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1.
生物炭和黄腐酸对滨海滩涂盐碱地土壤性质的提升   总被引:3,自引:0,他引:3  
为探讨生物炭和黄腐酸对滨海滩涂围垦盐碱地的改良作用,采用田间玉米种植试验法,设置生物炭使用量7.5 t/hm2(BC1)、30 t/hm2(BC2)和黄腐酸用量1.5 t/hm2(FA)及其组合,共6种处理:CK、BC1、BC2、FA、BC1+FA、BC2+FA,研究材料施加对土壤重要盐碱状况表征指标的影响。结果表明,BC2处理降低土壤容重,但低用量BC1处理下土壤容重没有降低,研究区土壤呈逐渐自然板结退化状态;随着生物炭施用量的增加,土壤持水能力呈减小的趋势。生物炭和黄腐酸施用明显提高土壤有机质含量,BC2+FA最高,达到6.31 g/kg;各处理中,周期性脱盐和返盐现象在各处理间的土壤表层呈现一致规律,但BC1+FA和BC2+FA处理的盐分累积明显低于其他处理。结果表明适量生物炭和黄腐酸施用可提高土壤肥力,改善土壤结构,抑制盐分累积,有利于滩涂围垦土地的快速耕地化利用,生物炭使用量为30 t/hm2并黄腐酸用量1.5 t/hm2处理效果最好。  相似文献   
2.
秸秆碳对不同施肥水平低肥力土壤碳组分的影响   总被引:1,自引:0,他引:1  
为探明不同施肥水平下秸秆碳对低肥力土壤溶解性有机碳(DOC)、微生物量碳(MBC)和颗粒有机碳(POC)含量的影响,采用碳化硅管原位法,向不同施肥水平(0、120、240 kg·hm-2,以纯氮计)的低肥力土壤添加13C标记小麦秸秆,定期取土样测定不同有机碳组分的含量及其δ13C值,并计算秸秆碳在各有机碳库中的转化及贡献比例。研究结果显示,秸秆添加后7 d是快速转化阶段,此后秸秆碳转化渐缓,以向POC转化为主。相较于DOC,秸秆碳更倾向转化为MBC和POC,秸秆添加60 d后的转化比例分别为0.12%~0.38%、4.01%~6.25%和4.74%~9.54%。秸秆添加后,土壤DOC、MBC和POC含量均显著增加,来自于秸秆碳的贡献分别为0.29%~15.01%、13.20%~32.85%和33.62%~59.69%。相较于0、240 kg·hm-2的施氮处理,施氮量为120 kg·hm-2时,秸秆添加能同时大幅提高试验土壤的活性和缓效性有机碳库含量。由此表明,秸秆还田条件下,适量施加氮肥更有利于低肥力土壤的培肥与固碳。  相似文献   
3.
探讨了一类多变时滞积分微分动力系统,并通过不动点方法给出了该系统零解渐近稳定的充要条件.在构造算子时,根据动力系统时滞特点,分别引入对应的连续函数h_i(s),i=1,2,…,n,然后利用这n个函数来构造算子,最后再利用Banach不动点方法来研究该动力系统的稳定性.  相似文献   
4.
随着花境在国内的推广与应用,花境本土化过程中存在一些问题,造成各地花境景观雷同、景观衰退严重、养护负担增加。基于此,保证景观效果的稳定性和低维护性是亟须研究的方向。本文在我国各地对花境植物材料的研究基础上,提出了长效低维护花境植物的选择原则,并结合南通当地实践经验总结了长效低维护花境植物的配置方案,以期为花境营造提供参考。  相似文献   
5.
为探究不同发育期及授粉方式对设施甜瓜稳定同位素比值变化的影响,本研究基于元素分析——稳定同位素比率质谱(EA-IRMS),测定在不同发育期和授粉方式中设施甜瓜的4种稳定同位素比值(δ13C、δ15N、δ18O和δ2H),采用单因素方差分析法解析激素授粉和中华蜜蜂授粉对甜瓜稳定同位素比值的差异性。结果表明,在相同的种植和环境条件下,自然分馏效应导致设施甜瓜在不同发育时期的同位素差异。在甜瓜发育期间,不同授粉方式设施甜瓜的δ13C、δ15N和δ18O值较稳定,无显著差异(P>0.05),而在发育30 d时激素授粉与蜜蜂授粉甜瓜的δ2H值分别为-43.63‰和-53.50‰,存在显著差异(P<0.05)。本研究初步揭示了稳定同位素在甜瓜发育过程中以及不同授粉方式下的分馏情况,其中δ2H值可作为甜瓜授粉方式的一项标识性指标,对丰富设施甜瓜溯源体系具有重要意义。  相似文献   
6.
Variation in movement between individuals can have important ecological effects on populations and ecosystems, yet the factors driving differences in movement and their consequences remain poorly understood. Here, individual variability in the movements of juvenile (age 0 +  and 1 +  year) pike Esox lucius was assessed using passive integrated transponder (PIT) telemetry in off‐channel nursery areas over a 26‐ month period. Differences in the movement patterns of individuals were tested against their body sizes, ages, growth rates and trophic positions using data collected through a combination of catch‐and‐release sampling and stable isotope analyses. Results revealed that variation in movement between individuals was affected by age, with 1 +  individuals moving more than individuals of age 0 + , but not length. Individuals whose TP was low on their initial capture event moved significantly less than those with a higher initial TP. Individuals that moved more grew faster and achieved a higher final TP. These results suggest that higher activity (i.e., increased movement) increases resource acquisition that enhances growth rates, which could ultimately maximise individual performances.  相似文献   
7.
