The effect of land cover/vegetation on soil water dynamic in the hilly area of the loess plateau,China

Severe soil and water loss has lead to widespread land degradation in China's loess plateau. During the past decades, a great deal of effort was made on vegetation restoration to reduce soil and water loss in the loess plateau. However, due to water shortage the efficiency of vegetation restoration was not as satisfactory as expected. As part of a vegetation restoration project, we conducted research aiming to understand the relationship between vegetation pattern and soil water dynamics. The goal was to find vegetation types appropriate for the loess plateau with scarce water resources. In 1986, fifteen plots of land were planted with five vegetation types: pine woodland, shrubland, sloping cropland, alfalfa and semi-natural grassland. Soil water content, runoff, soil erosion were measured for each plot. Environmental variables, such as rainfall, evaporation and temperature, were recorded simultaneously by an automated meteorological station. The relationship between land cover pattern and soil water dynamic was evaluated by using statistical models. We found that: (1) soil water loss occurred during the growing season, and it reached the maximum in the second half of July; (2) soil water was not fully replenished from rainfall during the rainy season; (3) pine woodland induced the largest water loss to surface runoff, followed by sloping cropland, alfalfa, semi-natural grassland and shrubland; the poor capability of pine woodland for water conservation may be attributed to soil compaction and poor ground coverage under the tree; (4) in most cases, soil water of the five vegetation types was low except for shrubland and semi-natural grassland where it was moderate-high during a few periods. These conditions inhibit sustainable vegetation growth in the semi-arid loess hilly area of the loess plateau, China.     

皮肤扩张术在兽医上的应用前景

皮肤的大面积损伤在兽医临床上较为多见,但现有的治疗手段很难满足动物美观的要求,皮肤扩张技术以其扩张获得的“额外”的皮肤与正常皮肤直接缝合以作修复疤痕组织或皮肤缺损,这样既解决了修复所需要的皮源问题,又可以避免大面积植皮形成的新的瘢痕组织,扩张皮肤克服了植皮色素沉着,与周围皮肤颜色不协调,遗留供区新创面的缺点,成为国内外医学界修复瘢痕广泛应用的新技术,应用前景十分广阔。     

微地形改造的生态环境效应研究进展

干旱缺水和生境不良使世界上许多地区的植被恢复和生态改善面临困难。为了提高植被成活率、遏制土壤侵蚀和土地退化态势,国内外许多重点地区都开展了多种微地形改造与下垫面整地措施,使得地表生境和植被状况得到一定改善。但微地形改造对生态环境影响的基础研究仍严重滞后于实践的客观需求,许多关键效应和科学机理不明。本文系统梳理和总结了国内外学者在不同生态系统类型区和自然地理单元上开展的相关研究。认为微地形改造对土壤属性和微生境、降雨入渗和水蚀过程、植被恢复的效果及其生态服务功能发挥等多个方面都有重要影响,并综述了相关研究进展。同时指出当前微地形改造研究中存在的突出问题。包括科学分类标准有待系统化、实地量化技术相对滞后、微地形改造的水文效应有待强化、影响植被恢复的机理不明等若干重要局限。建议应进一步加强微地形改造的分类体系研发、发展微地形改造方式的定量刻画技术;设立野外定位站,跟踪监测其长期效应,并加强不同微地形改造措施的生态环境效应对比,为科学筛选和优化下垫面改造技术、服务区域生态改善和应对气候变化提供科学依据。     

猕猴桃果浆中叶绿素和颜色的热降解动力学

为了研究猕猴桃果浆加工中叶绿素和绿色的热降解规律,测定了不同温度(70、80、90℃)和pH值(pH值3.3、6.0、8.0)对猕猴桃果浆叶绿素含量和色差的影响。结果表明,猕猴桃叶绿素a、b和绿色值(-a*)的热降解属一级动力学反应;在相同pH值条件下,随温度升高,叶绿素a、b和绿色值(-a*)的反应速率常数(k)降低,半衰期(t1/2)缩短;随pH值增加,叶绿素a的活化能(Ea)变化范围为14.69～66.02kJ/mol,叶绿素b为40.88～54.64kJ/mol,绿色值(-a*)为48.55～64.14kJ/mol;pH值3.3时叶绿素a、b的降解和绿色值(-a*)相关性较好。猕猴桃果浆加工中适量提高pH值可减少叶绿素和绿色的损失。     

城市生态景观建设的指导原则和评价指标

在人口膨胀和快速城市化的全球化背景下,构建人与自然和谐的生态景观是城市景观规划和设计的基本美学观和价值观.缺乏统一的指导原则和评价标准使得城市生态景观建设出现了很多问题,也限制了生态景观的进一步推广和实践.基于文献调研和专家咨询的方式,归纳了城市生态景观的基本内涵和指导原则,并提出了针对性的评价指标.通过问卷调查的方式,获取了170余份有效问卷,据此分析公众对城市生态景观的理解和需求.可以依据该结果为城市生态景观的定量评价提供初步的权重值,为进一步完善生态景观建设的理论和方法提供了参考和依据.     

A precipitation-weighted landscape structure model to predict potential pollution contributions at watershed scales

Context

The impact of landscape structure—often described by landscape composition and configuration—on ecological processes is well-known. Appropriately quantifying landscape structure that critically affect nutrient processes within watersheds remains challenging.

Objective

A precipitation-weighted landscape structure model (LSM) was developed to predict nutrient concentrations at a large number of watersheds.

Methods

The LSM was developed based on the landscape location features including topography and precipitation within the watershed. The inequality function of Lorenz curve was used to quantify the spatial structure of different landscape types. The LSM was fitted and validated using the measurements of total nitrogen (TN) and total phosphorus (TP) in 132 watersheds. Regression models predicted the spatial patterns of TN and TP concentrations in 1578 watersheds of the Haihe River Basin, China.

