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1.
高寒草甸植被生产量年际变化及水分利用率状况   总被引:3,自引:3,他引:0  
分析了海北地区高寒草甸植被2001-2011年11 a耗水量、 生物现存量、 净初级生产量、 水分利用率及其相关性, 结果表明: 植物生长期5-9月耗水量416.30 mm, 植被地上净初级生产量(ANPP)、 地下净初级生产量(BNPP)以及总的净初级生产量(NPP=ANPP+BNPP)分别为393.07 g·m-2、 945.26 g·m-2、 1 338.33 g·m-2, BNPP与ANPP之比为2.404. 8月底植被现存生物量达3 422.92 g·m-2, 其中地上和地下现存量分别为411.07 g·m-2、 3 011.85 g·m-2, BNPP与ANPP之比高达7.327, 说明植被现存量巨大, 归还土壤碳能力强. NPP与5-9月植被耗水量相关性很差, 但与5-9月平均气温具有显著的正相关关系, 表明高寒草甸地区水分条件可满足植物生长的基本需求, 而同期温度是影响NPP提高的重要因素. 11 a来BNPP、 ANPP和NPP平均水分利用率分别为0.958 g·m-2·mm-1、 2.326 g·m-2·mm-1和3.284 g·m-2·mm-1, 表明高寒草甸植被净初级生产具有较高的水分利用率.  相似文献   

2.
中国西部植被水分利用效率的时空特征分析   总被引:8,自引:1,他引:8  
卢玲  李新  黄春林 《冰川冻土》2007,29(5):777-784
利用净初级生产力模型C-FIX,陆面过程模型CoLM以及高时空分辨率的遥感数据集,定量估算了2002年西部地区1 km分辨率的水分利用效率(WUE)时空格局分布.模型估算2002年西部地区净初级生产力总量约为0.96 PgC,蒸散发总量约为2 098 km3,整个西部地区平均单位面积上年均WUE约为0.32 gC.mm-1.西部地区WUE时空分布格局具有显著的异质性:WUE最高值区主要分布在新疆西北部的天山和阿尔泰山区域,年均WUE最高可达4 gC.mm-1.m-2;其次为西藏东南隅以及陕西和甘肃南部山区,年均WUE约在1~2 gC.mm-1.m-2之间.WUE最低值广泛分布在青藏高原地区和西北沙漠地区,年均WUE基本在0.4 gC.mm-1.m-2以下.研究发现,西北干旱区内陆河流域荒漠植被呈现出相对高的WUE水平,反映出适度水分亏缺地区的天然植被生态系统可能具有较水分充足地区植被生态系统更高的水分利用效率功能.通过定量分析比较不同植被生态系统WUE特征及其季节变化廓线,得到西部地区主要植被生态系统的年均WUE大小为山区森林>荒漠乔灌丛>灌溉农田>高寒草地>寒漠和戈壁.  相似文献   

3.
张宏 《第四纪研究》1998,18(4):372-372
地带性植被净初级生产力(NPP)的形成除受自身的生物生态学特性制约外,主要决定于环境中热量和水分状况的分配及组合。随着全球变化与陆地生态系统研究的开展,以模型为主要手段预测植被生产力对气候变化响应的研究逐步深入,相继提出了一些利用气候指标或指数估算植被净初级生产力的模型,如Miami模型、Chikugo模型和北京模型等。但利用上述模型无法估算盐化草甸植被等非地带性植被的NPP,因为它们的形成不依赖于大气降水,而主要依靠地下水。由于土壤蒸发能综合反映土壤的水热状况,与NPP的形成关系密切。因此,作者利用以阿维扬诺夫公式计算所得的不同地下水埋深的潜水蒸发与实测的盐化草甸植被净初级生产力数据,拟合了  相似文献   

