共查询到20条相似文献,搜索用时 15 毫秒
1.
民勤绿洲退耕地植物群落多样性研究 总被引:1,自引:0,他引:1
通过对民勤绿洲内部退耕地植被恢复系列不同阶段的群落取样,研究了植被恢复过程中群落物种的组成、多样性变化过程。结果显示:在50 a自然恢复过程中,群落可大致划分为1年生草本植物群落阶段、多年生草本植物群落阶段、草本灌木植物过渡阶段和灌木植物阶段。所有调查群落的物种组成简单,单科单属植物种所占的比重很大。随恢复年限的延长,群落中物种丰富度指数S和Margalef指数呈下降趋势;物种多样性指数Simpson和Shannon-Wiener指数在退耕初期和退耕30、40 a的植被群落中最高;退耕地群落中的均匀度指数Pielou和Alatalo指数都高于原始自然群落,说明经过50 a的自然恢复,绿洲退耕地仍然没有达到相对稳定的状态,群落仍然在发展。 相似文献
2.
土壤-植被系统演变对生物防沙工程的影响 总被引:10,自引:0,他引:10
包兰铁路横穿腾格里沙漠的沙坡头段 ,全长近 5 0km ,这里年降水量 186mm ,流动沙丘相对高度 2 0m以上 ,以 4m·a- 1 的速度向东南方向移动。无灌溉条件下、工程措施与生物措施相结合的防沙固沙工程体系始建于195 6年 ,近半个世纪以来该体系确保了包兰铁路的畅通无阻 ,累计经济效益逾百亿人民币。虽然当初的建设者充分考虑了耐旱的乡土树种、有效的工程固沙系统 ,但很难想到几十年后的土壤 -植被系统的演变会危及整个防护体系的稳定性。植被在从人工系统向自然系统的演变中经历了覆盖度从增加到减少的自疏过程、从灌木到半灌木到草本的变化 ,其降低风速和防风的功能减弱 ;土壤从流动风沙土发育成钙积旱成土 ,地表生物结皮发育 ,增加了表土的抗风蚀的能力 ;土壤 -植被系统的演变使得降水在生态系统中的再分配过程已经彻底改变 ,并由于防护林体系配置不完善 ,在 5 0~ 5 0 0cm的土层深度一个生物成因的干旱层逐渐形成 ,新的水分平衡格局明显威胁到现有的防风固沙体系。 相似文献
3.
长白山区主要野生饮料植物资源 总被引:9,自引:0,他引:9
长白山区主要野生饮料植物共有14科、28属、54种。其中乔木类:3科、7属、17种;灌木类:4科、10属、20种;木质藤本类:3科、3属、5种;多年生草本类:7科、8属、11种;1,2年生草本类:1科、1属、1种。同时还介绍了主要野生饮料植物在5个不同景观带的分布情况,提出了开发利用和保护的具体建议。 相似文献
4.
Comparison of fractal characteristics of species richness patterns among different plant taxonomic groups along an altitudinal gradient 总被引:1,自引:0,他引:1
This study was done using the non brown fractal model to quantify and compare the variations in the species richness of trees,
shrubs, herbs and all plants along an altitudinal gradient and to characterize the dominating ecological processes that determine
the variations.
Two transects were sampled far away from any anthropogenic disturbances along the shady slopes of the Dongling mountains in
Beijing, China. Both transects were continuous and 2 m wide, and every individual tree and shrub was recorded in each of them.
Discrete quadrats of 1 m × 1 m were located along the transects A and B for estimation of the herb species richness along
the altitudinal gradients. The level interval between the quadrats was 10 m and 25 m respectively. In this study, transects
A and B were combined into one transect AB, and 40 m was selected as the optimal quadrat length along the altitudinal gradients
for measuring the plant species richness patterns. Species richness in each quadrat was calculated using a program written
in Matlab 6.0.
Direct gradient analysis was used to describe the overall trends in the species richness of trees, shrubs, herbs and other
plants with change in altitude, while the non-brown fractal model was used to detect more accurately their variations at various
scales along the gradient. The model assumed that each class of ecological processes affecting the distribution of a variable
could be represented by an independent spatial random function. Generally, ecological phenomena are determined not by a single
ecological process but by multiple ones. These processes act on ecological patterns within their own spatial scales. In the
non-brown fractal model, the spatial random functions are nested within a larger range of spatial scales. The relative contribution
of the spatial random functions to the spatial variation of a variable is indicated by a weighting parameter that has to be
greater than or equal to zero.
