Dynamics of water usage in Haloxylon ammodendron in the southern edge of the Gurbantünggüt Desert

植物的水分来源是荒漠地区植物水分关系研究的重要方面, 有助于理解荒漠植物对干旱环境的适应。为了研究古尔班通古特沙漠主要建群种梭梭(Haloxylon ammodendron)生长季的水分利用动态, 以及其对发生在不同时期相似量级降水脉冲的响应, 利用稳定性同位素技术测量了梭梭小枝木质部水、降水、0-300 cm不同土层的土壤水和地下水的δ ¹⁸O值。水源依据深度划分为4个: 浅层土壤水(0-40 cm), 中层土壤水(40-100 cm), 深层土壤水(100-300 cm)和地下水。然后, 应用IsoSource模型计算了梭梭对潜在水源的利用比例。结果表明: 4月份, 梭梭主要利用浅层土壤水, 利用比例为62%-95%; 5-9月份梭梭主要利用地下水, 利用比例为68%-100%。梭梭对不同时期发生的两场相似量级的降水具有不同程度的响应。5月22日, 6.7 mm降水后第1天, 梭梭对土壤水的吸收达到最大值, 由降水前的9.8%增长为降水后的40.4%, 同时降低了对地下水的吸收, 由降水前的83%-98%下降为42%-81%。8月31日7 mm降水后, 梭梭对土壤水的吸收没有增加, 仍然保持对地下水的高比例利用, 达71%-98%。低的土壤含水量可能抑制了表层根系的活性, 导致梭梭对降水不敏感。由冬季融雪和春季降水补给的浅层土壤水和地下水是梭梭种群可利用的两个重要水源。梭梭的水分利用动态反映了其对干旱环境的适应。     

What is the optimal number of leaves when measuring leaf area of tree species in a forest community?

植物形态性状叶面积简单易测, 能够反映植物对环境的适应与响应, 指示生态系统的功能与过程。在野外测定叶面积时, 叶片取样数量往往采用约定俗成的10-20片, 但到底采集多少叶片才是最优和最具代表性, 却少有探究。该研究以浙江金华山常绿落叶阔叶混交林的优势树种木荷(Schima superba)与枫香树(Liquidambar formosana)为研究对象, 通过对5个胸径等级植株和每个植株6个方位开展大批量叶片取样(>2 500个), 分析两个树种的叶面积变异特征, 探讨叶片取样数量为多少才能最代表该森林类型的叶片大小性状规律。结果表明, 常绿乔木木荷平均叶面积与变幅均小于落叶乔木枫香树。木荷叶面积与胸径无显著相关性, 而枫香树叶面积与胸径有较显著相关性, 但两个树种均在中胸径等级(15-20 cm)差异不显著; 两个树种的叶面积与采样方位无显著相关性, 但在东、西和底部的差异不显著。因此, 综合考虑代表性与野外可操作性, 叶片采集首选中胸径成树的底部叶片。随机抽样统计可知, 树木叶面积测定的最适叶片采集数量因物种而异, 木荷的最适叶片采集数量为40, 而枫香树最少为170片。因此, 在叶面积测定时, 叶片采集的数量应该不能只局限在10-20片, 在人力、物力和时间等条件允许的情况下, 应该尽可能多地测定较多叶片的叶面积。     

Association classification of a 30 hm2 dynamics plot in the monsoon broad-leaved evergreen forest in Pu’er,Yunnan, China

季风常绿阔叶林是我国南亚热带典型的地带性植被, 建立森林动态监测样地是研究生物多样性维持和群落构建机制的重要平台。该文以普洱30 hm ²森林动态监测样地为研究对象, 采用多元回归树、重要值、主成分分析与指示种相结合的方法对样地内750个样方进行群丛数量分类, 以获取季风常绿阔叶林森林植被群丛类型。结果表明: 森林动态监测样地共发现木本植物271种, 隶属于78科178属, 群落类型为短刺锥(Castanopsis echidnocarpa)群系, 可划分4个群丛类型, 分别是珍珠花+毛银柴-短刺锥+泥柯群丛(Lyonia ovalifolia + Aporosa villosa - Castanopsis echidnocarpa + Lithocarpus fenestratus Association)、云南瘿椒树+耳叶柯-短刺锥+西南木荷群丛(Tapiscia yunnanensis + Lithocarpus grandifolius - Castanopsis echidnocarpa + Schima wallichii Association)、大果杜英+黄药大头茶-短刺锥+西南木荷群丛(Elaeocarpus sikkimensis + Polyspora chrysandra - Castanopsis echidnocarpa + Schima wallichii Association)、西桦+尼泊尔桤木-短刺锥+枹丝锥群丛(Betula alnoides + Alnus nepalensis - Castanopsis echidnocarpa + Castanopsis calathiformis Association)。群丛间物种分布存在较多过渡重叠, 指示物种是区分群丛类型的主要依据, 海拔与坡向对群丛分类有较大的影响, 坡度对群丛分类影响较小。     

