Growth, reproduction and resource allocation of Tithonia diversifolia and Tithonia rotundifolia

Growth, reproduction and resource allocation of the polycarpic Tithonia diversifolia and the monocarpic Tithonia rotundifolia were studied in mixed and monoculture populations. The aim was to identify the characteristics contributing to the invasive habits of these species. Tithonia rotundifolia attained reproductive maturity at 2 months and T. diversifolia 4 months after planting. Tithonia rotundifolia completed its life cycle after 4 months, just as T. diversifolia was starting to flower. Both plant species produced a high number of seeds per capitulum (136–144 seeds in T. diversifolia; 113–120 in T. rotundifolia). Tithonia diversifolia reproduced asexually and sexually and produced many small light seeds. Tithonia rotundifolia produced large seeds, had early rapid growth, short life cycle and high reproductive effort. Growth in mixture did not significantly affect plant height, numbers of branches and leaves, or leaf size, but affected biomass allocation to reproductive and vegetative activities in the species. The attributes contributing to the invasiveness of these species are large seeds, early rapid growth, short life cycle and high reproductive effort in T. rotundifolia, with many small light seeds and asexual and sexual reproduction in T. diversifolia. For both species, control of recruitment would be a means of limiting their invasiveness.     

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。     

河西走廊石羊河流域民勤县水资源优化配置研究

将民勤县的用水部门分为农业、工业、生活、生态四个方面。运用德菲尔结合变异系数法分别得出各部门的综合效益系数为:0.238、0.280、0.209、0.272;代入线性规划目标方程得到三个典型年的不同部门的最优配置方案为(亿m3):枯水年:农业2.222、工业0.1616、生活0.082、生态1.5677;平水年:农业2.223、工业0.1616、生活0.082、生态1.8390;丰水年:农业2.223、工业0.1616、生活0.082、生态1.8394。采用熵变原理验证该方案的可行性。结果表明:生态水量占总水量的38.87％～ 42.72％,远高于现行配置方案的18.92％.将2010与2020年的数据代入计算得熵值分别为3.62、3.49,呈减小趋势,说明方案可行。     

隋唐时期都城选址迁移的资源环境因素分析

通过对隋代大兴城的选址建设及唐末迁都洛阳的资源环境因素的深入分析,表明在隋代关中地区温暖湿润的气候背景下,为了规避不利的灾害风险而移址大兴城;唐朝末年,由于气候转向冷干,为了寻求更好的自然环境和资源条件则迁都洛阳。     

Growth and patterns of resource allocation in Eupatorium odoratum L. in the secondary successional environments following slash and burn agriculture (Jhum)

Biomass, nitrogen, phosphorus and potassium in Eupatorium odoratum L. (Asteraceae), an abundant early successional perennial weed, were studied in seral stages after slash and burn. Increment in individual biomass and nutrient uptake declined with increasing time after fallow. A higher proportion of the available resources was allocated to the supporting organs but a lower proportion to the photosynthetic organ in the older fields compared to recently fallowed fields. The allocation of biomass to reproduction, and also nutrient content, decreased during seral development. However, cost of reproduction to the plants (considered as the proportion of increment in biomass or nutrient uptake during the current growing season) was much higher in the older fields than the younger ones. Growth was adversely affected by low nutrient availability in soil in the recently fallowed fields but the allocation pattern remained unaffected. Biomass was not allocated in the same manner as nutrients. A higher proportion of nitrogen and phosphorus compared to that of biomass and potassium was devoted to reproduction in all the fields.     

