气候变化对我国油菜生产的影响

近年来,我国气候发生了显著变化：一是年平均气温显著升高;二是年降水总量有增加趋势,但区域性和季节性明显;三是极端气候事件频率和强度显著增加;四是CO2浓度持续升高;五是日照时数缩短明显。受其影响,我国油菜种植面积近年来显著增加,特别是冬油菜,有明显的“北移、西扩”趋势,这与气温升高引起作物种植北界北移有关。尽管我国油菜的单产也呈现增加趋势,但其与气象因子变化之间的关系目前还不明确。由极端气候引起的农业灾害显著增加,油菜生产的不稳定性增大。因此,提高综合抗逆能力、促进稳产是油菜生产急需解决的问题。     

基于DSSAT模型模拟气候变化对不同品种冬小麦产量潜力的影响

以石家庄地区为例分析了1955－2008年冬小麦不同生育阶段的积温、太阳辐射量和降雨量的变化趋势,并运用DSSAT模型模拟了不同年代主栽品种碧玛1号、泰山1号、济南13、冀麦30和石家庄8号的光温生产潜力和雨养产量,探讨了气候变化对冬小麦产量潜力的影响。结果表明：经过调试校正品种参数的模型模拟效果良好, 产量模拟值与实测值吻合度高;近50 a来冬小麦各品种光温生产潜力均随年份的推移呈现下降趋势,表明积温和太阳辐射量变化的减产效应;其中,拔节－抽穗期间积温的极显著增加趋势是影响20世纪90年代以前品种碧玛1号、泰山1号和济南13产量潜力的重要因素,而抽穗－成熟期间太阳辐射量的极显著减少趋势是影响近20 a品种冀麦30和石家庄8号产量潜力的重要因素;近50 a来冬小麦各品种雨养产量呈不显著增加趋势,返青-拔节期间降雨量的增加可以提高冬小麦雨养产量,并弥补生育后期降雨量减少引起的减产。     

1961-2008年陕西省年际气温和降水区域性变化特征分析

采用陕西省1961-2008年63个测站均一化订正后的气候资料,分析了陕西省不同区域近48a来的气候变化,结果表明:年平均气温近48a上升趋势明显,在1993年前后发生突变,突变前后年平均气温显著上升了0.8℃,上升幅度呈由南到北逐渐增强的趋势;冬、春季气温在突变后上升最为明显,升温幅度较大区域分别为长城沿线风沙区和渭河河谷平原区,年平均最高气温在1990年以后迅速升高,最低气温在2000年开始迅速升高;全省年平均降水呈明显的减少趋势,年平均降水的线性减少率为19.6mm/10a,秦岭南麓浅山区、汉江河谷平原及巴山区年平均降水的减少趋势比较明显。1980年前后和2000年前后为暴雨多发期,但中、大雨的总日数呈明显减少。     

土壤侵蚀/水土保持与气候变化的耦合关系

通过综述土壤侵蚀对碳循环的影响、全球气候变化对土壤侵蚀的影响以及水土保持植被恢复对碳循环与土壤碳素积累的影响,研究土壤侵蚀/水土保持与气候变化的耦合关系。结果表明:因侵蚀造成的土壤碳素损失是巨大的,但土壤侵蚀是碳源还是碳汇过程依然存在争议,焦点集中于因侵蚀造成土壤团聚体解体,暴露在空气中的土壤有机碳的矿化速率的大小;随着全球气温升高以及降雨格局的变化,全球土壤侵蚀强度和范围都在不断增加,但土壤侵蚀对全球气候变化的响应程度依然值得深入研究;水土保持生态恢复主要通过改变下垫面性质来改变土壤有机碳含量、影响土壤CO2释放并促进土壤碳素积累,对抑制大气CO2浓度升高能产生积极影响。尽管土壤侵蚀/水土保持与气候变化的耦合关系方面的研究已取得重大进展,但仍有待于在土壤侵蚀过程中碳素变化模型、土壤侵蚀过程中氮素迁移转化特征以及侵蚀劣地生态恢复过程中土壤碳素积累机制等方面加强研究。     

Interactive effects of warming, soil humidity and plant diversity on litter decomposition and microbial activity

Human activity has induced a multitude of global changes that are likely to affect the functioning of ecosystems. Although these changes act in concert, studies on interactive effects are scarce. Here, we conducted a laboratory microcosm experiment to explore the impacts of temperature (9, 12 and 15 °C), changes in soil humidity (moist, dry) and plant diversity (1, 4, 16 species) on soil microbial activity and litter decomposition.We found that changes in litter decomposition did not mirror impacts on microbial measures indicating that the duration of the experiment (22 weeks) may not have been sufficient to determine the full magnitude of global change effects. However and notably, changes in temperature, humidity and plant litter diversity/composition affected in a non-additive way the microbial parameters investigated. For instance, microbial metabolic efficiency increased with plant diversity in the high moisture treatment but remained unaffected in low moisture treatment suggesting that climate changes may mask beneficial effects of biodiversity on ecosystem functioning. Moreover, litter decomposition was unaffected by plant litter diversity/composition but increased with increasing temperature in the high moisture treatment, and decreased with increasing temperature in the low moisture treatment.We conclude that it is inevitable to perform complex experiments considering multiple global change agents in order to realistically predict future changes in ecosystem functioning. Non-additive interactions highlight the context-dependency of impacts of single global change agents.     

