长江流域城镇化对生境质量的影响梯度差异研究

作为我国最大的流域,长江流域城镇化对生境质量的影响呈现出明显的沿江梯度差异。揭示城镇化对生境质量影响的梯度差异对长江大保护以及生境修复差异化管控措施的制定具有重要意义。然而,城镇化对生境质量影响的沿江梯度差异规律仍然不清楚。基于此,沿长江建立了三个缓冲梯度,并基于多源数据,借助一系列动态分布和空间回归分析方法分析了2000年、2010年和2020年城镇化对生境质量影响的梯度差异规律。结果表明：(1)长江流域的生境质量沿缓冲梯度先减少后增加,且在不同梯度区间内均随时间发生恶化,而城镇化水平沿缓冲梯度不断降低,但在不同梯度区间随时间发生了剧烈增长;(2)不同梯度区间生境质量的区域内差异以及区域间差异均不断增加,超变密度是区域差异的主要来源,且不同梯度区间生境质量的转移趋势也具有较大差异;(3)城镇化水平与生境质量以负相关为主,且城镇化对生境质量的负向影响沿着缓冲梯度不断增强,但随时间均有所减弱。针对长江流域地区的生境治理,应当充分考虑生境质量及其影响因素的梯度差异,以支持差异化生境保护政策与措施的制定与实施。     

长江中游水系鲢和草鱼群体mtDNA遗传变异的研究

采用PCR技术进行了长江中游鲢和草鱼四个地理群体的线粒体DNA（mtDNA)限制性片段长度多态性（RFLP）的研究。四个地理群体包括长江中游的湖北嘉鱼和江西瑞昌两个地理群体,长江中游的两大支流江汉和湘江群体。PCR技术扩增出mtDNA ND5-ND6基因,选用10种限制性内切酶对PCR产物进行酶切。从鲢中共检出18种单倍型,在草鱼中没有发现多态现象,只有一种单倍型存在。进一步地证实了长江鲢的遗传多样性比草鱼的要丰富得多,与这两种鱼类在长江现有生物量成反比的反常现象。     

Identifying freshwater mussels (Unionoida) and parasitic glochidia larvae from host fish gills: a molecular key to the North and Central European species

Freshwater mussels (order Unionoida) represent one of the most severely endangered groups of animals due to habitat destruction, introduction of nonnative species, and loss of host fishes, which their larvae (glochidia) are obligate parasites on. Conservation efforts such as habitat restoration or restocking of host populations are currently hampered by difficulties in unionoid species identification by morphological means. Here we present the first complete molecular identification key for all seven indigenous North and Central European unionoid species and the nonnative Sinanodonta woodiana, facilitating quick, low-cost, and reliable identification of adult and larval specimens. Application of this restriction fragment length polymorphisms (RFLP) key resulted in 100% accurate assignment of 90 adult specimens from across the region by digestion of partial ITS-1 (where ITS is internal transcribed spacer) polymerase chain reaction (PCR) products in two to four single digestions with five restriction endonucleases. In addition, we provide protocols for quick and reliable extraction and amplification of larval mussel DNA from complete host fish gill arches. Our results indicate that this new method can be applied on infection rates as low as three glochidia per gill arch and enables, for the first time, comprehensive, large-scale assessments of the relative importance of different host species for given unionoid populations.     

广东湛江鲤鱼墩遗址人骨的C、N稳定同位素分析:华南新石器时代先民生活方式初探

相对于长江流域和黄河流域而言,华南地区先民生活方式的了解一直较为缺乏。广东湛江鲤鱼墩遗址人骨的C和N稳定同位素分析,显示此遗址的先民主要以海生类资源为食,陆生资源(包括可能的块茎类原始农业和动物)只占次要地位。通过与约同时代黄河流域、长江流域先民的稳定同位素数据比较,可以看出,早在6000年前,我国先民的生活方式就已出现3大类型。     

黄河流域景观破碎化时空特征及其成因探测

黄河流域快速的人口增长和城市扩张加剧了土地利用转型和生态景观破碎化,引发了诸如生态系统功能退化、生物多样性功能减弱以及生境破碎化等一系列严重问题。探明黄河流域景观破碎化时空特征及其成因对维护流域生态系统稳定和生态修复具有重要指导意义。但是以往研究缺乏对黄河流域景观破碎化时空特征及其归因分析的相关研究,难以为黄河流域生态环境治理以及景观格局优化提供科学指导。基于FRAGSTATS4.2软件测度了2000—2018年黄河流域县域单元景观破碎化时空格局特征,并借助地理探测器模型探讨了黄河流域景观破碎化时空分异的成因。研究表明：(1)研究期间黄河流域斑块密度(PD)无显著变化,边缘密度(ED)、景观形状指数(LSI)、平均斑块面积(Area＿AM)均呈先增后减的变化趋势,聚集度指数(AI)呈先减后增的趋势;蔓延度指数(CONTAG)持续降低,分离度(DIVISION)、香农多样性指数(SHDI)逐年增高。(2)研究期间黄河流域景观破碎化程度总体逐渐加剧,流域中下游各省破碎化程度变化剧烈,上游各省破碎化程度变化趋于平稳。(3)地理探测器结果显示,黄河流域景观破碎化受到自然、社会等多重因素影响,因...     