4.
冻土是冰冻圈要素的重要组成部分,是气候变化最敏感的区域之一,冻土环境变化引起水热条件差异是引发植被生态系统能量交换、水循环和碳循环的重要因素。水分利用效率(WUE)是联系生态系统碳循环与水循环关系的关键,反映了植被生态系统对冻土退化的调整和适应策略。本研究基于MODIS的植被总初级生产力(GPP)和蒸散发(ET)产品,估算并分析了2000—2020年祁连山多年冻土与季节冻土区植被GPP/ET/WUE空间变化特征,并结合自适应帕尔默干旱指数(scPDSI),研究了多年冻土区与季节冻土区植被WUE对干旱的响应。结果表明:2000—2020年祁连山地区植被WUE、GPP和ET的平均值分别为0.56 gC·m-2·mm-1,307.79 gC·m-2和443.02 mm,三者空间分布特征均为东南高、西北低;WUE高于0.8 gC·m-2·mm-1的植被主要分布在季节冻土区,WUE低于0.4 gC·m-2·mm-1的植被主要分布在多年冻土区。近...  相似文献   

5.
郭晓寅  何勇  沈永平  冯丁 《冰川冻土》2006,28(4):512-518
基于EOS/MODIS卫星遥感资料的分析表明,2000-2004年江河源地区陆地植被平均年NPP为82.04 gC.m-2,相当于同期全国陆地植被年NPP的23%,其中2001年的年NPP最小,只有78.04gC.m-2,2002年最大,为85.44 gC.m-2.根据年NPP分布显示,黄河源区的植被生长状况要好于长江源区,其中在黄河源东南部陆地植被的年NPP>250 gC.m-2,为江河源区植被年生长最大的区域;该地区的植被年NPP最小值的区域分布在长江源的西北部地区,年NPP大部分<50 gC.m-2.江河源地区植被的年NPP表现为显著的年际变化特征,不同地区年NPP的变化特征各不相同;高寒草甸的年NPP为该地区所有陆地植被年NPP中最大,其5 a平均值为89.38 gC.m-2,其次为高寒草原和灌木及草本植被;由于地处高寒地区,温度成为影响该地区陆地植被净初级生产力的主要因素.  相似文献   

6.
利用卫星遥感资料和地面气象观测资料,基于CASA模型及其他数理方法估算了浑善达克沙地2000-2013年生长季(4-10月)植被净初级生产力(NPP),并对其时空变化特征进行了分析,讨论了气候因子和人类活动对植被净初级生产力的影响.结果表明:14年间,研究区生长季的植被净初级生产力呈波动中增加趋势,多年平均NPP为239.8 gC·m-2·a-1.整个研究区表现为高NPP值(大于150 gC·m-2·a-1)的植被面积在增加,低NPP值(小于150 gC·m-2·a-1)的植被面积在减少.在空间分布上,研究区的北部、中部和南部边缘区域的植被NPP增加趋势较明显,而东部和西部部分区域未发生明显的趋势性变化.总体而言,研究区植被净初级生产力变化趋势与降水量的关系更密切,其相关系数达到0.86,是驱动植被NPP年际波动的最直接因素.而与温度呈负相关,相关系数为-0.42.综合考虑气候因素和人类活动对沙地NPP的影响发现,温度降低、种饲料面积、年末牲畜存栏头数和羊的数量的减少是NPP值提高的关键因素.  相似文献   

7.
杜灵通  徐友宁  宫菲  丹杨  王乐  郑琪琪  马龙龙 《地质通报》2018,37(12):2215-2223
准确评估大型能源基地矿业开发活动对区域植被生态系统影响具有重要的科学意义和实践价值。利用2000—2017年中分辨率成像光谱仪(MODIS)连续观测的生态系统参量,定量研究宁东煤炭基地开发建设以来的植被生态系统时空变化特征,分析矿业开发对植被生态系统的影响。结果表明,随着宁东煤炭基地开采活动的持续,区域植被生态系统的生产力及其与大气之间的水汽交换强度整体增强,归一化植被指数、总初级生产力、净初级净生产力和蒸散的年增长幅度分别为0.0053、5.10g·C/(m2·a-1)、4.10g·C/(m2·a-1)和6.62mm/a;这4种指标在空间像元上也以增长趋势为主,且未来多数像元有持续增强的特征,但生态系统的水分利用效率却在降低。空间分析表明,大尺度植被生态演变受矿业活动影响微弱,其主要受制于气候和区域性的生态治理工程。  相似文献   