Spatial variations in yield occur in all agricultural fields to some degree. Knowledge of the reasons for these variations, especially temporally stable yield patterns, is needed in order to improve productivity by changing production methods or inputs. This information must be provided in a simple, cost-effective way. This study investigated whether field-scale measurements of penetration resistance (PR) could identify temporally stable yield patterns without complementary measurements of other properties. The PR measurements were also compared with field-scale apparent electrical conductivity (ECa) measurements and correlations between yield and PR and yield and ECa were investigated. Measurements with a newly constructed horizontal penetrometer and a non-invasive proximal electromagnetic induction sensor were carried out in three fields in east-central Sweden. The measurements were made once in each field, apart from one field where PR was measured twice in one season. The sensor measurements were compared with crop yield measured over the course of several years. The horizontal penetrometer was able to identify low-yielding areas in one field. However, single measurements of PR or ECa were insufficient to consistently identify yield variations. Parts of the fields showed more consistent patterns, with stronger correlations between PR, ECa and yield. PR and ECa data were better at explaining yield variations in drier years, but showed diverging patterns in different fields and neither showed a much stronger correlation to yield than the other. In future studies, simultaneous measurement of soil water content is recommended and also PR measurements at a water content drier than field capacity.  相似文献   
8.
Differential use of habitat and prey resources is an important mechanism that may allow coexistence of sympatric species. Unlike interactions between smaller cyprinid and percid fishes, the resource use by coexisting predatory asp (Leuciscus aspius) and pikeperch (Sander lucioperca) is relatively unknown. Here, gut content and stable isotope analyses were used to study ontogenetic dietary shifts and interspecific trophic niche overlap between asp and pikeperch coexisting in two reservoirs. The hypothesis that both species show an ontogenetic dietary shift from small invertebrates to large fish prey, but at the same time use different prey resources to reduce potential competitive interactions, was validated. The isotopic niches of the two predators showed no, or only a moderate, degree of overlap (0%–65%). The ontogenetic changes in the degree of interspecific isotopic niche overlap were different in the two reservoirs, suggesting that trophic segregation can be dynamic and variable among systems. Gut contents revealed that small (<100 mm standard length) asp consumed mostly terrestrial invertebrates and emerged aquatic insects, whereas small pikeperch foraged on zooplankton, larval and pupal stages of aquatic insects and fish. Larger individuals (>100 mm) of both species were predominantly piscivorous, with asp consuming more cyprinid prey and pikeperch more percid prey. Coexisting asp and pikeperch populations are able to utilise different prey resources, thereby reducing potential negative competitive interactions.  相似文献   
9.
基于C、N同位素技术的河流食物网基础碳源研究进展   总被引:1,自引:0,他引:1  
基础碳源是河流生态系统最重要的特征之一,它通过生物间能量传递,影响着河流生态系统生物多样性、群落结构及其稳定性。本文基于稳定性同位素技术综述了河流基础碳源类型、食物网能量贡献率估算模型、食物网基础碳源理论模型(河流生产力模型RPM、河流连续模型RCC和河流脉冲模型FPC)及其交互作用以及它们在实际应用上的利弊,介绍了能较好平衡各种模型利弊、适应于多样化水文特征的河流生态系统综合体(RES)新假说,并展望了稳定性同位素技术与非致命取样方法相结合建立长期河流同位素数据库的重要意义,旨在推动对河流生态系统中不同生物之间营养关系的理解,为河流生态系统的修复与保护提供理论依据。  相似文献   
10.
Cannibalism is a taxonomically widespread phenomenon that can fundamentally affect the structure and stability of aquatic communities, including the emergence of a bimodal size distribution (“dwarfs” and “giants”) in fish populations. Emergence of giants could also be driven or facilitated by parasites that divert host resources from reproduction to growth. We studied the trophic ecology of giant nine‐spined sticklebacks (Pungitius pungitius) in a Finnish pond to evaluate the hypotheses that gigantism in this population would be facilitated by cannibalism and/or parasitic infections by Schistocephalus pungitii cestode. Stomach content analyses revealed an initial ontogenetic dietary shift from small to large benthic invertebrates, followed by cannibalism on 10–20‐mm‐long conspecifics by giant individuals. However, stable nitrogen isotopes (δ15N) indicated a concave relationship between fish size and trophic position, with relatively low trophic position estimates suggesting only facultative cannibalism among giants. The unexpectedly high trophic position of the intermediate‐sized fish may reflect substantial, but temporary, predation on eggs or young‐of‐the‐year conspecifics, but may also partly result from starvation caused by S. pungitii infection. However, it seems implausible that parasitic infections (i.e. castration) would explain gigantism among nine‐spined sticklebacks because all >100‐mm giants were unparasitised. Hence, the present results suggest that an ontogenetic niche shift from an invertebrate diet to intercohort cannibalism may facilitate the occurrence of gigantism in nine‐spined sticklebacks.  相似文献   
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