杉木幼林地水土流失与降雨特性关系研究

本文通过连续三年定位研究，全面探讨降雨特性对炼山与不炼山的杉木幼林地水土流失的影响，结果表明：本区年均降雨量和降雨侵蚀力（ＥＩ３０）为１５０８．０ｍｍ和６０２．１［１００Ｊ·ｃｍ／（ｍ２·ｈ）］，侵蚀性降雨占全年降雨次数的３４％～４０％；杉木幼林地水土流失随降雨侵蚀力增大而增加；林地水土流失量主要由大雨和暴雨两种降雨类型所引起，充足的前期降雨会加剧林地水土流失，尤其是在旱季；炼山的杉木林地水土流失随降雨的年分布特点而呈明显的季节性变化；在不同降雨条件下，炼山林地水土流失均明显大于不炼山林地．因此增加地表覆盖和选择合适的营林作业方式和时间是防止炼山林地大量水土流失的有效途径。     

等养分条件下稻草还田替代双季早稻氮钾肥比例的研究

【目的】研究等量氮磷钾养分投入条件下,长期稻草原位全量还田配施化肥对双季早稻氮 (N)、磷 (P)、钾 (K) 养分吸收累积、转运及养分利用的影响,为南方稻区稻草资源有效利用,维持并提高土壤肥力及水稻合理施肥提供理论依据。【方法】以江西温圳国家级耕地质量监测点长期定位试验为研究对象,陆两优 996 为供试材料,在不施化肥和施用化肥基础上设稻草还田、稻草烧灰还田和稻草不还田共 6 个处理,除空白对照外,所有处理养分投入量相等。于 2015 年在早稻移栽期、分蘖期、幼穗分化期、抽穗期和成熟期取地上部植株样,分析水稻植株不同部位的 N、P、K 含量和累积量以及转运比例,并计算 N、P、K 养分利用效率。【结果】稻草还田提高了水稻产量,施肥条件下稻草还田处理比稻草烧灰还田和稻草不还田处理平均增产 2.9%～ 6.4%,比不施肥区产量增幅高达 23.8%～ 26.0%,且差异达显著水平。无论是施肥区处理,还是无肥区处理,与稻草烧灰还田和稻草不还田处理相比,稻草还田植株中 K 含量及 N、P、K 积累量在整个生育期均较高,而 N、P 含量在生育后期较高,N、P、K 积累量以施肥区处理大于相应的无肥区处理;稻草还田提高水稻 N、P、K 养分农学效率、回收率和养分偏生产力,且 N、K 差异达显著水平,同时显著增加 K 的收获指数;稻草还田还提高了抽穗至成熟期茎鞘中 N、P、K 的转运量、转运率及转移养分对籽粒的贡献率,而叶片各处理间差异不显著。【结论】稻草还田配施化肥能提高水稻产量,同时还可以调节 N、P、K 养分的积累和转运,提高养分的吸收利用效率。本试验条件下,稻草还田可替代化肥氮肥 (N) 29.5%、磷肥 (P₂O₅) 4.0% 和钾肥 (K₂O) 50.0%。综合考虑,稻草还田相比稻草烧灰还田而言是南方稻区土壤养分管理实现高效利用的有效途径之一。     

我国秸秆发电技术的应用及前景

根据我国目前能源紧缺和秸秆资源利用水平低的现状,介绍了国内秸秆发电技术的研究和应用情况.分别阐述了秸秆直接燃烧发电、秸秆与煤混合燃烧发电和秸秆气化发电3种发电形式的技术原理、工艺流程和工程应用情况.结合工程实践经验,分析了秸秆发电技术应用中存在的问题,从秸秆收集、技术改进、国家配套政策等3个方面提出了建议,指出我国秸秆发电技术和产业将进入一个快速发展时期.     

小麦高留茬田间水分效应研究

通过小区和大田试验,研究了留茬、灭茬和烧茬三种处理土壤、近地层空气温湿度的变化,比较了三种处理夏玉米生长发育状况,分析了小麦高留茬的田间水分效应。结果表明,留茬明显降低了土壤温度,测定日0cm地表温度全天内留茬都处于最低,其中10时到14时降温效果最明显,土壤5￣25cm平均温度分别较灭茬和烧茬低1.45℃和2.3℃;土壤0￣70cm含水量自始至终留茬高于灭茬和烧茬;留茬对近地层空气湿度的影响主要在晚上,麦秆凝结的水汽增大了空气湿度,白天留茬高度内气温低湿度较大,留茬高度外气温高湿度较小(与灭茬和烧茬相比)。留茬对夏玉米生长发育的影响主要表现在中后期,试验结束时留茬株高、茎粗均高于灭茬和烧茬,表现出较大的后劲。     

不同秸秆还田年限对稻麦轮作系统温室气体排放的影响

为揭示稻麦轮作系统不同秸秆还田年限下温室气体排放特征及减排调控机制,本研究采用大田小区试验,考察了稻麦轮作不同秸秆还田年限[空白对照(CK)、常规处理秸秆不还田(NT)、1年秸秆还田(SR1)和5年秸秆还田(SR5)]对CH4、CO2和N2O 3种温室气体排放规律的影响,同时测定了土壤固碳量,估算了秸秆焚烧产生的温室气体排放量,综合计算了4种处理对全球变暖的贡献。试验结果表明,SR1和SR5均显著提升CH4和CO2的排放通量,分别高出NT、CK处理73.52%、309.49%和13.29%、13.06%;同时显著降低N2O排放通量,较NT降低29.68%和42.55%;但SR1和SR5之间温室气体排放通量差异不显著;与NT相比,SR1和SR5可以显著提高土壤固碳量517.9%和709.03%,SR5土壤固碳量高出SR1达30.93%;NT秸秆焚烧产生的全球气温变暖贡献为9 698.49 kg(CO2-eqv)·hm?2,比CK高126.98%。综合分析温室气体排放、土壤固碳以及秸秆焚烧3个因素,SR1全球升温贡献最低,显著低于NT 4.72%。短期全量秸秆还田有助于降低总体温室气体排放,长期进行秸秆还田后降低幅度会逐步减小。     