8.
研究了黑河流域下游额济纳荒漠河岸不同立地条件下胡杨(Populus euphratica Olivier)叶片稳定碳同位素组成及水分利用效率的变化特征.结果表明:5个典型样地中,胡杨叶片δ13 C值在(-25.80±0.05)‰~(-29.19±0.05)‰间变化,均值为(-27.70±0.13)‰;就生长季胡杨叶片δ13 C均值而言,沙丘样地具有最高的δ13 C值,其次为戈壁样地,最低值出现在河岸低地.样地间δ13 C值的差异主要是由样地间土壤含水量和地下水埋深的不同导致的;整个生长季胡杨叶片δ13 C值在样地间表现为2种变化趋势.5个典型样地生长季胡杨水分利用效率在(60.41±0.47)~(95.46±0.47)μmolCO2.(mmolH2O)-1间波动变化,其平均值为(75.69±1.37)μmolCO2.(mmol H2O)-1,从水分利用效率波动范围和平均值可以看出,胡杨是个具有高水分利用效率的物种.从河岸低地到河岸沙堆再到戈壁、沙丘,随着土壤含水量逐渐下降,地下水埋深逐渐加深,胡杨逐渐提高了其水分利用效率.  相似文献   

9.
植被退化对高寒土壤水文特征的影响   总被引:11,自引:6,他引:5  
在黄河源冻土严重退化地区,采用选择典型区域和样地进行实验和模型模拟的方法,对不同植被退化特征条件下高寒土壤的水分特征曲线、土壤饱和导水率、土壤入渗及土壤水分进行研究.结果表明:Gradner和Visser提出的经验方程θ=AS-B对该地区土壤水分特征曲线有良好的模拟性;不同植被盖度条件下土壤的饱和导水率和土壤入渗有明显的区别,表层0~10cm范围内,黑土滩的饱和导水率和入渗强度最强,30cm以下土层中土壤饱和导水率、入渗强度以及土壤含水量几乎不受植被的影响.随植被退化表层土壤含水量出现明显降低,退化越严重,水分流失越多,最多时能达到38.6%,植被根系最发达的10~20cm范围的土壤含水量流失对高寒草甸土壤环境影响最大,水分流失导致退化草甸恢复难度较大.通过比较研究,在黄河源地区考斯加科夫(Kostiakov)入渗公式f(t)=at-b更适用于该研究区域高寒草甸土壤水分入渗过程的研究.  相似文献   

10.
青藏高原多年冻土区典型高寒草地生物量对气候变化的响应   总被引:12,自引:3,他引:12  
多年冻土区冻土生态系统对气候变化极其敏感,利用在长江黄河源区实测的高寒草甸和高寒草原植被生物量数据以及青藏高原降水、气温以及地温等的空间分布规律,建立了长江黄河源区高寒草甸与高寒草原等主要高寒生态系统地上与地下现存生物量对气候要素变化的多元回归模型.预测分析表明:如果未来10 a气温增加0.44℃.(10a)-1,在降水量不变的情况下,高寒草甸和高寒草原地上生物量分别递减2.7%和2.4%,如果同时降水量小幅度增加8 mm.(10a)-1,则地上生物量可基本保持现状水平略有减少;在气温增加2.2℃.(10a)-1,在降水量不变的情况下,高寒草甸和高寒草原地上生物量年分别平均减少达6.8%和4.6%,如果同期降水量增加12 mm.(10a)-1,高寒草甸地上生物量可基本维持现状水平略有增加,而高寒草原地上生物量则递增5.2%.高寒草原植被地上生物量对气候增暖的响应幅度显著小于高寒草甸,而对降水增加的响应程度大于高寒草甸.明确高寒草地植被生物量随气候变化的演变趋势,对于青藏高原生态环境保护和研究气候变化对青藏高原生态系统碳循环和河源区水循环的影响具有重要意义.  相似文献   

