亚区;荒化草原蚁类亚区、草原化茺蚁类亚区、典型荒蚁类亚区和荒漠绿洲蚁类亚区)、荒漠沼泽蚁类区、高寒灌草丛蚁类区、贺兰山蚁为区和六盘山蚁类区。利用主成分分析对不同草原类型的蚂蚁群落进行了相似性分析,结果表明:荒漠化草原群落、草原化荒漠群落、典型荒漠群落和荒漠绿洲群落明显靠近,构成荒类集团,荒漠森林草原(贺兰山)群落明显远离于荒漠类群,反而与典型草原(黄土高原区)群落靠近,这与蚁类区划结果是十分吻合的。此外,利用主成分分析对79种蚂蚁划分为10个生态种组。  相似文献   
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