1981-2001年内蒙古草地净初级生产力时空变化特征

利用遥感和气象数据,采用CASA(Carnegie Ames Stanford Approach)模型和统计分析方法,研究了1981-2001年内蒙古自治区草地7-8月植被净初级生产力(net primary productivity, NPP)的时空变化特征,并分析了气候因素和放牧强度对NPP的影响。结果表明,1）1981-2001年,内蒙古草地NPP显著减少、显著增加和变化不明显的面积分别占1%、30%和69%;NPP显著增加的区域位于内蒙古东北、东南和南部,NPP显著减少的区域零星分布于该区中部荒漠草原和典型草原分界处。总体而言,该区NPP增加不甚明显, 21年7-8月草地NPP（均以C变化计）平均值为192.0 g/m2,年际变化范围为150.5～255.5 g/m2。2）7-8月降水是该区NPP年际变化的主要驱动因子,降水量高的年份NPP亦高。NPP与气候因素间的关系表现为NPP随降水增多而升高,随温度升高而下降,辐射对NPP的影响不明显。3）综合考虑气候因素与人类活动对草地NPP的影响发现,21年间,土默特左旗和土默特右旗境内放牧强度增加导致NPP显著下降。     

1999-2012年三江源区植被净初级生产力及固碳释氧量测评

[目的]估算近14 a三江源地区植被净初级生产力(net primary productivity,NPP)以及固碳释氧量,为河源区的生态环境建设以及制定碳减排与碳增汇政策提供科学依据.[方法]基于遥感、气象、土地等数据,通过CASA模型、碳排放模型、Sen+ Mann-Kendall模型,分析三江源地区植被NPP及其固碳释氧量的时空变化特征.[结果](1)三江源区植被NPP单位面积多年均值主要集中在0～750 g/(m2·a)之间,约占研究区81.72%;空间分布特征呈东南—西北递减规律,高值分布在海拔较低、河流密集以及林地地区,而高寒地区NPP值相对较低.(2) 1999-2012年研究区NPP物质量年际变化呈增加趋势,增速约为7.26 g/(m2·a),没有通过0.05显著水平检验;年际变化空间特征中,约23.64％呈下降趋势,其中通过0.05置信水平者约占2.3％,主要分布在人类活动较频繁的地区;在受人类活动影响较少且水资源丰富地区呈增加趋势,约占研究区的76.36％,其中30.58％通过0.05置信水平检验.(3)固碳释氧物质量变化中,耕地变化幅度较大,其次是林地和其他用地,牧草地变化波动性较小.与人类活动因素有关,人为因素作用越明显,其变化幅度就越大,反之亦然.[结论]三江源高寒牧草地生态总体改善较好,受人类影响较少,而在海拔较低、河流密集以及人类活动频繁地区生态变化相对较复杂,局部地区存在退化现象,需要进一步加强该地区的生态环境保护建设.     

区域农田有机物质投入量的估算方法 —— 以陕西长武县为例

以黄土高原典型沟壑区长武县为研究区域,进行区域农田有机物质投入量估算方法的研究。将农田有机物质投入分为秸秆还田、秸秆根茬残留、作物地下生物量和有机肥4个部分分别进行估算。基于LANDSAT 5卫星遥感资料,利用CASA模型估算植物第一净生产力,获得作物整株重,结合作物根冠比估算作物地上生物量和地下生物量,以地上生物量和实地秸秆调查来估算秸秆根茬量和秸秆还田量。估算结果显示,长武县农田年总有机物质投入量为42 700 t。     

基于CASA模型的海河流域生物量估算及特征分析

生物量估算研究有助于寻找陆地植被从大气中固定碳的数量及影响其时空分布的驱动因子,在此基于CASA（Carnegie AmesStanford Approach）模型,结合遥感数据和匹配的温度、降水、太阳辐射资料以及全国1∶400万植被图,估算海河流域2002 ～ 2007年的生物量,并以2007年为例分析了不同植被类型、不同植被覆盖度的生物量差异以及生物量随季节变化特征和空间分布.结果表明,CASA模型适用于海河流域生物量研究;6年来,海河流域年均生物量总量为405.5 Tg;海河流域的年生物量分布呈东南高西北低的趋势,平原生物量＞山区生物量＞高原生物量.     