11.
Net primary production was measured in three characteristic salt marshes of the Ebre delta: anArthrocnemum macrostachyum salt marsh,A. macrostachyum-Sarcocornia fruticosa mixed salt marsh andS. fruticosa salt marsh. Above-ground and belowground biomass were harvested every 3 mo for 1 yr. Surface litter was also collected from each plot. Aboveground biomass was estimated from an indirect non-destructive method, based on the relationship between standing biomass and height of the vegetation. Decomposition of aboveground and belowground components was studied by the disappearance of plant material from litter bags in theS. fruticosa plot. Net primary production (aboveground and belowground) was calculated using the Smalley method. Standing biomass, litter, and primary production increased as soil salinity decreased. The annual average total aboveground plus belowground biomass was 872 g m−2 in theA. macrostachyum marsh, 1,198 g m−2 in theA. macrostachyum-S. fruticosa mixed marsh, and 3,766 g m−2 in theS. fruticosa biomass (aboveground plus belowground) was 226, 445, and 1,094 g m−2, respectively. Total aboveground plus below-ground net primary production was 240, 1,172, and 1,531 g m−2 yr−1. There was an exponential loss of weight during decomposition. Woody stems and roots, the most recalcitrant material, had 70% and 83% of the original material remaining after one year. Only 20–22% of leafy stem weight remained after one year. When results from the Mediterranean are compared to other salt marshes dominated by shrubbyChenopodiaceae in Mediterranean-type climates, a number of similarities emerge. There are similar zonation patterns, with elevation and maximum aboveground biomass and primary production occurring in the middle marsh. This is probably because of stress produced by waterlogging in the low marsh and by hypersalinity in the upper marsh.  相似文献   

12.
Responses ofSpartina alterniflora marsh to combinations of feral horse grazing, clipping, simulated trampling, and a late winter burn were studied on Cumberland Island National Seashore, Georgia. Replicated 200-m2 plots were established and sampled bimonthly from July 1983 to November 1984. Clipping and trampling each reduced peak aboveground biomass by 20% in 1983 and 50% (clipping) and 55% (trampling) in 1984. A March burn reduced peak aboveground biomass by 35% in 1984. Trampling and burning earch reduced net aboveground primary production (NAPP) by 35%, but clipping did not reduce NAPP. Standing stocks of live rhizomes were correlated with aboveground biomass and were reduced with experimental treatments. Abundance of the periwinkle snail (Littorina irrorata) was also reduced. Horse grazing had a substantial impact on standing stocks and NAPP ofSpartina, but grazing was not uniform throughout the marsh. Moderately grazed plots had NAPP reduced by 25% compared to ungrazed plots. Heavily grazed plots had extremely low NAPP, and abovegroundSpartina never exceeded 40 g m?2 dry mass compared to 360 g m?2 within exclosures.  相似文献   

13.
In Louisiana, salt marshes are being created in an effort to offset the large loss of such habitat that has occurred over the last 50 yr. Primary productivity is an important function and indicator of success for salt marsh creation and restoration projects. The aim of this study was to determine whether the aboveground and belowground productivity of the dominant salt marsh grassSpartina alterniflora in created marshes in southwest Louisiana began to approximate productivity levels in natural marshes, over time. Net annual aboveground primary productivity (NAPP) was measured by a harvest technique, while the ingrowth core method was used to estimate net annual belowground primary productivity (NBPP). NAPP levels were similar to those found in other, Louisiana salt marshes, while NBPP levels were similar to or higher than the reported range forS. alterniflora studied along the Atlantic and Gulf of Mexico coasts. NAPP tended to decrease as the created marshes aged, but the levels in the oldest, 19 year old, created marsh were still well above values measured in the, natural marshes. It was estimated that it would take 35 yr after marsh creation for NAPP in the created marshes to become equivalent to that in natural marshes. NBPP in the created marshes became equivalent to levels found in the natural marshes after 6–8 yr, but then belowground production increased with marsh age, reaching an asymptote that surpassed natural marsh levels. Equivalency in primary productivity has not been reached in these marshes. Elevation also affected productivity, as higher elevational sites with greater topographic heterogeneity had significantly lower aboveground and belowground biomass levels than those with elevations closer to mean sea level. This underscores the need to construct marshes so that their mean elevation and degree of topographic heterogeneity are similar to natural marshes.  相似文献   

