浅埋滴灌水氮运筹对春玉米产量及水分利用效率的影响

采用二因素二次饱和D-最优设计，于2016-2017年在辽西半干旱区移动遮雨棚内进行了水氮精量控制试验，设灌溉量和施氮量2个因素，灌溉量分别设145.4、271.7、348.2、436.2 mm 4个水平，施氮量分别设0、84.6、136.1、195.0 kg·hm^-2 4个水平，共6个处理。试验分析了水氮交互作用对春玉米产量和水分利用效率的影响，建立了产量回归模型。研究结果表明：浅埋滴灌条件下，灌溉量在145.4~350.5 mm时，春玉米产量随灌溉量的增加而增高至11 005.60 kg·hm^-2；灌溉量在350.5~436.2 mm时，产量随灌溉量的增加而降低至10 730.09 kg·hm^-2；施氮量在0~146.9 kg·hm^-2时，产量随施氮量的增加而增高至10 983.19 kg·hm^-2，施氮量在146.9~195.0 kg·hm^-2时，产量随施氮量的增加而降低至10 862.39 kg·hm^-2。灌溉量因素的影响大于施氮量，水氮之间有明显的正向交互效应，当灌溉量为373.1 mm，施氮量为165.6 kg·hm^-2时产量最高。作物耗水量在拔节-抽雄期和灌浆-收获期较大，分别为115.64、127.50 mm；水分利用效率随灌溉量的增加呈逐渐降低趋势，降低幅度达到52.21%，随着施氮量的增加则呈先升高后降低趋势，增幅为14.73%~20.08%；其中处理6（灌溉量348.2 mm，施氮量195.0 kg·hm^-2)最利于水分利用效率的提高。综合产量和水分利用效率两方面的因素，初步建立了春玉米浅埋滴灌水氮施用优化模式，参数组合为灌溉量348.2 mm、施氮量165.6 kg·hm^-2。     

蔬菜幼苗叶面积快速测定方法筛选与优化

为得到一种快速且准确测定蔬菜幼苗叶面积的方法,以番茄幼苗为试材,以方格法为对照,研究扫描分析法、叶面积仪法、打孔称重法测定叶面积的准确性、精确性与测定速度,然后采用黄瓜、辣椒叶片及纸片的面积对测定结果进行验证,最后基于不同扫描分辨率对筛选出的方法进行优化。结果表明,相比叶面积仪法和打孔称重法,扫描分析法测定结果更接近真实值,且精度更高,用时更短。扫描分析法不同分辨率下测定结果无显著差异,且扫描分辨率越低所需测定时间越短。扫描分辨率50 dpi下的扫描分析法可作为一种快速准确测定蔬菜幼苗叶面积的方法。     

青海湖南部近57年大风日数的变化特征

为了更好地剖析青海湖南部大风日数的演变特征，笔者利用青海湖南部共和县气象局1961—2017 年的大风日数观测资料，采用线性倾向估计、M-K突变分析、滑动平均等方法，对大风日数的年代际、年际和季节变化趋势进行分析。结果表明：（1）自1961 年以来该地大风日数随年份的延长呈显著减少趋势，每10 年减少2.0 天；（2）共和地区春、夏、秋、冬四季大风日数均呈现出减少趋势，大风日数的减少幅度大小依次是：春季＞夏季＞秋季＞冬季，其中春季和夏季大风日数的减少趋势显著；（3）突变分析表明，春、夏、秋、冬四季大风日数未发生突变，年大风日数在1975 年发生了由多到少的突变。对于防灾减灾，合理利用气候资源，改善生态环境很有价值。     

Bio‐physical models of marine environments reveal biases in the representation of protected areas

1. The significant shortfall in global marine protection targets is likely to continue to drive rapid growth in marine protected areas (MPAs). Systematic conservation planning to fill gaps in marine protection requires sufficient knowledge of both the distribution of biodiversity and the threats to species and ecosystems. Yet such data are lacking for much of the marine environment, creating significant challenges for planning effective marine protection.
2. In the absence of habitat mapping data, critical environmental variables associated with species' distributions can be used to model the spatial distribution of different environments. Although this approach has been used in some jurisdictions to assist MPA planners, the increased availability and resolution of spatial data now provide an opportunity to improve assessments of MPA representation.
3. Capitalizing on advances in spatial data, this study uses a range of biological and physical environmental attributes to model the distribution of Australian marine environments. Given many Australian MPAs were implemented without knowledge of the distribution of species and benthic habitats, this Bio‐physical model is used to assess MPA coverage and equality of protection for Australian marine environments.
4. Results of the Bio‐physical model revealed that Australian MPAs overrepresent warm, offshore waters (such as the Coral Sea) and underrepresent temperate environments. Furthermore, the distribution of protection in Australian MPAs is heavily skewed, with no‐take protection disproportionately targeting tropical environments, leaving major gaps in the protection of both temperate and nearshore habitats.
5. Without comprehensive habitat mapping, the representativeness and adequacy of an MPA system cannot be accurately evaluated, nor can the required expansion of MPAs be planned effectively. In the interim, the biological and physical attributes chosen for this model provide useful proxies to assist in efforts to better target current and future protection based on the most up‐to‐date knowledge.