Biomass allocation and leaf stoichiometric characteristics in four desert herbaceous plants during different growth periods in the Gurbantünggüt Desert,China

荒漠草本植物是荒漠生态系统物种多样性的主体, 对其生物量分配及叶片化学计量特征随植物生长的变化规律的研究有助于深入了解荒漠草本植物生存策略和功能特征。该文选择古尔班通古特沙漠4种优势草本(2种短命植物, 2种一年生长营养期植物)为研究对象, 通过野外原位多时段取样, 对比研究了四者生物量分配、叶片N-P化学计量学随植物生长的变化特征, 以及二者之间的关系。结果表明, 在生物量累积过程中, 4种植物根冠比逐渐减小, 地上与地下生物量间的相关生长关系也发生变化, 其中琉苞菊(Hyalea pulchella)和角果藜(Ceratocarpus arenarius)的相关生长指数先增加后减小, 并趋于稳定, 而尖喙牻牛儿苗(Erodium oxyrrhynchum)和沙蓬(Agriophyllum squarrosum)的相关生长指数由小到大并趋于等速生长。琉苞菊叶片N、P含量呈逐渐增长趋势, 而另外3种植物呈下降趋势, 表明所研究的荒漠植物在生长过程中, 叶片N-P化学计量发生改变, 叶片化学计量特征与生物量指标的相关性较弱。     

Community characteristics of main vegetation types in the ecological “green-core” area of Changzhutan urban cluster

长株潭城市群生态绿心地区地处南方红壤丘陵区的中心地带, 植被区划上属中亚热带常绿阔叶林北部植被亚地带。该区植被以次生林为主, 植被类型复杂多样, 在南方红壤丘陵区现状植被中具有典型代表性, 可为区域植被演替动态和植被恢复研究提供良好的平台。该研究采用统一、规范的方法设置了50个样方, 对区内主要植被类型的物种组成、数量特征、生境信息等进行调查。计算乔木层、灌木层和草本层物种重要值, 运用《中国植被志》编研规范进行植被类型划分和命名, 描述群落物种组成和特征, 并提供10个植被型、22个群系、33个群丛共50个样方的原始数据, 包括森林样方43个, 灌丛样方5个, 草地样方1个, 沼泽样方1个。     

Effects of groundwater salinity on the characteristics of leaf photosynthesis and stem sap flow in Tamarix chinensis

