类短命植物粗柄独尾草器官生物量分配与估测

粗柄独尾草(Eremurus inderiensis)是古尔班通古特沙漠特有类短命植物。采用全株挖掘法研究粗柄独尾草盛花期的生物学特征、器官生物量分配及生物量估测模型。结果表明：粗柄独尾草地上形态指标之间及其与器官生物量间均呈显著正相关,协同生长关系较强。粗柄独尾草地下生物量平均为(12.00±5.85) g/株,占全株58.23%±6.07%,地上生物量平均为(9.15±5.75) g/株,占全株41.77%±6.07%,根冠比为1.44±0.34。根生物量所占比例最大(51.61%±5.93%),其次为有性繁殖器官(25.14%±5.02%)和光合器官(16.63%±3.75%),这种分配模式体现了类短命植物生活型的特点。根冠比与地上形态指标间均为负相关关系。叶片、花序、地上及地下生物量间的相关生长分析表明,仅叶片重与地上生物量、叶片重与花序生物量间呈等速生长关系,其他均为异速关系。基于D (花柄基径)、HD² (H为株高)的地上、地下和总生物量直接估测模型均较为精确,且地下生物量的直接和间接估测(基于异速关系)效果相同。     

乌拉特荒漠草原红砂生物量预测模型

红砂(Reaumuria soogorica)是一种广泛分布在中国半荒漠地区的多年生半灌木,是干旱荒漠区分布最广的植物种之一,具有固沙、固土的优良特性。其生物量估算对评价荒漠草原红砂的生态功能和荒漠草原经营管理具有重要作用,红砂生物量模型是估测红砂生物量的重要方法之一。本研究采用全挖法,以乌拉特荒漠草原优势种之一红砂为研究对象,基于对红砂地上、地下和整株生物量及株高(H)、冠幅(C)、基径(D)等的测定,通过数理统计的回归分析方法,利用相关生长模型(幂函数W=aX^b),分别构建了地上部分(W1)、地下部分(W2)和全株生物量(W)的预测模型。通过对比判别系数R2的大小,挑选最佳生物量估测模型。结果表明:①以冠幅(C)为指标的估测模型W1=0.555×C^1.867(R^2=0.866)能较好地反映红砂单株地上生物量累计特征。②以复合因子基径×基径×株高(D2H)为指标的估测模型W2=2.259×(D^2H)^0.762(R^2=0.769)能较好地反映红砂单株地下生物量累计特征。③以复合因子基径×基径×株高(D^2H)为指标的估测模型W=7.057×(D^2H)^0.813(R^2=0.859)能较好地反映红砂总生物量的累计特征。利用此类方法建立的生物量模型,精度高,简便易行,为评价乌拉特荒漠草原红砂的生态功能和准确测定其生物量提供科学依据。     

白梭梭幼苗生长和生物量分配对不同盐分类型和浓度的响应

采用盆栽实验,设置3种盐分类型（NaCl,Na₂SO₄以及两者等摩尔比例混合盐）和6个浓度梯度〔0（CK）,50,100,200,300,500 mmol/L）〕,探讨了白梭梭（Haloxylon persicum Bunge ex Boiss. et Buhse）幼苗生长以及不同生长期地上地下生物量分配,对不同盐分类型及浓度的响应。结果发现：① 不同盐分类型和浓度处理下,白梭梭幼苗同化枝直径和分叉数具有明显差异,幼苗株高、基径和同化枝枝长随盐分浓度增大而减小,适度盐分浓度（300 mmol/L）促进主根生长,高盐分浓度（500 mmol/L）则具有显著抑制作用。② 随处理时间和盐分浓度的增加,白梭梭幼苗生物量积累受到的抑制不断增大,与对照相比,处理后期（第75 d）500 mmol/L浓度的NaCl,Na₂SO₄和混合盐处理下,白梭梭幼苗总生物量分别降低77%,87%和78%,地上生物量分别降低78%,87%和74%,地下生物量分别降低75%,81%和76%。③ 随时间的延长,白梭梭幼苗根冠比在各盐分处理下均呈增大趋势,但随盐浓度增加,根冠比变化趋势随盐分类型和处理时间的不同而有所区别。④ 白梭梭幼苗地上-地下生物量存在明显异速生长关系,且盐分处理未显著改变异速生长指数,均表现为地下生物量累积速率大于地上生物量。研究结果表明,在盐分胁迫下,白梭梭幼苗地上地下生物量分配对Na₂SO₄作出的响应要先于NaCl和混合盐,随处理时间的延长,对3种盐分类型作出的响应趋于一致,即将更多的生物量分配给地下根系,以缓解盐分过多造成的水分短缺等影响,维持植物的存活,符合最优分配理论。     

