West Sichuan Research Articles

Gas and water reservoir differentiation by time-frequency analysis: a case study in southwest China

Since the favorable conditions of gas migration and accumulation in the deep Xujiahe formation of west Sichuan depression, a couple of high-yielding gas wells have been developed successfully, prime examples include X851, X856, X2, X3 and X10, which have confirmed the great exploration potential within the area. However, the appearance of some water production wells, such as CX565 and X201, has led to uncertainty within the reservoir prediction. Seismic signal based Time-frequency analysis has been used to distinguish the gas reservoir from water-bearing reservoir in Xujiahe formation. When the seismic wave propagates in the gas and water reservoir, it is difficult to identify the dynamic differences, in terms of amplitude, frequency and energy in the time field. Given that time-frequency analysis allows transformation of the seismic data from the time field into the time-frequency field, it is employed to highlight the seismic responses of gas reservoirs. Usually, the characteristics of ‘low-frequency shadows’ and ‘high-frequency attenuation’ are very obvious in gas reservoirs, while there is no such indication in water reservoirs, which can help to distinguish the gas reservoir from water reservoir. In this paper, we present the theoretical approaches and the in-situ model analyzing results, as well as, a case study. The application of time-frequency analysis on the deep Xujiahe formation in the western Sichuan Depression, provides robust indications for reservoir prediction of gas and water differentiation and validates investigation.

Research on Soil-Water Characteristic Curve of Unsaturated Mixed-Soil in West Sichuan

A series of tests are conducted to get the physical composition, physical form and the soil-water characteristic curve in different dry density of three typical composite unsaturated soils in west Sichuan. Test data shows that the variation of physical composition, particle size and dry density can result in great change of soil-water characteristic curve. The bigger the dry density is, the more hydrophilic mineral the soil has, the more gentle the soil-water characteristic curve is, and the higher its residual moisture content is. In addition, under the same water content, matrix suction decreases with less clay content and more content. For the three typical composite unsaturated soils, with relatively bigger water content, the change of soil-water characteristic curve resulting from variation of dry density is less, but with the water content getting smaller, the change becomes clearer.

Soil-Water Characteristic Curve for Unsaturated Mixed-Soil Considering Physical Form and Dry Density Effect

A test is conducted to get the soil-water characteristic curve for three typical composite unsaturated soils in west Sichuan, considering its physical composition, physical form and dry density. Test data shows that the variation of physical composition, particle size and dry density can result in great change of soil-water characteristic curve. The bigger the dry density is and the more hydrophilic mineral it has, the more gently the soil-water characteristic curve is, and the higher dry density soil sample has higher residual moisture content. In addition, matrix suction decreased with less clay content and more content under the same water content. For three typical composite unsaturated soils, the change of soil-water characteristic curve resulting from variation of dry density is less in bigger water content, and is more in lower water content.

Experimental Study on Shear Strength of West Sichuan Unsaturated Mixed-Soil

By controlling moisture content to control matrix suction indirectly, three typical unsaturated remolded mixed-soil from west Sichuan are studied by the consolidated untrained triaxial shear test .The test data show that for different kinds of soil samples, the sample with less amount of clay and high content of quartz has bigger internal friction angle relatively, and the sample with hydrophilic mineral and high content of clay has bigger cohesive force. Meanwhile, for the sample without or less hydrophilic mineral, cohesive force is affected mainly by water content, and for the sample with large content of hydrophilic mineral, water content and dry density affect cohesive force together. For a certain sample, the variation of moisture content and dry density affects internal friction angle less, while affects cohesive force more. In addition, the change of internal friction angle resulting from the variation of matrix suction is less, and cohesive force increases as matrix suction increases.

Strategies and Empirical Research for the Development of New Rural Community Space in West Sichuan

The paper aims to have a clear image on rural community's living spaces in West Sichuan,China and forward ideal planning strategies. The empirical research in Heming Village is a case study with abundant interviews and site observations. Based on these first-hand data,A new developing module can be set up which integrate Chinese tradtional couryard and modern living apartment.Via analysing the case study,these strategies creatively sum up vernacular living's advantages and lead to a sustainable development for Chinese new rural communities.

