亚热带-温带过渡区秦岭落叶阔叶林幼苗存活机制

【目的】物种幼苗的存活与各种生物和非生物因素密切相关,研究关键因素对幼苗存活的影响有助于理解群落物种共存的主要作用机制。【方法】以秦岭落叶阔叶林25 hm²固定样地的木本植物幼苗为对象,对11 408棵幼苗的生存动态开展连续5年(2015—2019年)的监测,利用广义线性混合模型(GLMMs)在群落水平上对影响不同年龄阶段幼苗存活的主要生物与非生物因素进行分析。【结果】(1)从群落水平来看,对幼苗存活影响最大的是生物因素,幼苗存活率与同种幼苗邻体密度和同种大树邻体胸高断面积呈显著负相关,与异种幼苗邻体密度呈显著正相关,表明物种在幼苗时期受到强烈的负密度制约效应;(2)从苗龄水平上来看,除了生物因素,影响幼苗存活的主要因素还包括海拔等非生物因素,但非生物因素的影响随着苗龄增大而减小。【结论】影响幼苗存活因素是多样的,其中生物因素的影响更显著,促进秦岭大样地中幼苗共存的主要机制为负密度制约效应。     

环境因子调控植物花青素苷合成及呈色的机理

花青素苷（anthocyanin）是决定被子植物花、果实和种皮等颜色的重要色素之一。花青素苷的合成与积累过程往往与植物发育过程密切相关,由内外因子共同控制。环境因子通过诱导植物体内花青素苷合成途径相关基因的表达来调控花青素苷的呈色反应。该文追踪了国内外相关研究,认为光是影响花青素苷呈色的主要环境因子之一,光质和光强均能在一定程度上影响花青素苷的合成,其中光质起着更为关键的作用;低温能诱导花青素苷的积累,高温则会加速花青素苷的降解;不同的糖类物质均能影响花青素苷的合成,大部分结构基因和调节基因的表达均受糖调控。关于花发育与花青素苷呈色的关系、观赏植物花色对环境因子的响应以及花青素苷抵御逆境的机理尚待深入研究。因此,综合考察花发育与植物花青素苷合成及其呈色之间的关系,特别是光周期对花发育的影响导致花青素苷合成及呈色的机理是花色研究的一个重要课题。利用环境因子调控花色将会极大地提高花卉的观赏价值。     

气孔参数与大气CO2浓度的相关性及其影响因素

通常认为气孔参数(气孔密度和气孔指数)和大气CO2浓度有负相关关系,但不是每种植物的气孔参数都与CO2浓度的变化有负相关关系,气孔参数对大气CO2浓度的显著反应也只在一定的CO2浓度范围内发生。大气CO2浓度是影响气孔参数变化的主要因素,同时温度、水分的供应和光照条件等其它环境因素也影响气孔参数。CO2浓度和光照条件主要影响气孔发生,而其它环境因素主要影响叶片表皮细胞的大小。气孔指数部分消除了表皮细胞大小带来的影响,用气孔指数指示大气CO2浓度比用气孔密度指示更为可靠。     

Can adults of the New Zealand mosquito Culex pervigilans (Bergorth) detect the presence of a key predator in larval habitats?

The influence of predators on mosquito populations may be direct through predation or indirect through sub‐lethal responses of adult mosquitoes in life history traits such as oviposition behavior. In New Zealand, the backswimmer, Anisops wakefieldi, is a common predator of mosquito larvae found in temporary and permanent water bodies. We predicted that the New Zealand native mosquito, Culex pervigilans, whose larvae are vulnerable to predation of Anisops, would likely avoid the containers with the presence of Anisops or its kairomone. We established temporary water containers without predators, free‐roaming predators, caged predators (which were unable to eat mosquitoes), or containers from which predators were removed immediately prior to the experiment (these containers would have remnant kairomones from the predators). Each treatment with Anisops had predator densities of one, three, or nine Anisops. Contrary to our predictions, when choosing oviposition habitats, Cx. pervigilans appeared to ignore the presence of free‐roaming Anisops, caged Anisops, and water with Anisops kairomone. We thus observed no significant differences between the numbers of egg rafts laid by Cx. pervigilans in the different predator treatments nor were the number of egg rafts significantly affected by the density of predators. Rather than the presence of predators, environmental factors including temperature, humidity, and pressure were significantly correlated with mosquito oviposition. These mosquitoes appeared to either ignore the presence of the predator, had no ability to detect the presence of predators, or perhaps the cues from Anisops predators were not sufficiently strong enough to alarm these mosquitoes. We argue that the mosquito has not evolved the ability to detect the presence of these predators while ovipositing.     

