Effect of rain enrichment on soil respiration of Nitraria sphaerocarpa community in a hyperarid area     

DianJun Liu  Bo Wu  YongHua Li  GuangHui Lin  ShiPing Chen  YaJuan Zhu  Qi Lu  Bin Yao 《寒旱区科学》2013,5(6):0722-0732

In order to analyze the effect of rain enrichment on soil respiration rate of a Nitraria sphaerocarpa community, we measured soil respiration rate in bare and vegetated areas in a hyperarid area （Dunhuang） during the growing season. Results show that rain enrichment can increase bare and vegetated soil respiration rates. The more rainfall enrichment, the greater the increment and the longer duration time effect for soil respiration rate. 200% （16 mm） and 300% （24 mm） of rain enrichment can significantly increase bare soil respiration rates by 90% and 106% （P〈0.01）, respectively. By contrast, areas with 100% （8 mm）, 200% （16 mm） and 300% （24 mm） of rain enrichment can significantly increase shrub area respiration rates by 68%, 157% and 205% （P〈0.01）, respectively. The response time of bare and vegetated soil respiration to rainfall enrichment is asynchronous. Response variable of soil respiration in vegetated soil is higher （118%） than in bare soil. There was significant positive correlation between soil respiration rate and soil water content during the growing season （P〈0.01）. For every 1 mm increment of precipitation, soil respiration rate increased by 0.01 and 0.04 pmol/（m2.s）, respectively in vegetated and bare soils.  相似文献   

3-D voxel-based solid modeling of a broad-leaved tree for accurate volume estimation using portable scanning lidar     

《ISPRS Journal of Photogrammetry and Remote Sensing》2013

We developed a method to produce a 3-D voxel-based solid model of a tree based on portable scanning lidar data for accurate estimation of the volume of the woody material. First, we obtained lidar measurements with a high laser pulse density from several measurement positions around the target, a Japanese zelkova tree. Next, we converted lidar-derived point-cloud data for the target into voxels. The voxel size was 0.5 cm × 0.5 cm × 0.5 cm. Then, we used differences in the spatial distribution of voxels to separate the stem and large branches (diameter > 1 cm) from small branches (diameter ⩽ 1 cm). We classified the voxels into sets corresponding to the stem and to each large branch and then interpolated voxels to fill out their surfaces and their interiors. We then merged the stem and large branches with the small branches. The resultant solid model of the entire tree was composed of consecutive voxels that filled the outer surface and the interior of the stem and large branches, and a cloud of voxels equivalent to small branches that were discretely scattered in mainly the upper part of the target. Using this model, we estimated the woody material volume by counting the number of voxels in each part and multiplying the number of voxels by the unit voxel volume (0.13 cm³). The percentage error of the volume of the stem and part of a large branch was 0.5%. The estimation error of a certain part of the small branches was 34.0%.  相似文献   

基于拓扑一致性的线目标空间冲突检测方法   总被引：2，自引：0，他引：2  

詹陈胜  武芳  翟仁健  朱强  张强 《测绘科学技术学报》2011,(5):387-390

现有的空间冲突检测方法需要将复杂的空间关系与定义的规则相比较.由于规则的不完备性,这些方法容易漏检或误检.为此,首先分析了拓扑冲突的类型和产生原因;然后以线目标间拓扑冲突为例,研究了线目标间拓扑关系的表达与计算、综合前后线目标间对应关系、拓扑关系的一致性评价方法;最后通过对对应的拓扑关系进行一致性检验,来检测已有方法漏...  相似文献   

昆虫多样性：一个被忽略的全球性重要问题     

邹怡  冯金朝  薛达元  桑卫国  Jan AXMACHER 《资源与生态学报(英文版)》2011,(4):380-384

昆虫不仅是世界上最多的物种,同时也对生态系统功能和全球经济有着十分重要的作用。因此,昆虫多样性的保护对全球来说都有着十分重要的意义。然而,昆虫多样性常被＂生物多样性＂研究者们所忽略, 昆虫多样性与植物、气候变化的关系更是不明确。本文对将来昆虫多样性的研究方向提出了几点建议,基于中国北部两大典型的森林生态系统——东北长白山地区和华北东灵山地区。这两大地区的植被和气候已经有长期并且完整的调查,而对于其中昆虫多样性的了解却不多。因此在这两个地区开展研究认识昆虫多样性格局和进一步分析昆虫和植物的关系具有重要的科学和应用价值。  相似文献   

Mechanical shaking and soil water affect the growth of Psammochloa villosa in the Mu Us Sandland     

Y.-H. Wang  M. DongF.-H. Yu  H. JiangS.-Q. Yu  X.-Q. LinW.-M. He 《Journal of Arid Environments》2011,75(10):974-977

The Mu Us Sandland is basically characterized by water shortage and high wind. Thus, wind-induced mechanical perturbation (MP) and soil water availability are likely to interact to affect plant growth. Since high water availability and MP can induce responses that are in the opposite direction, we hypothesized that MP effects on perennial grasses might be mitigated by increased soil water availability in the Mu Us Sandland. We counducted an experiment in which seedlings of Psammochloa villosa were subjected to two levels of MP (non-MP vs. MP 1 min d⁻¹) and two levels of water availability (200 ml d⁻¹vs. 400 ml d⁻¹) and measured three plant traits. MP significantly decreased plant height, total biomass, and root/shoot ratio. There were significant interactions between MP and soil water availability on plant height and root/shoot ratio. These findings imply that MP alone is a stressful factor for P. villosa and MP effects on its growth can be partially mitigated by increased soil water availability, and also suggest that P. villosa may respond to MP in a way that allows plants to survive in the windy semiarid environments.  相似文献   