乌拉特荒漠草原群落物种多样性和生物量关系对放牧强度的响应

以内蒙古乌拉特荒漠草原灌丛和草本植物群落为对象,研究这2种植物群落的物种组成、物种多样性及其与地上生物量关系对不同放牧处理(对照、中牧、重牧)的响应。结果表明:①随着放牧强度的增加,灌丛群落中红砂(Reaumuria songarica)和碱韭(Allium polyrhizum)的优势度增大,沙生针茅(Stipa glareosa)的优势度减小;重牧降低草本群落中沙生针茅的优势度,增加了蒙古韭(Allium mongolicum)和碱韭的优势度。②不同放牧处理显著降低了灌丛和草本群落的盖度、高度以及灌丛群落的密度,消除了灌丛和草本群落之间盖度的差异(P> 0. 05)。中牧降低灌丛群落的Pielou均匀度指数,重牧降低灌丛群落的物种丰富度,灌丛和草本群落的其他多样性指数在放牧处理之间无显著差异(P> 0. 05)。除物种丰富度外,其他多样性指数在灌丛和草本群落之间差异显著(P <0. 05)。③不同放牧处理降低了灌丛和草本群落的地上生物量和凋落物量,导致灌丛和草本群落之间地上生物量的显著差异(P <0. 05)。④地上生物量与Simpson优势度指数负相关,与Shannon-Wienner多样性指数和Pielou均匀度指数正相关;放牧处理下地上生物量与密度、物种丰富度正相关。放牧处理改变了荒漠草原植物群落组成、结构和功能,进而改变了群落结构和功能的重要关系。     

Community structure and carbon and nitrogen storage of sagebrush desert under grazing exclusion in Northwest China

Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China.Grazing exclusion(GE)is one of the most common pathways used to restore degraded grasslands and to improve their ecosystem services.Nevertheless,there are still significant controversies concerning GE’s effects on grassland diversity as well as carbon(C)and nitrogen(N)storage.It remains poorly understood in the arid desert regions,whilst being essential for the sustainable use of grassland resources.To assess the effects of GE on community characteristics and C and N storage of desert plant community in the arid desert regions,we investigated the community structure and plant biomass,as well as C and N storage of plants and soil(0-100 cm depth)in short-term GE(three years)plots and adjacent long-term freely grazing(FG)plots in the areas of sagebrush desert in Northwest China,which are important both for spring-autumn seasonal pasture and for ecological conservation.Our findings indicated that GE was beneficial to the average height,coverage and aboveground biomass(including stems,leaves and inflorescences,and litter)of desert plant community,to the species richness and importance values of subshrubs and perennial herbs,and to the biomass C and N storage of aboveground parts(P<0.05).However,GE was not beneficial to the importance values of annual herbs,root/shoot ratio and total N concentration in the 0-5 and 5-10 cm soil layers(P<0.05).Additionally,the plant density,belowground biomass,and soil organic C concentration and C storage in the 0-100 cm soil layer could not be significantly changed by short-term GE(three years).The results suggest that,although GE was not beneficial for C sequestration in the sagebrush desert ecosystem,it is an effective strategy for improving productivity,diversity,and C and N storage of plants.As a result,GE can be used to rehabilitate degraded grasslands in the arid desert regions of Northwest China.     

