松嫩平原人工草地野大麦无性系冬眠构件的结构及形成规律

野大麦属短根茎丛生型禾草 ,是典型的无性系植物。在松嫩平原 ,野大麦无性系的冬眠构件是由冬眠芽和冬眠苗组成。按照分蘖节营养繁殖世代的龄级划分方法 ,在生长季末期 ,野大麦无性系的芽库由 5个龄级组成 ,苗库由 4个龄级组成 ,均呈增长型的龄级结构。苗库对潜在无性系的贡献将远远大于芽库。结合建植时间估计 ,人工草地野大麦的分蘖节最多存活了两个年度 ,分蘖节在一个生长季最多可繁殖 4个世代。野大麦无性系的根茎芽数、分蘖节芽数、总芽数、总苗数、总冬眠构件数均随着丛径、丛面积和亲株数量的增加呈幂函数形式增长。野大麦无性系冬眠构件各组分具有相同的形成规律 ,但在形成过程中则存在着不同的生态可塑性。     

松嫩平原水淹恢复演替过程中羊草无性系种群构件的年龄结构

对松嫩平原羊草草甸水淹恢复演替过程中不同大小羊草无性系斑块的种群构件年龄结构进行了研究。结果表明 ,羊草种群分蘖株在斑块中心由 4个龄级组成 ;最外圈层由 3个龄级组成。根茎在斑块中心和中间圈层均由 2～ 4个龄级组成 ,最外层由1～ 2个龄级组成。潜在种群冬性苗和分蘖节芽总量各圈层均由 4个龄级组成。斑块中心的分蘖株种群为稳定型年龄结构 ,向外发展至增长型年龄结构。根茎长度和潜在种群在各圈层均呈增长型年龄结构。在水淹羊草草甸的恢复过程中 ,不同大小羊草无性系斑块均呈不断扩展的趋势。在生存空间充足时 ,羊草的分蘖节在一个生长季里可以繁殖多个世代。通过羊草根茎的年龄结构可预测演替的进程     

放牧干扰对根茎冰草无性系种群年龄结构的影响

根茎冰草（Agropyron michnoi)是典型的无性系禾草。在松嫩平原,根茎冰草的分蘖节最老为４龄,可存活５个年度。不同季节的放牧干扰可导致根茎冰草无性系种群分蘖株的年龄结构发生变化,全年放牧样地和夏秋休牧样地均为稳定型年龄结构,两个冬季放牧样地均为增长型年龄结构。１龄分蘖株的生产力和营养繁殖力力均最大。４龄分蘖株均已丧失了营养繁殖力。营养繁殖芽的年龄结构可以更好地预测预报无性系种群和群落的未来。全年放牧可保护稳定型年龄结构,冬季放牧可保持增长型年龄结构,夏秋休牧可使种群发展为增长型年龄结构,两个冬季放牧样地将仍然保持单优势种群落,全年放牧地将仍为混生群落,夏季林牧样地具有向着单优势种群落演替的潜在趋势。     

松嫩平原异质生境羊草种群营养繁殖特征

多年生无性系禾草主要依靠营养繁殖实现种群的持续更新,而各类芽和由芽形成的苗为其种群进行营养繁殖的潜在种群。通过单位面积挖掘取样,利用营养繁殖世代数划分分株、根茎和各类型芽和苗的龄级,对松嫩平原封育草甸、长期割草草甸、封育积沙草甸和林间草地的羊草潜在种群组成和大小进行了比较研究。结果表明: 在生长季末期,羊草的潜在种群均由根茎芽和各龄级分蘖节向上生长的芽以及根茎苗和分蘖节苗组成。在4种生境条件下,羊草分株潜在种群由3～4个龄级组成,1～4龄级根茎均可形成潜在种群,其中,根茎潜在种群占整个羊草潜在种群数量比例为68.3%,占绝对优势。1龄分株和根茎产生的潜在种群占总体的60.2%,是潜在种群组成的主要部分,是种群更新的主要来源。分株潜在种群数量以长期割草草甸最高,根茎潜在种群数量以封育积沙草甸最高。营养繁殖力均以年轻龄级分株和根茎最高,根茎的营养繁殖力是分株的10.0倍,在羊草种群营养繁殖过程中始终占据优势。羊草的潜在种群构成在不同生境条件下变异较大,但体现出对生境差异的趋异适应。     

松嫩草原水淹恢复演替过程中羊草无性系种群构件的物质生产与贮藏

在松嫩平原羊草草甸,对水淹恢复演替过程中半径为0.5、1、3、和10 m的羊草无性系种群斑块分蘖株的物质生产和根茎的物质贮藏进行了研究.结果表明,0.5、1、3、 m斑块各圈和10 m中间及边缘根茎的物质贮藏以1龄级、不同斑块各圈分蘖株的物质生产以1、2龄级对种群的贡献最大,其物质贮藏和生产所占比例均逐圈增加.整体上,年轻龄级分蘖株和根茎具有旺盛的物质生产力和贮藏力.无性系斑块由中心至外围的物质生产和贮藏规律与斑块扩展趋势具有一致性.0.5～10 m斑块分蘖株物质生产力和根茎贮藏力的变异以最外圈最大.在水淹羊草草甸的恢复过程中,不同大小羊草无性系斑块种群构件的物质生产和贮藏策略为种群不断扩展和群落进展演替奠定了物质基础.     

