共查询到19条相似文献，搜索用时 46 毫秒
1.
《植物生态学报》1958,44(6):642
放牧是草原的主要利用方式, 但对牧草造成了一定的生物胁迫。面对生存压力, 牧草会通过调节初级与次级代谢过程启动防御机制。该研究以内蒙古温带典型草原优势种植物为研究对象, 通过测定其在5个放牧水平下不同营养器官中的次级代谢产物及木质素等含量, 探讨大针茅(Stipa grandis)和羊草(Leymus chinensis)的各营养器官在防御机制中的角色及其碳氮权衡策略。结果表明: 面对放牧胁迫, 大针茅和羊草会产生大量的单宁、总黄酮、酚类以及生物碱等次级代谢产物, 并以叶片为主要的合成及储存器官。中度放牧使羊草的化学防御机制得到较充分的诱导及表达。但二者地上部分木质素含量并无显著增加, 因此, 二者在避牧性机制上更倾向于化学防御而非机械防御。由于羊草有更高的氮利用效率, 这使得羊草可以通过碳氮两种代谢途径进行防御, 但大针茅在生长初期并不能将氮高效地分配到化学防御中。大针茅和羊草在生长初期面对轻度放牧胁迫, 较多的资源仍然用于初级代谢, 增加了植物耐牧性。因此, 轻度放牧有利于提高牧草的碳氮资源利用效率、提高生态系统生产力及稳定性。 相似文献
2.
放牧影响下羊草草原和大针茅草原植物多样性的变化 总被引：74，自引：0，他引：74
李永宏 《Acta Botanica Sinica》1993,35(11):877-884
牧压梯度上羊草草原和大针茅草原植物多样性的研究表明：随着放牧强度的增加,群落的植物种度降低,但其均匀度和多样性在中度放牧的群落中最高。牧压梯度上草原群落的植物多样性变化决定于群藻中种间竞争排斥和放牧对不同植物的抑制或促进,而群落的层片结构是这两种作用的综合反映,表征着群落内生态位分化程度的高低,决定了群落的物种多样性。中度的放牧削弱了建群植物层片的竞争排斥,又不抑制其它层片的发育,是群落具有较高植 相似文献
3.
大针茅是亚洲中部草原亚区特有的蒙古草原种,以大针茅建群的草原在内蒙古的分布面积为2 798 081hm^2.从遗传多样性上探讨了大针茅种群在放牧压力下的适应机制,结果表明：虽然放牧导致部分基因位点丢失,但整个种群仍表现出丰富的多态性,ISSR检测的多态性条带比率为89%.Nei＇s指数计算的大针茅种群间的遗传分化为0.1984,说明有19.8%的遗传变异存在于种群之间, 80.2%的遗传变异存在于种群内. 由Shannon＇s和Nei＇s多样性指数检测的大针茅种群内遗传多样性随着放牧压力的增加有逐渐减弱的趋势.根据遗传距离构建的UPGMA聚类图中, 中度和重度放牧样地首先聚为一类, 不放牧和轻度放牧样地聚为一类, 随后聚在一起. 相似文献
4.
以呼伦贝尔克氏针茅草原不同放牧强度下的演替群落为对象,开展群落及其群落建群种的地下生物量和根系形态特征研究.结果表明:从轻度放牧到重度放牧,群落种类组成和根系功能群类型趋于简单化;群落地下生物量的空间分布形态呈“T”型;不同放牧强度下草原群落的建群种出现了明显替代现象,轻度放牧样地群落建群种为密丛型根系的克氏针茅,中度放牧为疏丛型根系的糙隐子草(Cleistogenes squarrosa,重度放牧为鳞茎型根系的碱韭(Allium polyrhizum);随着放牧强度的增大,群落建群种根冠比逐渐增加,分别为0.47、1.0、4.1,并且群落建群种根系数量、根系体积、根系生物量、比根长及根长密度等各指标均发生了明显变化.另外,3种放牧强度样地群落建群种根冠比、根长密度均与土壤速效氮含量呈现显著正相关(P＜0.05). 相似文献
5.
