首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 906 毫秒
1.
The catchment of South Luohe River in Central China is an important region for investigating modern pollen-environment relationship, because it is located in the transitional zone between south and north China, an environment which is sensitive to climate changes. In this study, 40 surface samples under ten vegetation types were collected to reveal the relationship between pollen assemblages and vegetation. The results show that the surface pollen assemblages reflect the vegetation quite well. In forest topsoils, the average of arboreal pollen content is greater than 40%, and the Selaginella sinensis spore is high. As to sparse forest grassland and shrub community, the average arboreal pollen is 13.2% and 16.6% respectively, and the shrub pollen is relatively higher than that of grassland samples. The grassland and farmland are characterized by low percentage of tree and shrub pollen(<10% and <1%), and high percentage of herbs(>80%). Pinus, Quercus and some other arboreal pollen can indicate the regional vegetation because of their dispersal ability. Quercus pollen is under-representative and so is Pinus. Artemisia pollen is significantly over-represented, has poor correlation with the plant coverage, and may reflect human disturbance. Gramineae can indicate plant quite well, but with low representation. High content of Chenopodiaceae probably suggests human impact. Predominant Selaginella sinensis can be used as an indicator of forest environment. Cluster analysis and principal components analysis of pollen assemblages can distinguish forest and non-forest vegetation well. The former method is better at separating pine and mixed forests, while the latter is more stable and could better differentiate farmland and other non-forest area. The first axis of PCA mainly reflects the humidity.  相似文献   

2.
The features of physical geography in the transitional region between Qinling Mountains and Huanghuai Plain possess transitional characters evidently in two directions: one is from the western mountain to the eastern plain and the other is from southern subtropical zone to northern temperate zone. Torrential rain, especially strong torrential rain is frequent in the transitional region, and there are many torrential rain centers. A majority of torrential rain is distributed among 100-200 m asl. The winter temperature at 100-400 m asl is higher than that in Huanghuai Plain whose altitude is lower than that of the transitional region, and the highest temperature in January appears at 350-400 m asl.The thickness of warm slope belt in the transitional region varies from 100 m to 250 m asl. The formation of torrential rain and warm slope belt is the result of joint action of atmospheric circulation and local terrain. Frequent torrential rains and warm slope belt had tremendous influences on the soil properties, plant distribution and local climate in the transitional region.  相似文献   

3.
The proxy records on typhoons in the Yangtze River Delta from 1644 to 1949AD were extracted from historical chorographies in the Qing Dynasty and the Republic of China Period.In reference to the basic principles for identifying historical typhoons,time series on the Yangtze River Delta over a period of 306 years were developed.The conclusions are as follows.(1) There were a total of 241 typhoons from 1644 to 1949AD.Using the historical chorographies from 1884 to 1949AD,the number of typhoons was 65,equal to 87.8% recorded by meteorological observation.The number of years with differences in typhoon activities reconstructed using two ways no more than once is 55,reaching 83.3% in the period from 1884 to 1949AD.This result means the series of historical typhoons reconstructed using historical chorographies can represent the change of typhoon activities over years.(2) The average number of typhoon activities is 0.79 times per year from 1644 to 1949AD,and they show an increasing trend.These 306 years can be divided into three periods by the average number of typhoon activities:it is low from 1644 to 1784AD,and more typhoon activities are found from 1785 to 1904AD.It is worth noting that the number of typhoon activities reaches the summit in the last period,which is 1.2 times per year from 1905 to 1949AD.(3) Before the 20th century,the number of typhoon activities in warm periods is less than the number of cold periods.However,the number of typhoon activities increased dramatically in the early 20th century.Comparing the typhoon activities with El Ni o events,the data show that the number of typhoon activities did not increase when El Ni o occurred.  相似文献   

