The effects of soil organic matter on soil water retention and plant water use in a meadow of the Sierra Nevada,CA          下载免费PDF全文

Kyle J. Ankenbauer  Steven P. Loheide II 《水文研究》2017,31(4):891-901

Tuolumne Meadows is a groundwater dependent ecosystem in the Sierra Nevada of California, USA, that is threatened by hydrologic impacts that may lead to a substantial loss of organic matter in the soil. In order to provide a scientific basis for management of this type of ecosystem, this paper quantifies the effect of soil organic content on soil water retention and water use by plants. First, we show a substantial dependence of soil water retention on soil organic content by correlating Van Genuchten soil water retention parameters with soil organic content, independent of soil texture. Then, we demonstrate the impact of organic content on plants by simulating the degree to which root water uptake is affected by soil water retention with the use of a physically based numerical model of variably saturated groundwater flow. Our results indicate that the increased water retention by soil organic matter contributes as much as 8.8 cm to transpiration, or 35 additional water‐stress free days, during the dry summer when plants experience increased water stress.  相似文献   

Insights into plant water uptake from xylem‐water isotope measurements in two tropical catchments with contrasting moisture conditions          下载免费PDF全文

Jaivime Evaristo  Jeffrey J. McDonnell  Martha A. Scholl  L. Adrian Bruijnzeel  Kwok P. Chun 《水文研究》2016,30(18):3210-3227

Water transpired by trees has long been assumed to be sourced from the same subsurface water stocks that contribute to groundwater recharge and streamflow. However, recent investigations using dual water stable isotopes have shown an apparent ecohydrological separation between tree‐transpired water and stream water. Here we present evidence for such ecohydrological separation in two tropical environments in Puerto Rico where precipitation seasonality is relatively low and where precipitation is positively correlated with primary productivity. We determined the stable isotope signature of xylem water of 30 mahogany (Swietenia spp.) trees sampled during two periods with contrasting moisture status. Our results suggest that the separation between transpiration water and groundwater recharge/streamflow water might be related less to the temporal phasing of hydrologic inputs and primary productivity, and more to the fundamental processes that drive evaporative isotopic enrichment of residual soil water within the soil matrix. The lack of an evaporative signature of both groundwater and streams in the study area suggests that these water balance components have a water source that is transported quickly to deeper subsurface storage compared to waters that trees use. A Bayesian mixing model used to partition source water proportions of xylem water showed that groundwater contribution was greater for valley‐bottom, riparian trees than for ridge‐top trees. Groundwater contribution was also greater at the xeric site than at the mesic–hydric site. These model results (1) underline the utility of a simple linear mixing model, implemented in a Bayesian inference framework, in quantifying source water contributions at sites with contrasting physiographic characteristics, and (2) highlight the informed judgement that should be made in interpreting mixing model results, of import particularly in surveying groundwater use patterns by vegetation from regional to global scales. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

根系水分胁迫响应函数对土壤水及作物生长动态和产量模拟影响的研究     

王铁英  王仰仁  柴俊芳  郭文俊 《干旱区地理》2022,45(2):566-577

为探究根系水分胁迫响应函数对农田水分动态及产量模拟的影响,基于Richards方程和PS123作物生长模型分别进行了土壤水分动态和小麦产量的模拟,对比分析了VG(S型曲线)、MP(凹凸型曲线)及LS(S型曲线)3种水分胁迫响应函数.采用山西省霍泉站(3 a)及潇河站(2 a)的试验资料对模型中的土壤水力特征参数、水分胁...  相似文献   

Responses of water yield and dissolved inorganic carbon export to forest recovery in the Houzhai karst basin,southwest China          下载免费PDF全文

Junhua Yan  Wantong Wang  Chuanyan Zhou  Kun Li  Shijie Wang 《水文研究》2014,28(4):2082-2090

Karst terrain (carbonate rocks) covers a vast land of 0.446 million km² in southwest China. Water yield and carbonate rocks weathering in this region have been receiving increased attention due to a large‐scale forest recovery. Using both hydrological measurements and forest inventories from 1986 to 2007 in the Houzhai karst basin (HKB), we analyzed the responses of water yield and dissolved inorganic carbon (DIC) export to forest recovery in southwest China. With implementation of both the Natural Forest Conservation Program (NFCP) and the Conversion of Farmland to Forests Program (CFFP), the fraction of forest area in HKB was increased from near zero to 18.9% during the study period, but the ratio of total water yield (surface and underground) to precipitation varied very little over the annual period, neither in wet season nor in dry season. By contrast, the concentration of DIC in water, especially in the surface water had a pronounced increase during the study period, with an increase of 0.53 and 0.25 g C m^?3 yr^?1 for surface water and underground water, respectively. As a result, total annual DIC export at mean annual rainfall significantly increased from the low to high forest area stage. This increase was largely driven by surface water during the wet season, presumably being related to biological activity. It was concluded that forest recovery in HKB had no significant effect on water yield, but resulted in more carbon dioxide (CO₂) dissolved in karst water accompanying with carbon uptake by forests. Our results suggested that implementations of both NFCP and CFFP had no shifted water yield regimes in southwest China; instead, they might have alleviated global climate change by increasing carbon uptake through combined biological processes and carbonate rocks weathering. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

