小叶章草地生态系统结构与功能的研究Ⅳ能量的固定和分配

小叶章草在生态系统年净初级生产力为３０５７９。１７ｋＪ／ｍ＾２．ａ,其中地上净初级生产力占３７．６４％,地下净初级生产力占６２．３６％。不同植物器官（组分）的能量现存量差异很大,上部根占植物亚系统总能量现存量的５４．８７％,穗的能量现存量仅占０．０３％,其它器官的能量现存量从大到小依次为：茎＞叶＞根茎＞枯落物＞下部根茎＞死根。不同植物器官（组分）热值含量水平亦存在较大差异,以去灰分热值比较,由大到     

Vesicular mycorrhizal colonization of seedlings of Pinaceae and Betulaceae after spore inoculation with Glomus intraradices

 Although Pinaceae and Betulaceae have been reported to contain Glomus–type root endophytes, its ecological importance and the conditions influencing this symbiosis are poorly understood. Seedlings of Abies lasiocarpa, Alnus rubra, Pinus contorta, Pinus ponderosa, Pseudotsuga menziesii, and Tsuga heterophylla were inoculated with Glomus intraradices to determine the vesicular-arbuscular mycorrhizae (VAM) development and responsiveness of these hosts. The role of companion VAM host plants on mycorrhizal colonization and nutrient uptake by Pseudotsuga menziesii was also examined by growing seedlings of Pseudotsuga menziesii in dual culture with VAM hosts Thuja plicata or Calamagrostis rubescens. After 8 weeks, no seedlings were colonized. At 16 weeks, 8 of 17 Thuja plicata seedlings grown with Pseudotsuga menziesii and all 18 inoculated Thuja plicata seedlings grown alone were colonized with vesicles and hyphae. Two of 17 inoculated Pseudotsuga menziesii seedlings grown in dual culture with Thuja plicata were colonized with abundant vesicles and hyphae. No ectomycorrhizal seedlings grown in monoculture were colonized. At 9 months, all 10 Calamagrostis rubescens and all 10 inoculated Pseudotsuga menziesii seedlings grown in dual culture were colonized by vesicles and hyphae. Two of 10 inoculated Pseudotsuga menziesiiand 1 of 10 inoculated Pinus ponderosa seedlings grown in monoculture were similarly colonized. The mean phosphorus content in the needles of colonized Pseudotsuga menziesii seedlings grown with Calamagrostis rubescens was about twice as high as in noncolonized Pseudotsuga menziesiiseedlings grown with Calamagrostis rubescens. Tissue nitrogen did not differ between these treatments. The results show that Glomus intraradices colonization of Pinaceae is most successful when a VAM host is present, although some vesicular colonization of Pinaceae occurred in the absence of a VAM host. Accepted: 24 September 1997     

Pattern of species dominance and factors affecting community composition in areas deforested due to air pollution

Vegetation of mountain areas affected by SO₂ pollution (Kruné hory Mts., Czech Republic) was analysed using multivariate methods. Communities with prevailing species Calamagrostis villosa, a rhizomatous grass expanding into deforested sites, were sampled by Braun-Blanquet relevé method. Canonical correspondence analysis was used to assess the effect of environmental variables (soil removal, deforestation, and shading). To test the effects of light, moisture, soil acidity and nitrogen, mean sample indicator values were correlated a posteriori with sample axes on ordination scores. Light, soil acidity, moisture, and site history (in terms of past deforestation and soil removal applied in reclamation procedures) were found to be the main factors responsible for the community composition. Nitrogen level had not a significant effect on the community composition. When analyzing the whole data set, i.e. including also remnants of natural spruce forests, light was the factor affecting at most the composition of communities. Within the bare spot vegetation, if treated separately, the highest variation was found along the soil acidity/moisture gradient. The effect of soil removal was only obvious at early successional stages. Species diversity increased with moisture and decreased with soil acidity. Species exhibiting S- and/or R-strategy are successful on extremely acid soils whereas forbs present in bare spots appear to be supported by disturbances.     