Ovarian fluid pH enhances motility parameters of rainbow trout (Oncorhynchus mykiss) spermatozoa

All evidence to date suggest that sperm motility is the primary determinant of fertilization success in externally fertilizing fish species. Ovarian fluid, which comprises 10–30% of the total egg volume in salmonids, enhances sperm motility with respect to swimming speed, trajectory and the duration of movement. It was recently demonstrated that there is individual variability in sperm motility enhancing potential of ovarian fluid of particular females. In the present study we examined the effect of particular ovarian fluids collected from 31 females on the sperm motility parameters of one male of rainbow trout (Oncorhynchus mykiss) using computer-assisted sperm analysis (CASA). During our experiment we also monitored the pH of ovarian fluid. We found that particular fluids differed in the ability to activate spermatozoa; sperm remained immotile in four fluids and exhibited 50–100% motility in 27 samples. The percentage of motile sperm, velocity and duration of movement positively correlated with ovarian fluid pH (r² = 0.34–0.62). These data strongly suggest that the pH of the ovarian fluid is the primary determinant of sperm motility in rainbow trout under natural conditions of fertilization.     

Effects on boar semen quality after infection with porcine reproductive and respiratory syndrome virus: a case report

The effect of porcine reproductive and respiratory syndrome virus (PRRSV) on semen quality was examined in a group of 11 spontaneously infected boars in a commercial boar stud. Semen samples were collected 4 weeks prior to 4 weeks post-infection (wpi). Infection with PRRSV of the European genotype subtype 1 (EU-1) was verified by specific quantitative real-time polymerase chain reaction (RT-PCR) in 36% of the serum samples. All boars seroconverted before 4 wpi and remained in normal condition throughout the study. Comparison of the percentage of morphologically intact spermatozoa revealed an increase of acrosome-defective spermatozoa (P = 0.012) between −4 and 4 wpi. Significant deleterious effects on semen quality were detected for membrane integrity when semen had been stored for 2 days after sampling. Analysis of sperm subpopulations in a thermoresistance test on day 7 after sampling revealed alterations in the percentage of circular, progressively motile spermatozoa (P = 0.013), in the percentage of non-linear, progressively motile spermatozoa (P = 0.01), and on the amplitude of lateral sperm head displacement (P = 0.047). There was no difference in the incidence of mitochondrially active spermatozoa (P = 0.075). Investigation of routine production data between pre- and post-infection status showed no differences on ejaculate volume (P = 0.417), sperm concentration (P = 0.788), and percentage of motile spermatozoa (P = 0.321). This case report provides insights into a potential control strategy for PRRSV outbreaks in boar studs.     

Effect of BAPTA-AM on Thawed Stallion Spermatozoa Extended in INRA 96 or Tyrode's Medium

We studied the effect of 1,2-bis-(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid, tetraacetoxymethyl ester (BAPTA-AM) on the outcome of cryopreservation of stallion spermatozoa and whether reextension of thawed sperm in a more physiological and Ca²⁺-containing medium might improve the characteristics of thawed stallion spermatozoa. Individual ejaculates from six stallions were collected and split into three subsamples. The first two samples were supplemented with the membrane-permeable Ca²⁺ chelator BAPTA-AM at final concentrations of 5 and 10 μM, respectively, while the third subsample served as control. After 4 weeks of storage, samples were thawed in a water bath at 37°C and evaluated using flow cytometry and computer-assisted sperm analysis (CASA). In a second experiment, in order to determine whether restoring Ca²⁺ could improve sperm quality after cryopreservation, thawed semen was washed by centrifugation and resuspended in Tyrode's complete medium. BAPTA-AM supplementation did not modify the outcome of cryopreservation; however, changing the spermatozoa from INRA 96 to Tyrode's complete medium resulted in significant improvements in the percentages of live sperm and total motility post thaw.     