14.
We examined the effect of nutrients and grazers on Thalassia testudinum in Jobos Bay, Puerto Rico by fertilizing sediment and manipulating grazer abundances. Bottom-up effects were variable: Added nutrients did not increase seagrass aboveground biomass, but decreased belowground biomass—perhaps as a result of less biomass being allocated to belowground structures in response to greater nutrient supply in porewater. Experimental fencing of 1.5 × 1.5 m plots provided shelter that attracted large aggregations of fish, including seagrass herbivores. Seagrass biomass and shoot density decreased with increasing abundance of herbivorous fish, indicating a significant top-down effect. There were interactions between nutrient supply, provision of shelter, and grazing pressure. Fertilization enhanced seagrass %N; however, %N also increased in unfertilized plots that were fenced, most likely due to uptake of N excreted from the large numbers of fish associated with the fences. Only plots where shelter was provided and fertilizer was applied to sediments exhibited evidence of heavy grazing, reducing both seagrass cover and aboveground biomass. In the unfertilized fenced plots, signs of grazing were fewer despite large abundances of fish and enhanced nutritional quality of seagrass leaves. This suggests the possibility that high nutrient availability in sediments lowered concentrations of chemical defense compounds in the seagrass and that cues other than %N may have been involved in stimulating grazing. This study highlights the complexity of bottom-up and top-down interactions in seagrass systems and the important role of refuge availability in shaping the relative strengths of these controls.  相似文献   

15.
青藏高原多年冻土区高寒草甸土壤水分入渗变化研究   总被引:4,自引:3,他引:1  
在多年冻土区典型坡面上,将坡面划分为坡下(L)、坡中(M)和坡顶(H)三个坡位,每个坡位上各选取92%、60%和30%植被盖度为研究对象,用双环入渗仪测定土壤水分入渗过程,对影响土壤入渗过程的环境因子进行了分析,并基于土壤物理特性及土壤水分的测定进行模型模拟。结果表明:研究区不同植被盖度下土壤水分入渗性能在活动层冻融过程中差异明显,初始含水量和初始入渗率具有较好的负相关关系;稳定入渗率大小为:活动层融化期,92%(0.61 mm·min~(-1))60%(0.50 mm·min~(-1))30%(0.29 mm·min~(-1));活动层开始冻结期,60%(0.56 mm·min~(-1))30%(0.39 mm·min~(-1))92%(0.26 mm·min~(-1))。土壤水分入渗速率具有显著的坡位差异并与冻土的冻融循环过程关系紧密。主要表现为,稳定入渗速率随坡位高度的降低依次递减;同一坡位下,开始冻结期入渗速率小于融化期。在整个入渗阶段,坡顶的累积入渗量是最大的,体现了较好的入渗性能。影响高寒草甸土壤水分入渗的环境因子主要有容重,有机质含量及粒径0.1 mm微粒。通过比较研究得出,在长江源地区,活动层融化期通用经验模型f(t)=a+bt~(-n)更适用于该研究区域高寒草甸土壤水分入渗过程的研究,而在开始冻结期Horton模型f(t)=i_c+(i_0-i_c)e~(-kt)则具有更好的适用性。  相似文献   