AimsThe objective of this study was to investigate the change pattern of leaves photosynthesis and stem sap flow of Tamarix chinensisin under different groundwater salinity, which can be served as a theoretical basis and technical reference for cultivation and management of T. chinensis in shallow groundwater table around Yellow River Delta.MethodsThree-year-old T. chinensis, one of the dominated species in Yellow River Delta, was selected. Plants were treated by four different salinity concentrations of groundwater—fresh water (0 g∙L^-1), brackish water (3.0 g∙L^-1), saline water (8.0 g∙L^-1), and salt water (20.0 g∙L^-1) under 1.2 m groundwater level. Light response of photosynthesis and the diurnal courses of leaf transpiration rate, stem sap flux velocity and environment factors under different groundwater salinity were determined via LI-6400XT portable photosynthesis system and a Dynamax packaged stem sap flow gauge based on stem-heat balance method, respectively.Important findings The result showed that groundwater salinity had a significant impact on photosynthesis efficiency and water consumption capacity of T. chinensis by influencing the soil salt. The net photosynthetic rate (P_n), maximum P_n, transpiration rate, stomatal conductance, apparent quantum yield and dark respiration rate increased first and then decreased with increasing groundwater salinity, while the water use efficiency (WUE) continuously decreased. The mean P_n under fresh water, brackish water and salt water decreased by 44.1%, 15.1% and 62.6%, respectively, compared with that under saline water (25.90 µmol∙m^-2∙s^-1). The mean WUE under brackish water, saline water and salt water decreased by 25.0%, 29.2% and 41.7%, respectively, compared with that under fresh water (2.40 µmol∙mmol^-1). With the increase of groundwater salinity from brackish water to salt water, light saturation point of T. chinensisdecreased while the light compensation point increased, which lead to the decrease of light ecological amplitude and light use efficiency. Fresh water and brackish water treatment helped T. chinensis to use low or high level light, which could significantly improve the utilization rate of light energy. The decrease in P_n of T. chinensis was mainly due to non-stomatal limitation under treatment from saline water to fresh water, while the decrease in P_n of T. chinensis was due to stomatal limitation from saline water to salt water. With increasing groundwater salinity, stem sap flux velocity of T. chinensis increased firstly and then decreased, reached the maximum value under saline water. The mean stem sap flux velocity under fresh water, brackish water and salt water decreased by 61.8%, 13.1% and 41.9%, respectively, compared with that under saline water (16.96 g·h^-1). Tamarix chinensis had higher photosynthetic productivity under saline water treatment, and could attained high WUE under severe water deprivation by transpiration, which was suitable for the growth of T. chinensis.     

Storage of carbon,nitrogen and phosphorus in temperate shrubland ecosystems across Northern China

Aims Studying storage of carbon (C), nitrogen (N) and phosphorus (P) in ecosystems is of significance in understanding carbon and nutrient cycling. Previous researches in ecosystem C, N and P storage have biased towards forests and grasslands. Shrubland ecosystems encompass a wide gradient in precipitation and soil conditions, providing a unique opportunity to explore the patterns of ecosystem C, N and P storage in relation to climate and soil properties.
Methods We estimated densities and storage of organic C, N and P of shrubland ecosystems in Northern China based on data from 433 shrubland sites.
Important findings The main results are summarized as follows: the average organic C, N and P densities in temperate shrubland ecosystems across Northern China were 69.8 Mg·hm^-2, 7.3 Mg·hm^-2 and 4.2 Mg·hm^-2, respectively. The average plant C, N and P densities were 5.1 Mg·hm^-2, 11.5 × 10^-2 Mg·hm^-2 and 8.6 × 10^-3 Mg·hm^-2, respectively, and were significantly correlated with precipitation and soil nutrient concentrations. The average litter C, N and P densities were 1.4 Mg·hm^-2, 3.8 ×10^-2 Mg·hm^-2, 2.5 ×10^-3 Mg·hm^-2 and were significantly correlated with temperature and precipitation. The average soil organic C, N and P densities in the top 1 m were 64.0 Mg·hm^-2, 7.1 Mg·hm^-2 and 4.2 Mg·hm^-2, respectively and the former two were significantly correlated with temperature and precipitation. The total organic C, N and P storage of shrublands in Northern China were 1.7 Pg, 164.9 Tg and 124.8 Tg, respectively. The plant C, N and P storage were 128.4 Tg, 3.1 Tg and 0.2 Tg, respectively. The litter C, N and P storage were 8.4 Tg, 0.45 Tg, 0.027 Tg, respectively. Soil is the largest C, N and P pool in the studied area. The soil organic C, N and P storage in the top 1 meter were 1.6 Pg, 161.3 Tg and 124.6 Tg, respectively.     

Interactive effects of ozone and drought stress on plants: A review

Ground-level ozone (O₃) and drought are two key factors limiting plant growth. O₃ can enter into the plant tissue through the stomata, then causing the formation of reactive oxygen species (ROS) which inspires programmed cell death. Drought usually induces the accumulation of ROS due to damage to antioxidant systems of plants. The effects of two kinds of stress on plants are similar due to the accumulation of ROS, resulting in reduced photosynthesis rate and physiological metabolism, eventually decreased plant growth and biomass. Nevertheless, O₃ and drought interacts synergistically to accumulate detrimental effects or antagonistically to reduce harmful effects. Actually, it is complex interactive process between O₃ and drought. On the one hand, O₃ triggers stomatal sluggishness or even dysfunction, which exacerbates water transpiration of leaves, water loss from plants and further O₃ phytotoxicity. On the other hand, drought induces stomatal closure, and thus protecting plants against the O₃ influx and evaporation of water. However, prolonged drought could limit the uptake of CO₂ and thus result in reduced plant growth. The response of plants to both O₃ and drought not only depends on the occurring sequence and duration of any factor but also rely on the difference in physiological metabolism of the plant itself. The interactive effects of O₃ and drought on stomatal characteristics, photosynthetic carbon mechanism, antioxidant response and growth development are reviewed in this paper and the aspects to be further studied are also suggested.     