4.
The varied altitudinal gradient of climate and vegetation is further complicated by mass elevation effect(MEE), especially in high and extensive mountain regions. However, this effect and its implications for mountain altitudinal belts have not been well studied until recently. This paper provides an overview of the research carried out in the past 5 years. MEE is virtually the heating effect of mountain massifs and can be defined as the temperature difference on a given elevation between inside and outside of a mountain mass. It can be digitally modelled with three factors of intra-mountain base elevation(MBE), latitude and hygrometric continentality; MBE usually acts as the primary factor for the magnitude of MEE and, to a great extent, could represent MEE. MEE leads to higher treelines in the interior than in the outside of mountain masses. It makes montane forests to grow at 4800–4900 m and snowlines to develop at about 6000 m in the southern Tibetan Plateau and the central Andes, and large areas of forests to live above 3500 m in a lot of high mountains of the world. The altitudinal distribution of global treelines can be modelled with high precision when taking into account MEE and the result shows that MEE contributes the most to treeline distribution pattern. Without MEE, forests could only develop upmost to about 3500 m above sea level and the world ecological pattern would be much simpler. The quantification of MEE should be further improved with higher resolution data and its global implications are to be further revealed.  相似文献   

5.
In order to study the element contents and distribution of various mosses collected in the Antarctica, we analyzed the heavy elements of 3 species of Polytri-chum in the Fildes Peninsula, P. alpinum, P. juniperinum and P. alpestre, by synchrotron radiation X-ray fluorescence ( SR-XRF). The result shows that the elements, such as K, Ca, Mn, Fe, Cu, Zn and Sr, are nearly the same in Potytrichum. The peak intensity of K is higher than that of Ca, and the peak intensity of Ca is higher than that of Fe in P. alpinum. In P. juniperinum, the peak intensity of K is higher than that of Ca, and the peak intensity of Ca is close to that of Fe. The peak intensity of K is nearly equal to those of Ca and Fe in P. alpestre. Therefore, the habitats of 3 species of Polytrichum are similar in the Fildes Peninsula. By XRF analyzing of different parts of P. alpestre, we found that the peak intensities of relative concentration of elements are obviously different. The peak intensity of K in apical-bud is the highest in orga  相似文献   

6.
From 2008 to 2010,a total of 15 snow pit samples were collected from 13 mountain glaciers in western China.In this study these samples are used to determine the spatial distribution of insoluble particle concentrations and dust deposition fluxes in western China.The results show that the mass concentrations of insoluble particles exhibit high spatial variation and strongly decrease(by a factor of approximately 50) from the north(Tienshan Mountains) to the south(Himalayas).However,the insoluble particles concentrations at the southeastern Tibetan Plateau(TP) sites are also high and approximately 30 times greater than those in the Himalayas.The spatial distribution of the dust flux is similar to that of the mass concentrations;however,the high dust deposition rate in the southeastern TP is very significant as a result of the extensive snow accumulation(precipitation) in this region.The average sizes of the insoluble particles at each site generally exhibit bimodal distributions with peaks at approximately 5 μm and 10 μm,which can be explained as resulting from dust emissions from regional and local sources,respectively.The enrichment factors for most of the elements measured in insoluble particles are less than 10 at all of the study sites,indicating primarily crustal sources.However,the sites located in the peripheral mountains of western China,such as the Tienshan Mountains and the Himalayas,are characterized by high levels of certain enrichment elements(e.g.,Cu,Zn,Cr,and V) indicative of sources related to the long-range transport of pollutants.  相似文献   

7.
《极地研究》1991,2(1):10-21
From the surface mass accumulation data in year of 1987/88, the distribution and variation of annual mass balance on Mizuho Plateau are discussed. The authors also analyze the effects of shortterm climatic and topographical variations on the mass balance. It is found that there are some differences in spatial distribution and annual average state in the year of 1987/88 and other years. Ia the area at elevation lower than 550 m near the coast, the mass balance appears to be negative. The annual mass balance over 80 km distance from S_(16) to inland is 0.84m snow depth. A low mass balance zone from 80 km site to Mizuho Station, is considered to be only 0.14 m snow depth. It is found from the comparison of mass balances that the mass-balance level on the glaciers in West China is 9 times higher than that on Mizuho Plateau, where the massbalance level appears to be low accumulative and low expensive, but inverse in middle and low latitude regions, such as on glaciers in West China. The effects of short-term  相似文献   