蘑菇圈是草原生态系统中独有的景观类型,是由蘑菇真菌菌丝体在土壤中生长和扩散所形成环状结构,影响植物生长和发育过程。蘑菇圈如何影响不同植物的种群特征进而改变群落结构和功能,目前缺乏系统的认知。在内蒙古典型草原两种蘑菇圈不同位置进行植被样方调查并分析数据后发现:羊草(Leymus chinensis)在草原黑蘑(Agaricus arvensis)蘑菇圈和蒙古白丽蘑(Leucocalocybe mongolica)蘑菇圈上的高度、盖度、密度和地上生物量均显著高于蘑菇圈内和圈外(P<0.05);与之相反,大针茅(Stipa grandis)在蘑菇圈上显著低于圈内和圈外,这些指标在圈内和圈外间无显著差异。两种蘑菇圈上羊草的重要值显著升高(草原黑蘑蘑菇圈:0.15→0.50;蒙古白丽蘑蘑菇圈:0.17→0.53)和大针茅的重要值显著降低(草原黑蘑蘑菇圈:0.27→0.13;蒙古白丽蘑蘑菇圈:0.39→0.10)。两种蘑菇圈上群落物种丰富度、Shannon-Wiener指数、Simpson指数和均匀度指数显著低于蘑菇圈内和圈外。在两种蘑菇圈的影响下,羊草优势度的提高和大针茅优势度的降低,提高了群落盖度和地上生物量,降低群落植物多样性,最终改变典型草原植物群落特征。对深入了解蘑菇圈影响下草原植物群落结构与功能变化具有重要的科学意义。 相似文献
6.
放牧和围封通过影响植物群落结构和土壤微环境来调控草地生态系统的碳循环。该研究在内蒙古温带草原设置轻度放牧后围封、轻度放牧、重度放牧后围封、重度放牧4种样地, 通过测定干旱年(2011年)和湿润年(2012年)地上、地下凋落物产量、质量及其分解速率和土壤养分含量, 分析不同放牧强度对凋落物形成和分解的影响, 以及围栏封育对生态系统恢复的作用。结果表明: 重度放牧地上凋落物产量和分解速率均高于轻度放牧。干旱年轻度放牧样地地下凋落物产量和分解速率高于重度放牧, 湿润年相反。短期围封显著提高了凋落物产量, 轻度放牧样地围封后地上凋落物分解速率和养分循环加快, 而重度放牧样地围封后地上凋落物分解减慢。因此, 与重度放牧相比, 轻度放牧草地的恢复更适合采用围栏封育措施; 而重度放牧草地的恢复可能还需辅以必要的人工措施。降水显著促进地上、地下凋落物形成和分解。地下凋落物的生产和分解受降水年际波动影响较大, 重度放牧草地对降水变化的敏感度比轻度放牧草地高。地上凋落物分解速率与凋落物N含量显著正相关, 与土壤全N显著负相关, 与地上凋落物C:N和木质素:N相关性不大; 地下凋落物分解速率与凋落物C、C:N和纤维素含量显著负相关。该研究结果将为不同放牧强度的草地生态系统恢复和碳循环研究提供理论依据。 相似文献
7.
为探讨长期(19年)放牧干扰下荒漠草原植物的响应与适生策略,该研究以荒漠草原优势种无芒隐子草(Cleistogenes songorica)作为研究对象,测量不同放牧强度(控制、轻度、中度、重度)下叶片解剖结构指标,探讨无芒隐子草叶片解剖结构对长期放牧干扰作出的响应。结果表明:(1)保护组织方面,角质层厚度、角质层厚度占叶片厚度比均随着放牧强度的增加呈先减小后增加趋势。泡状细胞厚度随着放牧强度的增加先减小后增加,与对照、中度、重度放牧区相比,轻度放牧区泡状细胞厚度显著减小。(2)维管组织方面,维管束面积、导管面积、韧皮部面积3个指标均随放牧强度的增加呈先增加后减小趋势。木质部面积随着放牧强度增加先减小后增加。维管组织占比方面,木质部占维管束面积比随着放牧强度增加而增加,而主导管占主脉维管束面积比随着放牧强度增加而减小。韧皮部面积随着放牧强度的增加呈先增加后减小趋势,与对照区相比, 3种放牧区韧皮部面积显著减小。(3)花环结构面积随着放牧强度的增加呈增加趋势,与对照区相比, 3种放牧区花环结构面积显著增加。上述结果表明无芒隐子草叶片各项解剖结构均对长期放牧干扰作出适当响应以确保自身在受放... 相似文献
8.
