Effects of different endogenous fungi on the mass loss and nutrient content of leaf litter of Cunninghamia lanceolata北大核心CSCD

To explore the role of endophytic fungi in the decomposition of litter, the endophytic fungi Penicillium sp. strain CG2 (A), Fusarium flavum strain AY13 (B), and Talaromyces strain AJ14 (C) of Cunninghamia lanceolata were added to experimental pots in different forms (mycelium, sterilized fermentation broth, single fungus, and mixed fungi), and a control treatment (CK) was set up (no fungi added). At 10, 30, 60, 90, and 120 days after litter decomposition, a study on the decomposition dynamics of C. lanceolata litter under different treatments was performed. The results showed that the rate of leaf mass loss was the highest in the sterilized fermentation broth treatment A after 120 days, and that there was a significant difference (P < 0.05) between the mycelium treatment AC and the control treatment after 60 days (23.97% higher than the control group). On day 60, the litter carbon content from the mycelium treatment A was significantly different from that of the control (P < 0.05), showing a 16.74% lower value, whereas the litter carbon content of the mycelium treatment B was 21.13% lower than that of the control after 90 days. The nitrogen content of the litters of most mycelium and sterilized fermentation broth treatments was increased compared to that of the control group; there was significant difference (P < 0.05) between the sterilized fermentation broth treatment A and the control (P < 0.05), with a 17.05% higher value than that of the control. Similar to nitrogen, the litter phosphorus content also increased; there was a statistically significant difference between the mycelium treatment A and the control group, with treatment A showing a 46.67% higher value than the control group. The potassium content was 28% lower than that of the control group under the sterilized fermentation broth treatment C, a result that was significantly different from that of the control group (P < 0.05). After treatment for 90 days, the ratio of carbon to nitrogen was the lowest under the treatments with the mycelium A and the mycelium B, with values 25.54% and 25.11% lower than that of the control group, respectively, and a statistically significant difference from that of the control group (P < 0.05). The ratio of carbon to phosphorus was the lowest under the treatment with mycelium A after 60 days, and the result was significantly different from that of the control (P < 0.05), with a 43.05% lower value than the control. Thus, the three endophytic fungi had different effects on the mass loss rate and nutrient content of the litter. The Penicillium sp. strain CG2 (A) had statistically significant effects on the mass loss and nutrient content of leaf litter, which was within the range of fungi fertilizer reference values for the breeding of C. lanceolata. © 2018 Science Press. All rights reserved.     

Development of a hydrothermal time seed germination model which uses the Weibull distribution to describe base water potential

Seed germination has been modelled extensively using hydrothermal time (HTT) models, that predict time to germination as a function of the extent to which seedbed temperature, T, and water potential, Ψ, exceed the base temperature, T_b, and base water potential, Ψ_b, of each seed percentile, g. Within a seed population the variation in time to germination arises from variation in Ψ_b(g) modelled by a normal distribution. We tested the assumption of normality in the distribution of Ψ_b(g) by germinating seed of two unrelated species with non-dormant seed (Buddleja davidii (Franch.) and Pinus radiata D. Don) across a range of constant Ψ at sub-optimal T. When incorporated into a HTT model the Weibull distribution more accurately described both the right skewed distribution of Ψ_b(g) and germination time course over sub-optimal T than the HTT based on the normal distribution, for both species. Given the flexibility of the Weibull distribution this model not only provides a useful method for predicting germination but also a means of determining the distribution of Ψ_b(g).     

丛枝菌根真菌对羊草凋落物降解作用的研究

丛枝菌根真菌（Abuscular mycorrhizal fungi）能够影响植物生长及养分含量,从而影响凋落物的降解。采用根袋的方法研究了接种两种丛枝真菌Glomus mosseae和Glomus claroideum对羊草（Leymus chinensis）地上部及根系凋落物降解的影响。结果表明,随时间的延长,凋落物的重量逐渐减少,凋落物氮、磷含量均表现出先下降后逐渐升高的趋势。接种对地上部凋落物的养分含量及降解速度未产生显著性影响,但显著降低了根系氮磷含量及降解系数。接种Glomus mosseae和Glomus claroideum羊草根系氮、磷含量均显著低于CK;接种与未接种相比羊草根系k值显著降低;根系C：N未接种处理显著低于接种处理。说明丛枝菌根真菌可能间接影响草原生态系统中有机物质的分解和养分释放。     

Made in conflict. Local residents' construction of a local environmental problem

The aim of this paper is to understand how local residents participate in the construction of local environmental problems and to evaluate a particular analytical approach in environmental sociology to study this phenomenon. The paper is based on an interview study with a sample of local residents. The analysis demonstrates how the local residents attempt to construct a local environmental problem. In particular, the study focuses on how involved actors are positioned, how different sorts of knowledge claims are used, and how the neglect the residents perceive from the authorities affects the attempt to construct a local environmental problem. The study shows that the local residents play a central role in the construction of the situation and that the evaluated model could be very helpful as an analytical tool in the investigation of local residents' participation in the construction of environmental problems.     

Climate changes in the past century and radial increment of pine in the Southern Ural steppe

Changes in the main climatic factors (air temperature and total precipitation) and their effect on the radial increment of Scots pine (Pinus sylvestris L.) over the period from 1933 to 2002 were studied in an insular pine forest growing in the steppe zone of the Southern Urals. Evidence for a significant increase in the amount of precipitation and air temperature in the second half of this period was obtained. Functions of response of radial increment indices to climatic parameters were analyzed. Relative contributions of air temperature and precipitation to variation in the radial increment of pine in different time intervals proved to differ in relation to climate changes during the past century.     

