松嫩平原假苇拂子茅无性系种群的年龄结构

假苇拂子茅是典型的无性系禾草,分蘖节存活时间最多为４年,根茎存活的时间最多为３年;１龄级分蘖株生产力最高,１龄级 物质贮存能力最大,放牧场和割草场假苇拂子茅无性系种群的分蘖株均为增长型的年龄级蘖的物质生产;放牧扰动对假苇拂子茅无性系种群各龄级要茎的养分贮藏均有不利影响。割草场和放牧场假苇拂子茅潜在无性系种群均属于增长型的年龄结构。     

松嫩平原野古草无性系种群的营养繁殖特征

野古草是典型的无怀系禾草,分蘖节存活时间最多为４ａ。割草场和放牧场野古草无性系种群的分蘖株为增长型的年龄结构;放牧能增加２、３龄分蘖株的形成与存活;野古草无性系种群１龄级分蘖株的生产力明显高于２龄级;割草场和放牧场的野古草无性系潜在种群均于增长的年龄结构。以硌潜在种群的数量估计,割草场将保护翌年群落的优势种地位和作用;放牧场具有向优势和演替的潜在趋势。     

伊犁河谷不同生境假苇拂子茅种群构件组成及其年龄结构

假苇拂子茅是根茎禾草,属典型的无性系植物。通过生长季末期单位面积取样的方法,对新疆伊犁河谷地区不同生境的假苇拂子茅种群构件的组成及其年龄结构进行了研究。结果表明,4个样地的假苇拂子茅种群仅有样地H3是由生殖和营养分蘖株组成,其他3个样地均由营养分蘖株组成。4个样地的分蘖株均由3个龄级组成,均呈增长型年龄结构;4个样地的根茎均为2个龄级,其中又以2龄根茎占绝对优势。在生长季末期,4个样地的假苇拂子茅潜在种群均由冬性分蘖苗、根茎顶芽和各龄分蘖节向上生长的芽组成,分蘖节芽占优势地位,各龄级芽又以1龄级的占显著优势,均属于增长型年龄结构。牲畜啃食和淹水扰动对分蘖株物质生产和根茎的物质储存均有不利影响。     

新疆伊犁2种生境大拂子茅种群年龄结构研究

通过单位面积取样的方法,测定分析了新疆伊犁2种生境下大拂子茅(Calamagrostis macrolepis)种群分蘖株、根茎和潜在种群的年龄结构,旨在探索大拂子茅种群对不同生境条件的响应策略,揭示大拂子茅种群的繁殖潜力.结果表明:大拂子茅种群分蘖株在2种生境下均由营养分蘖株和生殖分蘖株组成;分蘖株、根茎、冬性苗和芽均有4个龄级;根茎分蘖节最多繁殖4个世代,最多可存活5个生长季;分蘖株数量和生物量为1龄＞2龄＞3龄＞4龄;芽数量为0龄＞1龄＞2龄＞3龄,以0龄芽占绝对优势;根茎生物量、冬性苗数量在2种生境样地也具有低龄级相对占优势的结构特征.2种生境下大拂子茅种群分蘖株、根茎、冬性苗和芽等构件均呈增长型年龄结构.     

通辽火电厂储灰池植被恢复过程中硬拂子茅种群构件的结构特征

植物种群年龄结构对于分析种群的动态和预测群落演替具有重要作用。通过对通辽火电厂储灰池植被恢复过程中硬拂子茅种群分蘖株数量和生物量、根茎长度和生物量的年龄结构以及分蘖株生产力和根茎贮藏力的比较,分析了不同恢复年限和家畜干扰条件下两个恢复区内(第1次取样,1区和2区恢复12和8年;第2次取样,1区和2区恢复16和12年)硬拂子茅种群构件的结构特征。结果表明:恢复年限至12和8年,两个恢复区分蘖株数量和生物量均为增长型年龄结构,根茎长度和生物量分别为增长型和稳定型;恢复至16和12年,两区分蘖株和根茎均为增长型,但龄级构成趋于复杂。两次取样中,两恢复区分蘖株物质生产力随龄级增加不断减少。同一恢复区第2次取样各龄级分蘖株生产力均显著低于第1次;除1龄根茎外,第2次取样各龄级根茎贮藏力均低于第1次。对于尚处于植被恢复演替初期的群落而言,继续围栏禁牧排除家畜啃食等干扰是确保植被恢复进程的可行而有效的方法。     