松嫩草原拂子茅种群热值、生物量和能量动态的研究

拂子茅（Calamagrostis epigejos)全株的叶的热值和季节变化规律相似,呈双峰曲线,2个峰值分别出现在6月中旬和8月初,茎热值的变化呈单峰曲线,峰值出现在8月初,穗笔立枯体的热值变化呈波动型,穗的最大值出现在9月初,立枯估出现在6月中旬,地上部能量现状量的季节变化与生物量变化同步,呈单峰曲线,不同季节能量在各器官中分配比率为：6月中旬为叶＞茎＞穗,7月初为叶＞茎＞立枯体＞穗,7月中旬为叶＞茎＞穗＞立枯体,8月至9月为叶＞茎＞立枯体＞穗,能量的垂直分配,地上部为从地表至20cm高度逐渐增加,最大值在１０－２０cm层占地上部总能量的２６．９１％,然后逐渐下降,地下部能量垂直分布规律是随着深度增加而逐渐减少,能量集中分布在地下0－10cm层在占地下部总能量69．01％。     

The use of internal nitrogen stores in the rhizomatous grass Calamagrostis epigejos during regrowth after defoliation

BACKGROUND AND AIMS: The regrowth dynamics after defoliation of the invasive grass Calamagrostis epigejos were studied. As nitrogen (N) reserves have been shown to play an important role during plant regrowth, the identity, location and relative importance for regrowth of N stores were determined in this rhizomatous grass. METHODS: Plant growth, nitrate uptake and root respiration were followed during recovery from defoliation. Water soluble carbohydrates, nitrate, free amino acids and soluble proteins were analysed in the remaining organs. KEY RESULTS: Nitrate uptake and root respiration were severely reduced during the first days of regrowth. Roots were the main net source of mobilized N. The quantitatively dominant N storage compounds were free amino acids. Free amino acids and soluble proteins in the roots decreased by 55 and 50%, respectively, and a substantial (approximately 38%) decrease in stubble protein was also observed. Although the relative abundance of several soluble proteins in roots decreased during the initial recovery from defoliation, no evidence was found for vegetative storage protein (VSP). Furthermore, rhizomes did not act as a N storage compartment. CONCLUSIONS: Production of new leaf area was entirely reliant, during the first week after defoliation, on N stores present in the plant. Mobilized N originated mainly from free amino acids and soluble proteins located in roots, and less so from proteins in stubble. Presence of VSP in the roots was not confirmed. The data suggest that rhizomes played an important role in N transport but not in N storage.     

Biogeochemical cycle of Sulfer in the Calamagrostis angustifolia wetland ecosystem in the Sanjiang Plain, China

To better understand the Sulfur (S) cycle in the wetland ecosystem, the S cycle and its compartmental distribution within an atmosphere-plant-soil system were studied using a compartment model in the Calamagrostis angustifolia wetland in the Sanjiang Plain, Northeast China. The results showed that the soil was the main S storage and flux hinge in which 97.78% S was accumulated. In the plant subsystem, the root was the main S storage, and it remained at 79.60% of the total S contents, which in the Calamagrostis angustifolia wetland ecosystem showed that the parts above the ground took up 0.75 g S/m², the S re-transferring biomass to the root was 0.24 g S/m², and to the litter was 0.51 g S/m²; the root took up 3.76 g S/m² and the S transferring biomass to the soil took up 3.07 g S/m²; the litter S biomass was 0.75 g S/(m²·a) and the S transferring biomass to the soil was more than 0.52 g S/(m²·a). The emission amount of H2S from the Calamagrostis angustifolia wetland ecosystem to the atmosphere was 1.42 mg S/m², whereas carbonyl sulfide (COS) was absorbed by the Calamagrostis angustifolia wetland from the atmosphere and the absorption amount was 1.83 mg S/m². The S input biomass from the rain to the ecosystem was 4.85mg S/m² during the growing season. The difference between input and output amounts was 5.26 mg S/m², which indicated that S was accumulated in the ecosystem and would lead to wetland acidification in the future.     

毛乌素沙地根茎禾草拂子茅对异质性水分供应的表型可塑性

拂子茅(Calamagrostis epigejos(L.)Roth.)为根茎型多年生禾草,具细长根茎.为了探讨拂子茅在异质性水分环境中的表型差异,在内蒙古鄂尔多斯高原的毛乌素沙地对拂子茅由母株、子株组成的分株对给予了高水、低水两种不同的异质性土壤水分处理.实验结果表明:土壤水分状况显著地影响着拂子茅分株的生长表型.在高土壤水分条件下,拂子茅的分株产生的根茎、新生后代分株较多,并使生物量主要分配于地上部分,地上生物量积累多;在低土壤水分条件下,拂子茅分株产生较少的根茎与新生后代分株,并且分配到根系的生物量明显增大.在具有一定对比度的异质性土壤水分环境中,拂子茅分株并不因相连的其他分株所处的土壤水分状况而在根茎生长、新生后代分株的产生和生物量分配等特征上,与同质环境中的具有相同土壤水分状况的分株相比,有明显差异.这些结果揭示:拂子茅仅以分株的形式对异质性水分供应发生表型反应;相连的克隆分株在向顶向和向基向这两个基本方向上,不能对另一分株的土壤水分状况在生长表型上发生反应,它们在水分关系上可能是相互相对独立的.分株的相对独立可能有利于在气候干旱、扰动强烈的沙地环境中实现风险分摊,提高基株的存活几率.     