内蒙古温带草地植被的碳储量

草地生态系统在全球碳循环中起着极为重要的作用。大部分草地碳储存在地下,但是实测数据十分匮乏,因此准确估算温带草地植被碳储量对评价草地生态系统碳循环具有重要意义。作为一个区域性资料积累工作,作者对内蒙古温带草地的碳储量进行了大范围的实测研究,以估算该地区草地植被的碳储量。主要结果如下:(1)内蒙古温带草地总面积为58.46×106hm2,总植被碳储量为226.0±13.27Tg C(1 Tg=1012g),平均碳密度为3.44Mg C.hm-2;(2)地下根系储存的碳是地上碳储量的6倍左右,地上、地下生物量碳储量分别为33.22±1.75和193.88±12.6 Tg C,平均碳密度分别是0.51和2.96 MgC.hm-2;(3)不同草地类型的碳储量差异较大,典型草原最大(113.25 Tg C),占草地总碳储量的50%,其次是草甸和草甸草原,荒漠草原碳储量最低(15.37 Tg C)。     

Allometric biomass equations of Larix sibirica in the Altay Mountains,Northwest China

Boreal forests are important carbon sinks and have tremendous potential to mitigate climate change. Aboveground biomass of Siberian larch (Larix sibirica Ledeb.) stands in the Altay Mountains, Northwest China was studied and allometric equations that are related to the biomass of aboveground components using diameter at breast height (DBH) or both DBH and height (H) as independent variables for L. sibirica trees were derived in this paper. A linear simultaneous equation system by using either DBH or both DBH and H (DBH&H) indices, was used to ensure additivity of the biomass of individual tree components, and was fitted for L. sibirica. Model performance was validated using the jackknifing test. Results indicate that the goodness-of-fit for the regressions was lowest for the needles (R² ranging from 0.696 to 0.756), and highest for the stem wood (R² ranging from 0.984 to 0.997) and the aggregated biomass components (R² ranging from 0.994 to 0.995). The coefficient of determination for each component was only marginally improved in terms of model fit and performance in the biomass equations that used DBH&H as the independent variables compared to that used DBH as the independent variable, and needles yielded an even worse fit. Stem biomass accounted for the largest proportion (87%) of the aboveground biomass. Based on the additive equations that used DBH as the single predicitor in this study, the mean aboveground carbon stock density and the carbon storage values of L. sibirica forests were 74.07 Mg C/hm² and 30.69 Tg C, respectively, in the Altay Mountains. Empirical comparisons of published equations for the same species growing in the Altay Mountains of Mongolia were also presented. The mean aboveground carbon stock density estimated for L. sibirica forests was higher in the Chinese Altay Mountains than in the Mongolian Altay Mountains (66.00 Mg C/hm²).     

中国北方天然草地的生物量分配及其对气候的响应

通过收集我国近20年来草地生物量的有关文献,估算了我国北方天然草地根冠比(R/S)及地下生产力占总生产力比例(fBNPP)的大小及其对气候变化的响应。结果表明:不同草地类型R/S比及fBNPP变异较大,根冠比为1.66~15.21,fBNPP为0.29~0.98;荒漠草原的R/S比及fBNPP较大,但变幅较小;森林草原R/S比和fBNPP较小,但变幅较大;R/S比及fBNPP随年降水的增加而显著降低,随年平均气温增加而降低的趋势不明显。采用生长季最大生物量估算的方法可能高估了R/S比及fBNPP。长期、高质量的生物量观测数据,尤其是地下生物量的数据以及开展不同研究方法对生产力估算结果的影响,对于准确评价草地在区域及全球碳循环中的作用是十分必要的。     

Biomass and carbon stocks in three types of Persian oak (Quercus brantii var. persica) of Zagros forests in a semi-arid area,Iran

