吕梁山地区植被物候变化及对气候的响应

吕梁山地区地形垂直差异明显,植被对气候变化反应敏感,研究吕梁山地区植被物候变化,探索植被物候变化与气候的响应关系,旨在为高海拔山区植被物候研究和生态治理提供借鉴。基于2000—2015年MODIS NDVI时间序列数据,通过动态阈值法提取吕梁山地区的植被物候,对气温、降水进行空间插值,并对植被2个关键物候期与气候因素进行偏相关分析。结果表明：（1）植被生长季开始日期(the start of the growing season,SOS)提前的区域约占85.7%,其中16.2%显著提前;植被生长季结束日期(the end of the growing season,EOS)推迟的区域约占90.6%,其中33.3%显著推迟。（2）区内74.8%、87.7%植被SOS分别与气温、降水呈负相关,气温升高或降水增加,植被SOS提前。植被SOS在高海拔山区受4月气温影响显著,而低海拔地区受4月降水影响显著。（3）区内72.6%、65.1%植被EOS分别与气温、降水呈正相关,气温升高或降水增加,植被EOS推迟。植被EOS在北部和西部地区受11月气温影响显著,而高海拔地区受9月降水影响显著。2000—2015年吕梁山地区植被物候发生显著变化,各地区对气温、降水的响应不同,研究结果可为区域物候、气候变化研究和陆地生态治理提供科学依据。     

Assessing the effects of vegetation and precipitation on soil erosion in the Three-River Headwaters Region of the Qinghai-Tibet Plateau,China

Soil erosion in the Three-River Headwaters Region (TRHR) of the Qinghai-Tibet Plateau in China has a significant impact on local economic development and ecological environment. Vegetation and precipitation are considered to be the main factors for the variation in soil erosion. However, it is a big challenge to analyze the impacts of precipitation and vegetation respectively as well as their combined effects on soil erosion from the pixel scale. To assess the influences of vegetation and precipitation on the variation of soil erosion from 2005 to 2015, we employed the Revised Universal Soil Loss Equation (RUSLE) model to evaluate soil erosion in the TRHR, and then developed a method using the Logarithmic Mean Divisia Index model (LMDI) which can exponentially decompose the influencing factors, to calculate the contribution values of the vegetation cover factor (C factor) and the rainfall erosivity factor (R factor) to the variation of soil erosion from the pixel scale. In general, soil erosion in the TRHR was alleviated from 2005 to 2015, of which about 54.95% of the area where soil erosion decreased was caused by the combined effects of the C factor and the R factor, and 41.31% was caused by the change in the R factor. There were relatively few areas with increased soil erosion modulus, of which 64.10% of the area where soil erosion increased was caused by the change in the C factor, and 23.88% was caused by the combined effects of the C factor and the R factor. Therefore, the combined effects of the C factor and the R factor were regarded as the main driving force for the decrease of soil erosion, while the C factor was the dominant factor for the increase of soil erosion. The area with decreased soil erosion caused by the C factor (12.10×10³ km²) was larger than the area with increased soil erosion caused by the C factor (8.30×10³ km²), which indicated that vegetation had a positive effect on soil erosion. This study generally put forward a new method for quantitative assessment of the impacts of the influencing factors on soil erosion, and also provided a scientific basis for the regional control of soil erosion.     

绿色富硒生物猪饲料中AFB1达标生产工艺优化研究

饲料中黄曲霉毒素(AFB₁)容易超标,检出率达80%~100%,毒性大,具强致癌性,可抑制生猪免疫机能,降低动物生产性能,引起动物继发感染,还会在动物产品中残留而威胁人类健康,给生猪养殖带来经济损失,降低猪肉食品安全性。本文通过使用先进固体发酵系统设备和益生菌发酵技术,采用单因素试验和响应面中试优化,获得发酵降解猪饲料AFB₁的最佳工艺参数为硒浓度0.3 mg/kg,发酵时间12 h,量子波强度30 Hz,益生菌菌种组合CGMCC NO.17328混合CGMCC NO.15611。该工艺将猪饲料AFB₁量从63.41μg/kg降解到2.98μg/kg,降解率达到95.30%,AFB₁含量达到国家饲料安全标准。生产工艺适合养猪场低成本快速生产AFB₁达标猪饲料。     