CO2浓度升高与氮添加对三江平原湿地小叶章生长的影响

利用开顶箱薰气室,设置正常大气CO₂浓度(350 μmol·mol^-1)、高CO₂浓度(700 μmol·mol^-1)2个CO₂水平和不施氮(0 g N·m^-2)、中氮(5 g N·m^-2)和高氮(15 g N·m^-2)3个氮素水平,研究CO₂浓度升高和氮肥施用对三江平原草甸小叶章生长的影响.结果表明：随着CO₂浓度升高,小叶章物候期提前,其中抽穗期提前1～2 d,成熟期提前3 d;不施氮、中氮和高氮水平下, CO₂浓度升高使小叶章的分蘖分别增加8.2%(P<0.05)、8.4%(P<0.05)和5.5%(P>0.05);在小叶章生长初期,CO₂浓度升高对其生物量的增加有促进作用,拔节期和抽穗期小叶章地上生物量分别增加12.4%和20.9%(P<0.05);生长后期则对小叶章地下生物量的促进作用增大,腊熟期和成熟期的地下生物量分别增加20.5%和20.9% (P<0.05).小叶章生物量对高浓度CO₂的响应与供氮水平有关,供氮充足条件下, 高浓度CO₂对生物量的促进效应更大.     

Predicting decay and ground vegetation development in <Emphasis Type="Italic">Picea abies</Emphasis> snag stands

In a Picea abies (L.) Karst. (Norway spruce) mountain forest on the Gandberg site in the northern Swiss Alps, trees were killed by bark beetles in 1992–1997. A combination of field studies and dynamic modelling was used to project snag decay and future ground vegetation succession in these steep, unharvested stands. In permanent plots, ground vegetation cover and natural tree regeneration have been monitored annually since 1994. To obtain additional information on the abundance of snags, logs, boulders and other microsite types in these stands, the relative frequency of the microsite types was quantified along four strip transects on the montane and subalpine elevational levels. A dynamic model of snag decay and ground vegetation development was constructed (modified matrix model approach). Based on field data and literature values, the model was parameterised and initialised separately for the montane and the subalpine level. For model validation, microsite types were quantified in 2001 with the line-intercept method on both elevational levels. Starting from the conditions in the stands before the bark beetle attacks, it was possible to project short-term succession and to accurately simulate the decay and ground vegetation patterns eight years after tree die-back. Long-term simulations suggest that on the montane level, raspberries (Rubus idaeus L.) will be replaced by Picea abies, while on the subalpine level ferns will dominate for a long time.     

CO2浓度升高与氮添加对三江平原湿地小叶章生长的影响

利用开顶箱薰气室,设置正常大气CO₂浓度(350 μmol·mol^-1)、高CO₂浓度(700 μmol·mol^-1)2个CO₂水平和不施氮(0 g N·m^-2)、中氮(5 g N·m^-2)和高氮(15 g N·m^-2)3个氮素水平,研究CO₂浓度升高和氮肥施用对三江平原草甸小叶章生长的影响.结果表明：随着CO₂浓度升高,小叶章物候期提前,其中抽穗期提前1～2 d,成熟期提前3 d;不施氮、中氮和高氮水平下, CO₂浓度升高使小叶章的分蘖分别增加8.2%(P<0.05)、8.4%(P<0.05)和5.5%(P>0.05);在小叶章生长初期,CO₂浓度升高对其生物量的增加有促进作用,拔节期和抽穗期小叶章地上生物量分别增加12.4%和20.9%(P<0.05);生长后期则对小叶章地下生物量的促进作用增大,腊熟期和成熟期的地下生物量分别增加20.5%和20.9% (P<0.05).小叶章生物量对高浓度CO₂的响应与供氮水平有关,供氮充足条件下, 高浓度CO₂对生物量的促进效应更大.