Development of a fluorescent computer‐assisted spermatozoal quantification method and a comparison of results for manual counting with a haemocytometer and computer‐assisted semen analysis in dogs

The aim of this study was to develop and validate a novel, computer‐assisted spermatozoal quantification (CASQ) method of determining spermatozoal concentration in canine semen. In Experiment A, the spermatozoal concentration was measured (n = 28) with a haemocytometer using light microscopy, CASQ and computer‐assisted semen analysis (CASA; MMC sperm), following three independent dilutions. The limits of agreement between the haemocytometer and CASQ were ?13.1% to 13.8% and ?27.0% to 28.6% between the haemocytometer and CASA. The precision CVs (limits of agreement) were 5.7% (?7.8% to 8.9%) for the haemocytometer, 6.2% (?8.8% to 12.3%) for CASQ and 10.8% (?16.0% to 19.5%) for CASA. In Experiment B, spermatozoa were manually counted (n = 42) with the haemocytometer under fluorescent illumination using the CASQ sample. The limits of agreement between the CASQ and the haemocytometer were satisfactory (?4.6% to 4.6%) and the precision CVs (limits of agreement) were 6.2% (?9.0% to 11.4%) for the haemocytometer and 4.4% (?5.8% to 8.6%) for CASQ. The CASQ method was then clinically applied to compare the haemocytometer (light and fluorescent methods) with CASQ and CASA. Outlying data were removed. These studies demonstrated that CASQ was reliable and that the MMC sperm CASA was unreliable as methods for determining spermatozoal concentration in canine semen. Computer‐assisted spermatozoal quantification was also determined to be more precise than manual counting with the haemocytometer. Using the clinical protocol, the agreement between the haemocytometer and CASQ method was acceptable, but it was worse than in the experiments where duplicate samples and a larger volume of semen were analysed. The CASQ method may be a useful method to measure the membrane status of canine spermatozoa; however, further investigation is required. Counting spermatozoa using fluorescent microscopy and the haemocytometer may improve the efficiency of counting and the accuracy of the method.     

基于CASA模型和MODIS数据的甘南草地NPP时空动态变化研究

植被净初级生产力(net primary productivity, NPP)在全球气候变化及碳循环研究中扮演着重要的角色,精准快速的估算NPP对评估区域生态系统承载力以及合理利用自然资源具有重要的意义。利用2011-2014年甘南地面实测草地地上生物量(aboveground biomass, AGB)数据和根冠比系数计算的草地NPP数据,分别验证了MOD17A3 NPP产品和基于CASA(Carnegie-Ames-Stanford approach)模型估算的草地NPP的精度,分析了2000-2016年甘南地区草地NPP的时空动态变化。结果表明:基于CASA模型模拟的草地NPP精度整体上高于MOD17A3 NPP产品的精度,其均方根误差(root mean square error, RMSE)较MOD17A3 NPP小9.94 g C·m^-2;CASA模型分析的甘南地区草地NPP总体上呈现由西南向东北逐渐减少的趋势;对不同草地类型而言,沼泽类的平均NPP最高(469.07 g C·m^-2),温性草原类最低(324.18 g C·m^-2),而占研究区草地总面积比例较大的高寒草甸类和高寒灌丛草甸类草地的平均NPP分别为449.22和465.27 g C·m^-2;2000-2016年间,甘南地区大部分草地NPP稳定不变,其面积占研究区草地总面积的75.31%,NPP呈增加趋势的区域占草地面积的22.63%,而NPP呈减少趋势的区域占比最小,仅为2.06%。以上研究结果表明CASA模型在高寒地区草地NPP评估、草地资源合理利用与管理方面具有重要的应用价值。     

地震灾区植被净初级生产力恢复效应评价

地震等重大灾害的发生,对区域植被及生态环境造成了巨大破坏,植被净初级生产力(net primary productivity,NPP)能够反映绿色植物的生长状况,进行地震灾区植被NPP恢复效应评价,对掌握震后植被恢复情况和变化趋势具有指导意义。以"5·12"汶川大地震的极重灾区为研究区,选择地震前后3个时期的TM及MODIS卫星遥感数据,结合气象资料等其他数据,利用改进的CASA模型估算了灾区前后三年植被NPP。结果表明,灾后2009年植被NPP总量为9.827亿gC/a,相比灾前2007年减少了31.99%,2011年恢复期相比2009年增长了28.55%,但仍比2007年低12.57%,震后两年,灾区植被净初级生产力有所恢复,但未达到震前水平;从植被NPP空间分布来看,离地震中心越近的地方,植被NPP受到的削减程度越大,其恢复能力越差;经验证分析,评价结果具有较高的可信度,可为相关部门制定灾区生态重建和生态恢复计划与实施提供科学依据。