Impact of land use chanse on water resource allocation in the middle reaches of the Heihe River Basin in northwestern China

In recent decades, China has been experiencing rapid economic development, population growth and urbanization. These processes have stressed the shortages of water resources in China, especially in the arid re- gions of northwestern China. In order to sustain the expanding cropland, people increased groundwater exploitation in these regions. The purpose of this study was to quantitatively analyze the changes in land use and water re- sources, and their relationship in the middle reaches of the Heihe River Basin, a typical inland river basin in northwest China. The data of land use change were interpreted using aerial photographs(1965) and Landsat TM images(1986 and 2007). The data of irrigation water volume in the irrigation districts were spatialized in the middle reaches of the Heihe River Basin. The spatial variation of the groundwater depth was interpolated using the geo- statistical method. The results showed that the cultivated cropland area along oasis fringe increased by 15.38% and 43.60% during the periods 1965–1986 and 1986–2007, respectively. Surface water amount for irrigation had almost doubled from 1956 to 2010. The decrease of grassland area mainly occurred at the alluvial fan in front of the Qilian Mountains, with 36.47% during 1965–1986 and 38.56% during 1986–2007, respectively. The groundwater depth in front of the mountain constantly increased from 1986 to 2007. We found that the overuse of surface water and overexploitation of groundwater had direct consequences on the natural environments. We suggests that the efficiency of surface water resources use among different irrigation districts needs to be improved, which will sig- nificantly ease the conflicts between increasing water demand for irrigation and a shortage of water resources in the middle reaches of the Heihe River Basin.     

Impact of land use change on water resource allocation in the middle reaches of the Heihe River Basin in northwestern China

In recent decades, China has been experiencing rapid economic development, population growth and urbanization. These processes have stressed the shortages of water resources in China, especially in the arid re- gions of northwestern China. In order to sustain the expanding cropland, people increased groundwater exploitation in these regions. The purpose of this study was to quantitatively analyze the changes in land use and water re- sources, and their relationship in the middle reaches of the Heihe River Basin, a typical inland river basin in northwest China. The data of land use change were interpreted using aerial photographs(1965) and Landsat TM images(1986 and 2007). The data of irrigation water volume in the irrigation districts were spatialized in the middle reaches of the Heihe River Basin. The spatial variation of the groundwater depth was interpolated using the geo- statistical method. The results showed that the cultivated cropland area along oasis fringe increased by 15.38% and 43.60% during the periods 1965–1986 and 1986–2007, respectively. Surface water amount for irrigation had almost doubled from 1956 to 2010. The decrease of grassland area mainly occurred at the alluvial fan in front of the Qilian Mountains, with 36.47% during 1965–1986 and 38.56% during 1986–2007, respectively. The groundwater depth in front of the mountain constantly increased from 1986 to 2007. We found that the overuse of surface water and overexploitation of groundwater had direct consequences on the natural environments. We suggests that the efficiency of surface water resources use among different irrigation districts needs to be improved, which will sig- nificantly ease the conflicts between increasing water demand for irrigation and a shortage of water resources in the middle reaches of the Heihe River Basin.     

水氮耦合对日光温室辣椒生长、光合特性及养分分配的影响

为探究不同灌水量和氮肥施用量对保护地辣椒生长、光合特性及养分分配的影响,为辣椒生产中合理灌水和施用氮肥提供理论依据。试验设置4个氮肥水平,不施肥(F0)为对照,F1、F2、F3依次按氮肥理论利用率的150%、100%和50%进行施肥; 3个基质含水率水平W1、W2、W3分别为基质最大含水率的80%、60%、40%。结果表明,在高水高肥条件下,干鲜重最大值分别为1314.02g、217.89g,株高茎粗最大值分别为193.57cm、19.57mm,均明显高于低水低肥处理;但在低水低肥处理下,辣椒的干物质积累率大于高水高肥处理,对辣椒光合荧光参数的影响主要表现为:在中、高基质含水率水平,施肥处理提高了辣椒的光能利用效率;高肥处理中辣椒的光合参数均比低肥处理中升高15%以上,降低了胞间CO_2浓度(Ci)和非光化学猝灭系数(NPQ),提高了辣椒叶片的光合作用,CO_2同化速率升高;同时,降低了叶片在光合过程中光能以其它形式的耗散。在低水条件下随着施氮量的增加,辣椒光合荧光各指标的变化与中、高基质含水率呈相反趋势。辣椒的养分分配的总体趋势是:在辣椒定植前期(0～60d)各处理辣椒对氮、磷、钾的积累差异不显著。辣椒各器官的钾和除茎外的磷素的积累量逐渐增加,在定植180～210d时积累量达到最大,氮素和茎的磷素先增加后降低。且在整个生育期辣椒各器官对氮、磷、钾素的积累量总体规律一致,大小依次为:果茎叶根,且含量依次为氮钾磷。结论:高水中肥显著促进了辣椒干鲜重、株高茎粗的生长,有利于辣椒叶片的光合和辣椒对氮、磷、钾的吸收和积累;低水高肥处理在前期对辣椒各指标影响不显著,在定植180d以后低水、高肥对辣椒的生长产生拮抗作用增强,该处理的辣椒长势最弱,不利于辣椒植株光合产物和对养分的积累。     