基于生态系统净化与人为调控耦合作用的水环境承载力评估

针对目前水环境承载力相关研究中未突显生态系统净化作用和人为调控作用的问题,从生态系统污染净化功能和人为调控污染削减功能两个角度,提出基于生态系统净化-人为调控耦合作用的水环境承载力概念,并构建流域环境承载力评估模型。以滇池流域为例,计算了2015年滇池流域水环境承载力。研究结果表明:滇池流域2015年水环境承载力综合指数为1.16,处于超载状态;流域环境承载力分布呈现北高南低,北部限制因子化学需氧量,南部为总磷;调水工程调入水量出境携带污染物约为流域水环境承载力的16%,对流域水环境改善十分重要;人为调控污染削减能力在流域水环境承载力中所占比例已超过50%,成为不可忽视的一部分。     

Nar与Nap结构生物学的研究进展

硝酸盐是全球氮循环的关键组成部分,同时也是植物有效氮的重要来源。研究硝酸盐的转化过程对于生态系统生产力的提高有重要意义,而自然环境中硝酸盐的转化主要是硝酸盐的异化还原。同时,硝态氮的大量输入导致了诸多环境生态问题,引起人们广泛关注。反硝化反应是环境中硝态氮去除的主要过程。硝酸盐异化还原是反硝化过程硝态氮去除的第一步,可以为后续的还原反应提供反应底物。研究硝酸盐还原过程还可以加深对微生物脱氮的理解。硝酸盐异化还原由膜结合硝酸盐还原酶(Nar)和周质型硝酸盐还原酶(Nap)共同催化,但二者在结构、细胞定位、反应机理以及基因调控等方面存在差异,并且二者对于环境因子的响应也不尽相同,因此可能在催化硝酸盐还原过程中存在一定的差异性。本文系统论述了硝酸盐还原酶Nar与Nap在上述几方面的异同,以提升对系统中硝酸盐发展动态的认识。     

中国主要树种木材物理力学属性的地理格局及其环境控制

木材的物理力学属性制约树木生长发育的重要过程,也是决定木材用途的主要依据.研究木材的物理力学属性及其影响因素,可为合理应用木材、科学开展林木选育、改进林业管理等提供必要参考.目前已有的研究多关注单一的木材密度指标,且缺乏多种影响因子的比较.本研究通过建立中国木材物理力学属性及影响因素综合数据库,对自然状态下我国主要树种木材力学属性的分布格局及其驱动因素进行了探讨.结果表明,选择气干密度、弦向干缩系数和冲击韧性作为评估木材物理力学属性的基础指标,比单一木材密度指标更准确,解释率更高;在选用的生活型、气候和土壤等3类因素中,生活型是影响木材力学物理属性变化的最重要因素,气候因子次之,土壤因子基本可忽略,并且气候和土壤因子的作用被生活型所掩盖,这意味着气候因子对于木材物理力学属性的影响是通过影响物种分布而产生作用的.     

Spatio-Temporal Distribution of Freshwater Snail Species in Relation to Migration and Environmental Factors in an Irrigated Area from Morocco

Nine sites were sampled 19 times over 2 years in an irrigation system in Morocco in order to study species abundance in a snail community in relation to environmental parameters (including human activities) and migration (geographic distance) among sites. Each site was made of a sink and the first meters of the downstream canal. The snail community included four species (Bulinus truncatus, Lymnaea truncatula, Mercuria similis and Physa acuta). Strong spatial variation in species occurrence and abundance was detected which might be partly due to variation in water availability. However abundance in sinks and canals in which water availability differs were correlated. There was, as predicted, limited evidence in favor of isolation by distance which might be due to fast water current. Dispersal might therefore be an important factor structuring this community. On the other hand, the temporal variation was much more limited. This is consistent with the analysis of individual size distributions in B. truncatus, since no clear-cut cohorts were detected. The environmental parameters recorded (e.g. temperature, occurrence of macrophytes or cleaning of sinks) were extremely variable in time and space, except temperature. Analyzing their association with species through multidimensional methods indicated that P. acuta is ubiquitous and B. truncatus positively associated with macrophytes. These two species were associated in sinks. Less clear trends were detected for the two other species. Annual cleaning of sinks affected all species, but population recovery was fast in B. truncatus and P. acuta.     

气候变化下野生扬子鳄(鳄目:短吻鳄科)在中国的分布模拟

气候变化及人类活动对极危物种的分布及生存产生重要影响。运用ENMeval优化后的MaxEnt模型对中国特有极危物种扬子鳄（Alligator sinensis）在CMIP6（Coupled Model Intercomparison Project 6,第六次国际耦合模式比较计划）未来气候情景下的潜在适生区做出模拟预测,通过Jackknife检验找出对影响其分布的主要环境因子,并对扬子鳄对主要环境变量的响应做出分析。结果表明,最冷季度降水量（Bio19）、最干季度平均温度（Bio9）、最湿月份降水量（Bio13）、海拔（Elevation）以及气温季节性变动系数（Bio4）是影响扬子鳄分布的最主要环境因素。最冷季度降水量132.12-156.84 mm、最干季度平均温度5.94-7.81℃、最湿月份降水量180.44-221.65 mm、海拔4.60-121.69 m、气温季节性变动系数872.08-903.30是最适宜扬子鳄生存的环境条件。人类活动会造成野生扬子鳄栖息范围的减小。在未来不同气候变化场景下,扬子鳄的适生面积在SSP126气候情景下高于SSP585气候情景,低脆弱性、低辐射强迫的可持续发展路径可以减缓扬子鳄适生范围的丧失。根据预测结果,可在江苏宜兴及湖南洞庭湖平原地区设置野外放归地或建立新的自然保护区。本研究对于扬子鳄的野外放归及遗传多样性保护具有科学指导意义。     

The demise of the population regulation controversy?