Persian oak (Quercus brantii var. persica) is a dominant tree species of Zagros forests in a semi-arid area, western Iran. However, the capacity of biomass and carbon stocks of these forests is not well studied. We selected three types of oak, i.e., seed-originated oak, coppice oak and mixed (seed-originated and coppice) oak of Zagros forests in Dalab valley, Ilam Province, Iran to survey the capacity of biomass and carbon stocks in 2018. Thirty plots with an area of 1000 m² were systematically and randomly assigned to each type of oak. Quantitative characteristics of trees, such as diameter at breast height (DBH), height, crown diameter and the number of sprouts in each plot were measured. Then, aboveground biomass (AGB), belowground biomass (BGB), aboveground carbon stock (AGCS) and belowground carbon stock (BGCS) of each tree in plots were calculated using allometric equations. The litterfall biomass (LFB) and litterfall carbon stock (LFCS) were measured in a quadrat with 1 m×1 m in each plot. One-way analysis of variance and Duncan's test were performed to detect the differences in biomass and carbon stocks among three types of oak. Results showed that AGB, BGB and BGCS were significantly different among three types of oak. The highest values of AGB, AGCS, BGB and BGCS in seed-originated oak were 76,043.25, 14,725.55, 36,737.79 and 7362.77 kg/hm², respectively. Also, the highest values of LFB and LFCS in seed-originated oak were 3298.33 and 1520.48 kg/hm², respectively, which were significantly higher than those of the other two types of oak. The results imply the significant role of seed-originated oak for the regeneration of Zagros forests. Further conservation strategy of seed-originated oak is an important step in the sustainable management of Zagros forests in Iran.     

Ecological stoichiometry and biomass response of Agropyron michnoi Roshev. under simulated N deposition in a sandy grassland,China

Sandy grassland in northern China is a fragile ecosystem with poor soil fertility. Exploring how plant species regulate growth and nutrient absorption under the background of nitrogen (N) deposition is crucial for the management of the sandy grassland ecosystem. We carried out a field experiment with six N levels in the Hulunbuir Sandy Land of China from 2014 to 2016 and explored the Agropyron michnoi Roshev. responses of both aboveground and belowground biomasses and carbon (C), N and phosphorus (P) concentrations in the plant tissues and soil. With increasing N addition, both aboveground and belowground biomasses and C, N and P concentrations in the plant tissues increased and exhibited a single-peak curve. C:N and C:P ratios of the plant tissues first decreased but then increased, while the trend for N:P ratio was opposite. The peak values of aboveground biomass, belowground biomass and C concentration in the plant tissues occurred at the level of 20 g N/(m²·a), while those of N and P concentrations in the plant tissues occurred at the level of 15 g N/(m²·a). The maximum growth percentages of aboveground and belowground biomasses were 324.2% and 75.9%, respectively, and the root to shoot ratio (RSR) decreased with the addition of N. N and P concentrations in the plant tissues were ranked in the order of leaves>roots>stems, while C concentration was ranked as roots>leaves>stems. The increase in N concentration in the plant tissues was the largest (from 34% to 162%), followed by the increase in P (from 10% to 33%) and C (from 8% to 24%) concentrations. The aboveground biomass was positively and linearly correlated with leaf C, N and P, and soil C and N concentrations, while the belowground biomass was positively and linearly correlated with leaf N and soil C concentrations. These results showed that the accumulation of N and P in the leaves caused the increase in the aboveground biomass, while the accumulation of leaf N resulted in the increase in the belowground biomass. N deposition can alter the allocation of C, N and P stoichiometry in the plant tissues and has a high potential for increasing plant biomass, which is conducive to the restoration of sandy grassland.     

水分胁迫下荒漠地区2种草本植物生物量分配策略

水分胁迫是荒漠地区生态系统结构和功能变化的主要驱动力。分析水分胁迫下,不同生长阶段荒漠植物生物量在地上-地下的分配比例,对精确估算地下有机碳存储量有重要的理论意义。通过盆栽控制实验,设置对照、中度和重度胁迫的水分梯度,选取荒漠地区2种草本植物涩荠（Malcolmia africana）和角果藜（Ceratocarpus arenarius）,分析其生物量在地上-地下的分配比例变化。结果表明：无论水分胁迫存在与否,总生物量累积均符合Sigmoidal生长模型;水分胁迫对植株早期发育阶段总生物量的累积无明显影响,但显著减少了发育后期总生物量的累积;植株每生长10 d,涩荠和角果藜叶片占总生物量的比例分别减少8.9%～10.6%和3.1%～3.4%。几乎等同于茎所增加的比例。水分胁迫使得地下生物量显著增加,但总生物量的累积仍以地上部分为主;根冠比在整个生长过程中呈4个渐变的阶段。     