青铜峡市气候资源及气象灾害分布特征分析

分析了青铜峡地区气候资源特点及其优势,给出了主要农作物的生长指标及气象灾害分布特征。并相应提出了合理利用气候资源的途径,开展生态农业建设及防灾减灾的对策措施。     

中国森林公园经营效率及其资源投入冗余分析

基于2004-2013年中国31个省份的面板数据,利用DEA-BCC模型对森林公园的经营效率及其资源投入冗余进行分析。结果表明:森林公园经营效率总体呈年度波动型增长趋势,区域间经营效率的差异较大;纯技术效率对经营效率的影响较大,规模效率在年际间及区域间的变动较小;各地区投入资源冗余情况差异较大,东部地区明显优于其它地区。调整资源投入规模及结构,提高资源配置效率是促进森林公园经营发展的重点。     

内蒙古资源环境要素对经济增长的影响路径研究

资源环境是制约经济增长的重要因素,而效率和创新是驱动经济增长的双轮,资源环境要素通过政府干预实现资源配置与效率的高度匹配是体制完善的重点,科技创新提升资源环境效率是经济增长的着力点,因此,研究资源环境要素对经济增长的影响可以借助政府干预与科技创新。政府干预有利于发挥资源环境要素的配置效率,科技创新有利于提高资源环境要素的利用效率,在节约资源环境要素的基础上推动经济增长。立足于此,文中以内蒙古自治区2003-2014年的调研数据为基础,建立结构方程模型,实证分析内蒙古地区资源环境要素如何通过科技创新与政府干预影响经济增长,研究发现,政府干预、科技创新与资源环境要素本身对经济增长都有一定影响,而内蒙古的经济增长以耗费地区特色资源为代价,本来科技创新对经济增长的直接促进效应为0.20,在资源环境要素的约束下,对经济增长的影响增加到0.30,内蒙古可通过加强资源环境的科技创新促进经济的增长。     

论森林资源与生态安全

森林是人类赖以生存的再生性资源,它不仅为人类提供大量木材和林副产品,还具有改良环境,维持生态平衡的巨大功能,是构建人类和谐社会的基础性产业,对整个生态安全起着致关重要的作用。     

山栏稻资源早期抗旱性评价及抗旱资源筛选

为明确山栏稻抗旱差异性,筛选抗旱性强的资源,采用PEG人工模拟干旱的方法,研究20个山栏稻资源的芽期、苗期抗旱性。结果表明,采用不同的评价指标,资源间的抗旱性排序有所不同;山栏稻资源的抗旱性具有显著差异;芽期、苗期抗性极显著正相关,芽期抗旱性较强的资源有L6、L30、L31、L33,苗期抗旱性较强的资源有L6、L26、L30、L31;采用隶属函数法进行抗旱性综合分级,结果显示山栏稻资源总体抗旱性较强,中抗以上的资源占55%,其中L6、L30、L31几个资源具有强抗旱性,建议在季节性干旱地区推广,同时为抗旱种质创新利用提供参考。     