通辽火电厂储灰池植被恢复过程中硬拂子茅种群构件的结构特征

植物种群年龄结构对于分析种群的动态和预测群落演替具有重要作用。通过对通辽火电厂储灰池植被恢复过程中硬拂子茅种群分蘖株数量和生物量、根茎长度和生物量的年龄结构以及分蘖株生产力和根茎贮藏力的比较,分析了不同恢复年限和家畜干扰条件下两个恢复区内(第1次取样,1区和2区恢复12和8年;第2次取样,1区和2区恢复16和12年)硬拂子茅种群构件的结构特征。结果表明:恢复年限至12和8年,两个恢复区分蘖株数量和生物量均为增长型年龄结构,根茎长度和生物量分别为增长型和稳定型;恢复至16和12年,两区分蘖株和根茎均为增长型,但龄级构成趋于复杂。两次取样中,两恢复区分蘖株物质生产力随龄级增加不断减少。同一恢复区第2次取样各龄级分蘖株生产力均显著低于第1次;除1龄根茎外,第2次取样各龄级根茎贮藏力均低于第1次。对于尚处于植被恢复演替初期的群落而言,继续围栏禁牧排除家畜啃食等干扰是确保植被恢复进程的可行而有效的方法。     

科尔沁草原区火电厂储灰池植被恢复阶段赖草种群生物量年龄结构

对不同植被恢复阶段赖草(Leymus secalimus)种群分蘖株和根茎构件生物量年龄结构进行了测定与分析。结果表明:在科尔沁草原,赖草的分蘖节和根茎均可存活4个年度;8月中旬,植被恢复12年和5年储灰池中赖草无性系种群的根茎分别由4和3个龄级组成,根茎生物量均呈稳定型年龄结构;两个恢复阶段赖草无性系种群的分蘖株均由两个龄级组成,生物量均为增长型的年龄结构,恢复时间短者增长型结构尤为明显;赖草无性系种群1龄级分蘖株的生产力均高于2龄级,各龄级根茎的物质贮藏具有较大的生态可塑性。     

松嫩平原湿地菰无性系种群结构的研究

菰是挺水型高大根茎禾草,是典型的无性系植物,在松嫩平原湿地条件下,野生菰分蘖节可繁殖２个世代,一般存活２年,最多存活３年。根茎一般存活１年,最多存活２年,无性系种群分蘖株和根茎均有２个龄级,并均以１龄级较大比重。其中,分蘖株为７４．１％,根茎累积长度为８９．４％,分蘖株立枯生物量为９２．８％,根茎生物量为９２．７％。     

伊犁河谷不同生境羊草种群构件的年龄结构

对伊犁河谷昭苏县杨树群落(H1)、羊草单优势种群落(H2)生境内的羊草无性系种群年龄结构进行对比分析.结果表明:(1)H1、H2样地内羊草无性系种群分蘖株数量分别由3个龄级和4个龄级组成,且随着龄级的增大迅速减少;各生境羊草种群年龄结构同为增长型.(2)两个样地羊草无性系种群根茎长度均由4个龄级组成,其中H1样地羊草无性系种群根茎长度年龄结构为增长型,H2样地为稳定型.(3)两个样地羊草无性系种群分蘖株生物量与分蘖株数量龄级构成相同,年龄结构均为增长型;根茎生物量均由4个龄级组成都为稳定型.各生境分蘖株和根茎生物量年龄结构均以低龄级居于优势位置.     

松嫩平原牛鞭草无性系种群的营养繁殖策略

牛鞭草是典型的无性系禾草，分蘖节和根茎存活时间最多均为２ａ，牛鞭草无性系种群的分蘖割草地仅有１个龄级，在放牧地有２个龄级。放牧地和割草地的根茎均有２个龄级。以潜在种群的数量估计，牛鞭草无性系种群在割草地将保持在单优势种群落中的地位和作用，在牧地有向着单优势种群落演替的潜在趋势。     

Long-Term Vegetation Productivity and Trend Under Two Stocking Levels on Chihuahuan Desert Rangeland

Vegetation changes were evaluated over an 11-year period (1995–2005) on 2 light- and 2 conservative-stocked Chihuahuan Desert pastures in south central New Mexico. Grazing treatments were applied to the pastures over a 5-year period from 1997 through 2001. Pastures were not grazed in the 1995–1996 and 2002–2005 periods due to drought. During the 1997–2001 grazing period, grazing use of primary forage species averaged 29% and 40% on light- and conservative-stocked rangelands, respectively. Grazing intensity was consistently higher on conservative-stocked than light-stocked pastures. During our study heavy grazing occurred only in 1 year on pastures with conservative stocking. There were no differences in species or species categories (grasses, forbs, shrubs) of autumn standing crop and basal cover between light-and conservative-stocked pastures. Standing crop of total vegetation and perennial grasses showed large fluctuations among the years due to variable rainfall. Under both treatments, total herbaceous standing crop was unchanged, but perennial grass standing crop declined by over 50% when the last 3 years of study were compared with the first 3 years of study. Broom snakeweed (Gutierrezia sarothrae Pursh), a poisonous half shrub, increased in standing crop and cover during the study. Basal cover of total perennial grasses declined less under light than conservative stocking during the study period. However, climatic conditions exerted the overriding influence on vegetation standing crop and basal cover. Our study indicates that light stocking in the Chihuahuan Desert does not increase perennial grass production compared to conservative grazing but it could have a small benefit in maintaining perennial grass cover during drought. We believe our findings have broad application in the Chihauhuan Desert, but caution they might not apply well to other arid rangeland types.     