Seasonal dynamics of soil fauna in the subalpine and alpine forests of west Sichuan at different altitudes

The climate (especially temperature) often plays an important role in the structure, function as well as composition of soil organisms in different latitudes and altitudes. As one of the essential components of soil ecosystem, soil faunal community not only lays their roles as soil engineer in material cycling and energy flow, but also acts as the sensitive bio-indicator to environmental change. However, little information has been available on the responses of soil faunal community to the changed environment at different altitudes and seasons. In order to understand the seasonal dynamics of soil faunal diversity under different forests with varying altitudes, three fir (Abies faxoniana) forests were selected covering a 600m vertical transition zone. The primary fir forest at 3600m (A1) of altitude, mixed fir and birch forest at 3300m (A2) of altitude, and secondary fir forest at 3000m (A3) of altitude are representative forests in the subalpine and alpine region of west Sichuan. A 2years study was conducted in the three subalpine and alpine forests from May in 2009 until October in 2010. Soil samples were collected in both the soil organic layer and mineral soil layer. Soil macro-fauna were picked up by hand in the fields. Meso/micro-fauna and damp living fauna were separated and collected from the soil samples by Baermann and Tullgren methods in laboratory, respectively. A total of 74,827 individuals were collected in the 2years, belonging to seven phyla, 16 classes, 31 orders and 125 families by preliminary identification. Similar dominant groups were detected in different forests at different altitudes, consisting of Spirostreptida, Formicidae, Staphylinidae, Hesperinidae, Onychiuridae, Isotomidae, Oribatuloidae, Alicoragiidae, Secernentea, and Adenophorea. In contrast, the ordinary species of macro-fauna and the ratios of Acarina to Collembolan were obviously different. For instance, the ordinary species were dominated by Cydmaenidae and Mycetophilidae at the A1, Scaphidiidae and Helicinidae at the A2, and Lumbricida and Agelenidae at the A3, respectively. Both the individual density and the number of soil faunal groups were significantly higher in soil organic layer than those in mineral soil layer. The density and group of macro-, meso- and micro-fauna in different forests showed the order as A2>A1>A3, but the density of damp living fauna showed the order as A1>A2>A3. The functional groups of macro-fauna were mainly dominated by saprozoic. The highest density and group of macro-fauna was observed in August, while the highest value of meso/micro-fauna was detected in October. In addition, the Jacard similarity indices showed that the composition and structure of soil fauna were similar in the different forests varied with altitudes, but the Shannon–Wiener indices were significantly different. The highest values of Shannon–Wiener indices were observed in October at both the A1 and A3, and in August at the A2. The results suggested that soil faunal community kept a high diversity in the subalpine and alpine forests of west Sichuan, and their structures were significantly affected by the variation of altitudes, which provided important scientific evidences for understanding the ecological processes in the subalpine and alpine coniferous forests.

Comparison of fluorite geochemistry from REE deposits in the Panxi region and Bayan Obo, China

Panxi region in west Sichuan province is one of the most economically significant REE mineralization belts in China, and includes the large Maoniuping and Daluxiang deposits and the minor Lizhuang deposit. The REE mineralization in these deposits is spatially and temporally associated with carbonatite–syenite complexes. Large proportional fluorites and REE minerals occurring as veins intrude Cretaceous granite and Oligocene syenite in Maoniuping, and Oligocene syenite and carbonatite in Lizhuang, and Miocene syenite in Daluxiang. Fluorite is also one of main gangue minerals in the world-class Bayan Obo REE deposit. We present a comparison of the trace element and isotopic compositions of fluorites from four REE deposits in the Panxi region and Bayan Obo. The fluorites from Maoniuping and Daluxiang are characterized by variable REE patterns, with either LREE enrichment or LREE depletion relative to MREE. Typically they have a larger range in La/Ho compared to Y/Ho ratios, and pronounced positive Y anomaly relative to chondrite-normalized REE patterns. Their REE distribution patterns are controlled by fluoride-complexes and the loss of separate LREE-rich minerals. Different Y/Ho (ca. 73 vs. 108) and initial Sr isotopic (ca. 0.7061 vs. 0.7077) ratios are observed between the fluorites from Maoniuping and Daluxiang, reflecting their different source compositions. This contrasts with the fluorites from Maoniuping and Lizhuang, which have similar initial Sr isotopes, and appear to be cogenetic. However, the Lizhuang fluorite shows a consistent depletion of LREE relative to MREE, as well as lower Y/Ho ratios and higher HREE content than that in Maoniuping. In this respect the Lizhuang fluorite may have precipitated from a late-stage fluid following abundant fluorite and REE mineral deposition in Maoniuping. Carbonate, more than fluoride complexing, appears to have a stronger control on REE fractionation in the Lizhuang fluorites.The fluorites from three deposits in Panxi region show uniform initial Sr and Nd isotopic compositions similar to their associated carbonatites, but differ from ore-veins found intruding wall rocks, e.g. granite in Maoniuping and syenite in Daluxiang. This is not consistent with a model for fluorite formation involving interaction of F-rich, carbonatite-exsoloved fluid with wall rocks. Instead, the fluorite in Panxi region may precipitate from a residual carbonthermal fluid, which was dominated by Ca, CO2 but also contained F, H2O and REE, and derived from the fractioned carbonatitic magma. Fluorite deposition produced a sharp drop in the activity of F−, which destabilized the REE fluoride complexes and caused deposition of REE minerals. In Bayan Obo, the fluorite typically has higher La/Ho than that in Panxi region and is characterized by a consistent LREE enrichment relative to MREE and negligible to positive Y anomalies. This is consistent with the compositional change of the hydrothermal fluids, which were infiltrated by external F-, LREE-rich fluids. The 87Sr/86Sr of Bayan Obo fluorite is relatively low radiogenic, and has a large range (0.7038–0.7065): similar characteristics to the carbonatite dykes found near the ore bodies. This supports a model for fluorite and REE mineral genesis involving the interaction of a carbonatite-derived fluid and the ore-hosted dolomitic marble.