Effects of streams on lignin degradation during foliar litter decomposition in an alpine forest

AimsStreams are widely distributed in alpine forests, and litter decomposition in which is an important component of material cycling across the forest landscape. The leaching and fragmenting effects as well as the unique environmental factors in streams may have significant impacts on lignin degradation during litter decomposition, but studies on this are lacking.
Methods Using litterbag methods, we investigated the dynamics of lignin mass remaining and concentration (percent litter mass, %) during the decomposition of four foliar litters, which varied significantly in the initial litter chemical traits, from the dominant species of Salix paraplesia, Rhododendron lapponicum, Sabina saltuaria, and Larix mastersiana under different habitats (forest floor, stream, and riparian zone) in the upper reaches of the Minjiang River.
Important findings After two year’s incubation, litter lignin mass remaining for a specific litter species varied significantly (p < 0.05) among habitats, with an order of stream < riparian zone < forest floor. Lignin was degraded substantially in the early stage of litter decomposition process, and the lignin concentration first decreased and then increased with the proceeding of litter decomposition, but varied significantly (p < 0.05) among different litter species. Lignin mass showed a general trend of decrease across the 2-year decomposition course. In addition, habitat type, decomposition period and microenvironmental factors (e.g., temperature, pH value and nutrient availability) showed substantial influences on lignin degradation rate. These results suggest that the traditional view that lignin was relatively recalcitrant with an increase of concentration in the early stage of litter decomposition is challenged, but the loss of lignin in the early phrase is in line with recent findings about the fate of lignin during litter decomposition. Moreover, the significant differences of lignin degradation rates among different decomposition period and habitat types indicated that local-scale environmental factors can play a significant role in litter decomposition and lignin degradation processes.     

Traits related to carbon sequestration of common plant species in a Stipa grandis steppe in Nei Mongol under different land-uses

为了探究植物与固碳相关属性在不同功能群、器官和物种间的差异, 以及这些属性对不同土地利用方式的响应, 2012年8月对内蒙古大针茅草原的4个样地(长期无干扰样地、长期自由放牧样地、4年围封样地和4年围封割草样地)进行了群落调查, 并采集样地中的常见植物, 测定了与植物固碳相关的属性, 包括全碳含量、全氮含量、碳氮比、纤维素含量、木质素含量和酸性洗涤纤维含量等。以常见植物为对象, 在功能群水平研究了各土地利用方式下全碳含量、全氮含量和碳氮比的差异; 针对各样地的共有种——糙隐子草(Cleistogenes squarrosa)、大针茅(Stipa grandis)、冷蒿(Artemisia frigida)、羊草(Leymus chinensis)和猪毛菜(Salsola collina), 从物种和器官水平分析了不同土地利用方式下植物的固碳相关属性。结果表明: 大针茅草原植物不同功能群、物种和器官间的固碳相关属性存在极显著差异, 不同土地利用方式下大针茅草原不同功能型、物种和器官的固碳相关属性有显著差异。与其他利用方式相比, 4年围封割草对植物与固碳相关属性的影响最为明显, 功能群、器官和物种水平的植物氮含量均有下降。糙隐子草和猪毛菜的这些属性对长期自由放牧的响应敏感, 且方向相反。     