Long-term effects of mowing on plasticity and allometry of Leymus chinensis in a temperate semi-arid grassland,China

Mowing is an important land management practice for natural semi-arid regions.A growing body of empirical evidence shows that different mowing regimes affect the functioning of grassland ecosystems.However,the responses of plant functional traits to long-term mowing and their allometric scaling under long-term mowing are poorly understood.For a better understanding of the effects of mowing on grassland ecosystems,we analyzed the allometric traits of leaves and stems of Leymus chinensis(Trin.) Tzvel.,a dominant grass species in eastern Eurasian temperate grassland,at different mowing intensities(no clipping,clipping once every two years,once a year and twice a year).Experiments were conducted on plots established over a decade ago in a typical steppe of Xilinhot,Inner Mongolia,China.Results showed that most of the functional traits of L.chinensis decreased with the increased mowing intensity.The responses of leaves and stems to long-term mowing were asymmetric,in which leaf traits were more stable than stem traits.Also significant allometric relationships were found among most of the plant functional traits under the four mowing treatments.Sensitive traits of L.chinensis(e.g.leaf length and stem length) were primary indicators associated with aboveground biomass decline under high mowing intensity.In conclusion,the allometric growth of different functional traits of L.chinensis varies with different long-term mowing practices,which is likely to be a strategy used by the plant to adapt to the mowing disturbances.     

3种棒果芥属植物生物量分配及异速生长分析

类短命植物是准噶尔荒漠早春草本植物类群的重要而独特的组成部分,研究其生物量分配和异速生长关系,有助于深入了解类短命植物的生存策略与生态功能。以棒果芥（ Sterigmostemum tomentosum ）、福海棒果芥（ S ． fuhaiense ）和黄花棒果芥（ S ． sulfureum ）为研究对象,采用挖掘法获取野外成株全株生物量,对三者的器官生物量、分配比例及异速生长关系进行了对比分析。结果表明,3种植物器官生物量及其分配比例均差异明显。福海棒果芥生物量最大,但根冠比（R／S）和叶冠比（L／S）最小;棒果芥生物量最小,但L／S最大;黄花棒果芥则具有最大的R／S。棒果芥和黄花棒果芥的根冠比（R／S）均随个体的增大而显著下降,表明二者地上（AGB）与地下生物量（BGB）分配受到个体大小的强烈影响。福海棒果芥AGB－BGB间为等速生长关系（幂指数α＝1）,而另外2种均为异速生长关系;棒果芥、福海棒果芥的叶生物量（LB）与AGB间为等速生长关系,而黄花棒果芥符合异速生长关系（α＜1）;3个物种的LB－BGB间具有共同的异速生长指数（0．816）,表现出强烈的功能趋同性。总之,3个物种间的生物量分配及异速生长关系没有一致规律,但体现了类短命植物生物量分配的特点。     

Late frost damage to olive trees1

In southern Italy, as in other Mediterranean areas where olive is grown, it is late frosts rather than winter frosts that are harmful. Injuries produced by spring freezes and spells of low temperatures (below ?5°C) are described for young leaves, adult leaves, and shoots, twigs and branches of olive.     