Potential distribution of <I>Miscanthus sinensis</I> and <I>M. floridulus</I> in China

Aims In recent years, Miscanthus sinensis and M. floridulus have attracted considerable attention as two of the most promising non-food energy crops in China. We attempt to determine the potential distributions of the two Miscanthus species to provide a reference for developing non-food energy crops using marginal lands in China. Methods We predicted the potential distribution and fundamental niches of M. sinensis and M. floridulus in China based on the maximum entropy (MAXENT) model using distribution data of the two species combined with 19 climatic factors. Important findings The potential distribution area for M. sinensis covers west Sichuan, north Shaanxi, Ningxia, central Inner Mongolia, Heilongjiang, west Jilin, west Liaoning, southeast Qinghai, etc. Its fundamental niche parameters are: precipitation of warmest quarter of 400–1 000 mm, average precipitation in August of 100–350 mm, average minimum air temperature in July of 15 °C, average precipitation in July of 100–350 mm, average maximum air temperature in November of –10 to 22 °C, mean temperature of driest quarter of –15 to 20 °C and average precipitation in December 100 mm. The potential distribution area for M. floridulus includes Yunnan, Shaanxi, Shanxi, Ningxia, Henan, Shandong, Jilin, Liaoning, west Sichuan, south Gansu and east Inner Mongolia, etc. Its fundamental niche parameters are: precipitation of warmest quarter400 mm, mean precipitation in June of 150–550 mm, average minimum air temperature of 15–30 °C in July and 10 °C in June and average precipitation in April of 50–100 mm. The results show that there are abundant land resources for growing M. sinensis and M. floridulus in China.

Ecological Wisdom and Renewal of Jiarong Tibetan Residence in Zhonglu West Sichuan Province

The paper is under the background of residence architecture and Tibetan culture, taking the settlements and architecture of Zhonglu Danba as the object of research, taking architectural culture of other ethnic groups as reference. Inspect the vernacular architecture on the aspects of architecture and culturology, and to conclude the common ecological wisdom in residence construction. The paper also does case study of renewal, revise the traditional architecture aim at the flaws, giving the idea of” excessive growth”, in order to fulfill the demand of local resident.