Carbon,nitrogen and phosphorus stoichiometry of Myrica nana in Yunnan,China

Aims Carbon (C), nitrogen (N) and phosphorus (P) play important roles in plant growth and physiological functions. We aimed at exploring the intrinsic relationships of C, N and P in Myrica nana—a common shrub in Yunnan Province—as well as their relationships with pant biomass and soil nutrients.
Methods We measured the concentration of C, N and P of M. nana from 29 sites for their magnitudes and correlations with soil nutrients.
Important findings 1) The arithmetic mean value of C, N and P concentration in the roots, stems and leaves of M. nana was 45.94%, 0.54%, 0.03%, and 46.32%, 0.58%, 0.03%, and 49.05%, 1.70%, 0.06%, respectively. C, N and P concentrations in the leaves were significantly higher than those in the roots and the stems. The C:N:P in roots, stems and leaves was 1531:18:1, 1544:19:1, and 818:10:1, respectively. 2) The C concentration and N:P in leaves of M. nana decreased with the increase of biomass of M. nana; the leaf C concentration was significantly correlated with biomass (p < 0.01), while the correlation between N:P and biomass was not significant (p > 0.05). The leaf N increased with the increase of plant biomass, the P was significantly correlated with biomass (p < 0.05), but the correlation between N concentration and biomass was not significant (p > 0.05). N:P in leaves was 34.2, suggesting that plant growth was limited by P. 3) C, N and P concentration in the roots were significantly correlated with soil P (p < 0.05), with N, P concentrations correlated with soil P positively (p < 0.01) and C negatively (p < 0.05). C concentration in the stems was significantly and negatively correlated with soil C, N, with significant correlation with C, N, and P concentration (p < 0.01). P concentration in the stems was significantly and positively correlated with soil P concentration (p < 0.01), while leaf P significantly and positively correlated with soil C, N and P (p < 0.01); leaf C concentration was significantly and negatively correlated with soil P (p < 0.01).     

Diversity of climbing seed plants and their reproductive habit in a karst seasonal rain forest in Nonggang,Guangxi, China

Aims Diversity of climbing seed plants and their reproductive habits and characteristics are central for the understanding of community structure and dynamics of forests and hence are important for forest protection. However, little is known about the climbing seed plants in northern tropical karst seasonal rain forests. Here, using the data of the species diversity and reproductive habits of climbing seed plants in Nonggang, Guangxi, China, we aim to 1) explore the species diversity and distribution of climbing seed plants in northern tropical karst seasonal rain forests, 2) study the flowering and fruiting phenology and 3) the associations of reproductive characteristics to the environment. Methods Species composition, preferred habitat, flowering time, fruiting time and fruit types of climbing seed plants were surveyed. The seasonality of flowering and fruiting were analyzed by concentration ratio and circular distribution. Climbing seed plants were divided into three groups according to their growth forms and places in spatial forest structure: bush ropes, herbaceous vines and lianas. Monthly flowering ratios, fruiting ratios, fruit types and their ratios in different groups were determined. These relationships of flowering ratio, fruiting ratio, fruit type and its ratio to meteorological factors were investigated using Pearson correlation analysis. Important findings There were a total of 333 species of climbing seed plants in Nonggang karst seasonal rain forest, belonging to 145 genera and 56 families. Bush ropes, herbaceous vines and lianas contained 119, 88 and 126 species, respectively. At species level, herbaceous vines were more abundance in valleys, while bush ropes and lianas were more abundance on slopes. Flowering and fruiting of climbing seed plants occurred seasonally, with flowering peaking in April to September, while fruiting peaking in July to December. The seasonality of flowering and fruiting in bush ropes was weaker than in herbaceous vines and lianas. Flowering ratio was significantly positively correlated with rainfall and air temperature, which suggest that flowering peaks in monsoon season. Peak time for fruiting was about three months later than the peak time of flowering, around the end of monsoon season. The ratio of samara species to all fruiting species in lianas was significantly positively correlated with wind speed, but negatively correlated with rainfall and air temperature. It showed that samara in lianas tended to occur in dry season with high wind speed. In conclusion, species diversity and the seasonal features of reproduction of climbing seed plants in Nonggang karst seasonal rain forest were closely related to the spatial and temporal variations of habitat resources.     

