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1.
 该文通过刈割和放牧样地的实生苗动态观测,试图揭示刈割和放牧干扰对冰草(Agropyron cristatum)、克氏针茅(Stipa krylovii)和糙隐子 草(Cleistogenes squarrosa )等 3种禾草实生苗出生、存活和死亡季节动态的影响,以及这种效应是如何受气温和降水影响的。利用有重复测 量的方差分析,比较了不同刈割留茬高度(0、5和15 cm)与放牧处理之间在实生苗密度、死亡率和出现率的时间动态方面的差异。结果表明:3 种禾草的实生苗密度自5月下旬至8月中旬一直呈增加态势。刈割在一定程度上抑制了克氏针茅的实生苗出现率,原因可能是相对高大的克氏针 茅在前一年刈割时会被去掉相当多的生殖部分,其种子数量必然受到影响,导致实生苗出现率的降低。同时,刈割对相对低矮的糙隐子草实生 苗有正向效应 ,即促进其实生苗的出现,可能的原因是刈割使植被高度降低、植被稀疏,植被冠层以下至地面的光照较好、地温较高,同时位 于下层的糙隐子草受到的高大植株的竞争压力减小。生长季早期和晚期实生苗死亡率较高,这与这两个时期的干旱和低温有关,而自6月中旬至 7月初之间的死亡率小高峰也是先前的干旱少雨导致的。3种禾草实生苗的大规模出现几乎都在5~7月,这与该时期相对适宜的气温、地温和水 分条件有关。对实生苗更新相关过程 (如种子萌发、休眠、种子库存量等)进行更加深入细致的研究,将进一步揭示种子生产和有性繁殖在群落 过程中的作用。  相似文献   

2.
内蒙古克氏针茅草原土壤种子库对刈割和放牧干扰的响应   总被引:2,自引:0,他引:2  
种子库是潜在的植物群落并在一定程度上预示着群落的演替方向。草原牧区自退牧还草政策实施以来,草原利用方式由自由放牧为主逐步转向以围封割草为主。为研究割草和放牧对土壤种子库密度、植物功能群和种类组成的影响及其与地上植被的相似性关系,在内蒙古克氏针茅(Stipa krylovii)典型草原区设置3个不同强度的刈割处理,即无刈割对照(CK)和分别留茬15 cm(M15)、5 cm(M5)的处理,以及一个自由放牧处理(GR),土壤种子库采用环刀法多点取样结合四唑染色法测定种子活力,计数所有被检测有生命力的种子,并计算土壤种子库与地上植被在物种组成方面的相似性。结果表明:不同处理的土壤种子库密度范围为6245.0±1351.9~8155.9±909.1粒·m-2,无刈割对照的土壤种子库密度显著高于M15;从种子库的功能群组成来看,多年生杂类草种子密度最大,占种子库总量的55%~60%,1年生杂类草占36%~43%,GR与M15有显著差异;从物种组成来看,只有克氏针茅、砂韭的种子数量在刈割和放牧处理下显著低于对照。采用Sorensen指数计算土壤种子库与地上植被的物种相似性,CK、GR、M5、M15相似系数分别为0.55、0.58、0.48和0.60;研究预示,内蒙古典型草原土壤种子库对割草和自由放牧有很强的敏感性,刈割和自由放牧均降低土壤种子库密度,将降低退化克氏针茅草原的自然恢复能力。  相似文献   

3.
冷蒿对三种禾本科植物种子萌发和幼苗生长的化感作用   总被引:7,自引:1,他引:6  
Li XF  Wang J  Xu WB  Wang K 《应用生态学报》2010,21(7):1702-1708
研究了冷蒿茎叶水浸提液及冷蒿斑块土壤对羊草草原3种禾本科植物(羊草、克氏针茅和糙隐子草)种子萌发及幼苗生长的影响.结果表明:冷蒿茎叶水浸提液使受试植物种子的发芽指数降低,平均发芽时间延长.羊草、克氏针茅和糙隐子草幼苗苗高及克氏针茅幼苗根长均受冷蒿茎叶水浸提液抑制;浸提液浓度≥0.075g.ml-1时显著抑制羊草幼苗根长生长,≤0.05g.ml-1时则无显著影响;而茎叶水浸提液对糙隐子草幼苗根长有"低促高抑"的作用.冷蒿斑块土壤抑制受试植物幼苗生长;3种植物对冷蒿化感效应的敏感性依次为克氏针茅羊草糙隐子草,且幼苗根长的敏感性均大于苗高.  相似文献   