川西亚高山/高山森林土壤氧化还原酶活性及其对季节性冻融的响应

川西亚高山/高山森林土壤通常具有明显的季节性冻融特征。为深入了解川西亚高山/高山森林冬季土壤生态过程,于2008年11月-2009年10月,在土壤初冻期、冻结期和融化期及生长季节,研究了不同海拔(3582 m、3292 m和3023 m)岷江冷杉林的土壤氧化还原酶活性及其对土壤冻融的响应。土壤冻结时间和冻融循环次数随海拔的增加而增加。冻融格局显著影响了土壤氧化还原酶活性,但不同土壤酶在不同海拔表现出明显差异。土壤过氧化物酶和脱氢酶活性受初冻期冻融循环和温度降低影响显著下降,而过氧化氢酶活性明显上升。3种土壤氧化还原酶活性在土壤温度相对稳定的冻结期变化不显著,但在融化期随着土壤温度急剧增加经历一个明显的活性高峰后快速降低,且冻结时间最长和冻融循环次数最多的3582 m变化更为显著。此外,海拔和土层的交互作用显著影响了过氧化物物活性,但对脱氢酶和过氧化氢酶活性不显著。脱氢酶活性与土壤温度极显著相关,但过氧化物酶和过氧化氢酶活性与土壤温度的相关性随海拔差异而不同。这些结果表明川西亚高山/高山森林冬季土壤氧化还原酶仍然具有较高的活性,但受到季节性冻融及其变化的显著影响。;Soil enzyme, the sensitive bio-indictor to environmental change in soil ecosystem, plays an essential role in soil ecological processes, such as litter decomposition, organic matter accumulation and nutrient cycling. Including others, climate change with temperature dynamics always have a great effect on soil enzyme activity. Seasonal freeze-thaw cycle in the subalpine/alpine region is a common climate phenomenon, which could change soil enzyme activity, and then soil ecological processes. However, little information has been available. In order to understand soil oxidordeuctases activities and their responses to seasonal freeze-thaw cycle in the subalpine/alpine forests of western Sichuan, three fir (<em>Abies faxoniana</em>) forests were selected covering a 600 m vertical transition zone. The primary fir forest at 3852 m of altitude, fir and birch mixed forest at 3298 m of altitude, and secondary fir forest at 3023 m of altitude are representative forests in the subalpine and alpine region of west Sichuan. Based on the simultaneous monitoring of soil temperature, soils were sampled in different stages as the onset of soil freezing period, soil frozen period, soil thawing period and growing period from November 2008 to October 2009. The activities of soil peroxidase, dehydrogenase, and catalase were measured. There were obvious seasonal freeze-thaw processes in sampled forests at different altitudes, and the length of seasonal freeze-thaw and the number of freeze-thaw cycle increased with the increase of altitude. Seasonal freeze-thaw cycle significantly affected the activities of soil oxidordeuctases, but the responses of soil oxidordeuctase activities were varied with soil enzyme types. The activities of soil peroxidase and dehydrogenase decreased in the onset of soil freezing period with the decrease of soil temperature, but soil catalase activity increased. Soil oxidordeuctases activities displayed few changes in soil frozen period. However, soil oxidordeuctases activities sharply increased with the increase of soil temperature in soil thawing period. The activities of all investigated soil oxidordeuctases reached to an obvious peak in soil thawing period. The changes of soil oxidordeuctases activity at 2583 m were more significant in comparison with those at 3298 m and 3023 m due to longer freezing length and more freeze-thaw cycles. Meanwhile, the interaction of altitude and soil layer had significant effects on soil peroxidase activities, but had insignificant effects on soil dehydrogenase and catalase activities. Additionally, soil dehydrogenase activities were significantly correlated with soil temperature, but the correlations between soil temperature and the activity of soil peroxidase and catalase differed with altitudes. The results suggest that soil oxidordeuctases in wintertime still keep relative higher activities in the subalpine and alpine forest of western Sichuan, although the seasonal freeze-thaw cycle and its changes have significant effects on the activities of soil oxidordeuctases.

The Characteristics of Mesoscale Convective Systems (MCSs) over East Asia in Warm Seasons

AbstractMesoscale convective system (MCS) cloud clusters, defined using an objective recognition analysis based on hourly geostationary infrared satellite data over East Asia during the warm seasons of 1996–2008 (except 2004), were investigated in this study. The geographical pattern of MCS distribution over East Asia shows several high-frequency centers at low latitudes, including the Indo-China peninsula, the Bay of Bengal, the Andaman Sea, the Brahmaputra river delta, the south China coastal region, and the Philippine Islands. There are several middle-frequency centers in the middle latitudes, e.g., the centraleast of the Tibet Plateau, the Plateau of west Sichuan, Mount Wuyi, and the Sayan Mountains in Russia; whereas in Lake Baikal, the Tarim Basin, the Taklimakan Desert, the Sea of Japan, and the Sea of Okhotsk, rare MCS distributions are observed. MCSs are most intensely active in summer, with the highest monthly frequency in July, which is partly associated with the breaking out and prevailing of ...

Ecological Wisdom and Renewal of Jiarong Tibetan Residence in Zhonglu West Sichuan Province

The paper is under the background of residence architecture and Tibetan culture, taking the settlements and architecture of Zhonglu Danba as the object of research, taking architectural culture of other ethnic groups as reference. Inspect the vernacular architecture on the aspects of architecture and culturology, and to conclude the common ecological wisdom in residence construction. The paper also does case study of renewal, revise the traditional architecture aim at the flaws, giving the idea of” excessive growth”, in order to fulfill the demand of local resident.

