低氧胁迫下外源硝态氮对樱桃根系功能及氮代谢相关酶活性的影响

以樱桃组培苗‘吉塞拉5号’（Prunun cerasus × P. canescens）为试材,采用营养液水培控制溶氧浓度的方法,研究了短期低氧胁迫下外源硝态氮对其根系功能及氮代谢相关酶活性的影响.结果表明：与对照（7.5 mmol NO₃^-·L^-1）相比,低氧加氮处理（15和22.5 mmol NO₃^-·L^-1）使樱桃体内代谢原料充足,保证了各类酶蛋白的合成,使植株根系活力升高,根系呼吸未受到明显抑制,与氮代谢相关的硝酸还原酶（NR）、谷氨酰胺合成酶（GS）及谷氨酸脱氢酶（NADH-GDH）活性升高,从而为低氧逆境下樱桃根系的吸收作用提供了足够的能量,保证了糖酵解和电子传递的顺利进行,并及时同化了NO₃^-还原生成NH₄⁺,避免了铵毒害,缓解了樱桃的低氧伤害,且22.5 mmol NO₃^-·L^-1处理的缓解效果优于15 mmol·L^-1处理;低氧缺氮处理（0 mmol NO₃^-·L^-1）的樱桃植株根系活力下降,根系呼吸受到抑制,NR、GS及NADH-GDH活性降低.这说明低氧胁迫下,适当提高生长介质中的NO₃^-浓度可调控樱桃的根系功能及氮代谢,缓解低氧胁迫对樱桃根系的伤害.     

中山市小榄镇城区绿地植物调查与评价

本文对小榄镇城区绿地植物种类进行了调查与研究.调查发现,小榄镇植物种类丰富,有105科433种.其中,公园绿地和苗圃区植物种类最多,街头与街道附属绿地植物种类较单调:乔木与灌木应用较多,藤本植物应用较少:乔木花卉于公园中应用较多;人工造林的林相、林型单一.旧城区绿地严重缺乏;部分工厂、学校对绿化不重视.研究提出,合理选择绿化树种,将木兰科植物作为乡土类的重点,紫葳科、木棉科和豆科作为外来树种引进的重点;对贺榄山现存桉树、相思疏残林进行林相改造,选择樟科、壳斗科、山茶科等作为骨干树种分期、分批进行混植.最后,筛选出适合各种类型绿地应用的绿化树种.     

Spatial distribution and human health risk assessment of heavy metals in campus dust: A case study of the university town of Huaxi

Abstract

A detailed investigation was conducted to understand the contamination characteristics of a selected set of heavy metals (HMs) in 34 campus dust samples from Huaxi University Town. The HMs spatial distribution analysis based on ArcGIS software, the geo-accumulation index (I_geo) and health risk model were employed for evaluation, and multivariate statistical methods were used to identify possible sources. Results showed that the mean concentrations of Cu, Zn, Pb, Cr, Ni, and Cd were 68.18, 123.81, 45.26, 140.36, 47.26, and 0.47?mg/kg, respectively. The spatial distribution characteristics displayed that the relatively large concentrations for the analyzed HMs were mainly located at both teaching areas and students’ dormitory areas. The average values of I_geo indicated that HMs contamination level followed the decreasing trend of Cd?>?Cu?>?Cr?>?Pb?>?Ni?>?Zn. The health risk assessment results indicated that HMs in campus dust generally do not pose any immediate health risk for both adult males and adult females but the cumulative effect is a matter of concern. The sources analyses demonstrated that Cu, Zn, Cr, and Cd, primarily from motor vehicle emission and waste incineration, Pb predominantly originated from construction source, while Ni had the mixed sources of nature and traffic.     

东莞桥头镇农业生态系统模式的研究

为探索东莞市桥头镇的农业现代化,运用面上调查和定点分析的研究方法,概括了全镇现有的４大类农业生态系统模式,对其进行了能流和磷流分析,得到如下结果：规模经营的综合种养场水稻产出较高,纯收益较好,光能利用和辅助能能效较高,而传统小规模水稻则有机肥投入比例大,磷效高;单－蔬菜种植模式的菜场,干物产量低,光能利用率和辅能能效低,磷素投入高,但有机磷比例低,故磷效低,但经济效益好。综合种养场猪和鱼的养殖,生产成本低,经济效益好,养猪和鱼分别可将生活废弃物中３９．６２％和１２．６８％的磷转化为产品磷。农科园集约化鸡场能量产投比低,但对全价饲料中磷素的转化率高达６２．６５％。本文还就该镇在新的经济环境下,调整农业布局、采纳王高农业模式方面展开了论述。     

基于高分辨率影像和GIS的辛庄镇景观动态变化

利用1980、1991、2001和2009年4期高分辨率(空间分辨率≤1m)遥感影像,选择景观动态度、转移矩阵和景观格局指数等方法,对常熟市辛庄镇景观变化总体特征、变化速率、转移流向以及景观水平和类型水平的格局特征进行了分析。结果表明:1980—2009年间,水田面积急剧下降,旱地和水体面积也逐渐减少;居民用地、工业用地和鱼塘面积持续快速增加;其他类型景观面积变化不太显著。水田始终是研究区景观转化最主要的"源",主要转移去向是鱼塘、工业用地和居民用地;2001年前,鱼塘和居民用地是景观转化的"汇";2001年后,随着农村城镇化和工业化的加速发展,建设用地成为最主要的"汇",工业用地和居民用地的转入贡献率逐渐增加。在景观水平上,研究区景观格局破碎化程度日益严重,异质性逐渐增加,景观优势类型对景观整体的控制作用逐渐减弱,景观向多样化和均匀化趋势发展。在类型水平上,居民用地、鱼塘和工业用地呈连片发展趋势,优势度不断加大,水田的优势地位逐渐降低;各时期水田和水域的最大斑块指数(LPI)值远大于其他景观类型,但随着时间的推移,居民用地、工业用地和鱼塘的LPI值逐渐增大。水域和旱地的景观形状指数(LSI)值最大,水田、居民用地和鱼塘次之,表明这几类景观形状较为复杂,其余各类景观的形状相对规则。     