塔克拉玛干沙漠腹地10种灌木光合器官的滞尘能力评价

通过全株光合器官取样,利用质量差减法,对塔中植物园10种灌木的滞尘能力进行多指标比较。结果表明：① 植物光合器官滞尘量与所处环境条件有关,在沙漠地区同种植物光合器官滞尘量大于沙漠以外区域。② 梭梭和沙拐枣的光合器官退化为同化枝,形态类似针叶树种的针叶,但尚有极度退化的叶片,其滞尘量大于其他区域针叶树种;与沙拐枣相比,梭梭同化枝节间距较短,叶片数量相对较多,因此梭梭的滞尘能力大于沙拐枣。③ 柽柳属植物虽然叶片也极度退化,但具有数量众多、分布密集、被覆绒毛、分泌盐分等特性,而且树冠光合器官密度大,具有很强的滞尘能力,光合器官滞尘量大于梭梭和沙拐枣,也大于阔叶灌木和阔叶乔木;由于光合器官表面滞尘特性、叶片数量以及树冠光合器官密度的差异,柽柳属植物光合器官滞尘能力也存在种间差异。④ 全植株光合器官滞尘量、单位重量光合器官滞尘量、单位表面积光合器官滞尘量都只能从一个侧面反映植物光合器官的滞尘能力,而单位树冠体积的光合器官滞尘量则可较全面地反映植物光合器官的滞尘能力。以单位体积树冠空间光合器官滞尘量为评价指标,10种灌木光合器官滞尘能力的排序为：甘蒙柽柳>长穗柽柳>华北柽柳>紫杆柽柳>刚毛柽柳>多花柽柳>多枝柽柳>沙生柽柳>梭梭>头状沙拐枣。     

Litter decomposition and nutrient dynamics of three woody halophytes in the Taklimakan Desert Highway Shelterbelt

Litter decomposition is a crucial biogeochemical process for C and nutrient cycling in nutrient-constrained environments, but the controlling factors on litter decomposition in an extremely arid desert region such as the Taklimakan Desert are relatively unknown. To evaluate the litter decomposition and nutrient dynamic characteristics, five primary litter types of three woody halophytes (Haloxylon ammodendron, Calligonum arborescens, and Tamarix ramosissima) along the Taklimakan Desert Highway Shelterbelt were monitored in litterbags during 420 days, when placed on the soil surface and buried by sand, respectively. The results indicated that the decomposition rate decreased in the order of assimilative branches of H. ammodendron (HA, 0.94), branches of T. ramosissima (TB, 0.55), assimilative branches of C. arborescens (CA, 0.53), seeds of C. arborescens (CS, 0.41), and old branches of H. ammodendron (HB, 0.21) in the surface placement. In contrast, the litters buried by sand displayed a significantly accelerated decomposition rate (F?=?12.28, P?H. ammodendron and branches of T. ramosissima presented P accumulation in both placements, whereas nutrients (N, P, K) and C showed a release pattern during the litter decomposition process, which was influenced by initial litter contents and decomposition rate.     

小针茅草原植被地下与地上生物量季节动态及根冠比变化规律

利用内蒙古苏尼特右旗小针茅荒漠草原生长季地上、地下生物量数据,分析小针茅草原植被地上、地下生物量以及根冠比的季节动态,并建立根冠比季节动态模型。研究结果表明：① 小针茅草原植被地上生物量季节变化呈单峰型曲线,地上生物量的峰值出现在6月下旬,为46.14 g•m^-2,地下生物量季节动态表现为“N”型变化规律,最高值出现在7月下旬,最低值出现在8月下旬,分别为1 275.46 g•m^-2和365.1 g•m^-2。② 2011年小针茅草原植被根冠比季节波动较大,最小根冠比为16.8, 出现在8月下旬, 最大根冠比为51.05, 出现在7月下旬。③ 小针茅草原植被地上生物量与根冠比具有较明显的相关关系,8月的相关关系最好,相关系数达到0.626,可以用8月的地上生物量模拟根冠比的变化。     

Sand-fixing characteristics of Carex brunnescens and its application with straw checkerboard technique in restoration of degraded alpine meadows