Study on the Land Cover/Land Use by Using Remote Sensing and GIS in the West Sichuan Plateau

An area located among of 98.5°～102.5°E and 31°～33.65°N with 49117.9 km~2, part of the West Sichuan Plateau, also part of the upper reaches of the Yangtze River and the West Engineering of Water Transfer from South to North China, was studied in the paper. The TM and ETM+ images (1995, 1999) were interpreted with the information resources of relief maps, by using the techniques of remote sensing, the geographical information system, the information extracting means of field investigation and the interpretation on the computer screen. And the database of land cover/land use and the land type of this area were also established. The database includes the TM image database, the digital relief maps database, the land cover/land use database (1∶100 000) and its attributing database. The results show that the types of high-cold meadow with high coverage, high-cold shrub meadow, high-forest and shrub forest , with the 84.14% of the total area ,are the main types in the test area. The spatial distribution of land cover/use show that: first, the region with altitude above 4 600 m a.s.l. in this area is usual a dividing ridge, where the vegetation is mainly high-cold meadow with low coverage; second, the region with altitude of 4 000~4 600 m a.s.l. is the main part of this area, where the vegetation is mainly high-cold meadow with high coverage, and high-cold steppe with low coverage; third, 40% of this area with altitude of 2 800~4 000 m a.s.l., where the vegetation is mainly high-cold steppe with high coverage, and part of high-cold shrub meadow, high-cold swamp meadow and shrub forest in the area with high moisture content; last, the area with altitude below 2800m a.s.l. is covered with by high-cold steppe, shrub forest and forest land. These results will provide the data for studying the hydrological characteristics of this area.

Young, active conjugate strike–slip deformation in West Sichuan: evidence for the stress–strain pattern of the southeastern Tibetan Plateau

The active kinematics of the eastern Tibetan Plateau are characterized by the southeastward movement of a major tectonic unit, the Chuan-Dian crustal fragment, bounded by the left-lateral Xianshuihe–Xiaojiang fault in the northeast and the right-lateral Red River–Ailao Shan shear zone in the southwest. Our field structural and geomorphic observations define two sets of young, active strike–slip faults within the northern part of the fragment that lie within the SE Tibetan Plateau. One set trends NE–SW with right-lateral displacement and includes the Jiulong, Batang, and Derong faults. The second set trends NW–SE with left-lateral displacement and includes the Xianshuihe, Litang, Xiangcheng, Zhongdian, and Xuebo faults. Strike–slip displacements along these faults were established by the deflection and offset of streams and various lithologic units; these offsets yield an average magnitude of right- and left-lateral displacements of ∼15–35 km. Using 5.7–3.5 Ma as the time of onset of the late-stage evolution of the Xianshuihe fault and the regional stream incision within this part of the plateau as a proxy for the initiation age of conjugate strike–slip faulting, we have determined an average slip rate of ∼2.6–9.4 mm/year. These two sets of strike–slip faults intersect at an obtuse angle that ranges from 100° to 140° facing east and west; the fault sets define a conjugate strike–slip pattern that expresses internal E–W shortening in the northern part of the Chuan-Dian crustal fragment. These conjugate faults are interpreted to have experienced clockwise and counterclockwise rotations of up to 20°. The presence of this conjugate fault system demonstrates that this part of the Tibetan Plateau is undergoing not only southward movement, but also E–W shortening and N–S lengthening due to convergence between the Sichuan Basin and the eastern Himalayan syntaxis.

Behaviour of Slope Protecting and Retaining Structures during Wenchuan Earthquake on May 12 2008

At 14:28, May 12th 2008, a strong earthquake measured Ms8.0 hits Longmenshan mountain area, west Sichuan province, China. The quake is induced by the thrust of Longmenshan central fault, results in around 50000 rock avalanches and landslides, destroys numerous villages and towns, and causes nearly 90000 fatalities or missing. Based on field reconnaissance, the geology and fault patterns in Longmenshan mountain area are firstly introduced, then the damage or failure phenomena of slope protecting and retaining structures in quake-hit area is described and discussed, including slide-resistant piles, gravity retaining walls, shotcrete, anchored concrete frame, cable bolts and protecting nets. Special discussion is given to the behaviour of cable bolts based on measured data. And finally design issues is discussed in quake-prone areas.