美国路易斯安那州土壤碳估算的尺度效应——美国STATSGO和SSURGO两大最新土壤数据库的比较研究

Estimation of soil organic carbon (SOC) pools and fluxes bears large uncertainties because SOC stocks vary greatly over geographical space and through time.Although development of the U.S.Soil Survey Geographic Database (SSURGO),currently the most detailed level with a map scale ranging from 1:12 000 to 1:63 360,has involved substantial government funds and coordinated network efforts,very few studies have utilized it for soil carbon assessment at the large landscape scale.The objectives of this study were to 1) compare estimates in soil organic matter among SSURGO,the State Soil Geographic Database (STATSGO),and referenced field measurements at the soil map unit;2) examine the influence of missing data on SOC estimation by SSURGO and STATSGO;3) quantify spatial differences in SOC estimation between SSURGO and STATSGO,specifically for the state of Louisiana;and 4) assess scale effects on soil organic carbon density (SOCD) estimates from a soil map unit to a watershed and a river basin scale.SOC was estimated using soil attributes of SSURGO and STATSGO including soil organic matter (SOM) content,soil layer depth,and bulk density.Paired t-test,correlation,and regression analyses were performed to investigate various relations of SOC and SOM among the datasets.There were positive relations of SOC estimates between SSURGO and STATSGO at the soil map unit (R2=0.56,n=86,t=1.65,P=0.102;depth:30 cm).However,the SOC estimated by STATSGO were 9%,33% and 36% lower for the upper 30-cm,the upper 1-m,and the maximal depth (up to 2.75 m) soils,respectively,than those from SSURGO.The difference tended to increase as the spatial scale changes from the soil map unit to the watershed and river basin scales.Compared with the referenced field measurements,the estimates in SOM by SSURGO showed a closer match than those of STATSGO,indicating that the former was more accurate than the latter in SOC estimation,both in spatial and temporal resolutions.Further applications of SSURGO in SOC estimation for the entire United States could improve the accuracy of soil carbon accounting in regional and national carbon balances.     

基于全球气候变暖的土壤侵蚀态势初见

前人对地质时期强土壤侵蚀发生期与气候期对应关系存在截然不同的三种看法,而对现代全球气候变暖对土壤侵蚀影响加大的看法则基本一致。在分析影响土壤侵蚀因子的基础上,提出未来全球气候变暖对土壤侵蚀产生影响的直接因子是降雨量,未来全球气候变暖仍存在不确定性;前人基于全球气候变暖的降雨变化研究结论是降雨变化不属全球同步性而存在区域差异,全球气候变暖的降雨变化具不确定性,因此土壤自然侵蚀量的增或减与气候变化的真正关系仍具不确定性。     

气候对巢湖东半湖水体环境变化的驱动效应

分析了小尺度气候变化对巢湖水体环境的影响,并揭示了水体营养生态对气候变化的响应机制。结果表明,年降雨量、年均温度、年日照时数变化稳定,平均值分别为1 176.2 mm,15.96℃和1 906 h,而高温天数(>35℃)年际变化显著(4~32 d/a)。调查期间总氮(TN)和总磷(TP)变化动态为开口向下的"凸"型抛物线形式,而高锰酸盐指数(CODMn)和叶绿素a(Chla)总体呈现为"凹"型曲线,水体总体呈现为中度营养状态。CCA分析发现巢湖区域的年降雨量、年均温度、年高温天数(>35℃)、年日照时数与湖水中TN,TP,CODMn和Chla呈显著相关性。其中TN,TP,CODMn和年日照时数对水体营养状态影响显著,贡献率分别为69%,45%,36%和27%。因此,可推测日照时数年际变化是导致水质变化的重要因素之一,气候因子与TN和TP在一定条件下对水体富营养化形成具有协同效应。     

近50年冬小麦主产区农业气候资源变化特征分析

在冬小麦主产区内选取113个气象站点的1961-2008年逐日气象资料,应用Mann-Kendall突变检测和气候线性倾向率方法,分析冬小麦生育期内农业气候资源变化趋势和特征。结果表明：研究区域近50a冬小麦生育期内≥0℃积温呈明显的增加趋势（P〈0.01）,90年代初期以来,≥0℃积温增加趋势更加显著（P〈0.05）;冬小麦生育期内的降水量变化趋势不显著,也不存在突变现象,但降水量年际间变化较大;冬小麦生育期内参考作物蒸散量的变化趋势不显著,80年代出现弱的减少趋势（P〈0.1）,90年代以后有弱的增加趋势（P〈0.1）;冬小麦生育期内的初霜冻日期呈推迟趋势（P〈0.01）,终霜冻日期呈提前趋势（P〈0.01）,导致霜冻日长度呈减少趋势。21世纪初初霜冻日的推迟趋势、终霜冻日的提前趋势更加显著（P〈0.05）。     

极端气候对福建省橄榄产量影响的风险评估

橄榄风险评估对其合理布局和防灾减灾具有重要意义。本文利用福建省橄榄种植区历年气象资料、橄榄种植面积、产量及其它社会经济资料,构建出由致灾因子危险性、承险体脆弱性以及种植区防灾减灾能力组成的极端气候对福建省橄榄产量影响风险指标体系;综合应用层次分析法、专家打分法和熵权系数法确定出风险评估指标权重;采用多指标综合评估法构建风险评估模型,以评估极端气候对橄榄产量影响的风险。结果表明：长乐市以南沿海低海拔橄榄种植区的极端气候对橄榄产量影响风险属轻度,主要原因是该区域致灾因子危险性较轻,脆弱性属轻度至中度,防灾减灾能力较高;重度以上的风险区域主要分布在尤溪县、上杭县、宁德市山区、福州内陆县（市）、莆田市西北部山区、安溪县西部、漳州市西部山区,主要原因是该区域的致灾因子危险性高,尤其以冻害危险性最大,同时防灾减灾能力也较低,部分县（市）种植面积大而导致脆弱性风险也加大;其余种植区的综合风险属中度。