8.
长江上游社会经济因子对侵蚀产沙的影响   总被引:1,自引:0,他引:1  
In recent years,the role of human activities in changing sediment yield has become more apparent for the construction of hydraulic engineering and water conservation projec-tions in the Upper Yangtze River,but it has not been evaluated at the macro scale.Taking Sichuan Province and Chongqing City as an example,this paper studies the relationship between socio-economic factors and sediment yield in the Upper Yangtze River based on section data in 1989 and 2007.The results show that sediment yield is significantly correlated with population density and cultivated area,in which the former appears to be more closely related to sediment yield.Moreover,in the relation of sediment yield vs.population density,a critical value of population density exists,below which the sediment yield increases with the increase of population density and over which the sediment yield increases with the decrease of population density.The phenomenon essentially reflects the influence of natural factors,such as topography,precipitation and soil property,and some human activities on sediment yield.The region with a higher population density than critical value is located in the east of the study area and is characterized by plains,hills and low mountains,whereas the opposite is located in the west and characterized by middle and high mountains.In the eastern region,more people live on the lands with a low slope where regional soil erosion is slight;therefore,sediment yield is negatively related with population density.In contrast,in the western region,the population tends to aggregate in the areas with abundant soil and water resources which usually lead to a higher intensity of natural erosion,and in turn,high-intensity agricultural practices in these areas may further strengthen local soil erosion.It is also found that popu-lation tends to move from the areas with bad environment and high sediment yield to the areas with more comfortable environment and less sediment yield.The natural factors have greater influence on sediment yield of western region than that of eastern region.Generally,the natural factors play a dominant role on sediment yield in the Upper Yangtze River.  相似文献   

9.
The net accumulation record of ice core is one of the most reliable indicators for reconstructing precipitation changes in high mountains.A 20.12 m ice core was drilled in 2006 from the accumulation zone of Laohugou Glacier No.12 in the northeastern Tibetan Plateau,China.We obtained the precipitation from the ice core net accumulation during 1960-2006,and found out the relationship between Laohugou ice core record and other data from surrounding sites of the northeastern Tibetan Plateau.Results showed that during 1960-2006,the precipitation in the high mountains showed firstly an increasing trend,while during 1980 to 2006 it showed an obvious decreasing trend.Reconstructed precipitation change in the Laohugou glacier basin was consistent with the measured data from the nearby weather stations in the lower mountain of Subei,and the correlation coefficient was 0.619(P<0.001).However,the precipitation in the high mountain was about 3 times more than that of the lower mountain.The precipitation in Laohugou Glacier No.12 of the western Qilian Mountains corresponded well to the net accumulation of Dunde ice core during the same period,tree-ring reconstructed precipitation,the measured data of multiple meteorological stations in the northeastern Tibetan Plateau,and also the changes of adjacent PDSI drought index.Precipitation changes of the Laohugou glacier basin and other sites of the northeastern Tibetan Plateau had significantly positive correlation with ENSO,which implied that the regional alpine precipitation change was very likely to be influenced by ENSO.  相似文献   

10.
The content and distribution of biogenic silica were investigated in sedi- ment cores from Prydz Bay,Antarctica,during the CHINARE-18/21.cruise.The re- sults show that the content of biogenic silica(BSiO_2) is ranged from 4.89% to 85. 41%,and the average content of biogenic silica is 30.90%,the highest value oc- curred at theⅣ-10 station.The profile of BSiO_2 in sediment is contrast to that of sili- cate in the interstitial water.The content of biogenic silica and organic carbon in the surface sediments in the central area of Prydz Bay gyre were much higher than those in other area,and closely related to the Chla content and primary productivity of phyto- plankton in the surface water column.  相似文献   