黄柏河流域不同区域浮游植物群落特征及总磷分析

黄柏河流域矿产资源丰富,磷矿开采导致的颗粒磷排放、地表径流汇聚沉积等会对流域内浮游植物的群落演替产生较大影响。为研究黄柏河流域磷矿开采后环境因子对浮游植物群落结构的影响,于2020年的春季（5月）、夏季（8月）和秋季（9月）分别对黄柏河流域10个监测断面水质和浮游植物采样。根据地区划分法和NMDS分析法将研究区分为磷矿开采影响区（A组）和非影响区（B组）,采用主坐标分析（PCoA）和聚类分析得到A组和B组的浮游植物群落结构具有明显差异,A组优势属为隐藻（Cryptomonas）、舟形藻（Navicula）和小环藻（Cyclotella）;B组优势属为隐藻（Cryptomonas）和针杆藻（Synedra）,且B组中物种数多于A组。采用典范对应分析（CCA）法分析了环境因子与浮游植物的关系。结果表明,溶解氧、水温、氨氮、氟化物、总磷对黄柏河流域的浮游植物影响较大,且A组浮游植物群落结构与总磷、溶解氧和水温呈负相关,与氟化物呈正相关;B组浮游植物群落结构与溶解氧、总磷呈负相关。研究结果可为该流域的生态环境保护和治理提供科学指导意义。     

The importance of facilitation in the zonation of shrubs along a coastal salinity gradient

Question: What are the interactive roles of abiotic stress and plant interactions in mediating the zonation of the shrub Tamarix chinensis along a salinity gradient? Location: Yellow River estuary (37°46′N, 119°09′E), northeast China. Methods: We surveyed the zonation of T. chinensis along a salinity gradient and quantified its salt tolerance using a pot experiment. In two field experiments, we transplanted T. chinensis seedlings into salt marsh, transitional zone and upland habitats, manipulated neighbours and quantified survivorship and biomass to examine neighbour effects. We also quantified vegetation effects on abiotic conditions in each zone. Results: Tamarix chinensis dominated the transitional zone, but was absent in upland and salt marsh habitats. In the pot experiment, T. chinensis grew well in freshwater treatments, but was inhibited by increasing salinity. Field experiments revealed that competition from neighbours limited T. chinensis growth in the uplands, while T. chinensis transplants were limited, with or without neighbours, in the salt marsh by high soil salinity. In the transitional zone, however, T. chinensis transplants performed better with than without neighbours. Vegetation removal significantly elevated soil salinity in the transitional zone, but not in other zones. Conclusions: Competition, facilitation and abiotic stress are all important in mediating the zonation of T. chinensis. Within its physiological stress tolerance range, or fundamental niche, it is limited by plant competition in low salinity habitats, and facilitated by neighbours in high salt stress habitats, but cannot survive in salt marshes having salinities above its salt stress tolerance limit. Our results have implications for understanding the relationships between facilitation and stress gradients.     

江河源区高寒草甸退化序列土壤粒径分布及其分形维数

江河源区高寒草甸退化日益严重,恢复治理已进行了大量工作,但收效甚微,主要是对退化机理认识不清.为阐明退化草地的形成机制,
本文以江河源区高寒草甸为对象,分析退化序列土壤粒径的分布特征、分形维数,以及分形维数与土壤侵蚀模数的关系.结果表明: 随着高寒草甸退化加剧,土壤的黏粒百分含量呈增加趋势,粉砂和极细砂呈减小趋势;退化序列土壤粒径分形维数与黏粒百分含量呈显著正相关,与极细砂和粉砂呈显著负相关;各粒级土壤侵蚀模数与分形维数呈二次函数关系,分形维数2.81为土壤侵蚀发生的阈值.以土壤粒径分形维数2.81作为草地恢复指标,选择使分形维数小于2.81的相应措施,是恢复退化草地的有力保证.     

基于生态系统服务供求评价的空间分异特征与生态格局划分——以长三角城市群为例

生态系统服务供给与需求能力存在显著的空间异质性与空间失衡,对区域经济发展与环境保护产生巨大影响。以长三角城市群区县为研究单元,分别核算其生态系统服务供给与需求值,引入梯度分析,分析生态系统服务供给与需求的空间特征,并基于供求分析提出长三角城市群生态格局分区方案,且针对性地提出相应片区的发展策略,为长三角城市群土地利用规划、区域协调发展提供科学依据。研究结果表明:(1)长三角城市群生态系统服务供给能力与土地利用类型密切相关,呈现从北到南逐渐升高趋势;(2)长三角城市群生态系统服务需求能力与社会经济发展联系紧密,在长江入海口附近形成生态系统服务需求高值区,然后向外围递减;(3)沪宁杭庐发展梯度带上,生态系统服务供需大致呈现负相关趋势;(4)基于生态系统服务供需关系构建,得到长三角城市群生态格局四大分区:生态保育区(高供给-高需求),生态修复区(低供给-高需求),生态重塑区(低供给-低需求),生态开发区(高供给-低需求)。