Results

(1) Predictive models can explain 64 and 52% of the variation in total TN and TP, respectively. (2) Agricultural and residential lands served as nutrient sources. The contributions of agricultural land were 18 and 21% while those of residential land were 46 and 38% to TN and TP concentrations, respectively. (3) Grassland and forest land were nutrient sinks. Grassland had major contributions of 22 and 30% to TN and TP concentrations, respectively. The contributions of forest land were 7 and 11% to TN and TP concentrations, respectively.

Conclusions

The LSM focuses on the nutrient processes and is feasible to implement across a large number of watersheds. This study provides useful implications for quantifying landscape structure and predicting potential pollution under different landscape scenarios.

     

绿地格局对城市地表热环境的调节功能

城市绿地作为一种稀缺资源,为城市可持续发展提供多种生态服务功能保障.探讨如何在有限的土地资源内合理配置城市绿地,使其发挥最大的生态服务功能非常重要.研究基于北京市2002年7月的QuickBird数据和Landsat 7 ETM+数据分别提取城市绿地格局和地表温度,分析城市绿地格局(绿地面积、形状指数、邻接关系)与绿地地表温度及冷岛强度的相关关系.邻接关系包括邻接绿地斑块个数百分比和邻接绿地斑块面积百分比.邻接绿地斑块面积百分比采用缓冲区分析法,主要以乔木林地对地表热环境的调节作用为例.结果表明绿地格局参数对地表温度的影响相差较大:①城区主要的绿地类型(乔木林地、水体、草地)的温度都与其面积呈显著负相关,其中水体的相关系数最高;②只有乔木林地、水体的温度与其形状指数呈显著负相关,而灌木林地的温度与各个格局参数不相关;③乔木林地的缓冲区分析显示温度与其大小、形状、邻接绿地面积百分比关系都呈负相关,其中与邻接绿地面积百分比的相关关系最强,其冷岛强度也主要受邻接绿地面积百分比的影响.基于遥感识别的城市绿地微气候调节功能研究,有助于提高有限的城市绿地的生态服务功能,并可为城市绿地的规划管理和景观分析提供依据.     

Effect of urban green patterns on surface urban cool islands and its seasonal variations

Urban green spaces often form urban cool islands (UCIs), which are important for human health and urban sustainability. Previous studies have emphasized the cooling effects of urban green spaces on their surrounding areas at landscape level. Less attention, however, has been directed to effects of urban green space patterns on their own UCIs at patch level. In this study, we focused on the effects of spatial patterns of urban green patches on their own surface UCIs. The urban green spaces of Beijing, China, were extracted from one QuickBird image and were classified as Trees, Shrubs, Grass, Crops, River and Lake. Land surface temperatures (LSTs) were derived from four Landsat images, each in one season. The UCI was represented by the minimum LST of each urban green patch. Results showed spatial patterns of urban green patches had significant effects on their UCIs in four seasons. In detail, the size, edge and connectivity of urban green spaces all affected the UCIs negatively, and the influence was stronger in warm seasons. Shape of urban green space also had effects on UCIs, but the effects were stronger in cool seasons. Great differences were found between predictive values of metrics for different green types. Shape metrics were more important for indicating UCIs of River, Trees and Crops than were patch size and connectivity. However, patch size and connectivity metrics were more effective in determining UCIs of Shrubs, Grass and Lake than were shape metrics. Further, among shape metrics, only shape index was a good indicator of UCIs. The results of this study suggest that a combination of specific urban green types and pattern metrics are a prerequisite for analyzing the influence of urban green patterns on UCIs and for urban green design.     

除草剂随滴灌水施用的除草效果及对烟草生长的影响

为了探讨不同土壤处理除草剂随滴灌水施用的效果,2012—2014年在河南省襄城县优质烟田,对筛选出的5种土壤处理除草剂(50%敌草胺可湿性粉剂、90%双本酰草胺可湿性粉、96%精异丙甲草胺乳油、72%异丙甲草胺乳油和48%甲草胺乳油)进行了试验,施用量均为生产厂家规定的最佳用量,杂草防治对照为微喷灌不喷洒除草剂(CK-1)处理,除草剂施用量对照为随滴灌水不施用除草剂(CK-2)处理。结果表明,随滴灌水施用除草剂处理的杂草防治效果,以CK-1为对照达90.97%以上,以CK-2为对照达72.56%以上,并且除草剂处理在提高烟叶产量、上等烟产量、有效叶片数、叶面积系数方面,与两对照间的差异达到了极显著水平;不同除草剂处理之间,除对株高的影响没有达到显著水平外,对其他性状的影响均达到了显著水平。其中,50%敌草胺可湿性粉剂和96%精异丙甲草胺乳油处理的除草和增产效果均较好,以CK-1为对照的除草效果分别达96.10%和95.36%,以CK-2为对照的除草效果分别达88.15%和85.90%;烟叶产量较CK-1分别提高19.98%和17.28%,较CK-2分别提高7.50%和5.08%;上等烟产量较CK-1分别提高95.30%和82.98%,较CK-2分别提高48.06%和38.71%;同时其烤烟株高、有效叶片数和叶面积系数也较其他3种除草剂处理有不同程度的提高。因此,这5种土壤处理除草剂随滴灌水施用是可行的,既可以有效防止杂草生长,又可显著改善烟草经济和农艺性状,建议豫中烟区随滴灌水施用土壤处理除草剂时首选50%敌草胺可湿性粉剂和96%精异丙甲草胺乳油。