11.
河北省中南部农田孢粉组合特征   总被引:4,自引:0,他引:4  
庞瑞洺  许清海  丁伟  张生瑞 《地理学报》2010,65(11):1345-1354
河北省中南部82 个农田表土花粉组合研究表明:农田花粉组合不仅有农作物花粉类型,也有临近山区的植物成分。山区农田乔木花粉含量与浓度高于平原,对平原的影响随距离增加而降低,距太行山0~50 km 松属花粉含量为20%~30%,50~100 km 为10%~20%,100~150 km 增至20%~30%,海滨区降至16%以下,平原中部含量增加可能与焚风效应有关;山区至平原乔木花粉含量空间上的变化,可能类似于历史时期人类活动介入森林区后时间上的变化。山区和平原灌木花粉含量较低,但主要成分不同,山区以胡颓子科、榛属、虎榛子较常见,平原区蔷薇科、葡萄科花粉相对较多。平原区草本花粉含量高出山区,其中藜科花粉由山区向平原逐渐增高,可能反映人类活动不断增强的特征。山区中华卷柏含量高于平原,但平原区高达7%。中华卷柏不易被风搬运,推测平原区农田的中华卷柏可能是平原沉积时由河流从山区搬运而来。相同类型农业单元乔木、灌木花粉和蕨类百分比山区一般高于平原,草本低于平原;不同类型农业单元乔木、草本百分比平原区相近,山区差异较大。山区乔木花粉含量差异主要受草本类型影响,平原区草本花粉组合差异主要是农作物花粉(人工禾本科、十字花科) 含量的差异;不同农业单元孢粉浓度差异主要为草本花粉浓度不同。  相似文献   

12.
53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).  相似文献   

13.
A 2.5-m-long sediment core was retrieved from Lake Somaslampi, a small lake located in a kame field on the north slope of the Scandes Mountains in Finnish Lapland. Holocene environmental changes were inferred from the lithological, geochemical, pollen, diatom and Cladocera records stored in the lake sediment. The chronology was based on six radiocarbon AMS dates supported by a palynological control chronology. The sediment profile consists of a glacial sedimentary sequence truncated by a lacustrine one. A hiatus, tentatively correlated with climate cooling and advances of glaciers during the 8.2 ka yrs BP “Finse cooling Event”, occurs between these sequences. The glacial sequence was composed of fluvioglacial clastics, smoothly changing into glacio-lacustrine diatomaceous ooze deposited in a meromictic proglacial lake that covered the kame field. The meromixis was probably caused by the greater depth of the lake, the extended ice-cover, and the microbial mats covering large areas of the lake bottom. A distinct change in the biota of the glacio-lacustrine sediments indicates higher trophic conditions than during deposition of the fluvioglacial clastics. The late-Pleistocene vegetation was characterised by subarctic birch tundra vegetation (BetulaSalix–Ericaceae) with low biodiversity gradually changing to BetulaPinus dominance in the early Holocene. The lake was deep and had a diatom inferred pH ~ 7 indicated also by the dominance of planktonic Cladocera. The base of the lacustrine sediment sequence (6,650–6,300 cal. BP) consisted of loess-rich sediment indicating an increase in eolian activity. This is also supported by the pollen record, which is dominated by more long-distant taxa such as Alnus and Pinus, and by the increased C/N ratio of the sediment. After the initial meromictic phase of the lake, an abrupt lowering of the water level occurred. Lake Somaslampi was isolated from the larger Pre-Lake Somas basin and became holomictic, shallow, much warmer and more productive, until the deterioration of climate around 3,000 yr BP and the increased input of clastics from the tundra soils. The vegetation followed the general climatic trend by gradually changing from the dominance of Betula and Pinus to the dominance of more tundra-related vegetation like Poaceae and Cyperaceae. However, the higher frequencies of planktonic Cladocera and centric diatoms in the most recent sediments indicates higher trophic conditions, increased turbulence and a prolonged ice-free period, which can possibly be linked to the recent climate warming especially in areas of higher altitude and latitude.  相似文献   

14.
利用方差极大旋转经验正交函数展开、最大熵谱、小波分析方法 ,对京津冀区域近 5 0年春夏季降水的地域特征与气候变化进行研究。结果表明此区域的降水场分别存在以下主要降水异常分布型 :夏季包括燕山迎风坡型、太行山迎风坡型、冀中平原型、冀东平原型、沿海平原型、冀北山地型、冀南平原型 ;春季包括平原中南部型、燕山南麓型、滨海平原型、京西山麓型、太行山迎风坡型、冀东北高原型、冀西北高原型 (坝上 )。同时 ,通过最大熵谱、小波分析 ,进一步分析各降水型的主要变化特征及主要周期。  相似文献   