16.
The monthly variations of below- and aboveground biomass of Spartina alterniflora were documented for a south Louisiana salt marsh from March 2004 to March 2005, and in March 2006 and 2007. The annual production rate above- and belowground was 1821 and 11,676 g m?2, respectively (Smalley method), and the annual production rate per biomass belowground was 10.7 g dry weight?1, which are highs along the latitudinal distributions of the plant’s range. The average root + rhizome/shoot ratio (R&R/S) was 2.6:1, which is lower than the R&R/S ratios of 4 to 5.1 reported for Spartina sp. marshes in the northeastern US. The belowground biomass increased from July to September and fluctuated between October and November, after which it declined until February when the growing season began. The belowground biomass was dominated by rhizomes, which declined precipitously in spring and then rose to a seasonal high in the month before declining again as the late summer rise in inflorescence began. Over half of the root biomass in a 30-cm soil profile was in the upper 10 cm, and in the 10- to 20-cm profile for rhizomes. The maximum March biomass above- and belowground was four to five times that of the minimum biomass over the four sampling years. The net standing stock (NSS) of N and P in live biomass aboveground compared to that in the belowground biomass was about 1.7 times higher and equal, respectively, but the NSS of N and P for the live + dead biomass was about six times higher belowground. The average nitrogen/phosphorous molar ratios of 16:1 aboveground is in agreement with the often tested N limitation of biomass accumulation aboveground, whereas the 37:1 belowground ratio suggests that there is an influence of P on R&R foraging for P belowground. Some implications for management and restoration are, in part, that salt marshes should be evaluated and examined using information on the plant’s physiology and production both below- and aboveground.  相似文献   

17.
塔里木河下游胡杨林耗水数值模型   总被引:1,自引:0,他引:1       下载免费PDF全文
基于SHAW(Simultaneous Heat and Water)模型,以基本观测要素、植被参数和土壤剖面水热观测数据为模型的输入,对河岸胡杨林的耗水过程、土壤剖面水分变化和能通量进行了较小时间尺度上的模拟研究。结果表明,采用SHAW模型模拟的胡杨耗水量与观测值间存在较大偏差。因此,为了进一步提升水热耦合SHAW模型在干旱区的实用性,引入了地下水位因子GSI(Groundwater-Soil water Interaction),建立了改进的SHAW(GSI-SHAW)模型,解决干旱区荒漠河岸林耗水过程模拟的方法问题。采用SHAW模型和GSI-SHAW模型对胡杨耗水量的模拟进行了对比研究。结果显示,SHAW模型和GSI-SHAW模型模拟的胡杨耗水量与观测值的相关性系数分别为0.8533、0.9075,其平均相对误差分别为21.4%、16.9%,可见,改进的SHAW模型的模拟值更加接近试验观测值。地下水位的考虑一定程度上提升了传统SHAW模型的模拟精度,为干旱区自然植被耗水量的计算提供了新的方法和科学依据。  相似文献   

18.
以贵州龙里典型喀斯特地区为例,通过集成RS/GIS技术,利用生态水文评估工具中模块化生态水文综合管理系统(EcoHAT)对研究区绿水资源进行定量模拟,模拟出该区2005年10月-2006年10月像元尺度上绿水资源量,并分析了其绿水资源消耗效用。结果表明:研究区林地、草地、灌丛和农用地单位面积土壤蓄变量月均值分别为5.6mm、6.3mm、6.9mm、7.7mm;林地、草地、灌丛和农用地绿水资源单位面积年有效消耗量分别为:423.0mm、344.2mm、386.7mm、407.5mm,其中低消耗量分别为相应植被类型条件下总有效消耗量的47.0%、48.3%、52.7%、61.3%。在有效消耗量中,农用地低消耗量占较大比重,林地和草地的高效和低效消耗量相近,但草地的低消耗量大于林地。据此,认为贵州龙里典型喀斯特地区绿水资源具有较大的利用潜力。但是在今后的绿水资源利用中,必须加强调控绿水资源消耗效用,增加植被盖度,减少裸地面积,以减少绿水资源的无效消耗量;与此同时,还应调整植被结构,以减少植被棵间土壤的低效消耗量。  相似文献   

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