茅台上游河谷地区苔藓植物生态学研究

对贵州茅台镇茅台上游河谷地区的苔藓植物生态学进行了研究。结果表明,该地区有苔藓植物30科53属116种;生态类型有石生、土生、沙生、树附生、腐木生和水生等6种;PCA排序分析表明,在大气候相同的环境下,苔藓植物生态分布格局差异大,主要受微环境的影响。淡色同叶藓、拟阔叶小石藓、毛口藓、齿边缩叶藓、褶叶青藓和拟脆枝曲柄藓为该地区的优势苔藓植物,其生物量为32.80~225.00 g m-2,饱和吸水量为23519.90~269999.96 g m-2。这说明,苔藓植物在该地区的生态修复过程中,以其特有的生态功能在水土保持和涵养水源、物质循环、土壤性质改善和更新等方面起到十分重要的作用。     

辽宁中部城镇密集区土地利用变化的碳排放及低碳调控对策

土地利用变化引起的碳排放对全球气候变化有重要影响,调整区域的土地利用方式对适应全球气候变化具有重要的科学意义.本研究利用辽宁省碳排放/吸收参数,估算了辽宁中部城镇密集区土地利用变化的碳排放量.结果表明： 1997—2010年,碳排放量为308.51 Tg C,碳吸收量为11.64 Tg C,碳吸收量可抵消
3.8%的碳排放量.土地利用变化的净碳排放为296.87 Tg C,其中,保持用地类型不变的土地上净碳排放量是182.24 Tg C,对总排放量的贡献为61.4%;发生用地类型转换的土地上净碳排放量是114.63 Tg C,对总碳排放量的贡献为38.6%.通过量化土地利用变化和碳排放之间的映射关系可知,1997—2004年,保持建设用地不变（40.9%）和农田转为建设用地（40.6%）类型对碳源的贡献最大,农田转林地（38.6%）和保持林地不变（37.5%）类型对碳汇的贡献最大;2004—2010年,土地利用类型对碳源和碳汇的贡献类型与前一时段相同,但保持建设用地类型对碳源的贡献提高到80.6%,保持林地类型对碳汇的贡献提高到71.7%.基于不同景观变化类型的碳排放强度,我们从两方面提出低碳土地利用的调控对策：从碳减排方面,严格控制土地利用向建设用地转变,提高建设用地能源利用效率,避免对林地和水域过度开发利用;从碳增汇方面,增加森林覆盖率,实施农田、草地还林,加强对森林、水域的保护,调整农用地内部结构和科学实施农田管理.     

Embedding ecological sensitivity analysis and new satellite town construction in an agent-based model to simulate urban expansion in the beijing metropolitan region,China

As the national center for politics and culture, Beijing’s urbanization level is very high. Many policies within the proposed Beijing–Tianjin–Hebei region coordinated development plan affect the expansion of urban land. Therefore, it is very important to predict urban land use changes in Beijing for planning and management purposes. In this paper, we integrated of MAS (multi-agent system) and CA (cellular automata) to simulate new satellite towns construction and ecological sensitivity impact on land use change. Physical and social driving factors were used in the combined model. The MAS involved the actions of three types of agent: regional authorities, property developers, and residents. The study used the CA model to simulate the neighborhood effects of urban land use, and the MAS model to simulate agents’ decisions. The new satellite towns and an ecological sensitivity analysis were embedded in the model to simulate the impact of decision making by the Beijing government on urban land expansion. Based on the land use data of 2005, the urban land area in 2010, 2015, 2020, and 2025 was predicted using the CA-MAS model. Urban expansion occurred faster during 2015–2025 than during the previous 10 years. Three land use types, i.e., cropland, woodland, and rural residential land, were the major sources of urban expansion. With respect to government decision making, the satellite towns were the priority areas of urban development, and urban development was restricted in ecologically sensitive areas. The New Districts of Urban Development were projected to become the main areas of future urban expansion in Beijing. The area designated for urban expansion around the ecologically sensitive areas was small. The results demonstrate that satellite towns and ecological sensitivity have large impacts on urban expansion. The results of this study will help to protect ecologically sensitive land, while enabling harmonious expansion of the city.     

珠三角河网区典型生境植物群落构成特征及生态修复

如何实现生态文明建设与三生空间高度混杂地区的高质量协同发展是珠三角河网区新时期面对的重要难题。以2018—2021年间积累的第一手田野调查资料为基础，针对广佛地区20处样地202个样点，综合生态学数量分析与风景园林学空间分析方法，研究河网区典型生境的植物群落构成特征及应用。结果表明：(1)珠三角河网区植物物种丰富，维管束植物共122科382属551种；植物群落“乔、灌、草、藤本”垂直结构完整，但乡土植物占比较低、外来入侵较严重；(2)动物友好植物种类丰富，共有鸟类友好植物88种、昆虫类友好植物90种、鱼类两栖类友好植物34种，但缺乏针对动物友好生境的科学配置；(3)河网区包括滨水、坑塘、农田、聚落四类典型生境以及9个稳定的植物群系，但在长期人为干扰下其生态功能和水乡风貌特征被严重削弱。最后，以佛山大美公园为例，探讨了以恢复河网区生物多样性和特色景观风貌为目标的生态修复实践。研究为珠三角河网区地域性景观恢复和三生空间混杂区域的近自然生态修复提供了重要的规划设计蓝本和实践示范。