我国北方两地环境臭氧浓度对矮菜豆生长的影响

地表臭氧对植物具有显著毒害作用,矮菜豆(Phaseolus vulgaris L.)已被证实对臭氧非常敏感.选用对臭氧敏感性不同的矮菜豆(R123,臭氧耐受性及S156,臭氧敏感性)分别在3个地点(北京昌平、北京生态中心、哈尔滨市)进行室外直接暴露实验,旨在探讨当前环境臭氧浓度对矮菜豆生长的影响.结果表明,生态中心和昌平两地菜豆在当前臭氧浓度下叶片都出现严重臭氧损伤症状,整个生长季S156型菜豆平均臭氧损伤比例比R123型菜豆高23.5%;臭氧损伤自开花期开始,开花期至结荚期损伤加剧,在豆荚成熟期臭氧损伤比例达到最大值.豆荚产量对比发现,昌平和生态中心两地S156型与R123型豆荚产量比值分别为0.48和0.24,哈尔滨地区为0.73,二者比值为1视为生长不受臭氧影响.可见,北京地区较高的环境臭氧浓度已使敏感性作物矮菜豆显著减产.     

混合碳源制备生物絮凝剂的絮凝效能及产量预测模型

为实现混合底物的高效定向转化,以产絮菌根癌农杆菌(Agrobactrium tumefaciens)F2为研究对象,考察不同单一碳源及不同初始浓度对菌体生长、絮凝效能及絮凝剂产量的变化规律,采用BP算法构建絮凝效能及产量预测神经网络.产絮菌F2利用葡萄糖时的絮凝效能和产量分别为88.98%和2.20 g·L-1,过低的初始浓度将影响产量,不低于7.5 g·L-1为佳.以D-(+)-葡萄糖、D-半乳糖和D-甘露糖3种单糖为混合碳源,构建网络结构为3-5-2的产絮效能及絮凝剂产量预测模型,对两个输出层的预测误差范围均在4%以内,预测葡萄糖、半乳糖、甘露糖浓度的最优解为6.59 g·L-1、1.32 g·L-1、3.57 g·L-1,经验证混合碳源发酵产絮可使絮凝效能和产量比单一葡萄糖发酵时分别提高6.87%和26.82%,本文为产絮菌F2利用含糖有机质废液发酵产絮凝剂提供数据参考.     

生态足迹方法的理论解析

论文系统地解析了生态足迹概念，在简要介绍生态足迹账户框架建立的假设条件，计算方法的基础上，系统总结了生态足迹最近的国际研究进展。同时，重点介绍了生态足迹计算中容易引起误解和疏忽的两个问题：化石能源用地的处理，均衡因子和产量因子的计算。在此基础上，从生态足迹计算过程中化石能源的处理和“利息”的处理两个角度评价了生态足迹方法的局限性。同时从贸易的处理缺乏可持续性基础，忽视国家和区域尺度上空间地理情况的差异，忽视人类社会对自然资产“利息”流的积累和储存，忽视自然资产存量的状况四个角度，分析了生态足迹在不同尺度上应用中存在的问题，最后通过将生态足迹分析还原到IPAT等式，并从热力学和生态经济学的角度解释了现有生态足迹分析政策建议少并且雷同、及其政策建议缺乏可操作性的实质价值的原因。     

绿肥在现代农业中的地位──论广东绿肥的发展前景

绿肥可以解决有机肥源不足的困难，减少化肥用量，节省成本和能源消耗，改善土壤环境，提高土壤肥力和地力；提高作物产量和产品质量；促进畜牧业的发展。本文根据广东的实际，指出广东的现代化农业需要大种绿肥，也可以大种绿肥。要使广东的绿肥生产得到恢复和发展，必须抓好如下的措施：从战略高度来认识绿肥的重要性；加强领导，把它提到重要的议事日程上来；广泛开展试验示范，并加强宣传发动；增加经济投入，省、市、县各级要设立绿肥种子繁育和经营风险金。     

单产提升潜力衰减模型法在河南粮食单产中长期预测中的应用研究

粮食单产水平的提高是河南粮食增产的主要原因,准确预测粮食单产水平,对科学判断河南粮食生产能力、制定粮食生产战略意义重大。论文针对目前直接以单产为变量建立的预测模型未能反映出单产增长的有限性和增速的减缓性之不足,研究提出了一种基于单产提升潜力衰减过程的单产预测方法。该方法利用河南耕地的平均单产潜力和历年实际单产数据,计算得到河南历年单产可提升潜力值;依据单产提升潜力理论上呈逐渐衰减之变化特点,可采用指数衰减函数建立单产提升潜力回归模型,以达到间接预测单产之目的。结果表明：1）单产提升潜力对数值与时间t之间具有高度负线性相关关系,适宜建立指数回归模型;2）回归模型V_q-V_t=e^{-0.009 5t+9.464 7}拟合优度R²=0.973 1,在0.01置信水平上回归显著;3）预测模型反映出了单产提升潜力的有限性和衰减性,即单产潜力对单产水平的限制性,模型理论诠释清晰;4）利用河南1978—2000年的单产数据作为样本建立预测模型,用样本以外2001—2015年的实际单产作为观测值,对预测单产进行模型预测检验,结果表明该模型预测单产绝对误差均值为129.15 kg/hm²,仅为现有方法的0.17~0.82倍,且误差平稳,适宜于单产中长期预测;5）预测得河南2020、2025、2030年的平均单产分别为6 375、6 765、7 155 kg/hm²,年均增幅为85.20~74.55 kg/hm²,增速呈逐渐减缓趋势。     