     

Looking beyond the horizon: An early warning system to keep marine mammal information relevant for conservation

1. Important marine mammal areas (IMMAs) are discrete portions of habitat, important to marine mammal species, that have the potential to be delineated and managed for conservation. Although IMMAs are not a blueprint for marine protected areas or other conservation designations, they are useful for providing a foundation for marine spatial planning and systematic conservation planning that can then lead to protected areas or special spatial regulations. To be most useful for supporting management and conservation, however, the information coming out of IMMAs needs to reflect current conditions.
2. An ‘early warning system’ is proposed with a generic set of indicators to flag when marine mammal species in IMMAs require management interventions due to changing distributions or decreasing populations. Rather than signifying that quantitative thresholds have been reached, these indicators comprise alerting information derived from visual or acoustic census, satellite imagery analysis, whale‐watching logs, or increases in mortality reported by stranding networks that can trigger additional targeted research.
3. Although it is possible that in some regions data will be sufficient to provide quantifiable indicators, the system is meant to rely on existing data sources, and be adaptable to the circumstances of each region.
4. Regional expert groups can utilize early warning system information and feed it into IMMA‐related spatial planning in two ways: by nominating additional areas of interest, and by providing a scientific rationale for revising IMMA boundaries, to be considered at the next decadal IMMA regional expert workshop.
5. IMMA‐driven consolidation of information that is as current as possible will prove valuable for enhancing regional cooperation to conserve marine mammals, and will be useful as countries implement new protected areas to conserve marine mammals and other marine biodiversity.

     

Habitat use of a coastal delphinid population investigated using passive acoustic monitoring

1. The population of bottlenose dolphins in eastern Scotland has undergone significant range expansion since the 1990s, when a Special Area of Conservation was established for the population.
2. Distribution of this population is well described within areas of its range where intensive work has been carried out, such as the inner Moray Firth, St Andrews Bay and the Tay estuary area. However, elsewhere in their range, habitat use is less well understood.
3. In this study, a large‐scale and long‐term passive acoustic array was used to gain a better understanding of bottlenose dolphin habitat use in eastern Scottish waters, complementing and augmenting existing visual surveys.
4. Data from the array were analysed using a three‐stage approach. First, acoustic occupancy results were reported; second, temporal trends were modelled; and third, a spatial–temporal‐habitat model of acoustic occupancy was created.
5. Results from the acoustic occupancy are in agreement with visual studies that found that areas near known foraging locations were consistently occupied. Results from the temporal trend analysis were inconclusive. Habitat modelling showed that, throughout their range, bottlenose dolphins are most likely to be detected closer to shore, and at a constant distance from shore, in deeper water.

     

基于稳定同位素技术的天津大神堂海域人工鱼礁区食物网结构研究

本研究对2016年6月在天津大神堂3个礁区(2010年建成的鱼礁区；2012年建成的鱼礁区；2014年建成的鱼礁区)和对照区域采集的生物消费者及其食物源样品的碳、氮稳定同位素组成进行了分析，通过IsoSource模型计算不同区域生物的食物网基础，并利用氮稳定同位素数据计算消费者的营养级。结果显示，根据δ13C值可以将其食物源分为浮游植物、悬浮颗粒有机物(POM)和沉积相颗粒有机物(SOM)三类；浮游植物对消费者的碳源贡献率(67.2%~81.5%)最大，是大神堂海域的生物食物网的基础。不同区域同一食物源的δ13C和δ15N值没有显著性差异；礁区内滤食性贝类毛蚶(Arca subcrenata)、菲律宾蛤仔(Ruditapes philippinarum)和长牡蛎(Crassostrea gigas)的δ13C值显著高于对照区，作为潜在碳源的浮游植物对其的贡献率显著增加。消费者的δ15N值则介于7.70‰~14.34‰之间，消费者的营养级介于2.0~3.95级之间。游泳生物食性生物的δ15N和营养级在礁区内有所提高，礁区建成的年份越长，其营养级与对照区域的差别越显著。稳定同位素研究表明，人工鱼礁建设可能导致鱼礁区内滤食性生物的食物来源组成改变，并提高游泳生物食性生物的营养级。     

Application of molybdenum fertilizer enhanced quality and production of alfalfa in northern China under non-irrigated conditions