松嫩平原野古草种群构件结构动态

野古草是根茎型无性系禾草,在松嫩平原草甸经常形成单优种群落。采用单位面积挖掘取样、分株按营养繁殖世代划分龄级、根茎按实际生活年限划分龄级的方法,对松嫩平原单优群落和混生群落的野古草种群构件结构进行了调查与分析。结果表明,在生长季初期两群落野古草种群均以春性分株和根茎芽占优势,且分株及芽构件结构相对稳定,芽库的输出率单优群落为80.4%,混生群落为62.5%;整个生长季分株由2—3个龄级组成,1a分株数量是2a的2.9—10.2倍,其生物量各月份所占比例平均为93%,随着龄级的增加依次明显减少,呈增长型年龄结构;根茎由3—4个龄级组成,根茎累积长度及生物量均以2a占绝对优势,为稳定型年龄结构;分株生产力1a明显高于2a,对种群贡献最大;根茎贮藏力除个别月份以3a、4a最高外,两群落大部分以2a最高,在生长季后期,1a根茎物质积累的速率最快。     

松嫩平原两个趋异类型羊草无性系种群特征的比较研究

松嫩平原上羊草(Leymus chinensis(Tzvel.)Tzvel.)有两个趋异类型:灰绿型和黄绿型。两个类型羊草的分蘖节一般均存活2～4年,最多可存活5年;根茎一般存活2～3年,最多可存活4年。两个类型无性系种群的分蘖株均为增长型的年龄结构类型。种群根茎的累积长度,灰绿型为18035cm/m~2,黄绿型为21218cm/m~2,其中,均以1、2龄占绝对比重。两个类型均以1龄分蘖株生产力最大,至3龄分蘖株明显减小;各龄根茎的生物量随着年龄的增加呈直线下降;1龄根茎的营养繁殖力甚强,至8月中旬所形成的芽数均已远远多于地上全部分蘖株数;2龄根茎尚存在较小的营养繁殖潜力,3、4龄根茎均已丧失了营养繁殖力。两个类型羊草无性系种群都是通过根茎芽补充更新。     

松嫩平原赖草无性系生长及其构件的年龄结构

赖草是长根茎型禾草,是典型的无性系植物．在松嫩平原栽培条件下,移植第1年的赖草无性系,经过一个完整生长季的营养繁殖,最多可形成215个分蘖株,在4个取样的无性系中,最大的无性系是最小的5．4倍;经过2个完整生长季最多可形成2852个分蘖株,最大为最小的2．7倍．在无性系整体水平上,2个年度间无性系扩展面积平均增长了13．2倍,分蘖株平均增长了13．3倍,根茎的累积长度平均增长了15．9倍,根茎节数平均增长了11．2倍,根茎生物量平均增长了14．7倍．无性系分蘖株由2个龄级组成,呈增长型年龄结构,并且随着无性系的生长,其增长型年龄结构更为明显．无性系的芽库均由3个龄级组成,亦呈增长型年龄结构,但随着无性系的生长,其增长型年龄结构趋于减缓．赖草无性系以形成大量的根茎顶端芽和根茎节间芽发育成分蘖株,实现无性系空间生态位的扩展和持续更新．     

松嫩平原旱地生境芦苇种群不同龄级根茎的干物质贮藏及水溶糖含量

通过对松嫩平原旱地生境单优种群落芦苇种群不同龄级根茎的调查测定,分析了一个生长季内3个生育期芦苇种群各龄级根茎干物质贮量和水溶糖含量的季节变化.结果表明:各生育期低龄级芦苇种群根茎中干物质贮量和水溶糖含量均较少,且与高龄级的差异较大;随着生长季的进程,低龄级根茎中干物质贮量和水溶糖含量迅速增加,且与高龄级的差异逐步缩小.在整个生长季,芦苇种群各龄级根茎均具有养分消耗和再贮藏乃至超补偿性贮藏的活性,其中,幼龄级根茎的活性更大.高龄级根茎的干物质贮量和水溶糖含量有一个逐年累积的增加过程.根茎干物质贮量在龄级间和龄级内的差异均达到了极显著水平(P<0.01),并且龄级间的差异大于龄级内.水溶糖含量仅在龄级间差异达到显著水平(P<0.05).随着龄级的增加,芦苇种群根茎的干物质贮量和水溶糖含量均呈二次曲线变化.     