4.
动物的食物选择受食物资源量、质量和喜好度决定。尽管放牧可减少鼠类喜食植物的数量和质量,但其如何影响鼠类的食物选择尚不清楚。本研究于2014年5月至10月,在内蒙古锡林郭勒盟锡林浩特市毛登牧场的大型试验围栏内进行了布氏田鼠的食物选择实验。利用大型实验围栏内5年连续放牧处理所构建的植被变化条件,采用扣笼试验,调查了布氏田鼠对其中3种主要植物的取食情况。研究发现:连续放牧后,糙隐子草的盖度增加,而羊草、克氏针茅盖度降低;糙隐子草的盖度显著高于羊草、克氏针茅,成为各季节的优势植物种类。放牧对布氏田鼠取食羊草、克氏针茅和糙隐子草的绝对取食频次均无显著影响。在季节上,布氏田鼠对克氏针茅和糙隐子草的取食在三个季节均无差异,但布氏田鼠对羊草取食的绝对频次夏季显著高于春季和秋季;布氏田鼠对3种植物的喜好程度依次为羊草克氏针茅糙隐子草,但季节和放牧因素不显著影响布氏田鼠对这3种植物的喜好度。结果表明,布氏田鼠的食物选择及食物组成相对稳定,表现为其对放牧或季节因素造成的喜食植物资源量的变化具有很好的适应性,推测是其调整取食努力来实现食物组成的平衡。  相似文献   

5.
草地利用方式对草甸草原植被空间异质性的影响   总被引:1,自引:0,他引:1  
研究不同利用方式下植物群落中物种的分布特征,有助于解释植物在不同利用方式干扰下的演替规律。本研究以内蒙古呼伦贝尔草甸草原为研究对象,通过野外调查,基于幂函数法则,探讨围封、放牧和刈割利用方式下草地植被物种分布状况和群落整体空间分布的变化。结果表明:在放牧和刈割利用及围封下,草甸草原植被物种分布规律符合幂函数法则;与围封相比,放牧增加了群落整体的空间分布异质性,而刈割则降低了这种变化,刈割和放牧草地物种异质性指数高于群落整体异质性指数的物种增多;物种出现频率发生变化,如对糙隐子草(Cleistogenes squarrosa)种群而言,围封地中糙隐子草的出现频率为0.010,刈割和放牧增加了糙隐子草的出现频率(0.151和0.521),刈割和放牧降低了狭叶青蒿(Artemisia dacunculus)的出现频率(0.132和0.028)。  相似文献   

6.
放牧和围封条件下克氏针茅草原土壤种子库的比较   总被引:29,自引:2,他引:27       下载免费PDF全文
 应用幼苗萌发法对比研究了我国北方农牧交错区克氏针茅(Stipa krylovii)草原在放牧和围封条件下土壤种子库的差异。围封样地的土壤种子库中记录有16个物种,其中禾草类6种,非禾草类10种;若以生活型划分,则全部为多年生植物;若以单子叶或双子叶植物 划分,则单子叶植物9种,双子叶植物7种。放牧样地的土壤种子库中记录有13个物种,其中禾草类4种,非禾草类9种;多年生植物12种,一二年生植物1种;单子叶植物5种,双子叶植物8种。放牧样地土壤种子库的密度为(3 664±1 087)粒•m-2,围封样地土壤种子 库的密度是(5 139±1 848)粒•m-2,差异显著。采用Sorensen指数计算土壤种子库与地上植被的物种相似性,围封样地和放牧样地分别是0.711 1和0.611 1。两个地点的全部种子中,81.0%属于冷蒿(Artemisia frigida)、克氏针茅、星毛委陵菜(Potentilla acaulis)、糙隐子草(Cleistogenes squarrosa)和砂韭(Allium bidentatum)5种优势植物,16.2% 属于二裂委陵菜(P. bifurca)、菊叶委陵菜(P. tanacetifolia)、猪毛蒿(A. scoparia) 、冰草(Agropyron cristatum)和羊草(Leymus chinensis)5种常见植物,而其余9种植物的种子数只占2.8%。此外,通常作为优良牧草的豆科植物的种子数仅占0.6%。上述结果表明 ,在放牧条件下由于土壤种子库中一些重要物种的缺失或数量很少以及极不均匀的分布,可能会降低退化克氏针茅草原的自然恢复速度。我们建议采取补播这些重要物种并结合其它恢复措施来加快退化克氏针茅草原的恢复进程。  相似文献   

