东北地区杨树烂皮病气象预报模型研究

为了研究东北地区杨树烂皮病气象预报预警技术,以2002-2008年东北地区杨树烂皮病发生程度为研究对象,利用相应气象资料,在相关分析、逐步回归和逐步判别分析方法的基础上,构建东北地区杨树烂皮病气象适宜度预报模型,并将气象适宜度指数划分为非常适宜、适宜、基本适宜、不适宜4个级别,以反映气象条件对杨树烂皮病发生发展的适宜程度。结果表明：东北地区杨树烂皮病发病面积与冬季气温日较差≥15℃的天数、春季和初夏平均气温呈正相关,冬季气温日较差越大、春季和初夏气温越高,越有利于杨树烂皮病发生发展;入冬冻害、春季温湿条件对东北地区杨树烂皮病发生发展起主导作用,气温、空气湿度与杨树烂皮病发生程度关系最为密切;影响东北地区杨树烂皮病发生发展的关键气象因子分别是3月下旬风速、3月空气相对湿度、4月温湿系数、3月和5月及4月上下旬气温、上年11-12月气温日较差≥15℃的天数。预报模型对2002-2008年的历史拟合和重发生年2009年预报取得了较好的效果,分级和分省外延预报平均准确率均在75%以上,3省预报准确率顺序为：黑龙江>吉林>辽宁。     

地被植物在园林中的配置探讨——以石家庄市城市绿地地被植物应用为例

选择出阳性及半阴性地被30种、阴生地被15种,提出四项地被植物应用设计原则和配置手法。对地被植物应用主要配置方式进行调查,按不同地域地被植物配置,分为空旷地、道路绿地、林缘疏林、林下、草坪、山体坡地、树池、和湿地八种应用形式。通过实例分析认为,地被植物景观配置必须了解其生态习性,选择与其生物学特性相适生的外界条件,并保证其必要的养护,以最大限度发挥其生态、景观效益。     

基于土地利用/覆盖的干旱绿洲区植被覆盖度变化--以新疆生产建设兵团第八师为例

为了探讨西北干旱绿洲区土地利用/覆盖类型景观格局特征,以及不同土地利用/覆盖类型植被覆盖度变化,本文以干旱典型绿洲区新疆生产建设兵团第八师为研究区,选取2000年、2005年的Landsat TM和2010年环境一号星CCD遥感影像数据,采用室内解译与野外核查相结合,运用RS和GIS技术分析了该区域的土地利用/覆盖和景观格局变化特征,并基于土地利用/覆盖类型选取3年的MODIS数据进行了植被覆盖度变化分析。结果表明:1)该研究区主要以耕地、草地和灌丛为主,占总面积的88.9%。在自然因素和人为因素的综合作用下,干旱绿洲区土地利用/覆盖类型发生明显变化,草地和灌丛呈减少趋势,面积分别由2000年的2 603.2 km2和1 166.2 km2减少至2010年的1 677.3 km2和933.8 km2;耕地和城镇逐步增加,面积分别由2000年的2 892.8 km2和209.2 km2增加至2010年的4 038.3 km2和259.1 km2;耕地主要由草地和灌丛转化而来,城镇主要由耕地转化而来,土地利用变化整体处于不平衡发展趋势。2)研究区景观特征趋于简单,土地利用变化改变了该区域景观格局,景观多样性、均匀度减少,优势度明显增大,破碎化程度降低,生物多样性也呈向单一方向转变的趋势。3)受气候等主要因素的影响,2000—2010年植被覆盖度呈先降低后逐步升高的趋势,不同土地利用/覆盖类型植被覆盖度表现为林地耕地草地灌丛荒漠,林地、灌丛、草地和耕地植被覆盖度分别增加6.7%、38.2%、15.6%和12.3%;较高和高等级植被覆盖面积增加,中、较低和低等级植被覆盖度面积减少。4)温度一定的条件下,降雨量是影响干旱绿洲区植被覆盖变化的关键因素。该研究结果可为新疆生产建设兵团生态环境保护管理以及合理规划生产模式提供科学的参考依据。     

怀来县土地利用/覆被变化及生态系统服务价值时空演变

为了揭示土地利用与生态环境之间的关系,指导区域土地合理利用,以怀来县为研究区,通过对1992年、2002年、2012年的Landsat TM遥感影像数据进行处理,利用土地利用变化强度指数分析怀来县近20年的土地利用类型间的变化强度,构建了生态系统服务价值的动态测算模型,引入动态度与相对变化率指数,对县域内近20年各地类以及各乡镇的生态系统服务价值的变化进行时空分异特征进行分析。结果表明:近20年怀来县土地利用整体呈现"三增两减"的趋势,即园地、林地、建设用地面积增长,分别增长了19.98%,5.66%,90.76%;水域、耕地面积减少,分别减少68.90%,23.27%。建设用地、耕地在近20年生态系统服务价值变化最大,即变化最剧烈,林地、园地变化相对较小;北部山地丘陵区与南部低山丘陵区的生态系统服务价值变化率较高,中部平原区变化率较小。     

基于灰色关联下的广西粮食主要生产影响因素评价

通过对1995—2010年主要年份广西主要粮食（稻谷、玉米、大豆、薯类）产量与相关生产因素的灰色关联度动态分析,提出广西主要粮食生产的可持续发展途径,为农业可持续发展提供参考。运用灰色系统理论中的关联度分析法对1995—2010年其中6个主要年份与粮食生产有关的7个影响因素进行量化动态分析。结果表明：粮食产量与相关生产因素的关联度为播种面积〉城镇居民家庭人均购买粮食数量〉化肥施用量〉乡村从业人员〉农田有效灌溉面积〉单位面积产量〉农田总用电量。     