A new angiosperms molecular specimen treatment method for field use

Aims This study aims to identify a more convenient drying method for obtaining molecular specimen of angiosperms in the field than the conventional silica gel drying method. Methods The leaves of Prunus serrulata var. lannesiana and Liriope spicata were dried under temperatures of 150 °C, 80 °C, 40 °C as well as under natural conditions, and by the silica gel drying method, respectively. The DNA extracts of various specimens were then analyzed using techniques of spectrophotometer detection, electrophoresis and PCR to evaluate the impacts of different drying treatments to the genomic DNA of testing plants. Important findings The concentrations of total DNA were higher for the specimens dried at 40 °C treatment and by the silica gel drying method than other treatments when assessed by the techniques of spectrophotometer detection and electrophoresis. The concentration of PCR products was highest in the specimens dried at 40 °C. Based on the results, the 40 °C drying can be recommended for obtaining molecular specimens of angiosperms because of its minimum degree of degradation, for convenience of operation and avoiding carrying large amounts of silica gel in field investigations.     

22年来西北不同类型植被NDVI变化与气候因子的关系

 为了研究气候变化对西北地区不同类型植被的影响,利用NASA GIMMS 1982～2003年逐月归一化植被指数（Normalized difference vegetation index, NDVI）数据集和西北地区138个气象站点同期的气温和降水资料,计算了各站22年月平均气温和降水与NDVI的相关系数。同时, 选西北 地区森林、草原、绿洲和雨养农业4类有代表性的植被类型为研究区,对各类植被NDVI与气温和降水的相关关系进行分析。研究结果表明：除无 植被的戈壁沙漠地区外,西北地区NDVI与气温和降水均有较好的相关性。除祁连山中部地区外,西北地区NDVI与气温的相关系数大于降水。天 山、阿尔泰山和秦岭的NDVI与气温相关系数最高,而青海东北部NDVI与降水相关系数最高。西北地区各种类型植被对气候变化反映敏感。其敏 感度因植被类型不同和同类植被所处的地理位置不同而有差异;纬度较高的新疆林区与温度相关性最高,高寒草甸次之。在植被生长最旺盛的 夏季（6～8月）,22年来西北地区各林区的NDVI均呈下降趋势。其中西北东部林区下降趋势显著,与这些地区的降水减少和气温增加有关。草 原区植被以上升趋势为主,高寒草甸和盐生草甸上升趋势最为显著,气温升高是这些地区植被生长加速的原因 之一。西北绿洲是NDVI增加极为 显著的地区,以新疆绿洲NDVI上升趋势最大。气候变暖是近年绿洲NDVI增加的主要驱动力之一,绿洲面积扩大、种植结构调整和种植品种变化 等人为因素对绿洲NDVI增加的作用不可忽视,这种作用在新疆表现的尤为突出。雨养农业区NDVI年际 间波动较大,各区域间变化不太一致。 NDVI的波动与降水变化有很好的正相关,与气温变化有很好的负相关,近年来西北东部气温升高和降水的减少是雨养农业区NDVI下降的原因, 农业措施的实施也改变了植被生长对气候条件的依赖性。     

水曲柳落叶松根系之间的相互作用研究

 通过水曲柳(Fraxinus mandshurica)和落叶松(Larix gmelinii)两个树种苗木纯栽和混栽试验,在温室条件下研究两树种根系之间的相互作用。结果表明,水曲柳与落叶松混栽使水曲柳细根和粗根生物量比纯栽分别增加47％和46％,叶和茎生物量分别增加30％和48％,同时改变了水曲柳地下部分与地上部分比率,促进了水曲柳细根和叶协调生长。而混栽的落叶松细根和粗根生物量比纯栽分别减少19％和35％左右,叶和茎生物量减少22％和34％,但是落叶松地下部分和地上部分各生物量组分变化不存在显著差异。混栽改变了水曲柳根系的空间分布和根系的形态,导致根系密度和根长度分别增加47％和34％,有利于水曲柳吸收较多的养分和水分,提高其竞争效率。落叶松起到改变土壤环境作用。     

Effects of calcium fertilizer on yield,quality and related enzyme activities of peanut in acidic soil