Carbon cycling and sequestration opportunities in South America: the case of Brazil

Abstract. A carbon emission inventory of the Brazilian agricultural sector was used to compare greenhouse gas emissions with estimated carbon offsets promoted by two main changes in agricultural management: the replacement of conventional tillage by no-tillage and the cessation of annual burning in sugar cane production. Using the IPCC revised 1996 guidelines for national greenhouse gas inventories, we estimate that 12.65 Mt C are emitted annually from agricultural land in Brazil. Ongoing conversion of conventionally tilled land to no-tillage currently accumulates 9 Mt C yr⁻¹. Industrial by-products like alcohol and bagasse from sugar cane processing substitute fossil fuel for transportation and power generation offsetting 10 and 8 Mt C yr⁻¹, respectively. An additional opportunity for 0.53 Mt C yr⁻¹ sequestration is presented by avoiding burning before harvesting of sugar cane. These data show that there could be almost full compensation between sources and sinks/offsets in the agricultural carbon cycle. There is a great opportunity to achieve this mitigation benefit because the adoption of new technologies is increasing rapidly.     

基于MODIS数据的河南省秋季作物秸秆焚烧火点监测研究

利用MODIS热异常产品数据,提取河南省秋季作物收获期的秸秆焚烧火点信息,经过初步筛选和地面验证,分析该时段内秸秆焚烧火点数量及时空分布格局,以期对政府为控制秋季秸秆焚烧采取的约谈措施进行效果评价。结果表明,利用MODIS热异常产品数据提取的河南省秋季作物收获期秸秆焚烧火点的准确度可达86.54%,能准确反映河南省秋季作物秸秆焚烧火点的空间分布与发展态势。河南省2015年秋季作物秸秆焚烧火点主要集中在豫中、豫东、豫南地区,尤其是周口、驻马店、南阳、信阳、开封等市,5个地区的秸秆焚烧火点总数占到全省秸秆焚烧火点总数的79.90%。2015年河南省秋季作物秸秆焚烧主要发生于9月27日至10月20日共24 d,整体表现平—增—减—平—增—减的趋势。河南省政府针对秋季作物秸秆焚烧采取政府约谈措施之后,秸秆焚烧火点数量大大减少,整体干预效果明显。利用遥感监测技术可对作物秸秆焚烧进行动态监测,为各级监管部门及时提供大范围内的秸秆焚烧信息,也为加强秸秆焚烧监控提供了可靠依据。     

Spatial patterns of large natural fires in Sierra Nevada wilderness areas

The effects of fire on vegetation vary based on the properties and amount of existing biomass (or fuel) in a forest stand, weather conditions, and topography. Identifying controls over the spatial patterning of fire-induced vegetation change, or fire severity, is critical in understanding fire as a landscape scale process. We use gridded estimates of fire severity, derived from Landsat ETM+ imagery, to identify the biotic and abiotic factors contributing to the observed spatial patterns of fire severity in two large natural fires. Regression tree analysis indicates the importance of weather, topography, and vegetation variables in explaining fire severity patterns between the two fires. Relative humidity explained the highest proportion of total sum of squares throughout the Hoover fire (Yosemite National Park, 2001). The lowest fire severity corresponded with increased relative humidity. For the Williams fire (Sequoia/Kings Canyon National Parks, 2003) dominant vegetation type explains the highest proportion of sum of squares. Dominant vegetation was also important in determining fire severity throughout the Hoover fire. In both fires, forest stands that were dominated by lodgepole pine (Pinus contorta) burned at highest severity, while red fir (Abies magnifica) stands corresponded with the lowest fire severities. There was evidence in both fires that lower wind speed corresponded with higher fire severity, although the highest fire severity in the Williams fire occurred during increased wind speed. Additionally, in the vegetation types that were associated with lower severity, burn severity was lowest when the time since last fire was fewer than 11 and 17 years for the Williams and Hoover fires, respectively. Based on the factors and patterns identified, managers can anticipate the effects of management ignited and naturally ignited fires at the forest stand and the landscape levels.     

林内就地火烧病死木防治松材线虫病试验

林内就地火烧病死木防治松材线虫病使病死树砍伐与除害同步进行即现砍现浇。该法操作方便、成本低,效果好,文内具体提出了现砍现浇的操作方法,以避免诱发森林火灾,消除燃烧不彻底的隐患。     

尾叶桉萌芽林炼山与不炼山生长比较研究

对广西高峰林场第二代尾叶桉林进行炼山与不炼山生长比较研究.结果表明:不炼山样地的尾叶桉树高与胸径生长均优于炼山样地的,不炼山的尾叶桉蓄积生长迅速,是同期炼山样地的2倍以上.炼山后造成地表覆盖物的销毁,枯落有机物和养分库大量损失,增大了幼林地的水土流失,不利于幼林的生长.