15.
Sediment cores from several localities in Agder and Telemark are pollen analytically investigated. The immigration of some plant species during the time interval from about 12,000 to 6,000 years B.P. is discussed. The oldest samples contained pollen typical of a pioneer vegetation. The plant immigration is partly 14C-dated, partly dated only by interpolation or estimation based on the 14C-dates. From these data, immigration and migration routes are suggested. Betula nana, Salix, Juniperus, Betula, Populus and some herbs immigrated to Vest-Agder from the south or west, Ulmus, Quercus and possibly Tilia platyphylla from the south, Hippophaë and possibly Alnus from the east. It is suggested that Corylus may have come to the area with the first human inhabitants. Perhaps Tilia cordata has more immigration routes. Pinus and Calluna were among the early but not the first immigrants. Their immigration routes arc uncertain.  相似文献   

16.
王佳月  辛良杰  戴尔阜 《地理研究》2020,39(8):1879-1891
为了解中国典型山区农业水土资源分布的匹配程度及其格局变化,研究以区域内单位面积耕地拥有的农业水资源量刻画太行山区、横断山区和黔桂喀斯特山区农业水土资源的时空匹配情况。结果表明:① 三大山区耕地分布的集中程度较高。太行山区的耕地主要分布在河北境内的北段地区和山西境内的南段地区,横断山区的耕地主要分布在南段地区,喀斯特山区的耕地分布呈现“南北多中部少”的格局。② 三大山区农业水资源的分布及变化都主要集中在低海拔地区。太行山区的农业水资源主要分布在山西、河南段,横断山区的农业水资源主要分布在四川境内,喀斯特山区的农业水资源较均匀地分布在广西和贵州境内。③ 太行山区农业水土资源匹配程度较差,横断山区、喀斯特山区农业水土资源匹配程度较好。2000—2015年间,太行山区中部、横断山区东部、喀斯特山区南部地区的农业水土匹配程度有变好趋势,而太行山区南部、横断山区西南部、喀斯特山区北部地区的农业水土匹配程度有变差趋势。研究时段内,太行山区的水田转旱地情况突出,太行山区也是三大山区中农业水土资源匹配程度最差的,应该关注太行山区的用水压力,重视农田水利设施维护和农田灌溉水有效利用。  相似文献   

17.
Multiple proxy indicators are regularly used to present robust arguments for paleoenvironmental change. We use fossil pollen and diatoms from a 495-cm core taken from Cootes Paradise, a coastal wetland in the western end of Lake Ontario, to investigate ecological changes in the late Holocene. We use consensus analysis to demonstrate that pollen diagrams are best zoned after the data have been split into source area, in this case upland and wetland taxa, because each group responds differently to environmental change. We also use consensus analysis to demonstrate the sensitivity of clustering to the distance measure used. The record begins at 2400 14C years BP, when the wetland was dominated by shallow water emergents and epiphytic diatoms. At 2100 14C years BP, a decline in the epiphytic diatoms Epithemia spp., a rise in Poaceae (cf. Zizania aquatica) pollen and a coincident increase in pollen concentration suggest a water level rise at this time. At about 800 14C years BP, the diatom record shows a pulse in small benthic Fragilaria species; shortly after, a shift occurs in the upland tree pollen spectra involving an increase in Pinus and a decline in Fagus. This shift in upland forest trees has been associated elsewhere with the Little Ice Age and the diatom data present some evidence for impacts of this climatic event on aquatic systems. The diatom and pollen records both indicate large changes associated with the effects of European settlement, including rises in Ambrosia as well as Typha angustifolia pollen. Planktonic diatoms dominate post-settlement assemblages indicating large-scale hydrological and ecological changes, probably associated with the introduction of carp and alterations to the Iroquois bar which separates the wetland from Lake Ontario. Our work at Cootes Paradise is important for multi-proxy coastal wetland studies in general, in addition to the late Holocene environmental history and prehistory of the Great Lakes region.  相似文献   