为了更好地理解放牧对草原生态系统物种多度分布格局的影响, 以及常见种和稀有种对维持群落多样性的作用, 以内蒙古典型草原为研究对象, 基于长期放牧控制实验平台(包括7个载畜率水平(0、1.5、3.0、4.5、6.0、7.5、9.0 sheep·hm-2)和两种地形系统(平地和坡地)), 研究了群落内全部物种、常见种和稀有种的丰富度和多度对放牧强度的响应规律, 并选取对数正态模型、对数级数模型和幂分割模型, 对物种多度数据进行拟合。结果表明: 1)平地系统中, 物种丰富度和多度在低放牧强度下(1.5、3.0 sheep·hm-2)增加, 而在中、高度放牧强度下(4.5-9.0 sheep·hm-2)降低, 全部物种的多度分布在大多数放牧强度下符合幂分割模型, 在高放牧强度下也符合对数正态模型; 坡地系统中, 物种丰富度和多度随着放牧强度增加而显著降低, 全部物种的多度分布在各个放牧强度下, 均符合幂分割模型和对数正态模型。2)随着放牧强度增加, 常见种的多度响应趋势与全部物种的响应趋势一致, 其多度分布均符合幂分割模型和对数正态模型; 稀有种的丰富度响应趋势与全部物种的响应趋势一致, 其多度分布符合幂分割模型, 同时也部分符合对数正态和对数级数模型。总之, 适宜的载畜率有利于生物多样性和初级生产力的提高, 平地系统中物种多度的响应在一定程度上支持放牧优化假说; 而坡地系统中不同物种多度的响应差异说明: 确定最佳载畜率时, 还需要考虑地形因素的影响。此外, 模型的拟合结果表明: 生态位分化机制对内蒙古典型草原物种多度分布起着主要作用, 常见种和稀有种通过不同的响应方式共同维持着草原生态系统的物种多样性。 相似文献
9.
放牧过程通过家畜的啃食、践踏干扰草原环境,使草原的物种组成发生变化,植物种群的优势地位发生更替。对退化草原中的冷蒿群落在经历13a不同放牧强度——无牧（0．00只羊,hm^2）、轻牧（1．33只羊／hm^2）、中牧（4．00只羊／hm^2）、重牧（6．67只羊,hm^2）的围栏放牧后的植物群落多样性进行研究,结果表明：经过13a的演替变化,（1）无牧处理下植被密度显著低于其它3个放牧处理下的植被密度,而其它3个放牧处理之间的植被密度差异不显著;（2）无牧处理下羊草成为群落的优势种,轻牧和中牧处理下冷蒿依然是群落的优势种。这3种处理下寸草苔的种群密度最大;重牧处理下优势种变为星毛委陵菜,并且其种群密度最大;随着放牧强度增加,不同放牧退化阶段指示植物的种群密度的变化趋势是：冷蒿为先增大后减小,而星毛委陵菜为先急剧增大,然后平缓增大,最后再急剧增大;（3）植物多样性和均匀度指数在中牧处理下最大,在无牧处理下最小,说明中牧处理下群落的多样性最高,无牧处理下群落的多样性最小。而优势度指数正相反。植物群落结构和多样性的变化主要是由放牧家畜选择性采食、不同植物对放牧响应的不同策略、植物种间的竞争、动植物协同进化以及由放牧改变的土壤理化性质等因素综合决定的。此研究有助于进一步认识退化草原在继续放牧干扰下的演替规律以及为退化草原的保护和恢复提供理论依据。 相似文献
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11.