Evaluation of nitrogen retention and microbial populations in poultry litter treated with chemical, biological or adsorbent amendments

Poultry litter is a valuable nutrient source for crop production. Successful management to reduce ammonia and its harmful side-effects on poultry and the environment can be aided by the use of litter amendments. In this study, three acidifiers, two biological treatments, one chemical urease inhibitor and two adsorber amendments were added to poultry litter. Chemical, physical and microbiological properties of the litters were assessed at the beginning and the end of the experiment. Application of litter amendments consistently reduced organic N loss (0-15%) as compared to unamended litter (20%). Acidifiers reduced nitrogen loss through both chemical and microbiological processes. Adsorbent amendments (water treatment residuals and chitosan) reduced nitrogen loss and concentrations of ammonia-producing bacteria and fungi. The use of efficient, cost-effective litter amendments to maximum agronomic, environmental and financial benefits is essential for the future of sustainable poultry production.     

小陇山林区主要森林群落凋落物及死木质残体储量

采用固定面积样方取样法研究了小陇山林区锐齿栎和油松天然林死木质残体及凋落物的总储量.结果表明:小陇山林区锐齿栎天然林粗死木质残体(Coarse woody debris,简称CWD)和细小木质残体(Fine woody debris,简称FWD)储量分别为29 350.92 kg hm-2和2 298.41 kg hm-2,分别为油松天然林的3.8和1.3倍.油松林CWD组成中枯立木占到85.65%,倒木只占14.35%,而锐齿栎天然林枯立木和倒木所占的比例基本为1.从CWD的径级结构上来说,锐齿栎林内以大径级CWD为主(≥20 cm),占样地CWD总储量的60.81%,天然油松林以小径级(20 cm≥小径级≥10 cm)CWD为主,大、小径级分别占CWD储量的55.33%和44.67%.油松林内凋落物储量为30 472.31 kg hm-2,是天然锐齿栎凋落物储量8 902.29 kg hm-2的3倍以上.凋落物和死木质残体储量的不同是锐齿栎天然林和油松天然林种群结构、林分更新和群落内部竞争状况及凋落物分解状况差异所导致的结果.     

云南高原典型林分林下枯落物持水特征研究

森林枯落物具有重要生态水文功能,通过实地调查与实验分析,对云南高原湖泊纳帕海流域3种典型林分枯落物储量、持水量和持水过程进行了研究。结果表明：高山松（pinus densata）林下枯落物储量最大,白桦林（Betula platyphylla Suk.）次之,川滇高山栎（Quercus aquifolioides）灌丛最小,林下枯落物储量最大持水量和有效拦蓄量大小排序表现出和枯落物储量相同的顺序;不论是储量、最大持水量还是有效拦蓄量,各林分枯落物都表现出半分层大于未分解层。3种林下枯落物在0～2 h内吸水较快,在10 h后吸水速明显减缓,用对数方程对3种林下枯落物未分解层和半分解层持水量与浸水时间进行拟合,用幂函数方程对吸水速率与浸水时间进行拟合,结果显示相关系数都较高。     

荒漠草原典型植物群落枯落物生态水文功能

在退化荒漠草原生态系统恢复过程中,枯落物是联系植被和土壤物质循环与能量流动的重要中间环节,且发挥着重要的生态水文功能。通过调查荒漠草原5种典型植物群落（蒙古冰草群落、甘草群落、赖草群落、杂类草群落和沙蒿群落）枯落物蓄积量、持水性能、对降雨的截留和对土壤水分蒸发的抑制作用,分析了荒漠草原不同植被类型枯落物的生态水文功能。结果表明：枯落物蓄积量和最大持水量均为蒙古冰草群落〉甘草群落〉赖草群落〉杂类草群落〉沙蒿群落;5种群落枯落物层对降雨的截留量在3.36～5.27 mm,截留率在3.40%～6.82%,枯落物对降雨的截留量与降雨量呈正相关,而降雨量与截留率呈负相关,且枯落物对降雨的截留具有显著的季节变化规律。在不同枯落物覆盖下,枯落物对土壤的抑制效应也存在显著差异,0.5~2 cm覆盖厚度比不盖枯落物土壤水分蒸发减少了19.25%～76.82%,枯落物层减少土壤水分蒸发效应随枯落物层厚度增大而增加。枯落物的蓄积与覆盖对土壤水分的运移和蓄存产生明显的生物学作用,已经成为荒漠草原最重要的生态过程之一。     

松毛虫遗传多样性研究中AFLP反应体系的建立

以油松毛虫为材料,对T4 DNA连接酶不同用量、预扩增中的Mg~(2+)浓度、dNTP浓度、引物浓度以及选择性扩增巾的预扩增产物稀释倍数、Mg2~(2+) 浓度、dNTP浓度、引物浓度和Taq酶浓度进行了比较分析.最终建立了适合松毛虫的AFLP反应体系.用优化的AFLP反应体系,以油松毛虫、赤松毛虫和马尾松毛虫为材料筛选引物,从81对引物组合中筛选出10对多态性高的引物组合.图9参17