污泥对水稻分蘖及产量形成影响的研究

为探讨工业废水处理后的污泥能否在农业上应用,以哈药集团制药总厂经生物处理产生的污泥为材料,研究水稻分蘖动态及产量形成.结果表明,该厂排放的污泥,有机质和速效氮、磷含量高,施入土壤后能迅速被水稻吸收利用.适量施用污泥,水稻返青加快、分蘖增多,体内叶绿素含量增高,同时水稻的产量也得到提高.污泥施用过量,会导致水稻返青率降低,后期分蘖无法控制,导致生育延迟,空秕粒率大幅度增高,产量显著下降.     

Using Fallout Lead-210 Measurements to Estimate Soil Erosion in Three Small Catchments in Southern Italy

Soil erosion and associated off-site environmental impacts have attracted increasing attention in recent decades, and there is a growing need for reliable information on rates of soil loss. The potential for using ¹³⁷Cs fallout to quantify rates and patterns of soil redistribution over medium-term timescales (ca. 45 years) has been successfully demonstrated in a wide range of environments around the world. The similar behaviour of fallout ²¹⁰Pb in soils offers potential for its use as an alternative to ¹³⁷Cs, in areas where ¹³⁷Cs inventories are low or are complicated by additional fallout from the Chernobyl accident. There have, however, to date been few attempts to validate the use of fallout ²¹⁰Pb measurements for assessing erosion rates. This paper reports an attempt to explore the use of fallout ²¹⁰Pb to estimate rates of water-induced soil erosion on uncultivated land. It focuses on three small forest/rangeland catchments located in Calabria, southern Italy, for which measurements of sediment output are available. Comparison of the estimates of net soil loss from the catchments derived from ²¹⁰Pb measurements with the measured sediment output, confirmed the validity of the ²¹⁰Pb approach. The soil redistribution rates estimated using ²¹⁰Pb measurements were also consistent with equivalent estimates obtained for the same study catchments using ¹³⁷Cs measurements.     

中国小麦生产的区域比较气候风险研究

以减产率〉5．0％界定灾年，分析了中国各省（市、自治区）小麦灾年发生的风险概率、平均减产率和变异系数，及其与全国平均水平相比的区域比较风险度、减产度和变异度。基于以上3个区域灾年减产率的比较指标，得到了区域比较气候风险指标；利用区域比较气候风险对中国小麦生产进行了分区论述，同时得出了小麦总产量损失与播种面积呈显著正相关，与小麦单产只有一般中度相关，而与比较气候风险基本不相关的关系，并指出了区域比较气候风险指标与防灾减灾工作的关系。     

PHYSICAL HYDROLOGY AND THE EFFECTS OF FOREST HARVESTING IN THE PACIFIC NORTHWEST: A REVIEW1

The Pacific Northwest encompasses a range of hydrologic regimes that can be broadly characterized as either coastal (where rain and rain on snow are dominant) or interior (where snowmelt is dominant). Forest harvesting generally increases the fraction of precipitation that is available to become streamflow, increases rates of snowmelt, and modifies the runoff pathways by which water flows to the stream channel. Harvesting may potentially decrease the magnitude of hyporheic exchange flow through increases in fine sediment and clogging of bed materials and through changes in channel morphology, although the ecological consequences of these changes are unclear. In small headwater catchments, forest harvesting generally increases annual runoff and peak flows and reduces the severity of low flows, but exceptions have been observed for each effect. Low flows appear to be more sensitive to transpiration from vegetation in the riparian zone than in the rest of the catchment. Although it appears that harvesting increased only the more frequent, geomorphically benign peak flows in several studies, in others the treatment effect increased with return period. Recovery to pre‐harvest conditions appeared to occur within about 10 to 20 years in some coastal catchments but may take many decades in mountainous, snow dominated catchments.     

Effect of grazing on plant attributes and hydrological properties in the sloping lands of the East African highlands

Extending livestock grazing to the steep slopes has led to unstable grazing systems in the East African Highlands, and new solutions and approaches are needed to ameliorate the current situation. This work was aimed at studying the effect of livestock grazing on plant attributes and hydrological properties. The study was conducted from 1996 to 2000 at the International Livestock Research Institute at Debre Ziet Research Station. Two sites were selected: one at 0–4% slope, and the other at 4–8% slope. The treatments were: (1) no grazing (control); (2) light grazing, 0.6 animal unit months per hectare (aum/ha); (3) moderate grazing, 1.8 aum/ha; (4) heavy grazing, 3.0 aum/ha; (5) very heavy grazing, 4.2 aum/ha; (6) initially plowed and continuously very heavily grazed, 4.2 aum/ha. The result showed that species richness, infiltration rate, bare ground, and soil loss significantly varied with grazing pressure. Species richness was higher in grazed plots compared to nongrazed plots. Biomass yield improved on heavily grazed plots as cow dung accumulated over years. Cynodon dactylon plant species persisted with livestock grazing pressure in both sites. Infiltration rate improved and soil erosion declined in all treatments after the first year.