Jing Wang Mengli Zhao Walter D. Willms Guodong Han Zhongwu Wang Yongfei Bai 《植被学杂志》2011,22(2):367-376
Question: Litter (dead leaves or stems) affects production by conserving soil moisture. However, that role is not clear for grasslands where most precipitation falls during the growing season when the demand for water is high. Our question was: Does litter affect forage production in such an environment? Location: Typical steppe, Inner Mongolia. Methods: We examined the role of plant litter in two experiments where litter was either removed or added in a protected or heavily grazed site, respectively, in autumn and in spring in a split plot design. The treatments (control, moderate and heavy litter application) were applied once in five replications but repeated at new locations in each of 3 years. This was done to examine only the direct effect of litter on annual net primary production and selected plant characteristics and not potential secondary effects. We also measured soil moisture and soil temperature. Results: Removing litter caused a reduction in the amount of grass (Leymus chinensis) that was produced, but litter addition caused an inconsistent effect among years, with moderate applications producing the most positive effects. Litter removal resulted in shorter and less dense plants of L. chinensis and Carex duriuscula, while heavy litter addition in autumn reduced plant height of both Cleistogenes squarrosa and C. duriuscula. Conclusions: Litter was effective for enhancing soil moisture status and reducing soil heat units in the typical steppe of Inner Mongolia. Therefore, litter mass may serve as an index of grassland health in such environments. 相似文献
12.
The Stipa grandis steppe in the Inner Mongolia Autonomous Region occupies an area of 2798081 hm2. On the basis of the genetic variation, it was found that its adaptability to the environmental conditions under grazing pressure was significant. Using the Inter-Simple Sequence Repeat (ISSR) procedure, the changes to the genetic diversity of the Stipa grandis population under different grazing pressures were observed. Plant samples were collected from a series of grazing gradients of the Stipa grandis steppe in Dalinuoer National Nature Reserve in the Inner Mongolia (located at 116°38′–116°41′E and 43°25′–43°27′N.), which has the following vegetation types in abundance: Leymus chinensis is the constructive species; the dominant species include Stipa grandis, Cleistogenes squarrosa, and Artemisia frigida; the companion species is Potentilla acaulis and others. According to the grazing pressure, the following four grazing gradients were identified from the dwellings of the herdsmen to the enclosure site: (1) no grazing (CK enclosure site); (2) light grazing (LG); (3) moderate grazing (MG); (4) heavy grazing (HG). Young leaves of each Stipa grandis were collected during the growing season. The results showed that the Stipa grandis showed abundant genetic diversity despite the fact that certain polymorphic loci were lost; at the same time, new polymorphic loci emerged when grazing pressure increased; a total of 10 primers were used, and 74 bands were produced in total, of which 65 bands were polymorphic; the total percentage of polymorphism was 89%; the percentage of polymorphic loci of the Stipa grandis population decreased with the increase of grazing pressure; the percentage of polymorphic loci was 62.2% in the no-grazing (CK) population, 64.9% in the light-grazing (LG) population, 58.1% in the moderate-grazing (MG) population, and 56.8% in the heavy-grazing (HG) population; the genetic diversity of the population in the descending order using the Shannon's information index is as follows: (1) light grazing (0.3486); (2) no grazing (0.3339); (3) moderate grazing (0.3249); (4) heavy grazing (0.2735) with the same distributional pattern as the Nei's genetic diversity index. The test showed the following: As the grazing pressures increased, the change of genetic diversity decreased; the genetic differentiation coefficient among the population (Gst) was 0.1984, which showed the presence of small partial genetic diversity (19.8%) among populations; gene flow (Nm*) between primers varied from 0.9806 to 3.4463, and the mean gene flow (Nm*) was 2.0202; the UPGMA cluster figure that was constructed on the basis of the genetic distance matrix showed four populations that became genetically closer at each step: (1) The first group was the moderate-grazing (MG) population and the heavy- grazing (HG) population; (2) The second group consisted of the no-grazing (CK) population and the light-grazing (LG) population; (3) The two groups gathered together. 相似文献
13.