中国消费者珠宝消费动机实证分析     

李亚楠  尹作为 《地质科学译丛》2011,(1):37-42

随着国民经济水平的提高和消费观念的转变,中国已成为全球珠宝市场的重要消费国家。利用奢侈品消费动机的相关理论,结合中国的传统文化,对中国消费者珠宝消费动机进行了实证分析。通过因子分析,验证了中国珠宝消费者存在社会导向与个人导向的消费动机,提出并验证了其独有的祈福动机。研究结果表明,有宗教信仰的珠宝消费者其祈福动机更明显,男性比女性更喜欢炫耀,更注重身份的体现;通过单因素方差分析发现,随着年龄的增大和收入的增多,消费者在珠宝消费和佩戴时,更注重炫耀性和身份象征,收入越高的消费者越重视自我感受。这些实证研究为我国珠宝企业的营销策略提供了一定的参考数据和资料。  相似文献   

缘管浒苔和羽藻氮、磷营养生理学研究     

邵魁双  巩宁  李珂  王宗灵  李大成 《海洋学报》2011,33(3):131-139

以无性繁殖系为材料,开展了缘管浒苔和羽藻对NO₃-,NH₄+和PO₄3-的吸收动力学、生长动力学研究。吸收动力学研究结果表明缘管浒苔和羽藻对NO₃- 和PO₄3-的吸收方式为主动运输,对NH₄+的吸收方式为被动扩散。缘管浒苔对NO₃-的最大吸收速率(V_max)、对NH₄+的吸收斜率都大于羽藻,说明缘管浒苔对高浓度的NO₃-和NH₄+具有更强的吸收能力。缘管浒苔吸收NO₃-和NH₄+的a值远大于羽藻,说明在低营养盐浓度时,缘管浒苔对NO₃-和NH₄+的亲和力更强。在PO₄3-的吸收中,羽藻的最大吸收速率(V_max)远大于缘管浒苔,说明羽藻对高浓度PO₄3-的吸收能力更强,但缘管浒苔的a值远大于羽藻,说明前者在低营养盐浓度时PO₄3-的亲和力更强。生长动力学研究结果表明,硝酸氮是促进两种海藻快速生长的最适宜氮源形式,氨氮更易促进藻体叶绿素的积累。在相同氮营养条件下,羽藻表现出比缘管浒苔更强的生长优势。  相似文献   

珠宝与奢侈品关系研究     

张鹏飞  李斌  周琦深  尹作为  包德清 《地质科学译丛》2013,(4):55-63

珠宝与奢侈品的关系尚不明确,珠宝所具有的审美价值、经济价值和稀有性等特征属性是否赋予其成为奢侈品这一问题在珠宝学界和业界没有清晰的定论。从多学科角度研究奢侈品内涵和本质特征并构建奢侈品属性特征的五维度模型,利用该模型比较探讨珠宝与奢侈品的关系,明确珠宝商品属性。通过比较发现珠宝是奢侈品的良好载体,可以直接成为奢侈品。除此之外,为珠宝产品注入奢侈品元素,使更多珠宝产品能够进入奢侈品核心区域。最后,针对目前珠宝产业低水平竞争、产品同质化等难题提出建议。  相似文献   