7.
对内蒙古羊草草原主要植物种群能量现存量对刈割频次响应的研究表明,在17年不同频次刈割干扰影响下,植物种群能量现存量随刈割频次的变化表现出不同的变化趋势,据此可以划分出3个不同的刈割响应类群:受抑种、耐刈种和受益种。受抑种包括羊草、羽茅、黄囊苔草、葱属植物和直根型杂类草; 耐刈种包括大针茅和冰草; 受益种包括洽草和糙隐子草。对于种群相对能量现存量而言,除羊草随刈割频次的增加呈显著下降趋势外,其他受抑种均随刈割频次的增加保持相对稳定,而受益种和耐刈种的相对值则随刈割频次的增加而呈增加趋势。同时,刈割对植物能量现存量的影响还表现在植物热值变化上,但变化幅度小于10%。  相似文献   

8.
刈割是内蒙古草原的主要利用方式之一。当植物面对刈割干扰时,可以通过繁殖策略的调节适应变化的环境。研究刈割干扰下植物繁殖策略的调节对于揭示植物的适应与进化机制具有重要意义。为此,选择内蒙古典型草原的大针茅(Stipa grandis)和糙隐子草(Cleistogenes squarrosa),在1979年围封的羊草(Leymus chinensis)样地(对照)和毗邻的长期刈割区对其繁殖策略进行了研究。结果显示:1)长期刈割干扰下,大针茅的种群生物量与对照区无显著差异,由于其株丛生物量显著降低,大针茅种群生物量的维持得益于种群密度的显著增加。糙隐子草的种群生物量比对照区显著提高,由于其株丛生物量与对照区无显著差异,糙隐子草种群生物量的增加也是因为密度的显著提高。因此,密度调节是两种植物应对长期刈割干扰的重要的调节机制。2)长期刈割干扰下,两种植物在无性繁殖和有性繁殖过程所采取的密度调节策略并不相同。大针茅种群生殖株丛的密度无显著变化,非生殖株丛的密度显著提高,导致其非生殖株丛的相对密度显著增加,而生殖株丛的相对密度显著降低。因此刈割干扰下大针茅种群在密度调节上采取了保持有性繁殖株丛密度,增加无性繁殖株丛密度的策略。糙隐子草种群非生殖株丛的密度显著增加,但生殖株丛的密度增加幅度更大,导致其非生殖株丛的相对密度显著降低,而生殖株丛的相对密度显著提高。因此刈割干扰下糙隐子草种群在密度调节上采取了增加无性繁殖株丛密度的同时,更大幅度地增加有性繁殖株丛密度的策略。3)长期刈割干扰下,两种植物对生物量生殖分配的调节采取了不同的策略。大针茅株丛生物量向生殖枝分配的比例无显著变化,通过降低生殖枝向穗的生物量分配比例,降低了对有性生殖过程的生物量分配的投入;而糙隐子草则通过增加株丛生物量向生殖枝分配的比例,维持生殖枝向穗的生物量分配比例,从而增加了对有性繁殖过程生物量分配的投入。4)长期刈割干扰下,大针茅的株丛面积和株丛分蘖数与对照区无显著差异。糙隐子草株丛面积降低,但是株丛分蘖数无显著变化。本实验说明,植物种群有性繁殖和无性繁殖之间的密度调节和资源分配调节是草原植物应对刈割干扰下的重要调节机制,不同的响应策略影响着植物种群的消长动态。  相似文献   