In this paper, we reached the following results and conclusions. Firstly, the direct gradient method describes the general
trends of trees, shrubs, herbs and all plants along the altitudinal gradient but is unable to provide further details on the
altitudinal variations in the species richness. The non-brown fractal model brought out the altitudinal variations in the
species richness of trees, shrubs and herbs at various scales and related them to the ecological processes. The sharp changes
in the double-log variograms suggest that the non-brown fractal model is suitable for characterizing the altitudinal patterns
in the species richness of trees, shrubs and herbs at various scales but is not appropriate for explaining the variations
in the plant species richness, since no significant changes were found in the double-log variograms in this case. Secondly,
for the trees, the double-log variogram was divided into two scale ranges (0–245 m and 245–570 m), with a fractal dimension
of 1.83 and 1.10, respectively, implying that changes in the tree species richness were random at small scales (0–245 m) and
almost linear at large scales (245–570 m) along the altitudinal gradients. This suggests that altitudinal variations in the
tree species richness are dominated by short-range processes at small scales and by long-range processes at large scales.
Thirdly, for shrubs and herbs, the double-log variograms exhibited three ranges (0–101 m, 125–298 m and 325–570 m), and the
fractal dimensions were 1.78 and 1.97, 1.56 and 1.43, and 1.08 and 1.25, respectively. The results indicate that, as in the
case of trees, species richness of shrubs and herbs are distributed randomly at small scales and change in a linear manner
at large scales although variations in the herb species richness is less heterogeneous than shrub species richness at large
scales. These results also indicate that species richness of shrubs and herbs change approximately like brown movement at
middle scales. The results also suggest that altitudinal variations in the specie richness of shrubs and herbs are dominated
by three ecological processes, short-range ecological processes at small scales, long-range ecological processes at large
scales, and brown fractal processes at middle scales. Interestingly, comparisons of the variations in the species richness
of shrubs and herbs reveal that shrubs and herbs present the same scale range in spatial variation in species richness but
display different trends in species richness along the altitudinal gradient, i.e. the shrub species richness decreased with
increasing elevation whereas the herb species richness peaked at the mid-high elevation. These patterns suggest that although
the scales at which the main processes affect patterns in species richness are the same, the processes are completely different,
or the processes are similar but the responses of the shrubs and herbs to the ecological processes are different. Finally,
the plant species richness did not show any obvious pattern along the altitude gradient and maintained a constant fractal
dimension across all scales, this is perhaps because the processes defining the patterns of plant species richness had similar
weights and acted over closely related scales.
__________
Translated from Acta Phytoecologica Sinica, 2005, 29(6): 901–909 [译自: 植物生态学报] 相似文献
5.
Tamarix plant is widely distributed in the arid areas of China for its great tolerance of draught, salt and alkali and attracts more
attention by its strong capacity in windbreak and sand-fixations. “Tamarix dunes” constitute special desert bio-landscape in arid area. During last several decades,Tamarix shrubs declined and “Tamarix dunes” were also severely destroyed due to the land exploitation and serious deforestation, etc. From the 1980s until now,
the extending phenomenon ofTamarix shrubs caused by developmental projects such as building highway, railway was studied in the western dry area of China, including
western section of Hexi Corridor of Gansu, railroads and highways around the two greatest basin in Xinjiang and interior regions
in Gurbantonggut desert, through on-the-spot survey along the transportation lines and setting up sampling plots along the
roads. It was found that large quantities ofTamarix plants grow in the catchment area of low-lying lands that were formed by bulldozer operation during road building period.
The extension ofTamarix shrubs caused by engineering was similar to that of the other section of the area to some extent, but went beyond the original
distribution. This extension is beneficial to the ecological restoration and re-vegetation of western region of China and
plays an important role in control of the sandstorms and improvement of ecological environments. As a result, it is necessary
to make a further study on the extending phenomenon ofTamarix shrubs and to seek approach to promote wider extension ofTamarix shrubs in suitable habitats.
Foundation Item: This study is supported by key projects of National Natural Science Foundation (39730100), National Foundation (30070640)
and part of Project 973(G19990435).