For many decades a controversy in population dynamics theory has been raging concerning whether or not populations are regulated by density dependent factors, without reaching a satisfactory conclusion. It is suggested that this failure to solve the problem is due to asking the wrong question and it is suggested that this controversy should be buried and forgotten.     

植物茎尖分生组织分化调控机制研究进展

茎尖分生组织是位于植物顶端具有持续分化能力的组织,通过细胞分裂、分化产生茎、叶和花等器官,形成植株地上部分。茎尖分生组织在分化过程中受外界环境因素、内源激素水平和分子调控等影响,表现出明显变化。该文综合国内外近年来有关茎尖分生组织分化调控的研究进展,从茎尖分生组织的形态结构和环境影响因素,以及激素调控和分子调控等方面,对茎尖分生组织分化活动的研究进行综述,并对目前研究现状存在问题及未来研究方向进行了分析和展望。     

Evaluation of maize productivity considering solar energy use limitation by environmental factors

Evaluation of maize productivity under different climatic conditions was made by determination of the amount of the incident solar radiation energy in the PAR range, which can be potentially used by plants for photosynthesis. An irradiance, which can be stored in primary photosynthesis, designated as photosynthetic energy, W _ph, was estimated taking into account the action spectra of photosynthesis. Limitation of the W _ph usage, owing to unfavorable environmental factors was considered. Quantitative evaluation of limitations by two such factors, air temperature and soil water potential, was made by means of the coefficients F(i), which were defined as the ratio between the photosynthetic rate at a given value of a particular environmental factor and that at the optimal value for this factor. The coefficients F(i), were determined from the dependencies of the photosynthesis rate on air temperature and soil water potential as obtained in chamber and field experiments. In general terms, the fraction of W _ph, which can be utilized under a given climatic condition, was named bioclimatic potential, W _pc. In our model, the effect of monodominancy, when strong action of one factor suppresses the influence of any other factor, was considered. In this case, the bioclimatic potential, designated W′_pc, was calculated by multiplying W _ph times the coefficient F, for the factor which was most limiting during the period of measurement. There was close correlation between values of bioclimatic potential for the period of vegetation, W′_pc,v, and total dry matter. W′_pc,v use efficiency in the maize crop was also evaluated for five variants of mineral nutrition. This revised version was published online in June 2006 with corrections to the Cover Date.     

青藏高原源头河流水体溶解性有机物组分及其关键调控因素

水体溶解性有机物(Dissolved Organic Matter, DOM)是河流生态系统的重要组成部分,其含量及组分的变化与生态系统功能密切相关。以青藏高原东缘龙苍沟流域27条Strahler 1级源头河流为研究对象,采用DOM荧光特性表示组分特征,同时调查各河流地理特征、气候特征和水化学特征,探究源头河流DOM含量和组分的关键调控因素。研究结果表明:溶解性有机碳(DOC)浓度在0.35-1.50 mg/L之间,平均值为0.85 mg/L。荧光指数(Fluorescence index, FI)的均值分别为0.91和1.11,类色氨酸与类酪氨酸比值(Trypto/Tyro)的均值为0.76,新鲜度指数β/α均值为0.61,表明蛋白质的生物可利用性较差、微生物活性较低。随着海拔的降低,龙苍沟流域河流DOC浓度降低,DOM组分外源性降低,而微生物生物活性升高(P ＜ 0.05)。DOM组分受地形、流域面积和气候因素影响不显著(P ＞ 0.05)。荧光指数 FI、新鲜度指数 β/α与Ca²⁺/Mg²⁺和NO₃^-浓度显著正相关(P ＜ 0.05)。逐步回归结果显示,海拔、坡降、温度、pH、氧化还原电位、DOC浓度、Ca²⁺/Mg²⁺和NO₃^-浓度都对DOM组分起到了一定作用(P ＜ 0.05)。结构方程模型结果显示,在Strahler 1级源头河流中Ca²⁺/Mg²⁺和 NO₃^-浓度是驱动DOM组分海拔变异的主要环境因素。综合以上分析,随着海拔降低,岩石风化加剧,同时人类活动的增加引起NO₃^-浓度的增加改变了水化学环境,导致DOM组分品质改善。对源头河流DOM组分空间变异和调控因素进行了研究,加深对源头河流有机物代谢过程的认识。