9.
不同频次刈割对羊草草原主要植物种群能量现存量的影响   总被引:10,自引:1,他引:9  
对内蒙古羊草草原主要植物种群能量现存量对刈割频次响应的研究表明,在17年不同频次刈割干扰影响下,植物种群能量现存量随刈割频次的变化表现出不同的变化趋势,据此可以划分出3个不同的刈割响应类群:受抑种、耐刈种和受益种.受抑种包括羊草、羽茅、黄囊苔草、葱属植物和直根型杂类草;耐刈种包括大针茅和冰草;受益种包括洽草和糙隐子草.对于种群相对能量现存量而言,除羊草随刈割频次的增加呈显著下降趋势外,其他受抑种均随刈割频次的增加保持相对稳定,而受益种和耐刈种的相对值则随刈割频次的增加而呈增加趋势.同时,刈割对植物能量现存量的影响还表现在植物热值变化上,但变化幅度小于10%.  相似文献   

10.
通过了解亚洲小车蝗Oedaleus asiaticus的取食特性,为有害生物的防治和草原生态环境的保护提供理论依据。在分析亚洲小车蝗发生与羊草Leymus chinensis、克氏针茅Stipa krylovii及糙隐子草Cleistogenes squarrosa等3种禾本科植物特征参数关系的基础上,通过罩笼试验调查了罩笼内亚洲小车蝗3~5龄蝗蝻的存活率,比较了亚洲小车蝗的取食数量、取食高度及取食率等特性。结果表明,克氏针茅和糙隐子草生态优势度与亚洲小车蝗发生数量显著正相关,亚洲小车蝗喜食克氏针茅和糙隐子草(0.25≤RFN0.5),少食羊草(0.025≤RFN0.25)。4龄和5龄蝗蝻对克氏针茅和糙隐子草取食量显著大于羊草。亚洲小车蝗取食高度位于植物中下部(9~10 cm),与3种植被高度无关;取食后上部掉落造成损失,特别是对克氏针茅的为害更大;亚洲小车蝗取食克氏针茅和糙隐子草时的存活率显著高于取食羊草时的存活率。结论:以克氏针茅和糙隐子草为优势植物的典型草原更适合亚洲小车蝗的发生与为害,应加强该类草原亚洲小车蝗的监测预警和防控。  相似文献   

11.
Abstract. The effects of topography, soil moisture, wind and grazing on the emergence and survival of seedlings of Festuca spp. were examined in the steppe zone of Patagonia, Argentina. Ungrazed and grazed field treatment plots were established on a plain and a north-facing slope at the Media Luna Ranch (43° 36′S, 71° 25′W). On the leeward and windward sides of each of 15 Festuca plants, 0.1 m × 0.4 m quadrats were censused bimonthly for seedling emergence and survival over three growing seasons. Three categories were distinguished: recently germinated and up to the first leaf, two to four leaves, and from five leaves up to one tiller. Soil moisture content, litter cover and frost heaving effects were also determined for each treatment at each sampling date. Festuca spp. showed two emergence peaks, one in late fall and the other in early to mid-spring. Seedling emergence was significantly correlated with soil moisture content in the 0–5 cm of the soil during the three growing seasons. Seedlings that emerged in the fall had higher survivorship than those that emerged in spring. Seedling emergence and survival was significantly (p < 0.01) lower on slopes, in the grazing treatment, and on windward sides of adult plants. In this grassland, an increase in the availability of safe sites for seedling emergence and survival might be achieved by protecting vegetation from grazing, particularly on north-facing slopes.  相似文献   

12.
Seedling emergence and early establishment of six fen species differing in seed mass and growth form were investigated under experimental land use with changed vegetation structure and under real land use in a calcareous fen. Seeds of all six species were sown in plots with different experimental land-use treatments: summer and autumn mowing with or without litter removal, trampling and abandonment. Additionally, emergence and survival of experimentally sown seeds was investigated under real land use on adjacent sites managed by mowing, grazing, intense trampling or abandonment.On abandoned plots and on plots without litter removal of the land-use experiment, emergence rates of all species were negatively affected either by high litter and moss cover or by tall canopy. No differences were found between autumn and summer mowing. Gap creation by experimental trampling did not increase germination rate. Under real land use, establishment of seedlings of most species was positively affected by litter cover and tall canopy. Trampling, in contrast, had a severe negative effect on seedling survival.The investigated species differed in their germination ability which was tested in the germination chamber and in their response to land use. Succisa pratensis with the highest seed mass germinated well in the chamber and in the field more or less regardless of land use. The low germination rate of Parnassia palustris in the germination chamber indicated a limitation of viable seeds. In the field, however, seedling emergence was additionally limited by microsite availability. Seeds of Serratula tinctoria and Primula farinosa germinated well in the germination chamber, but seedling recruitment in the field was hampered in the presence of a high litter or moss cover. Seeds of Tofieldia calyculata and Pinguicula vulgaris were strongly dependent on the availability of suitable microsites in the field. They hardly germinated under natural conditions, in spite of a high number of germinable seeds in the germination chamber.  相似文献   