新疆霍城假苇拂子茅种群构件的年龄结构

通过生长季末期单位面积取样的方法,对新疆霍城县沟谷中不同生境的假苇拂子茅(Calamagrostis pseudophragmits)种群构件的组成及其年龄结构进行了研究。结果表明,3个生境的假苇拂子茅分蘖节的存活年限最长为6 a,分蘖株在数量上均由5个龄级组成,属稳定型年龄结构。就单株生产力的整体水平而言,3个生境的生产力水平表现为生境H2>生境H3>生境H1,且各生境间存在显著差异(P<0.05),反映了单株生产力在不同生境间具有一定的差异。根茎的存活年限最长为5 a,根茎的生产力则以1 a或2 a龄级最高,各生境根茎长与根茎生物量均以1 a或2 a龄级所占比例最高,且随龄级的增加而递减,反映出潮湿、疏松的沙质土壤有利于假苇拂子茅根茎的生长和物质储存。     

A comparison of grass and grass/legume pastures under irrigation in the Outeniqua area of the southern Cape

Two grass and five grass/legume pastures were evaluated over a period of two seasons at two seasonally set grazing pressures and under two grazing management systems, involving five and seven paddocks per flock and a seven‐day period of stay. Grazing capacity was most limiting during winter. Pastures with fescue as grass component had, overall, the highest grazing capacity, while white clover‐based pastures had the highest animal production. The legume content of the grass/legume pastures was markedly higher on the seven than on the five‐paddock system. Dry matter and animal production of white clover‐based pastures was favoured by a seven‐paddock system as opposed to a five‐paddock system, while mixtures containing lucerne and pure grass pastures were either not influenced by grazing management or promoted by a five‐camp system.     

Grazing History Effects on Rangeland Biomass,Cover and Diversity Responses to Fire and Grazing Utilization

Exclusion of large grazers from rangelands that evolved with significant grazing pressure can alter natural processes and may have legacy effects by changing magnitude or direction of community responses to subsequent disturbance. Three moderately grazed pastures were paired with 12-ha areas with 15 yr of livestock exclusion. Six treatments were assigned to each in a 2 x 3 factorial arrangement of fire (fall fire or no fire) and grazing utilization (0%, 50%, or 75% biomass removal) to determine grazing history effects on rangeland response to subsequent disturbance. Livestock exclusion increased C₃ perennial grass (1 232 vs. 980 ± 50 kg ? ha^-1) and forbs (173 vs. 62 ± 19 kg ? ha^-1) and reduced C₄ perennial grass (36 vs. 180 ± 25 kg ? ha^-1) with no effect on total current-year biomass. Diversity was greater in pastures than exclosures (H’ = 1.5400 vs. 1.3823 ± 0.0431). Every biomass, cover, and diversity measure, except subshrub biomass, was affected by fire, grazing utilization, or both. Contrary to expectations, grazing history only interacted with fire effects for old standing dead material and interactions with grazing utilization were limited to old dead, bare ground, richness and dominance. Fire by grazing utilization interaction was limited to bare ground. Fire reduced annual grass (64 vs. 137 ± 29 kg ? ha^-1), forbs (84 vs. 133 ± 29 kg ? ha^-1), and diversity (H’ = 1.3260 vs. 1.5005 ± 0.0537) with no difference in total current-year biomass (1 557 vs. 1 594 ± 66 kg ? ha^-1). Grazing to 75% utilization reduced total current-year biomass (1 467 vs. 1 656 ± 66 kg ? ha^-1) and dominance (0.4824 vs. 0.5584 ± 0.0279). Grazing history affected starting points for most variables, but changes caused by grazing utilization or fire were similar between pastures and exclosures, indicating management decisions can be made based on independent knowledge of grazing or fire effects.     

通辽火电厂储灰池植被恢复过程中赖草种群构件的年龄结构(简报)

赖草是科尔沁草原区沙质土壤生境广泛生长的优良禾草,是典型的无性系植物.在内蒙古科尔沁草原区,赖草的分蘖节和根茎均可存活4个年度.在8月中旬,经历了11～12年植被恢复的储灰池中,赖草种群的根茎是由4个龄级组成, 4～5年植被恢复的储灰池则由3个龄级组成.2个样地赖草无性系种群的分蘖株均由2个龄级组成,均为增长型的年龄结构,恢复的时间越短,其增长型结构就越明显.     

天然羊草草地在放牧和刈割条件下的种子生产性能

天然羊草草地是优良的放牧场和割草场。本文报告了东北天然单优种羊草草甸,在放牧、割草、休闲等不同利用方式下,羊草的分蘖成穗、生殖器官的性状、产量和质量等种子生产性能。放牧破坏一些个体的成穗过程,单位面积上成穗少,籽粒的净生产量低,但籽粒饱满,品质优良。割草能引起土壤贫瘠化和密度增大,割草的时间越长,对种子生产的影响越严重。休闲能恢复羊草种群种子生产的潜在性能。