基于Logit-ISM模型的肉牛养殖户粪污资源化利用行为及影响因素分析——以蒙、黑、吉三省为例

粪污资源化利用是促进畜牧业健康发展实现乡村振兴的重要举措。文中基于335份问卷调查,首先运用Logit模型确定了影响肉牛养殖户粪污资源化利用行为的影响因素,然后运用ISM分析法解析了各影响因素之间的递阶结构。研究结果表明:对肉牛养殖户粪污资源化利用行为影响显著的因素有养殖户的教育水平、风险偏好、声誉诉求、预期收益、耕地情况、养殖规模、饲养方式、养牛收入占比、环保部门的监管、政府宣传以及是否加入了肉牛养殖合作组织。其中,预期收益是影响养殖户行为的表层因素;声誉诉求、风险偏好、环保部门监管、政府宣传以及是否加入了肉牛养殖合作组织是中间层因素;深层因素有养牛收入占比、饲养方式、养殖规模、养殖户的接受教育程度和耕地情况。     

Mycelial growth rate and toxin production in the seed pathogen Pyrenophora semeniperda: resource trade‐offs and temporally varying selection

Pyrenophora semeniperda, an important pathogen in Bromus tectorum seed banks in semi‐arid western North America, exhibits >4‐fold variation in mycelial growth rate. Host seeds exhibit seasonal changes in dormancy that affect the risk of pathogen‐caused mortality. The hypothesis tested is that contrasting seed dormancy phenotypes select for contrasting strategies for increasing pathogen fitness, and that increased fitness on nondormant seeds involves a resource trade‐off between toxin production and growth. The strategy for successfully attacking rapidly germinating nondormant seeds at high inoculum loads in autumn involves increased post‐infection aggressiveness to prevent seed escape through germination. An earlier study demonstrated that slow‐growing strains caused higher mortality than faster‐growing strains on nondormant host seeds at high inoculum loads. In this study, production of the toxin cytochalasin B was significantly higher in slower‐growing strains, and was induced only in seeds or in seed‐constituent‐containing media. Its production was reduced in vivo by Bromus tectorum seeds, suggesting direct involvement in pathogenesis on seeds. Fast‐growing strains caused significantly higher mortality than slow‐growing strains at low inoculum loads on dormant seeds, which apparently have resistance that is overcome at high loads or through rapid mycelial proliferation. In a co‐inoculation study, the fast‐growing isolate produced 3 × more stromata than the slow‐growing isolate on dormant seeds, whereas the slow‐growing isolate was twice as successful on nondormant seeds. These results provide evidence that mycelial growth rate variation and associated variation in cytochalasin B production represent a trade‐off maintained through temporally varying selection resulting from seasonal variation in host seed dormancy status.     

基于HEM的甘肃省2002年土地资源的部门关联效应分析

土地资源是一切资源可持续利用的基础,是社会经济可持续发展的关键。文中在介绍基于假想抽取方法的经济系统部门关联效应分析方法之后,通过引入土地资源转换数,修改部门关联效应分析方法,得到土地资源的部门关联效应各指标,并计算了甘肃省2002年9部门块的土地资源关联效应指标。结果表明:以农业部门为主的部门块1与以邮电运输业构成为主的部门块7,可以向本部门块外的其它部门块转让一定量的土地资源;并且部门块1转让土地资源的潜力较大。农业生产部门在社会经济生产过程是土地资源供给中的关键部门。     

固体水对苗木生长作用效应分析

通过野外和室内不同梯度固体水处理盆栽实验(自然模拟),分析了固体水对苗木生长作用效应,结果表明:固体水可提高苗木根系土壤含水率、苗木成活率、生物量及光合速率、减少蒸腾速率,从而保证苗木良好的生长;从室内不同梯度固体水处理盆栽实验得出,经过两个月连续干旱,维持根系周围土壤的水分含量,从高到低依次为:1000g、750g、500g、250g固体水;环境因子对野外苗木的光合蒸腾速率的影响明显于对室内盆栽苗木光合蒸腾速率的影响;各树种由于其不同的生理生态特征,因而对固体水的适应性不同,这方面内容需进一步研究。     

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(...