Molybdenum (Mo) is an essential micro-mineral nutrient for plant growth and development. As an important legume forage, alfalfa (Medicago sativa) is frequently planted in marginal lands of northern China where water scarcity and infertile soil are limiting factors for alfalfa production. Mo plays an important role in nitrogen (N) metabolism in general and N fixation in legume species in particular. To evaluate the role of Mo fertilizer in alfalfa quality and production in semi-arid areas of northern China, we conducted a three-year field experiment in Inner Mongolia from 2012 to 2014. Mo fertilizer at the doses of 0, 150 g hm^?2, 300 g hm^?2yr^?1 was applied consecutively across the three years. Application of Mo at 300 g hm^?2yr^?1 significantly increased dry yield of alfalfa in 2014. Crude protein (CP) content of alfalfa without application of Mo exhibited a decline trend from 2012 to 2014. Application of Mo significantly enhanced total CP in 2012 and 2014, and delayed the reduction in total CP across the three years. In contrast to CP, Mo fertilizer had no significant effects on neutral detergent fiber and acid detergent fiber content. In addition, we found that nitrate reductase activity of alfalfa was increased by Mo fertilizer, which may account for the enhanced CP content in alfalfa. These findings highlight that application of Mo fertilizer can be an effective way to improve alfalfa production and quality in semi-arid areas in northern China.     

Low soil temperature reducing the yield of drip irrigated rice in arid area by influencing anther development and pollination

Drip irrigation can produce high rice yields with significant water savings; therefore, it is widely used in arid area water-scarce northern China. However, high-frequency irrigation of drip irrigation with low temperature well water leads to low root zone temperature and significantly reduce the rice yield compared to normal temperature water irrigated rice, for example, reservoir water. The main purpose of this paper is to investigate the effects of low soil temperature on the yield reduction of drip irrigated rice in the spike differentiation stage. The experiment set the soil temperatures at 18°C, 24°C and 30°C under two irrigation methods(flood and drip irrigation), respectively. The results showed that, at the 30°C soil temperature, drip irrigation increased total root length by 53% but reduced root water conductivity by 9% compared with flood irrigation. Drip irrigation also increased leaf abscisic acid and proline concentrations by 13% and 5%, respectively. These results indicated that drip irrigated rice was under mild water stress. In the 18°C soil temperature, drip irrigation reduced hydraulic conductivity by 58%, leaf water potential by 40% and leaf net photosynthesis by 25% compared with flood irrigation. The starch concentration in male gametes was also 30% less in the drip irrigation treatment than in the flood irrigation treatment at soil temperature 18°C. Therefore, the main reason for the yield reduction of drip irrigated rice was that the low temperature aggravates the physiological drought of rice and leads to the decrease of starch content in male gametes and low pollination fertilization rate. Low temperature aggravates physiological water deficit in drip irrigated rice and leads to lower starch content in male gametes and low pollination fertilization rate, which is the main reason for the reduced yield of drip irrigated rice. Overall, the results indicated that the low soil temperatures aggravated the water stress that rice was under in the drip irrigated environment, causing declines both in the starch content of male gametes and in pollination rate. Low temperature will ultimately affect the rice yield under drip irrigation.     

干热河谷冲沟侵蚀劣地坡积区土体性质与裂缝形态发育特征

采用实地调查和室内分析等方法,并结合数字图像处理技术,研究了干热河谷冲沟侵蚀劣地坡脚堆积区(PJ)、坡底沉积区(PD)和平地漫流区(PM)土体性质和裂缝形态发育特征,并探讨了土体性质对裂缝形态特征的影响。结果表明,(1)侵蚀劣地坡积区不同部位土体性质差异显著,其中土壤体积质量及黏粒质量分数均表现为PDPJPM,毛管孔隙度为PMPDPJ,有机质为PMPJPD;不同部位土体性质极值比:黏粒质量分数最大(1.94),有机质(0.65)次之,再次是毛管孔隙度(0.27),土壤体积质量(0.09)最小;PJ、PD土体性质变化主要受物源特性和沉积方式的影响,而PM土体性质主要与植被分布以及漫流有关。(2)干热河谷侵蚀劣地不同部位土体裂缝形态特征差异也十分显著,其中裂缝长度密度(Lc)及连通性指数(K)均表现为PDPJ≤PM,面积率(Rc)、面积周长比(APc)及加权平均分形维数(AWMFRAC)则整体上表现为PD≥PJPM(Ⅲ号坡积区的Rc除外);表明裂缝发育强度(Rc)及复杂程度(APc、AWMFRAC)PD最高,其次为PJ,再次是PM。(3)相关分析表明,长度密度与土壤体积质量(p=-0.782)、黏粒质量分数(p=-0.626)均呈显著负相关,连通性指数与黏粒质量分数呈显著负相关(p=-0.618),这表明土壤体积质量及黏粒质量分数对裂缝发育产生了重要影响。