The Stipa grandis steppe in the Inner Mongolia Autonomous Region occupies an area of 2798081 hm2. On the basis of the genetic variation, it was found that its adaptability to the environmental conditions under grazing pressure was significant. Using the Inter-Simple Sequence Repeat (ISSR) procedure, the changes to the genetic diversity of the Stipa grandis population under different grazing pressures were observed. Plant samples were collected from a series of grazing gradients of the Stipa grandis steppe in Dalinuoer National Nature Reserve in the Inner Mongolia (located at 116°38′–116°41′E and 43°25′–43°27′N.), which has the following vegetation types in abundance: Leymus chinensis is the constructive species; the dominant species include Stipa grandis, Cleistogenes squarrosa, and Artemisia frigida; the companion species is Potentilla acaulis and others. According to the grazing pressure, the following four grazing gradients were identified from the dwellings of the herdsmen to the enclosure site: (1) no grazing (CK enclosure site); (2) light grazing (LG); (3) moderate grazing (MG); (4) heavy grazing (HG). Young leaves of each Stipa grandis were collected during the growing season. The results showed that the Stipa grandis showed abundant genetic diversity despite the fact that certain polymorphic loci were lost; at the same time, new polymorphic loci emerged when grazing pressure increased; a total of 10 primers were used, and 74 bands were produced in total, of which 65 bands were polymorphic; the total percentage of polymorphism was 89%; the percentage of polymorphic loci of the Stipa grandis population decreased with the increase of grazing pressure; the percentage of polymorphic loci was 62.2% in the no-grazing (CK) population, 64.9% in the light-grazing (LG) population, 58.1% in the moderate-grazing (MG) population, and 56.8% in the heavy-grazing (HG) population; the genetic diversity of the population in the descending order using the Shannon's information index is as follows: (1) light grazing (0.3486); (2) no grazing (0.3339); (3) moderate grazing (0.3249); (4) heavy grazing (0.2735) with the same distributional pattern as the Nei's genetic diversity index. The test showed the following: As the grazing pressures increased, the change of genetic diversity decreased; the genetic differentiation coefficient among the population (Gst) was 0.1984, which showed the presence of small partial genetic diversity (19.8%) among populations; gene flow (Nm*) between primers varied from 0.9806 to 3.4463, and the mean gene flow (Nm*) was 2.0202; the UPGMA cluster figure that was constructed on the basis of the genetic distance matrix showed four populations that became genetically closer at each step: (1) The first group was the moderate-grazing (MG) population and the heavy- grazing (HG) population; (2) The second group consisted of the no-grazing (CK) population and the light-grazing (LG) population; (3) The two groups gathered together. 相似文献
14.
吴连杰；荆元芳；任安芝；高玉葆 《植物研究》2012,32(6):669-674
以我国内蒙古草原常见优势种羊草（Leymus chinensis（Trin.) Tzvel.）及克氏针茅（Stipa krylovii Roshev.）为实验材料;在离体器官和整株植物水平上探讨内生真菌感染是否会影响宿主植物羊草对克氏针茅种子萌发的作用。实验结果表明:内生真菌感染能够影响羊草对克氏针茅种子萌发的作用;其影响程度与羊草的作用部位、处理方法以及处理浓度相关。与未染菌羊草相比;染菌羊草绿叶在低浓度处理下显著促进了克氏针茅的萌发;高浓度下显著抑制了克氏针茅的幼根生长;染菌羊草枯叶显著抑制了克氏针茅幼根的生长;而染菌羊草地下部显著促进了克氏针茅的萌发;感染和不感染内生真菌的整株羊草对克氏针茅的发芽率和发芽速度无显著影响。在处理浓度相同的情况下;草粉对克氏针茅种子萌发的抑制作用比浸提液处理更为显著;绿叶比枯叶抑制作用更为显著。 相似文献
15.
放牧强度引起的草原植物群落物种多样性与地上生物量变化是近年来草地生态系统研究的热点问题。以内蒙古锡林郭勒克氏针茅草原为研究对象,探究植物群落结构特征、物种多样性与地上生物量之间相互关系及其对不同放牧强度的响应。结果表明：随着放牧强度的增加植物群落结构逐步向退化方向演替;植物群落高度逐渐降低（P<0.05）,密度逐渐增加（P<0.05）,盖度总体呈下降趋势（P<0.05）;植物群落和原有群落优势种地上生物量总体呈下降趋势（P<0.05）,而退化指示物种的地上生物量逐渐增加（P<0.05）;轻度、中度放牧条件下群落物种Margalef指数、Pielou指数、Simpson指数均显著高于重度放牧（P<0.05）;地上生物量与Shannon-Wiener指数、Margalef指数和Pielou指数呈正相关关系,而与Simpson指数呈负相关关系。综上所述,克氏针茅草原植物群落结构和功能在不同放牧强度下产生不同的响应,适度放牧有利于提高群落物种多样性与生物量。 相似文献
16.