自然生草桃园表层土壤水分和草地地上生物量的空间分布及其关系

【目的】阐明桃树果园短期自然生草条件下土壤水分空间分布特征及其与草地地上生物量的关系。【方法】以信阳沙壤土五月鲜桃园为研究对象,在冬春季短期自然生草条件下,采用1 m×1 m网格采样法,以经典统计学和地统计学半方差函数为工具,研究表层(0~5 cm)土壤水分和草地地上生物量空间分布特征。【结果】表层(0~5 cm)土壤含水量和地上草地生物量符合正态分布,平均体积含水量为10.08%,95%置信区间为9.84%~10.32%,变异系数为16.36%,0.2 m×0.2 m草地地上生物量均值为9.17 g,变异系数为56.71%。区域田块尺度上,自然生草桃园草地地上生物量和表层(0~5 cm)土壤水分空间分布均符合指数函数模型,模型块金值/基台值分别为0.477 3和0.499 8,变程分别为7.20和2.51。即二者均具有中等程度的空间依赖性,草地地上生物量较表层(0~5 cm)土壤含水量具有更强的空间依赖性。克里格插值结果表明,表层(0~5 cm)土壤含水量和草地地上生物量空间上呈斑块状分布,且表现为距离树体越远值越大的分布特征。相关分析结果表明,地上生物量与表层(0~5 cm)土壤含水量之间极显著正相关(P<0.001)。【结论】果园短期自然生草有利于保蓄表层土壤水分,改善土壤水分条件,草地地上生物量是影响果园表层土壤水分空间分布的重要因素。     

植物源活性成分对有机磷农药的降解效果研究

为探索有机磷农药降解的新途径和方法,以大黄、海桐皮、木槿皮、五倍子按9:4:3:2质量份数混合,粉碎并以水浸泡,以GC-MS定量检测法、农残速测法,通过比较试验前后有机磷农药浓度变动,明确其对有机磷农药的降解效果。结果表明,2 min内浸提液对毒死蜱、对硫磷2种有机磷农药降解率分别达到93.6%、92.9%;浸提液17 h内对敌敌畏降解率为66.67%,11 h内对毒死蜱降解率为48.69%。本研究表明,大黄、海桐皮、木槿皮、五倍子浸提液对毒死蜱、对硫磷、敌敌畏等有机磷农药有显著降解效果。     

茶叶微生物固态发酵中咖啡碱降解途径初探

为探究微生物作用下咖啡碱的降解产物与途径,将普洱茶发酵中筛选鉴定的Aspergillus sydowii NRRL250（聚多曲霉）、Aspergillus pallidofulvus NRRL4789、Aspergillus sesamicola CBS137324和Penicillium mangini CBS253.31等优势菌株分别接种至晒青毛茶进行单菌种固态发酵,并采用高效液相色谱（HPLC）测定咖啡碱、可可碱、茶碱的含量,探究微生物对咖啡碱代谢的影响;另外,基于UHPLC-QTOF-MS代谢组学技术,以灭菌处理组（ST组）和原料组（RM组）为对照,对聚多曲霉接种发酵样进行代谢组学分析。结果表明,A. pallidofulvus NRRL4789、A. sesamicola CBS137324和Penicillium mangini CBS253.31等优势菌株对咖啡碱等嘌呤类碱代谢均无显著影响,而在聚多曲霉接种发酵中,咖啡碱含量显著下降（P<0.05）,降幅达83.89%;茶碱含量显著增加（P<0.05）,发酵末期含量为(25.03±1.17) mg·g^-1;而可可碱保持基本稳定。由此可知,聚多曲霉对咖啡碱降解代谢有显著影响。采用UHPLC-QTOF-MS方法检出茶碱、3-甲基黄嘌呤、1,7-二甲基黄嘌呤等9种与咖啡碱降解相关的代谢物。在聚多曲霉作用下,茶碱、3-甲基黄嘌呤、1,7-二甲基黄嘌呤、7-甲基黄嘌呤含量显著提高（P<0.05）。茶碱、3-甲基黄嘌呤、1,7-二甲基黄嘌呤和1-甲基黄嘌呤与咖啡碱及其相关代谢物的N-脱甲基化途径相关。1,7-二甲基尿酸、1-甲基尿酸与咖啡碱相关代谢物的氧化途径相关。由此可知,聚多曲霉为降解普洱茶咖啡碱的优势菌株,且具有将咖啡碱转化为茶碱的潜在能力;在咖啡碱降解代谢过程中,存在聚多曲霉作用下的N-脱甲基化和氧化,并以N-脱甲基化为主。     