Biography: Huang Pei-You (1936-), Male, Professor in College of Life Science and Technology, Xinjiang University, Urumqi, 830046
Responsible editor: Chai Ruihai 相似文献
6.
7.
P. Barnes 《Agroforestry Systems》1998,42(1):25-32
There is keen interest in feeding small ruminants with herbage from forage shrubs and trees in Ghana because of the general
perception about these plants being perennial and remaining green for lengthy periods. In this study, plant growth rate, herbage
production and quality of two indigenous woody plants, Griffonia simplicifolia and Baphia nitida were compared to those of
two introduced shrubs, Leucaena leucocephala and Gliricidia sepium. Gliricidia sepium achieved the greatest height and produced
the highest herbage dry matter (2t/ha) compared to average production of 0.15 t/ha by the three other species. Gliricidia
sepium herbage also had high contents of crude protein, calcium and ash. In regrowth herbage production at cutting intervals
of 6 and 12 weeks, Gliricidia sepium again outperformed the three other species, however, there was little difference in herbage
yield among the three other species. In all species one harvest at 12 weeks regrowth interval produced more herbage than the
combination of yield of two six week interval harvests.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
Theosierx`,eevilxvasfirstfoundinHarbin,Chinainl953['].ltisascriouspestofpoplarandwillows.ltslarvaen1inetrtmksofhosttreesTheinLfestedtreeslosetheirvigorandwindfalloftenoccurs.Thelosscausedbythispestisverygreat.9o66.6hm2poplartreeshavebeeninfestedand5O22.2hIn2havebeendestroyedinHeilonaiiangPro1'incesincel97O.Inotherprovinces,suchasLiaoning,JilinandInnerMongolia,agreatnumberofpoplarhavebeendestroyedbythispest,too.Thispestbe-comesoneofthemostdesthectivepestsinChina.Thisstudvismai11lvtofindou… 相似文献
9.
坡耕地退耕还林后的植被恢复 总被引:10,自引:2,他引:10
生态公益林建设是坡耕地恢复森林植被最重要的模式 ,但对退耕还林后的植被恢复特点和规律的研究却很少报道。本文选择在四川省退耕还林工程中普遍发展的桤木生态公益林为研究对象 ,对其植被恢复特点和规律进行了探讨。1 试验地概况选择坡耕地退耕还林后形成的桤木 (Alnuscremastogyne)生态林和弃耕 1年形成的杂草群落为研究对象。试验地位于四川西缘山地区的天全县境内 ,东经 10 2°4 5′ ,北纬 30°0 3′ ,海拔 80 0m ,坡度 2 6° ,坡向西北 ,坡位中部 ,母质为砂岩风化物 ,土壤类型为紫色土 ,属亚热带季风湿润气候区 ,年平均降雨量 1735 … 相似文献
10.
华中神农架箭竹(Fargesia spathacea)群落之海拔多样性(英文) 总被引:5,自引:0,他引:5
通过对华中神农架海拔1500米至2600米之间11个箭竹样方的研究,阐述了箭竹群落物种丰富度,物种多样性,物种均匀性,生活型谱及群落类型的海拔变化。从最低样方(1680米)到最高样地(2570米),微管束植物从30种降为7种,服从线性模型:Y=55.991.83X(R2=0.84,P<0.001);物种多样性从3.18降为1.78,服从线性模型:Y=4.670.10X (R2=0.72,P=0.001;物种均匀度在0.83至0.99之间变化,但与海拔并不相关。在生活型谱中,一年生植物,地下芽植物和大高位芽树木的百分比随海拔升高而升高;灌木和中高位芽树木随海拔升高而降低;多年生草本和半灌木与海拔关系不大。箭竹群落可分为5种类型:常绿阔叶林下,落叶阔叶林下,温性针叶林下,寒温性针叶林与混交林下,纯箭竹林。图4表2参19。 相似文献
11.
选取河西走廊中部封育3、5、8、12、13、14年和未封育的荒漠植被,采用样带结合样方法进行野外植被调查,运用重要值、Levins生态位宽度指数和Pianka生态位重叠指数进行研究,分析了荒漠植被对资源的利用情况,揭示不同封育年限荒漠植被群落中种群生态位格局。结果表明,随着封育年限的延长和群落的演替,物种丰富度指数先增高后降低;物种均匀度指数和多样性指数呈先增高后降低再增高的变化趋势;物种重要值呈先降低再增高又降低的变化趋势。生态位宽度大的主要集中在盐生草、驼蹄瓣、刺沙蓬、苔草、沙蒿、画眉草、锋芒草、羊茅、红砂、青蒿等,说明这些植物适应环境能力强,能够充分利用环境资源,而且在群落中处于优势地位。 相似文献
12.