Carex brunnescens(Pers.), a typical clonal species, is considered to be the only herb found to date that can develop on sand dunes in Maqu alpine region of northwestern China. However, the characteristics that C. brunnescens resists to harsh alpine environment have not been documented. In this study, we conducted a field investigation to determine the morphological, reproductive, and sand-fixing characteristics of C. brunnescens. Concomitantly, we transplanted the belowground rhizomes of C. brunnescens to sand dunes and compared the abilities to restore degraded alpine meadows among sand dunes that had no further treatment(SD+N), sand dunes that had straw checkerboard technique but no transplanted rhizomes of C. brunnescens(SD+SCT), and sand dunes that had both SCT and transplanted rhizomes of C. brunnescens(SD+SCT+P). We found that belowground vertical rhizomes and horizontal rhizomes(including branching rhizomes and main rhizomes) of C. brunnescens were highly developed and that population reproduction was dominated by horizontal rhizomes. C. brunnescens exhibited a significant sand-fixation effect under following conditions: population density was 145–156 ramets/m~2, vegetation cover was 31.2%–39.3%, total length of belowground rhizomes was 11,223 cm/m~2, total length of belowground first-order roots was 9161–10,524 cm/m~2, fresh weight of aboveground part was 198.5–212.6 g/m~2, and fresh weight of belowground part was 578.8–612.4 g/m~2. It should be particularly noted that SD+SCT+P treatment(sand dunes that had both straw checkerboard technique and transplanted rhizomes of C. brunnescens) was the best and SD+N(sand dunes that had no further treatment) was the worst in terms of following biotic indicators: total number of reproductive ramets, total number of belowground rhizomes, and fresh weight of aboveground and belowground parts of C. brunnescens, contents of soil organic carbon, available nitrogen, microbial biomass carbon, and microbial biomass nitrogen. It implies that applying SCT in sand dunes and transplanting belowground rhizomes to sand dunes with SCT could improve both soil fertility and growth of C. brunnescens. These results suggest that the SCT-promoted high reproductive abilities of belowground rhizomes of C. brunnescens can successfully facilitate the establishment of ramets and can thus be an effective strategy to restore degraded vegetation in Maqu alpine region of northwestern China.     

Vertical distribution and storage of soil organic and inorganic carbon in a typical inland river basin,Northwest China

Knowledge of soil carbon(C) distribution and its relationship with the environment can improve our understanding of its biogeochemical cycling and help to establish sound regional models of C cycling. However, such knowledge is limited in environments with complex landscape configurations. In this study, we investigated the vertical distribution and storage of soil organic carbon(SOC) and soil inorganic carbon(SIC) in the 10 representative landscapes(alpine meadow, subalpine shrub and meadow, mountain grassland, mountain forest, typical steppe, desert steppe, Hexi Corridor oases cropland, Ruoshui River delta desert, Alxa Gobi desert, and sandy desert) with contrasting bioclimatic regimes in the Heihe River Basin, Northwest China. We also measured the 87 Sr/86 Sr ratio in soil carbonate to understand the sources of SIC because the ratio can be used as a proxy in calculating the contribution of pedogenic inorganic carbon(PIC) to total SIC. Our results showed that SOC contents generally decreased with increasing soil depth in all landscapes, while SIC contents exhibited more complicated variations along soil profiles in relation to pedogenic processes and parent materials at the various landscapes. There were significant differences of C stocks in the top meter among different landscapes, with SOC storage ranging from 0.82 kg C/m~2 in sandy desert to 50.48 kg C/m~2 in mountain forest and SIC storage ranging from 0.19 kg C/m~2 in alpine meadow to 21.91 kg C/m~2 in desert steppe. SIC contributed more than 75% of total C pool when SOC storage was lower than 10 kg C/m~2, and the proportion of PIC to SIC was greater than 70% as calculated from Sr isotopic ratio, suggesting the critical role of PIC in the C budget of this region. The considerable variations of SOC and SIC in different landscapes were attributed to different pedogenic environments resulted from contrasting climatic regimes, parent materials and vegetation types. This study provides an evidence for a general trade-off pattern between SOC and SIC, showing the compensatory effects of environmental conditions(especially climate) on SOC and SIC formation in these landscapes. This is largely attributed to the fact that the overall decrease in temperature and increase in precipitation from arid deserts to alpine mountains simultaneously facilitate the accumulation of SOC and depletion of SIC.     

西天山雪岭云杉林分密度对森林生物量分配格局和异速生长的影响

雪岭云杉林是新疆天山北坡山地森林中广泛分布的优势种,探讨林分密度对天山雪岭云杉林器官生物量分配格局和树高-胸径异速生长的影响,对于阐明雪岭云杉林生物量在不同环境中的适应具有重要意义.通过分析在不同林分密度(≤300株·hm-2、300～450株·hm-2、450～600株·hm-2、>600株·hm-2)下雪岭云杉林(...