华南花岗岩侵蚀区不同植被类型坡面土壤有机碳分布和团聚体稳定性

植物是影响土壤有机碳含量和土壤团聚体稳定性的重要因素。选取华南典型花岗岩侵蚀区荒草地、桉树林、湿地松林和木荷林4种植被类型径流小区的土壤为研究对象,分析测定不同坡位、不同土层深度的土壤有机碳特性和团聚体稳定性等指标,评价不同植被类型对土壤养分的分布特性以及团聚体稳定性差异,明确花岗岩侵蚀退化区较为理想的生态恢复措施,旨在为合理利用土壤、重建坡面植被和改善土壤结构提供科学依据。结果表明:土壤总有机碳(TOC)、全氮(TN)和溶解性有机碳(DOC)含量随土层加深逐渐降低,而林地小区土壤碳氮比(C/N)则相反,荒草地碳氮元素的坡面变异系数(CV)显著高于其他3种林地,其中桉树林地TOC、TN、DOC和C/N的坡面分布的变异系数较荒草地分别降低40%,56.18%,68.5%和25.81%;湿地松林地TOC、TN、DOC和C/N的坡面分布的变异系数较荒草地分别降低62.73%,33.71%,46.46%,58.06%;木荷林地TOC、TN、DOC和C/N的坡面分布的变异系数较荒草地分别降低41.82%,38.2%,51.18%,48.39%,表明林地较荒草地更有利于土壤碳氮在坡面的均质化和有机质的积累。荒草地和木荷林地0.25 mm粒径以上的团聚体在上、中坡位的质量分数显著高于其他植被类型,而林下植被生物量较高的木荷林地的平均质量直径(MWD)和几何平均直径(GMD)显著高于其他植被类型。其中木荷小区水稳性团聚体平均质量直径(MWD)较荒草地、桉树和湿地松分别高20.10%,19.58%,23.20%;几何平均直径(GMD)较荒草地、桉树和湿地松分别高20.00%,19.54%,22.23%,表明在花岗岩侵蚀区林地空间结构较好的林草模式有利于土壤有机碳的积累和土壤结构的稳定。     

Regional and local scale variations in soil organic carbon stocks in West Greenland

The soil organic carbon (SOC) pool of the Northern Hemisphere contains about half of the global SOC stored in soils. As the Arctic is exceptionally sensitive to global warming, temperature rise and prolonged summer lead to deeper thawing of permafrost‐affected soils and might contribute to increasing greenhouse gas emissions progressively. To assess the overall feedback of soil organic carbon stocks (SOCS) to global warming in permafrost‐affected regions the spatial variation in SOCS at different environmental scales is of great interest. However, sparse and unequally distributed soil data sets at various scales in such regions result in highly uncertain estimations of SOCS of the Northern Hemisphere and here particularly in Greenland. The objectives of this study are to compare and evaluate three controlling factors for SOCS distribution (vegetation, landscape, aspect) at two different scales (local, regional). The regional scale reflects the different environmental conditions between the two study areas at the coast and the ice margin. On the local scale, characteristics of each controlling factor in form of defined units (vegetation units, landscape units, aspect units) are used to describe the variation in the SOCS over short distances within each study area, where the variation in SOCS is high. On a regional scale, we investigate the variation in SOCS by comparing the same units between the study areas. The results show for both study areas that SOCS are with 8 kg m^?2 in the uppermost 25 cm and 16 kg m^?2 in the first 100 cm of the soil, i.e., 3 to 6 kg m^?2 (37.5%) higher than existing large scale estimations of SOCS in West Greenland. Our approach allows to rank the scale‐dependent importance of the controlling factors within and between the study areas. However, vegetation and aspect better explain variations in SOCS than landscape units. Therefore, we recommend vegetation and aspect for determining the variation in SOCS in West Greenland on both scales.     

三唑酰草胺在不同类型土壤中的降解特性

为科学评价除草剂三唑酰草胺在土壤环境中的生态风险，采用室内模拟方法，研究了三唑酰草胺在吉林黑土、江西红土和安徽水稻土中的降解特性。结果表明:三唑酰草胺在土壤中的降解符合一级动力学方程。好氧条件下三唑酰草胺在3种土壤中的降解半衰期分别为86.5、106和91.4 d；厌氧条件下半衰期分别为106、130和127 d；水稻田厌氧条件下半衰期分别为162、219和188 d。研究表明，三唑酰草胺在水稻田厌氧条件下的降解速率明显慢于其他2种试验条件下。