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| 1 | 自然状况下头状沙拐枣对水分条件变化的响应显示文摘对塔克拉玛干沙漠南缘沙漠-绿洲过渡带前沿人工植被头状沙拐枣(Calligonum caput-medusae)水分关系的研究表明:头状沙拐枣在生长季节中一直保持着正的膨压,水分亏缺的发展并不严重,植被所受水分胁迫在正常范围内,因而在现存条件下干旱引起的水分胁迫不足以威胁植被的存在。在生长进程中,随着环境胁迫的加剧,头状沙拐枣依然维持了比较高的水势和渗透势,实验结果也显示植株体内可溶性物质(N_sDM)的累积程度并没有升高,因而其生理过程仍然在比较宽松的环境中进行。相对含水量(RWC_p)在生长季节一直保持很高的水平,这对植株保持体内水分防止水分过度损失有利。头状沙拐枣在干旱胁迫下表现出的这些生理特点说明,植物对干旱环境的生理适应类型属于抵抗型。在叶水平上植株对干旱胁迫的水分生理适应主要表现为质外体水比例的增高,细胞壁弹性的增加,持续较高的相对含水量(RWC_p)以及灌水后RWC_p和枝条水分比值(WC_(sat))的增加上。夏季的引洪灌溉有助于头状沙拐枣水分状况的恢复,并很可能是植被免于严重水分胁迫的原因之一。 | 李向义 Frank M.THOMAS Andrea FOETZKI 曾凡江 张希明 何兴元 | 2003 | 植物生态学报2003，27，4： | 24 |
| 2 | Regulation of the water status in three co-occurring phreatophytes at the southern fringe of the Taklamakan Desert显示文摘Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water. | Frank M.Thomas Andrea Foetzki Dirk Gries Helge Bruelheide Xiangyi Li Fanjiang Zeng Ximing Zhang | 2008 | Journal of Plant Ecology2008，1，4： | 13 |
| 3 | Stand structure and productivity of Populus euphratica along a gradient of groundwater distances at the tarim River(NW china)显示文摘Aims Along central-Asian rivers in arid regions,lowering of the ground-water level constitutes a major threat to the riparian forests,whose tree layers are dominated by Euphrates poplar(Populus euphratica).Some of these fragile ecosystems are supplied with additional(‘eco-logical’)water for protection and conservation.We investigated interrelationships among groundwater distance,stand structure and above-ground wood production(at the tree and the stand level)in P.euphratica stands along a groundwater gradient(distances of 2.0-12.0 m)that also included a plot supplied with‘ecological water’.Methods We measured the height,diameter at breast height and basal area of poplar trees and determined the annual above-ground wood production for the three most recent years on the basis of tree-ring analyses and allometric regressions at three sites at the upper,mid-dle and lower reaches of the tarim River,Xinjiang,NW china.Important Findingsthe distribution of age classes differed significantly among the plots:in accordance with their life histories,stands growing at a larger distance to the groundwater harboured a larger fraction of old trees(>80 years)and,in most cases,a smaller fraction of young trees(≤20 years).the annual above-ground wood production per ha was highest on a plot with a short groundwater distance(2.0 m;maxi-mum of the 3-year investigation period:3.0 t ha−1 a−1)and lowest,at a plot with a large distance to the water table(6.6 m;minimum:0.23 t ha^(−1)a^(−1)).However,the plot located close to the groundwater(and to the river)at the middle reaches exhibited a relatively large interannual variation in above-ground wood production,which can be attributed to interannual variations in the river discharge.At the middle and the lower reaches,these interannual variations on plots with the most favourable water supply were even more obvious at the tree level.For the fraction of mature trees(60-99 years old),no significant differences in above-ground wood production were found between the plots with the most and the least favourable water supply.Overall,the productivity at the stand level was most closely correlated with the stand density(number of trees per ha,tree cover percentage).Productivity was negatively related to tree age,whereas groundwater distance alone was not a good predictor of above-ground wood production.In conclusion,vigorous growth of P.euphratica is possible at sites with groundwater distances of up to 12 m.Supply with‘ecological water’may be beneficial to trees growing at groundwater distances not larger than~6 m.However,allocation of water should focus on stands with a short distance to the groundwater because only under these conditions,natural gen-erative reproduction of the poplars is possible. | Frank M.Thomas Michael Jeschke Ximing Zhang Petra Lang | 2017 | Journal of Plant Ecology2017，10，5： | 4 |