AimsPeanut (Arachis hypogaea) is one of the calcium (Ca)-like crops. In acidic soil, low soil exchangeable Ca²⁺ content, which usually is caused by eluviation, can affect peanut pod development, even causes pod unfilled. The objective of this study was to investigate the effects of calcium fertilizer on yield, quality and related enzyme activities of peanut in acidic soil.Methods ‘Huayu22’ was used as materials, and field experiments were conducted in Wendeng, Weihai (2013) and Sanzhuang, Rizhao (2014), respectively. Three treatments were carried out, i.e. No Ca-application (T₀), 14 kg·667 m^-2 fused CaO (T₁) and 28 kg·667 m^-2 fused CaO (T₂). Top 3rd leaves of main stems were harvested to determine the activities of carbon and nitrogen metabolism enzyme every 15 days from anthesis to mature period. Additionally, the pod traits and yield were investigated at harvest time. Uniform dry pods were used to determine the quality of kernel.Important findings Application of calcium fertilizer significantly increased the pod yield of peanut in acid soil. Yield of T₁ treatment increased by 26.92% and T₂ increased by 21.65% on average at two sites. It might be related to higher pod numbers per plant, higher double kernel rate, and higher plumpness of kernel under T₁ and T₂ treatment than under T₀ treatment. Simultaneously, application of calcium fertilizer also significantly increased the protein and fat content of peanut in acidic soil. The protein content increased 2.02% and the fat content increased 3.01% on average in T₁ treatment, respectively. The protein content increased 1.56% and the fat content increased 2.58% in T₂ treatment, respectively. Additionally, Calcium fertilizer not only improved the lysine and total amino acid content but also improved oleic/linoleic acid (O/L) ratio of peanut in acidic soil. These might be due to higher activities of glutamine synthetase (GS), glutamate synthetase (GOGAT) and glutamate pyruvate transaminase (GPT) in the leaves of peanut in acidic soil under T₁ and T₂ treatments than under T₀ treatment. What’s more, the activity of GS of peanut treated with T₁ was higher than that treated with T₂. Application of Calcium fertilizer also improved the activities of phosphoenolpyruvate carboxylase (PEPCase), sucrose synthase (SS) and sucrose phosphate synthase (SPS) of peanut at early growing period, but the activities at late growth stage were lower than T₀ treatment. Our results demonstrate that the economic performance of 14 kg·667 m^-2 fused CaO was the best one among these three treatments applied.     

西双版纳土地利用/覆盖变化与地形的关系

 土地利用/覆盖变化是全球变化研究的重要领域。该文利用6个时期的MSS/TM/ETM影像和1:50 000DEM数据分析了1976~2007年西双版纳地区不同地形下的土地利用/覆盖变化动态, 结果表明: 1)31年间, 该区土地利用/覆盖变化剧烈, 有林地面积由1976年的69.0%下降到2007年的43.6%, 橡胶园面积由1976年的1.3%增加到2007年的11.8%; 2)有林地在海拔1 600 m以下不断减少, 而橡胶园的海拔分布上限则持续增加, 由1976年的1 000 m上升至2007年的1 400 m, 面积在400~1 000 m处占优。农业用地主要分布在海拔400～600 m, 在600 m之上迅速减少; 3)各坡度带上的有林地面积逐年减少, 橡胶园则逐年增加, 而灌木林与旱地则先升后降; 橡胶园、农业用地等主要分布在坡度较缓的区域, 坡度越大, 有林地越多; 1988年后, 橡胶园面积在坡度5°以下基本保持不变, 但在坡度大于5°的区域持续扩张; 4)坡向对橡胶园与农业用地等分布的影响较大, 南坡的橡胶发展最为迅速, 且有向北坡发展的趋势。有林地在北坡分布比例较大, 旱地在北坡分布比例较小。人口增加与橡胶园和茶园等经济种植园的不断扩展是导致西双版纳土地利用/覆盖变化的直接因素。要实现西双版纳的可持续发展, 必须控制经济种植园的盲目扩张, 科学合理垦殖, 保护热带森林。     

EFFECTS OF LONG-TERM SUBMERGENCE ON SURVIVAL AND RECOVERY GROWTH OF FOUR RIPARIAN PLANT SPECIES IN THREE GORGES RESERVOIR REGION, CHINA