The genetic diversity of Stipa grandis P.Smirn and its relationship with the climatic variables were studied using the RAPD technique for 90 genes from five natural populations sampled in the Xilingol steppe, China. Sixteen oligonucleotides screened from 100 random primers were used to amplify 310 trackable RAPD loci, which were all polymorphic. By analyzing the RAPD data using POPGENE software, different geographic S. grandis populations were studied, which indicated a high level of genetic diversity, and the maximum variation was observed within the populations with a 28% variation observed among the populations. Using Pearson correlation analysis, significant (P < 0.05) or highly significant (P < 0.01) relationships were found between gene diversity indexes and temperature factors (≥10C cumulative temperature in a year, annual mean temperature and mean temperature in January). Mantel's tests showed that there was no significant correlation between Nei's unbiased genetic distance and the geographic distance of S. grandis populations (r = 0.184, P = 0.261). However, there were significant or highly significant correlations between Nei's genetic distance and the several climatic divergences in pairwise S. grandis populations. All results indicated that natural selection resulting from variations in water and temperature was responsible for the adaptive eco-geographical differentiation indicated by the RAPD markers of different S. grandis populations, and that immigration and gene drift did not play an important role in affecting the differentiation of S. grandis populations. 相似文献
17.
The genetic diversity of Stipa grandis P.Smirn and its relationship with the climatic variables were studied using the RAPD technique for 90 genes from five natural populations sampled in the Xilingol steppe, China. Sixteen oligonucleotides screened from 100 random primers were used to amplify 310 trackable RAPD loci, which were all polymorphic. By analyzing the RAPD data using POPGENE software, different geographic S. grandis populations were studied, which indicated a high level of genetic diversity, and the maximum variation was observed within the populations with a 28% variation observed among the populations. Using Pearson correlation analysis, significant (P < 0.05) or highly significant (P < 0.01) relationships were found between gene diversity indexes and temperature factors (≥10°C cumulative temperature in a year, annual mean temperature and mean temperature in January). Mantel's tests showed that there was no significant correlation between Nei's unbiased genetic distance and the geographic distance of S. grandis populations (r = 0.184, P = 0.261). However, there were significant or highly significant correlations between Nei's genetic distance and the several climatic divergences in pairwise S. grandis populations. All results indicated that natural selection resulting from variations in water and temperature was responsible for the adaptive eco-geographical differentiation indicated by the RAPD markers of different S. grandis populations, and that immigration and gene drift did not play an important role in affecting the differentiation of S. grandis populations. 相似文献
18.
择伐强度对天然次生林乔木层6种优势种群生态位的影响 总被引：1，自引：1，他引：1
为探讨择伐强度对天然次生林乔木优势树种生态位的影响,运用定量分析方法对不同强度择伐下6种乔木优势树种[马尾松(Pinus massoniana)、木荷(Schima superba)、虎皮楠(Daphnipyllum oldhamii)、米槠(Castanopsis carlesii)、甜槠(C. eyrei)、黄瑞木(Adinandra millettii)]的生态位宽度、生态位相似性比例和生态位重叠进行了测定。结果表明：择伐干扰下,优势种群的生态位宽度随择伐强度增大呈下降趋势;除黄瑞木外,其余5种优势树种的生态位宽度均大于0.5;生态位重叠值大于0.8的种对比例,也随择伐强度增大而下降。在皆伐干扰下,优势种群的生态位宽度均小于0.5,生态位重叠值大于0.8的种对比例仅占46.7%。这说明适度择伐(弱度和中度择伐)干扰,有利于保持优势种群在群落中的较大生态位宽度和较强生态适应性。因此,合理择伐有利于中亚热带天然次生林的保护和利用,择伐强度应以弱度或中度为宜。 相似文献