| 4 | Weather or weathering?Growth of Nothofagus dombeyi on volcanic soils differing in nitrogen and phosphorus concentrations显示文摘Aims We tested whether—in addition to weather conditions—the concentrations of nitrogen and phosphorus in the substrate have an effect on the radial stem increment of Nothofagus dombeyi trees in old-growth forest stands on volcanic soil at the western slopes of the Andes in South-Central Chile.Methods We took soil samples and tree increment cores from five proximate sites(1000-1300 m a.s.l.)that are located in the volcanic region of the Conguillío National Park and differ in the age of the substrate(Miocene—3500 years B.P.)and in its concentrations of nitrogen(N)and phosphorus(P).The soil samples were also analysed on their concentrations of other plant mineral nutrients,carbon(C)and nitrogen isotope ratios(δ^(15)N).Tree-ring widths and the stem basal area increment(BAI)were related to climate parameters.In selected tree rings,the stable isotope ratios of carbon(δ^(13)C)and oxygen(δ^(18)O)were determined and related to growth and climate parameters.Important FindingsConsistent with theory,the soils on the oldest substrate showed the highest(least negative)δ^(15)N values,but mineral N was the only nutrient whose concentration exhibited a straightforward(increasing)relationship with increasing substrate age.The BAI was largest on the soil with the highest concentration of plant-available P.In contrast to BAI,tree-ring chronologies did not differ among the study sites.However,tree-ring chronologies and BAI exhibited significantly positive correlations with summer precipitation,and negative correlations,with summer(December)temperature.A negative correlation was found betweenδ^(13)C and precipitation anomalies in the growing season(November-March).We interpret the negative correlations between growth and temperature,and betweenδ^(13)C andδ^(18)O in the tree rings,as an impairment of net carbon assimilation by anomalously warm weather conditions during the growing season.We conclude that the growth of N.dombeyi is mainly affected by high temperature and low precipitation in spring and summer irrespective of the substrate’s age,and enhanced by higher concentrations of plant-available P in the soil.Our results may be representative of N.dombeyi stands on volcanic substrate within their principal distribution range along the Andes of South America. | Christoph Walter Cecilia A.Pérez Frank M.Thomas | 2016 | Journal of Plant Ecology2016，9，5： | 1 |
| 5 | Growth of the tropical Pinus kesiya as influenced by climate and nutrient availability along an elevational gradient显示文摘与温带地区相比,人们对在热带山脉中,尤其是热带针叶林中,沿海拔梯度的个体树种生长减少的原因知之甚少。我们的研究目的是检验气候或土壤条件是否会导致在高海拔分布的卡西亚松(Pinus kesiya,一种在南亚和东南亚广泛分布的松树)的生长减少。我们对越南中南部山脉中沿海拔梯度约在900~2000米之间的卡西亚松的树干直径增量和其年轮中^(13)C(△^(13)C)的同位素判别进行分析。同时确定其生长与△^(13)C、气候和土壤变量的关系。研究发现,树木的断面积生长量(BAI)与温度或降水之间没有一致的相关关系。相反,沿海拔梯度,我们发现BAI与△^(13)C以及与上层矿质土壤的C/N比和δ^(15)N特征呈显著负相关。BAI与土壤中有效磷(P_(a))和“碱性”阳离子(钙、镁、钾)的浓度呈正相关。我们的结论是,较高海拔下的较低温度会对树木生长产生间接影响,主要通过产生较高的C/N比并降低氮(N)和P矿化率而产生作用,而这些影响因其他负面反馈而进一步受到阻碍。主要包括:降水增加的淋溶作用而导致较低浓度的“碱性”阳离子以及较高海拔土壤矿化的N和P的有效性降低。本研究结果可以进一步解释卡西亚松的最高生长极限以及该物种在其他山区出现的情况。 | Le Tuan Ho Raimund Schneider Frank M.Thomas | 2020 | Journal of Plant Ecology2020，13，1： | 1 |
| 6 | How competitive is the‘pioneer-climax’tree species Nothofagus alpina in pristine temperate forests of Chile?显示文摘Aims Nothofagus species are constitutive elements of the temperate forests along the Southern Andes Mountains.The deciduous Nothofagus alpina is a fast-growing,but long-lived opportunistic pioneer spe-cies(‘pioneer-climax species’)and co-occurs with the evergreen N.dombeyi.We tested whether N.alpina is competitively superior to N.dombeyi in mature stands and whether intra-specific competition in N.alpina is stronger than inter-specific competition with N.dombeyi.Methods In a pristine old-growth forest in South-Central Chile,we compared the growth of N.alpina trees in pure stands and in mixture with N.dombeyi to the growth of N.dombeyi and calculated compe-tition indices.We related growth variables to climate data and weather extremes.Important Findings In N.alpina,juvenile basal area increment was signifi-cantly higher in pure than in mixed stands.Contrary to our hypothesis,N.dombeyi exhibited larger radial stem increments than N.alpina in the most recent 40 years.In the most recent two decades,this was caused by high growth rates of large N.dombeyi trees.In both Nothofagus species,stem growth was negatively related to temperature,but N.dombeyi responded more sensitively to weather conditions than N.alpina.In N.alpina,stem increment was negatively related to the intensity of competition,but the size of the competition effects on this species was similar in pure and mixed stands.Thus,compared to N.alpina,the‘pioneer-climax species’concept is even more appropriate for N.dombeyi with its relatively high growth rates even in the early stages of its life. | Rebekka Bögelein Cecilia APérez Philipp Schäferand Frank M.Thomas | 2019 | Journal of Plant Ecology2019，12，1： | 0 |
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