 地瓜藤(Ficus tikoua)、荻(Triarrhena sacchariflora)、牛鞭草(Hemarthria altissima)和狗牙根(Cynodon dactylon)是三峡库区常见的岸生植物, 自然分布于河岸带不同垂直高程的地段。为了明确它们在成库后“三峡库区消落区”长期完全水淹条件下的存活和生长情况, 实验设置对照(不进行水淹, 常规供水管理)和完全水淹两个处理, 30、60、90、120、150和180 d 6个水淹时间水平, 研究了4种植物在完全水淹条件下的存活、生物量变化和恢复生长。结果发现: 1) 4种植物在完全水淹条件下的存活率与其在河岸带上的垂直分布高程密切相关。分布于距江面高程较高的河岸段的地瓜藤植株, 在全淹30 d后就全部死亡; 分布在中高程河岸段的荻在全淹150和180 d后全部死亡; 可以分布于低高程河岸段的牛鞭草和狗牙根, 淹没180 d后存活率分别为90%和100%。2)全淹抑制了荻、牛鞭草和狗牙根的生长, 总生物量增量显著低于对照植株。与水淹0 d相比, 全淹处理植株的地上部分生物量显著降低, 荻在全淹60和120 d后, 地下部分生物量显著降低, 但牛鞭草和狗牙根的地下部分生物量与水淹0 d水平相比无显著差异。3)水淹处理结束后, 存活的荻、牛鞭草和狗牙根植株都能很好地恢复生长。在恢复生长过程中, 全淹30、60和90 d后, 荻、牛鞭草和狗牙根植株的总分枝长相对生长速率与对照植株无显著差异, 全淹120、150和180 d后, 牛鞭草和狗牙根植株的总分枝长相对生长速率显著高于对照植株。全淹处理的荻、牛鞭草和狗牙根植株的总叶片数相对生长速率始终显著高于对照植株。遭受长期完全水淹后, 植株在有限的营养储备条件下, 快速产生叶片以迅速积聚光合产物可能是植物更为优化的恢复生长方式。     

Fine root production of Pinus massoniana plantation and Castanopsis carlesii plantation at different successional stages in subtropical China

AimsOur objectives were to determine differences in fine root production, its relationships with environmental factors, and its diameter- and depth-related distribution patterns between plantations of two subtropical tree species differing in successional stages. MethodsPlantation forests of an early-successional species, Pinus massoniana, and a late-successional species, Castanopsis carlesii, in Sanming, Fujian Province, were selected. Fine root production was monitored for two years using minirhizotrons methods. At the same time, environmental factors including monthly air temperature, monthly precipitation, soil temperature, and soil water content were determined.Important findings 1) During the two years, there was significant difference in annual fine root length production between these two forests, with annual production of P. massoniana plantation nearly four times that of C. carlesii plantation. Fine root length production under both forests showed significant monthly dynamics and maximized in summer, a season when most of fine roots were born. 2) Roots of 0-0.3 mm in diameter accounted for the largest proportion of total fine root length production. Fine roots were concentrated mostly at the 0-10 cm soil depth in P. massoniana plantation, but happened mostly at the 30-40 cm soil depth in the C. carlesii plantation. 3) Partial correlation analysis suggested that, monthly fine root production of both forests was significantly correlated with both air temperature and soil temperature, while it had no significant correlation with either rainfall or soil water content. Linear regression analysis illustrated that monthly fine root production was more correlated with air temperature and soil temperature in the P. massoniana plantation than in the C. carlesii plantation. It was concluded that fine root production in the early-successional P. massoniana plantation was not only much higher in amount, but also more sensitive to temperature, than that in the late-successional C. carlesii plantation.     

The relationship between the reduction of nonstructural carbohydrate induced by defoliator and the growth and mortality of trees

Large scale herbivorous insect outbreaks can cause death of regional forests, and the events are expected to be exacerbated with climate change. Mortality of forest and woodland plants would cause a series of serious consequences, such as decrease in vegetation production, shifts in ecosystem structure and function, and transformation of forest function from a net carbon sink into a net carbon source. There is thus a need to better understand the impact of insects on trees. Defoliation by insect pests mainly reduces photosynthesis (source decrease) and increases carbon consumption (sink increase), and hence causes reduction of nonstructural carbohydrate (NSC). When the reduction in NSC reaches to a certain level, trees would die of carbon starvation. External environment and internal compensatory mechanisms can also positively or negatively influence the process of tree death. At present, the research of carbon starvation is a hotspot because the increase of tree mortality globally with climate change, and carbon starvation is considered as one of the dominating physiological mechanisms for explaining tree death. In this study, we reviewed the definition of carbon starvation, and the relationships between the reduction of NSC induced by defoliation and the growth and death of trees, and the relationships among insect outbreaks, leaf loss and climate change. We also presented the potential directions of future studies on insect-caused defoliation and tree mortality.