松嫩平原杂类草草甸阿尔泰狗哇花无性系种群构件年龄结构

阿尔泰狗哇花为根蘖型菊科多年生无性系草本植物.采用主根芽区的繁殖世代数划分分株和芽龄级的方法,研究了松嫩平原杂类草草甸阿尔泰狗哇花无性系种群不同构件的年龄结构.结果表明:分株构件和芽构件均由4个龄级组成.在孕蕾期,分株构件中1龄级占22.6%、2龄级44.8%、3龄级28.8%、4龄级3.8%,呈稳定型年龄结构.在乳熟期,生殖分株构件以2龄级比重最大,占45.6%,4龄级最小,占0.8%,为稳定型年龄结构;而营养分株构件以1龄级比重最大,占47.5%,4龄级最小,占1.1%,为增长型年龄结构.分株主根的生活年限最多为5年.不同生育期分株构件的生产力均以2龄级最高.在乳熟期,1龄级分株具有较大的生产潜力,4龄级分株的生产力已普遍减弱.芽库中潜在种群呈增长型年龄结构.     

Belowground bud production is linked to population establishment in Sorghastrum nutans (Poaceae)

Belowground bud production mediates many responses of tallgrass prairie grasses to temporal environmental variation, and clonal spread contributes to dominance in successional plant communities. However, we know little about the importance of these regenerative traits for vegetation establishment in grassland restoration and about their regional variability. Further, geographic seed or transplant sources affect plant performance. We investigated the effects of seed source on the number of belowground buds per tiller, clonal spread (total rhizome length adjusted for plant biomass), and population establishment in the native C₄ grass Sorghastrum nutans sown into tallgrass prairie restorations using reciprocal common gardens in three sites (in Nebraska, Kansas, and Oklahoma). We characterized buds per tiller and clonal spread at the plant level and related both traits to population establishment at the restoration plot level. Plant-level bud production significantly differed among seed sources and common garden sites, and was positively associated with plot-level establishment (density and canopy cover), but plant-level clonal spread did not differ among seed sources or common garden sites and was not associated with the plot-level establishment. Our results are among the first to link bud production, which varied among source populations, to differences in plant population establishment. These results suggest that we should more often consider differences among sources in traits closely tied to post-seeding population establishment. The use of sources that possess such traits may facilitate successful establishment in restoration settings.     

Post-invasion evolution of native plant populations: a test of biological resilience

Contemporary evolution may explain the success of some exotic plant invasions. However, the evolutionary response of recipient native plant populations to exotic invasion has received relatively little attention. Because plant populations are genetically variable, contemporary evolution may also occur in native populations following entry of invasive species. Previously, we documented molecular differences in native populations; here we extend these studies to evaluate growth of native species in a common garden experiment. We seek to determine if three populations of two native grass species ( Hesperostipa comata and Sporobolus airoides ) demonstrate evidence of contemporary evolution in response to invasion by Acroptilon repens . We obtained 50 genets of the two native grass species from communities long-invaded (25–80 years) by A. repens and from adjacent, noninvaded areas, and planted five transplants of each genet into two A. repens infestations (Laramie and Fort Steele, Wyoming, USA) to document their growth and survival. Cumulative differences between collections from invaded and noninvaded communities were species-specific. S. airoides displayed a consistent positive response to long-term coexistence with A. repens , whereas the performance of H. comata originating from invaded communities was not different from H. comata collected from noninvaded communities. In general, genets from invaded communities had fewer tillers than genets from noninvaded communities, but their relative tiller production (percent increase) was greater for genets from invaded communities at both field transplant sites for both grass species. Basal area increase and overall performance of collections from invaded and noninvaded communities of origin depended on transplant site and grass species. The results suggest that native species have the potential for adaptation to coexist with exotic invasives, although that potential may differ among species.     

An Analysis of Age Structure and the Strategy for Asexual Propagation of Aneurolepidium chinense Population

Aneurolepidiurn chinense (Trin.) Kitag. is a rhizome grass. Among the total earing plants of the population in natural cutting grassland, 87 % was winterness plants. The oldest tillering node was four age, and its life time would reach five years. The plants of one and two age held the absolute dominant position and their proportion was 92.5% in the age structure of developing plants from the tillering nodes. The productivity of one age plants was the highest among plants of the total ages, whereas the vitalities of plants were evidently weakened by the third age. On the age structure, A. chinense population in the cutting grassland was a type of mixed population which was an expanding and a stable population. The strategy of asexual propagation, in which the age structure of the population would be regulated by developing plants from rhizome end, and the mechanism of biology and ecology on natural sustaining renovation of A. chinense grassland were comprehensively analysed.     

羊草种群年龄结构及无性繁殖对策的分析

天然割草场羊草 ( Aneurolepidium chinense( Trin.) Kitag.)种群的生殖枝中有 87%为冬性植株。羊草分蘖节最老为 4龄 ,其生活时间可达 5个年度。在分蘖节成株的年龄结构中 ,1、2龄株占绝对优势 ,其所占比重达 92 .5 %。 1龄株生产力最高 ,至 3龄株生活力已明显衰弱。割草场羊草种群为增长型与稳定型混合的年龄结构类型。综合分析了羊草以根茎顶端成株调节种群年龄结构的无性繁殖对策 ,以及羊草草地自然持续更新的生物生态学机制