Reforestation is one of the most important and efficient measures of water and soil conservation. Based on field investigations
in the Shangyang Soil Conservation and Reforestation Station in Huizhou, Guangdong Province, China, we studied the variation
in vegetation development, vegetation succession processes and soil erosion. The regional vegetation consists mainly of monsoon
evergreen broad-leaved forests (MEBF). The area was deforested and became a denuded hill area with extremely high soil erosion
in the 1960s and 1970s. Then, the area was closed in order to allow recovery of the vegetation. Under natural conditions the
vegetation development and succession processes were slow during which soil erosion and strong sunshine and evaporation slowed
down the development of the vegetation. About 25 years later, the vegetation cover was still merely 35% or so. The dominant
vegetation types were heliophilous herbage and shrubs which formed a poorly developed shrub-herbage community and erosion
remained high. In contrast, reforestation with selected tree species dramatically speeded up the vegetation succession process.
About 12 years after reforestation, vegetation cover of the Acacia auriculiformis plantations in the Shangyang Station was 90% and erosion was under control. After 23 years, understory vegetation, consisting
of indigenous species, had developed in the plantations. The planted trees and naturally developing herbage, shrubs, bamboo,
local trees and liana formed a complex vegetation community in three layers. It will take 60 years for the vegetation to succeed
from bare land to a secondary growth forest under natural conditions. Reforestation may speed up the vegetation succession
process. The time may be reduced to 20 years. Reforestation is the most effective measure of vegetation restoration and erosion
control in this area.
__________
Translated from Acta Ecologica Sinica, 2006, 26(8): 2558–2565 [译自: 生态学报] 相似文献
13.
Four equations were developed for predicting the probability of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] and ponderosa pine (Pinus ponderosa Dougl. ex Laws.) survival for the first (0–1) and first to third (1–3) growing seasons after applying mulching, scalping, or artificial shading (shade cards) treatments in plantations in southwestern Oregon, U.S.A. Variables describing conifer size, levels of competing vegetation, presence of silvicultural treatments, site factors, and climate factors were collected from 13 sites ranging from 0 to 6 years after planting and examined as potential predictors of survival. Age, stem diameter, a competition index for shrubs, severity of growing season at time of treatment, average annual precipitation, aspect, and slope angle were predictors of Douglas-fir survival during 0–1 and 1–3 growing seasons after treatment; the presence of silvicultural treatments was also a predictor only during the first growing season after treatment. Age, aspect, and slope angle were predictors of ponderosa pine survival over both 0–1 and 1–3 growing seasons after treatment; height-diameter ratio, competition indices for herbs, shrubs, and hardwoods, silvicultural treatment, severity of growing season at time of treatment, and average annual precipitation were also predictors only during the first growing season after treatment; crown width was a predictor of survival only during 1–3 growing seasons after treatment. When significant in the models, predicted probability of survival increases with treatments, less severe weather conditions, diameter, crown width, age, and precipitation; probability decreases with increasing height-diameter ratio and competition indices for herbs, shrubs, and hardwoods. 相似文献
14.
以人工拣种结合种子萌发法研究了庞泉沟自然保护区9种河岸林群落的土壤种子库特征,结果表明: 9种群落的土壤种子库密度间于684±108 - 2 696±266粒·m-2,69.27% - 88.65%的种子留存于0 - 5 cm的层次,沙棘灌丛的种子库密度最大,乌柳灌丛最小;离河岸10 m和20 m处的种子库密度大于岸边、离河岸30 m和40 m处;种子库包含的40种植物以多年生草本为主,灌木和草本种多为耐干扰种,存在典型的湿地植物,但种子储量以先锋种白桦最丰;辽东栎无完整种子,白桦、华北落叶松、云杉和油松的种子活力保持期为1 - 2年,多数草本的种子活力保持期超过2年;按照群落土壤种子库的相似性,将群落划分为林分开始期、林分排除期、下层再现期和老熟期4个演替阶段。演替后期群落的种子库密度、丰度以及与地上植被的相似性都小于前期群落。土壤种子库是森林自然更新及种群恢复的重要基础,本文对于研究地区河岸林的保护和重建具有重要的理论意义。 相似文献
15.
Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of fine roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m–2, respectively. The fine root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m–2, respect... 相似文献
16.
通过对华中神农架海拔1500米至2600米之间11个箭竹样方的研究,阐述了箭竹群落物种丰富度,物种多样性,物种均匀性,生活型谱及群落类型的海拔变化。从最低样方(1680米)到最高样地(2570米),微管束植物从30种降为7种,服从线性模型:Y=55.99-1.83X(R2=0.84,P<0.001);物种多样性从3.18降为1.78,服从线性模型:Y=4.67-0.10X (R2=0.72,P=0.001;物种均匀度在0.83至0.99之间变化,但与海拔并不相关。在生活型谱中,一年生植物,地下芽植物和大高位芽树木的百分比随海拔升高而升高;灌木和中高位芽树木随海拔升高而降低;多年生草本和半灌木与海拔关系不大。箭竹群落可分为5种类型:常绿阔叶林下,落叶阔叶林下,温性针叶林下,寒温性针叶林与混交林下,纯箭竹林。 相似文献
17.
采用样方法对广州6个湿地公园自生植物群落调查,分析物种构成、重要值与园林应用潜力。结果表明:滨水绿地自生植物共42科72属77种,其中菊科、禾本科、伞形科为优势科;生活型主要为多年生草本;优势物种有芦竹Arundo donax、南美天胡荽Hydrocotyle verticillata、纸莎草Cyperus papyrus、梭鱼草Pontederia cordata和水竹芋Thalia dealbata;观赏特性以观花类为主,色彩鲜艳且富有趣味性。推荐具有园林应用潜力的15种自生植物,配置要求适地种植和有空间层次。 相似文献
18.
Fude Liu Wenjin Wang Ming Zhang Jianwei Zheng Zhongsheng Wang Shiting Zhang Wenjie Yang Shuqing An 《Frontiers of Forestry in China》2008,3(3):308-314
Species association is one of the basic concepts in community succession. There are different viewpoints on how species interaction
changes with the progress of succession. In order to assess these relationships, we examined species associations in the tropical
montane rain forest at early and late successional stages in Diaoluo Mountain, Hainan Island. Based on data from a 2 × 2 contingency
table of species presence or absence, statistical methods including analysis of species association and X
2 tests were applied. The results show that: 1) an overall positive association was present among tree species in the communities
during the two successional stages and were statistically significant at the late stage. The number of species pairs with
positive and negative associations decreased throughout the process of succession, while the number with null associations
was greatly increased. The same trend existed among the dominant and companion species. The results indicate that the communities
are developing towards a stable stage where the woody species coexist in harmony. 2) In the early-established and later invading
species, all positive associations were not significant. Compared with positive and null associations, fewer negative associations
were found. This implies that these species are inclined to coexist independently through portioning of resources. 3) Among
the later invading species, positive associations were significant and no negative associations were found which suggest that
these species have similar adaptive ability in the habitat and occupied overlapping niches in the community.
__________
Translated from Biodiversity Science, 2007, 15(3): 257–263 [译自: 生物多样性] 相似文献
19.
Kari HELIVAARA 《中国林学(英文版)》2009,11(1):55-60
Taking the communities of the sample sites in Aershan of Inner Mongolia as an investigation object, the indices affecting plant diversity were studied. The investigation was carried out in three different forest types (natural forests, plantations and regenerated forests after fire). Results show that 95 plant species belonging to 19 families and 50 genera were identified in total. Of these species, nine were arbors, six were shrubs and the other 80 were herbs. We found some differences in the dominant species of different layers in three forest types. Natural forests had the largest importance value for the total number of species, followed by plantations and regenerated forests after fire. Plantations and natural forests had a similar change in richness indices. The largest value of richness indices was obtained in natural forests, while the lowest value was in regenerated forests after fire. Three diversity indices (Simpson’s, Shannon-Wiener and Pielou’s indices) indicate a similar trend in all sample plots. With an increase in elevation, values of diversity indices first increased and then decreased. In different forest types, similarity between natural forests was largest, while similarity between the regenerated forests and plantations was lowest. 相似文献