18.
The structure and function of many Korean ecosystems have been rapidly modified since the 1960s when industrialization of the nation began. Ulsan City was the first in Korea to develop into a major industrial complex. To assess anthropogenic impacts on ecosystems surrounding Ulsan, sediment cores were collected from Mujechi-neup (bog) and Sanggae reservoir of Ulsan, and these cores were 210Pb dated using the CRS model. Physical and chemical characteristics and pollen were analyzed, and the rates of sediment accumulation were calculated. Unsupported 210Pb inventories in Mujechi-neup and the Sanggae reservoir were 18.04 and 16.53 pCi cm–2, and the corresponding 210Pb fluxes were 0.56 and 0.52 pCi cm–2 yr–1, respectively. The overall accumulation rate of dry matter was 0.26 kg m–2 yr–1 since 1852 (14 cm in depth) in Mujechi-neup. In the Sanggae reservoir, the accumulation rates of dry matter were increased from 2.1 in 1965 to 6.0 kg m–2 yr–1 in 1999. Pollen analysis revealed that three pollen zones existed in Mujechi-neup; a Pinus pollen-dominated zone from 0 to 5 cm in depth (1974 year), an Alnus pollen-dominated zone from 5 to 15 cm in depth (1827 year), and a Quercus pollen-dominated zone below 15 cm in depth. The shift from an Alnus dominated zone to a Pinus dominated zone was related to the Korean War between 1951 and 1953 and reforestation activities in the 1970s. In the Sanggae reservoir, there was an increase of Humulus pollen since 1996, an increase of Ambrosia pollen since the 1960s and the decrease of Graminae pollen since 1993 with the expansion of the industrial area. Similar to Mujechi-neup, the Sanggae reservoir also consists of three pollen zones: a Pinus and Typha pollen-dominated zone from 0 to 10 cm in depth (since 1993), a Graminae pollen-dominated zone from 10 to 22 cm in depth (between 1947 and 1993), and a Pinus pollen-dominated zone below 22 cm in depth (before 1947). The increase of Typha and Humulus in the 1990s indicates an increase in the inflow of nutrients into the wetlands. Also, pollen analysis revealed that Ambrosia was introduced in the 1960s during industrialization of the area. The sediment was composed of humic peat in Mujechi-neup and was composed of clay in the Sanggae reservoir. High LOI, P, and low C/N ratio between the depths of 5 to 7 cm in the Sanggae reservoir indicates an increased input of P and N. As a result, the growth of Typha was at its maximum. The total Pb content in Mujechi-neup has been increasing since the 1870s, and its accumulation in the Sanggae reservoir has been increasing since the 1960s. Thus, the history of local-scale disturbances and human activities in the watershed was reconstructed through paleoecological studies in Ulsan.  相似文献   

19.
The catchment of South Luohe River in Central China is an important region for investigating modern pollen-environment relationship, because it is located in the transitional zone between south and north China, an environment which is sensitive to climate changes. In this study, 40 surface samples under ten vegetation types were collected to reveal the relationship between pollen assemblages and vegetation. The results show that the surface pollen assemblages reflect the vegetation quite well. In forest topsoils, the average of arboreal pollen content is greater than 40%, and the Selaginella sinensis spore is high. As to sparse forest grassland and shrub community, the average arboreal pollen is 13.2% and 16.6% respectively, and the shrub pollen is relatively higher than that of grassland samples. The grassland and farmland are characterized by low percentage of tree and shrub pollen (<10% and <1%), and high percentage of herbs (>80%). Pinus, Quercus and some other arboreal pollen can indicate the regional vegetation because of their dispersal ability. Quercus pollen is under-representative and so is Pinus. Artemisia pollen is significantly over-represented, has poor correlation with the plant coverage, and may reflect human disturbance. Gramineae can indicate plant quite well, but with low representation. High content of Chenopodiaceae probably suggests human impact. Predominant Selaginella sinensis can be used as an indicator of forest environment. Cluster analysis and principal components analysis of pollen assemblages can distinguish forest and non-forest vegetation well. The former method is better at separating pine and mixed forests, while the latter is more stable and could better differentiate farmland and other non-forest area. The first axis of PCA mainly reflects the humidity.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号