发展保护性耕作 促进农业可持续发展

保护性耕作是在少耕、免耕基础上发展起来的一种土壤耕作方式。其主要内容是作物收获后残茬、秸秆留在田间覆盖地面,春季不进行整地,使用免耕播种机进行播种,喷施化学药剂防治病虫草害,尽量减少机械进田次数,保护耕层土壤的自然结构,实现经济、生态、社会效益的有机统一。     

1986—2016年黄河三角洲土地利用/覆被变化及景观格局分析

基于Landsat影像获取1986年、1996年、2006年和2016年的土地利用/覆被变化数据,使用变化轨迹模型和景观格局指数研究黄河三角洲近30年土地利用/覆被结构变化、变化轨迹时空特征及景观格局。结果表明：1996—2016年黄河三角洲耕地、人工水体、建设用地面积呈增加趋势,未利用地、林地、草地和天然水体面积减少,其中未利用地面积减少2 072.75 km²,变化幅度最大。人工水体、建设用地及耕地的增加速度不断减缓;草地和天然水体于1986—1996年缓慢增加,1996年后持续减少;林地、未利用地在3个时段均呈快速减少趋势。“人为因素”驱动轨迹面积占研究区总面积的56.13%,主要类型变化为耕地与人工水体,分布在河流两侧和滩涂向陆一侧;“自然因素”驱动轨迹占比15.80%,主要类型为变化为海域、草地和天然水体,集中分布在北部和东部沿海地区;研究区28.07%的土地利用/覆被类型未发生变化。黄河三角洲“人为因素”驱动轨迹的景观破碎度、集聚程度和结构复杂程度均高于“自然因素”驱动轨迹,人类活动在研究区土地利用/覆被变化过程中起主导作用。该研究结果可为黄河三角洲土地资源开发、管理与保护提供参考。     

Indirect selection for resistance to Stenocarpella maydis and Fusarium graminearum and the prospects of selecting for high‐yielding and resistant maize hybrids

Stenocarpella maydis and Fusarium graminearum affect grain yield and quality as a result of mycotoxins produced. A negative association of yield with resistance to cob rots has been reported. The objectives of this study were therefore to investigate the influence of cob characteristics on the response to F. graminearum and S. maydis disease reaction and evaluate the prospects of direct selection for high‐yielding and resistant maize hybrids. In this study, the pathogens were directly introduced to the cob through toothpick inoculation. Correlation of husk cover to disease severity of each pathogen, separately toothpick inoculated, was significant (P < 0.01). However, the low r values (<0.45) of traits associated with the response to inoculation by S. maydis and F. graminearum imply that indirect selection would not be beneficial for obtaining the type of resistance shown under inoculation. Several hybrids combined good yields with at least moderate resistance to both pathogens.     

A leakiness index for assessing landscape function using remote sensing

The cover, number, size, shape, spatial arrangement and orientation of vegetation patches are attributes that have been used to indicate how well landscapes function to retain, not ‘leak’, vital system resources such as rainwater and soil. We derived and tested a directional leakiness index (DLI) for this resource retention function. We used simulated landscape maps where resource flows over map surfaces were directional and where landscape patch attributes were known. Although DLI was most strongly related to patch cover, it also logically related to patch number, size, shape, arrangement and orientation. If the direction of resource flow is multi-directional, a variant of DLI, the multi-directional leakiness index (MDLI) can be used. The utility of DLI and MDLI was demonstrated by applying these indices to three Australian savanna landscapes differing in their remotely sensed vegetation patch attributes. These leakiness indices clearly positioned these three landscapes along a function-dysfunction continuum, where dysfunctional landscapes are leaky (poorly retain resources). This revised version was published online in July 2006 with corrections to the Cover Date.     

Quality assessment of three warm-season turfgrasses growing in different substrate depths on shallow green roof systems

In an effort to increase the accessibility and functionality of shallow green roof systems, the ability of warm-season grasses to provide acceptable growth needs to be further investigated. In the current study, which was conducted during 2011 and 2012, three warm-season grasses (hybrid bermudagrass, Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy ‘MiniVerde’; seashore paspalum, Paspalum vaginatum Swartz ‘Platinum TE’ and zoysiagrass, Zoysia japonica Steud. ‘Zenith’) were established in outdoor lysimeters. The lysimeters were equipped with all necessary green roof layers placed below a coarse-textured substrate that comprised pumice, thermally treated attapulgite clay, peat, compost and zeolite. Half of the lysimeters had a substrate depth of 15 cm, while the other half had a substrate depth of 7.5 cm. Irrigation was applied at crop evapotranspiration (ET_c). Measurements included determination of substrate moisture content, green turf cover (GTC) and leaf stomatal resistance. Significant differences were observed in the values of GTC among the three turfgrass species and the two substrate depths. Zoysiagrass exhibited the best adaptation at the lower depths of shallow green roof systems. At 15 cm substrate depth, zoysiagrass managed to sustain green coverage for the two study periods. In addition, it was the only turfgrass species that managed to perform well at the substrate depth of 7.5 cm. Seashore paspalum exhibited limited green cover at both substrate depths, while hybrid bermudagrass could provide acceptable green coverage only at 15 cm substrate depth.