13.
Question: What is the effect of gap size on the seedling emergence, growth and survival of four common tree species in wooded pastures? Location: A pasture in the Jura mountains, Switzerland. Methods: Seeds were sown in a complete three‐way factorial design with eight blocks in May 2003. Each block consisted of a competition treatment (four gap sizes including zero) and a mowing treatment (mown and unmown). Emergence, survival and total biomass of tree seedlings of three species (Picea abies, Acer pseudoplatanus and Fagus sylvatica) were measured. A fourth species (Abies alba) failed to germinate. Results: Gaps had a positive influence on the early stages of tree development for all species. Larger gaps favoured growth and survival more than small gaps. Seedling growth was higher when vegetation around the openings was mown. Mowing the vegetation at gap size zero enhanced both growth and survival compared to unmown vegetation. Mown gaps larger than zero had increased seedling desiccation but decreased seedling predation. Species showed similar trends in their emergence and growth responses to gap size and mowing treatments but for Picea emergence rate was higher and survivorship was lower than for Acer and Fagus. Conclusions: Gap size does matter for tree seedling success but even in more favourable large gaps only a small percentage of seedlings emerged and survived. The effects of gaps on tree seedling establishment are complex as a result of interactions between biotic and abiotic changes caused by gaps.  相似文献   

14.
万志强  杨九艳  谷蕊  闫玉龙  梁艳  杨劼  高清竹 《生态学报》2016,36(17):5477-5484
在草原生态系统中,土壤是植物生长发育最重要的基质,对植物群落动态有显著的影响。刈割是内蒙古典型草原区除放牧外最重要的利用方式。研究不同刈割频度对典型草原区群落特征和若干土壤性质的影响及土壤因子与群落特征的相关性,旨在得出对群落多样性最有利并最适宜生产利用的刈割频度。研究区设置在内蒙古锡林浩特市东部以大针茅建群的典型草原;在2009—2013年进行不同频度的刈割处理,共设置处理,一年两次刈割、一年一次刈割、两年一次(割一年休一年)刈割、围封,在2013年8月采集测定土壤养分的样品。刈割对群落多样性影响显著,割一年休一年Shannon-Wiener多样性指数、Pielou均匀度指数、丰富度指数均高于其他刈割处理(P0.05);不同频度刈割下,一年两次刈割处理下土壤20—30cm和30—40cm的有机质含量显著高于其他处理(P0.05);不同频度刈割处理下土壤中的速效磷和速效氮的含量没有显著差异;一年两次处理的土壤全氮含量显著高于其他处理(P0.05)。Shannon-Wiener多样性指数与有机质含量、全氮含量呈显著负相关;Pielou均匀度指数与土壤元素间无显著相关关系;Richness指数与有机质含量呈显著负相关,与全氮含量为极显著负相关关系。割一年休一年刈割处理下土壤元素含量呈现更好的状态,结合群落物种多样性及生产利用的角度,割一年休一年为最合理的刈割频度。  相似文献   

15.
 本文将定位研究与路线考察相结合,将放牧影响下草原的动态演替及其在牧压梯度上的空间变化相对比,研究了内蒙古主要草原草场的放牧退化模式,并在此基础上初步探讨了判别草场退化的数量指标和退化监测专家系统。1)植物种与牧压关系的分析,区别出放牧的定性和定量指示植物及宜中牧植物,并划分植物为不同的放牧生态种组。2)退化草原恢复过程的研究表明,根茎禾草的恢复快于丛生禾草;群落恢复过程是单稳态的,且恢复演替动态与其牧压梯度上的空间变化相对应。3)内蒙古高原主要草原草场在持续放牧影响下均趋同于冷蒿(Artemisia frigida)草原。冷蒿是最可靠的正定量放牧指示植物,但同时又是优良牧草和草原退化的阻击者。4)讨论了草原草场退化的概念,论述了草原逆向演替与草场退化的区别和联系,提出了区分草原的逆向演替为草场熟化和退化两个过程,并依草场群落与牧压的关系建立了判定草场是否退化及退化程度的数量指标。5)初步设计了草原草场退化监测—决策专家系统,包括监测、判别和决策三个步骤。  相似文献   