Inorganic nitrogen acquisition by the tropical seagrass Halophila stipulacea     

Ana Alexandre  Dimos Georgiou  Rui Santos 《Marine Ecology》2014,35(3):387-394

The tropical seagrass Halophila stipulacea is dominant in most regions of the Indo‐Pacific and the Red Sea and was introduced into the Mediterranean Sea after the opening of the Suez canal. The species is considered invasive in the Mediterranean Sea and has been progressively colonizing new areas westward. Growth and photosynthetic responses of H. stipulacea have been described but no information is yet available on the nitrogen nutrition of the species. Here we simultaneously investigated the uptake kinetics of ammonium and nitrate and the internal translocation of incorporated nitrogen in H. stipulacea using ¹⁵N‐labelled substrates across a range of N_i levels (5, 25, 50 and 100 μm ). The ammonium uptake rates exceeded the nitrate uptake rates 100‐fold, revealing a limited capacity of H. stipulacea to use nitrate as an alternative nitrogen source. The uptake rates of ammonium by leaves and roots were comparable up to 100 μm ¹⁵NH₄Cl. At this concentration, the leaf uptake rate was 1.4‐fold higher (6.22 ± 0.70 μmol·g^?1 DW h^?1) than the root uptake rate (4.54 ± 0.28 μmol·g^?1 DW h^?1). The uptake of ammonium followed Michaelis–Menten kinetics, whereas nitrate uptake rates were relatively constant at all nutrient concentrations. The maximum ammonium uptake rate (V_max) and the half‐saturation constant (K_m) of leaves (9.79 μmol·g^?1 DW h^?1 and 57.95 μm , respectively) were slightly higher than that of roots (6.09 μmol·g^?1DW h^?1 and 30.85 μm , respectively), whereas the affinity coefficients (α = V_max/K_m) for ammonium of leaves (0.17) and roots (0.20) were comparable, a characteristic that is unique among seagrass species. No substantial translocation (<2.5%) of ¹⁵N incorporated as ammonium was detected between plant parts, whereas the translocation of ¹⁵N incorporated as nitrate was higher (40–100%). We conclude that the N_i acquisition strategy of H. stipulacea, characterized by a similar uptake capacity and efficiency of leaves and roots, favors the geographical expansion potential of the species into areas with variable water‐sediment N levels throughout the Mediterranean.  相似文献   

组织培养获得的海黍子幼孢子体的营养盐吸收和生长特性的研究     

顾玲玲  张俊涛  刘岩  宫庆礼  李景玉 《中国海洋大学学报(自然科学版)》2014,44(1)

以组织培养间接获得的海黍子幼孢子体为实验对象,研究温度和氮、磷浓度对其营养盐吸收和生长的影响。结果显示,15~30℃范围内幼孢子体均可吸收NO-3-N、NH+4-N和PO3-4-P。25~30℃下NH+4-N的吸收显著高于10~15℃时,而NO-3-N和PO3-4-P的吸收速率在实验温度下差异不显著。NO-3-N、NH+4-N和PO3-4-P的最大吸收速率分别出现在15、25和25℃。当氮浓度3 000μg·L-1时,幼孢子体均可吸收NO-3-N和NH+4-N,且二者均呈现开放型吸收模式。当磷浓度30μg·L-1时,幼孢子体可吸收PO3-4-P,且呈现饱和型模式。温度对幼孢子体的生长影响显著。10~30℃范围内,富含氮磷组和去除氮磷组的特定生长率(SGR)均随着温度的升高先增大后减小,且最大SGR(分别为19.58%·d-1和14.58%·d-1)均在25℃时取得;叶绿素a、c的含量随着温度的升高先减小后增大。氮、磷浓度对幼孢子体的生长影响显著。富含氮磷组的SGR、叶绿素a含量和叶绿素c含量分别在15~25℃、15~30℃和20~30℃范围内显著高于去除氮磷组。  相似文献   

改进的UD模式及其在海洋碳循环中的应用          下载免费PDF全文

陈中笑  刘兆祎 《大气科学学报》2014,37(6):772-779

针对政府间气候变化专业委员会历次报告中"表层—深层"海水间碳通量的差异,利用改进的"上升—扩散"(upwelling-diffusion,UD)模式模拟海洋碳循环状态。除了改进模式结构外,还建立了直接计算海洋溶解无机碳(dissolved inorganic carbon,DIC)δ13C分布的控制方程。区别于目前广泛采用的深度参数的方法,直接利用沉积物捕获器的观测计算分解流量,减少了参数的引用。为更加符合海洋生物地球化学循环,采用地球化学海洋断面研究计划GEOSECS(Geochemical Ocean Sections Study)的海洋磷酸盐分布来标定两个深海动力参数:垂直扩散系数3 000 m2/a和上涌速率3.5 m/a,从而得到温跃层平均深度为860 m,这些参数都在直接观测和其他模式标定的结果之间。通过复原稳定状态下DIC分布并与GEOSECS的观测进行对比,得出自产业革命到20世纪70年代中期的海洋吸收大气CO2约为78 Gt C(Gigatonnes Carbon,1 Gt=1×1015g),与其他的模式估计及观测计算结果相吻合。模式模拟的"混合层—深层"海水间的碳通量为46 Gt C/a,远小于IPCC第四次报告(101 Gt C/a)而与第三次报告(42 Gt C/a)的估算相一致,但仍小于δ13C质量守恒法确定的范围(60~80 Gt C/a)。  相似文献