A model for predicting reservoir fracturing pressure of perforated wells after acid damage

Abstract Acid damage is an effective technology to solve the problem of high fracturing pressure for the deep, tight, low permeability sandstone reservoirs during fracturing or acid fracturing. A model for quantitatively predicting reservoir fracturing pressure of perforated wells with acid damage was established combining with damage mechanics, fracture mechanics and the finite element theory. The model considered the effects of rock mineral composition, acid type, acid amount and temperature on fracturing pressure. The model was used to quantitatively predict the damage variable and fracturing pressure of the acid damaged formation in the Well DY1 in west Sichuan. The results showed that the higher the acid concentration, the higher the rock damage variable and the larger the rock strength reduction, and it will be more favorable for reducing fracturing pressure. The optimal 15%HCl+3%HF acid was applied and the fracture pressure was reduced by 6.5 MPa successfully, which ensured the following “fracture network” acidation implementation. Field application results agreed with the prediction results, which verified the reliability of the model.

Numerical Simulation of Three-Dimensional Ground Stress Field on XinChang Gas Reservoir in the West Sichuan

Upper Triassic Xujiahe formation locates in the deep west Sichuan depression, where abundant hydrocarbon resources were supplied and geological conditions for reservoir forming were favorable,contains three big structural belts with rich resources:Longmenshan, Xiaoquan-XinChang-Hexinchang-Fenggu, Shiquanchang-Longquanshan, especially the XinChang belonged to Xujiahe Formation of middle depression, the present ground stress has important effect in the exploitation of oil field. Base on the hydraulic fracturing data analyzing, determine the magnitude of horizontal stress as the constraint condition, use the FLAC3D software, and simulate the present ground stress distribution characteristic of second segment of Xujiahe formation, the results show the maximum principal stress direction is mainly east-west, which supply helpful reference to the future exploration and development.

Precipitation and temperature trends for the Southwest China: 1960–2007

AbstractDaily temperature and precipitation data from 136 stations of Southwest China (SWC) during the last five decades, from 1960 to 2007, were analysed to determine the spatial and temporal trends by using the Mann–Kendall trend test. Results show that SWC has become warmer over the last five decades, especially in the recent 20–25 years. The increasing trends in winter months are more significant than those in the months of other seasons, and spatially Tibet, Hengduan mountains area and west Sichuan Plateau have larger temperature trend in magnitude than the other regions have. A downward trend was detected in Sichuan Basin also, but the region with cooler temperature was shrinking due to the statistically significant increasing trend of temperature after 1990s. Both annual and seasonal means of daily maximum and minimum temperatures show an increasing trend, but trend magnitude of minimum temperature was larger than that of maximum temperature, resulting in the decrease of diurnal temperature range for SWC in the last 50 years. Annual precipitation showed slightly and statistically insignificant increasing trend, but statistically significant increasing trend has been detected in winter season while autumn witnessed a statistically significant decreasing trend. The results could be a reference for the planning and management of water resources under climate change. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Community ecology of Acanthopanax giraldii in west Sichuan plateau

To study the community characteristics of Acanthopanax giraldii and its role and adaptability in the community. The methods of community ecology were used to investigate vegetation composition in different sample plots and the number of the clumps and clonal ramets. The importance value of species and biodiversity index of each plot was calculated. The life form spectra in different community were counted. The chi-square test was applied to analyze the dependence degree of A. giraldii to other main shrub species in the community. The investigation had showed that A. giraldii community could be divided into three types. The number of A. giraldii population in each type had great difference. Statistical analysis had shown that there's no correlation between the growth of A. giraldii with biodiversity and no significant interspecific association between A. giraldii and other main shrub species in the community yet. The population growth of A. giraldii was sensitive to Sunshine. A. giraldii maybe has the biological characteristics for artificial planting as a single population.

Age structure and biomass accumulation of Acanthopanaxgiraldii population in west Sichuan plateau

To study age structure and medicinal parts biomass accumulation of Acanthopanax giraldii population in West Sichuan Plateau. The methods of plant population ecology were applied to the study. The ramets of A. giraldii were collected in sample plot, survey the age, height, basal diameter and biomass of ramets,and also survey the number,stem bark height and length of the one-year-shoot growing in clonal ramets. Then statistically analyzed the survey data. The article revealed growth rule of A. giraldii population. The mortality rate of clonal ramets reached a peak after six years growth. The power exponential fuction could reflect the correlation of age to the height, basal diameter and biomass of ramets. The production of medicinal parts was stable between two to six years growth of clonal ramets. Suggested to harvest medicinal parts after three years growth of the clonal ramets. The study could provide biologic basis to population management and sustainable harvest of A. giraldii.