16.
汪诗平 《生态学报》2000,20(6):951-957
在围栏封育4a的1mh^2放牧样地内,放牧4只内蒙古细毛羊,分别于6、7和9月份用显微技术法进行了绵羊食性的研究。结果表明,在放牧率较低食物资源比较丰富的条件下,绵羊的食性表现为明显的季节性变化。6月份,由于禾草在群落中的相对生物最较小,故在食物中的比例相应较小,为31%;而在7月份,则上升到45%,部分替代了冷蒿在食物中的比例;同时,在禾草中,羊草、冰草主要在春季或初夏(7月份以前)被利用,随着  相似文献   

17.
Abstract Field experiments examined herbaceous seedling emergence and survival in temperate grassy woodlands on the New England Tablelands of New South Wales. Effects of intensity of previous grazing, removal of ground cover by fire or clearing, burial of seeds, grazing and seed theft by ants on seedling emergence and survival were studied in two field experiments. Thirteen species with a range of traits were used in the experiments and their cumulative emergence was compared with laboratory germination studies. Field emergence correlated to laboratory germination but all species had lower emergence in the field. Little natural emergence of native species was observed in the field in unsown treatments. Short‐lived forbs had the highest emergence, followed by perennial grasses; rhizomatous graminoids and perennial forbs had the lowest emergence. Soil surface and cover treatments did not markedly enhance emergence suggesting that intertussock spaces were not prerequisites for forb emergence. No consistent pattern of enhanced emergence was found for any treatment combination across all species. Seedling survival varied among species, with perennial grasses and short‐lived forbs having the highest seedling mortality. Low mortality rates in the graminoids and rhizomatous forbs appeared partially to compensate for lower seedling emergence. All perennial grasses and some short‐lived forbs showed increased risk of mortality with grazing. Differences in emergence and survival of species were related to ground cover heterogeneity, soil surfaces and, to some extent, herbivory. The complexity of these patterns when superimposed on temporal variability suggests that no generalizations can be made about the regeneration niche of herbaceous species groups. Strong recruitment limitation and partitioning of resources in the regeneration niche may reduce competition among native species and explain the high species richness of the herbaceous layer in the temperate grassy communities of eastern Australia.  相似文献   

18.
BACKGROUND AND AIMS: Plant functional trait responses to processes such as grassland management have been analysed frequently; however, the scaling-up from individual traits to the outcomes of vegetation dynamics has seldom been tested. In this experiment, germination success was studied with respect to the relationships between grassland management (mowing and grazing), as well as abandonment, and two traits that are relevant for seedling recruitment: seed mass and germination season. On the basis of discussions in the literature and indirect trait analyses in our previous studies, the following hypotheses are proposed: (1) with respect to seed mass, mowing and grazing favour the germination of small seeds, whereas after abandonment the germination success of larger seeds is higher; and (2) with respect to germination season, mowing and grazing favour autumn-germinating seeds, whereas succession promotes spring-germinating seeds. METHODS: The germination experiment took place in a semi-natural, dry grassland in north-east Germany. Seeds of eight herbaceous species that differ with respect to seed mass and germination season were sown in mown, grazed and abandoned plots. Germination success was documented during the following year. KEY RESULTS AND CONCLUSIONS: Contrary to the hypothesis, germination of small seeds was not promoted by mowing or grazing and they germinated relatively more often than expected in the abandoned plots. A relationship between abandonment and gaps of bare soil below the vegetation cover that favour germination of small seeds was likely, but could not be proved statistically. It is possible that the small seeds suffered less from predation. Mowing favoured autumn germination, which could be explained by the removal of biomass in late summer. Contrary to our expectation, there was relatively more spring germination after grazing than after mowing, yet vegetation height was smallest in spring. Generally, germination season was found to be related to the temporal occurrence of favourable light conditions.  相似文献   

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