Late early Oligocene East Asian summer monsoon in the NE Tibetan Plateau: Evidence from a palynological record from the Lanzhou Basin,China     

《Journal of Asian Earth Sciences》2013

The latest Early Oligocene record from the Lanzhou Basin, northeast Tibetan Plateau, presents an opportunity to investigate early stage of the Asian monsoon patterns due to its special location. The record provides insights into the global zonal climate and the development of the non-zonal monsoon system. The study identifies possible links between factors governing the monsoonal patters and paleoaltimetry of the Tibetan Plateau. Sporomorphs results indicate the dominance of arboreal plants (both coniferous and broad-leaved) corresponding to a wetter environment, while xerophytes were rare. Based on the Coexistence Approach (CA), the climate of the Lanzhou Basin is likely to have been similar to that of present-day sites in Southeast China, i.e., characterized by relatively high precipitation and a warm climate. Both qualitative analysis of the sporomorph assemblages and quantitative calculations indicate that monsoons similar to those of the present daywere formed in East Asia and reached the Lanzhou region in inner Asia. High percentages of Picea, generally associated with the relatively high topography of the NE Tibetan Plateau, correlate well with the high paleoaltimetry of the main Tibetan Plateau during the Oligocene. Thus, the East Asian monsoon during this time can be closely linked to an uplifted Tibetan Plateau, following modeled relationships between the Tibetan Plateau and monsoon patterns. However, we believe such high precipitation may have mainly resulted from the orographic barrier, rather than being driven by zonal climate factors. Further investigation into the extent of, and controls on, the region of high precipitation should help clarify the role of these processes.  相似文献   

Kappa (k) derived from accelerograms recorded in the 2008 Wenchuan mainshock,Sichuan, China     

《Journal of Asian Earth Sciences》2013

High-frequency spectral decay factor, kappa (k), in the accelerograms of the Wenchuan mainshock was measured using strong motion data from 52 stations within 311 km of the epicenter. The derived k range from 0.0034 s to 0.0468 s. The correlation of k versus fault distance was given, which is k = 0.01288 + 5.9068 × 10^–5 R for the N-S component, k = 0.01881 + 1.4219 × 10^–5 R for the E-W component, and k = 0.00855 + 5.6086 × 10^–5 R for the U-D component. The analysis on the spatial variation of k demonstrates that k relates to source effect and propagation effect besides local site effect. Ground motions for the 52 stations were simulated using derived k and compared to actual recordings in terms of waveforms, amplitude spectra and response spectra. The results show agreement at shorter periods (<1 s), but a slight overestimation at longer periods (1–7 s).  相似文献   

盘锦湿地芦苇群落冠层内辐射分布特征   总被引：2，自引：0，他引：2       下载免费PDF全文

贾庆宇  周莉  王笑影  周广胜  谢艳兵 《气象与环境学报》2008,24(4):19-22

基于盘锦湿地芦苇群落冠层内不同层次的微气象要素与生物学特性观测,探讨芦苇群落冠层内总辐射分布与叶面积指数(LAI)的关系。结果表明:芦苇群落内太阳辐射的垂直分布在生长前期(5月)和后期(9月)呈S型曲线,生长盛期(6月和7月)呈指数曲线变化。冠层内不同层次的太阳辐射透射率随叶面积指数的增加而减少,消光系数(k)存在明显的季节变化,表现为从萌芽期到成熟期逐渐减小趋势(最小值k=0.436)。  相似文献   

辽宁省人口承载力研究          下载免费PDF全文

赵先丽  周广胜  隋兴华  于文颖  李丽光 《气象与环境学报》2009,25(4):61-65

随着人口的不断增加,资源、环境、人口与发展之间的矛盾日益突出,土地资源能否生产足够的食物供养未来人口的问题受到普遍关注。基于1997—2006年辽宁省10 km×10 km分辨率的气象资料,通过自然植被净第一性生产力模型和农业生产力模型计算了农田、草地和湿地的生产力及其动态。结果表明：近10 a来辽宁省年平均气温呈略下降趋势,年降水量呈增加趋势。1997—2006年辽宁省植被年平均总净第一性生产力为（农田、草地和湿地）3.63×107 t&#8226;yr-1,其中农田、草地和湿地分别为2.18×107 t&#8226;yr-1、0.99×107 t&#8226;yr-1和0.46×107 t&#8226;yr-1。应用人口承载力模型计算出在宽裕型、小康型和富裕型3种消费水平下1997—2006年辽宁省的年平均总人口承载力,分别为2226.9万人、2035.3万人和2015.1万人。  相似文献   

辽宁农田土壤田间持水量的空间变异性分析   总被引：1，自引：0，他引：1       下载免费PDF全文

蔡福  明惠青  张淑杰  陈鹏狮  米娜  周广胜 《气象与环境学报》2009,25(1):27-30

利用常规统计方法、地统计学方法及GIS空间分析技术,分析了辽宁5—50 cm土壤田间持水量的空间变异性。结果表明：10—50 cm各层次土壤田间持水量以辽东地区最大、中部地区次之、辽西地区最小;30 cm以上各层次土壤田间持水量,辽北地区大于辽南地区,而30cm以下则相反;5 cm土壤田间持水量与其他层次差异较大,40 cm和50 cm土壤田间持水量最接近,30 cm有可能是土壤田间持水量的分界层;5 cm土壤田间持水量的空间分布格局与其他层次亦差异明显,存在3个高值中心,分别为辽西西部、中部和辽东地区。10—50 cm土壤田间持水量的空间分布格局基本相似,低值分布在辽西东部和沈阳北部地区,高值中心分布在辽东地区。  相似文献