Effects of nitrogen addition and litter properties on litter decomposition and enzyme activities of individual fungi

Litter decomposition is an important process of C and N cycling in the soil. Variation in the response of litter decomposition to nitrogen (N) addition (positive, negative or neutral) has been observed in many field studies. However, mechanism about variability in individual fungal species response to N addition has not yet been well demonstrated in the literature. Therefore, the objective of this study was to investigate the effects of N addition and litter chemistry properties on litter decomposition and enzyme activities of individual fungi. Three fungal species (Penicillium, Aspergillus, and Trichoderma) were isolated from a subtropical mixed forest soil. An incubation experiment was conducted using the individual fungi with two types of litter (leaf of Pinus massoniana and needle of Cryptocarya chinensis) and different N addition levels (0, 50 and 100 for N-deficient treatments, and 500 and 1000 μg N for N-excessive treatments). Cumulative CO₂-C, enzyme activities, and lignin and cellulose loss were measured during the incubation period of 60 days. Litter decomposition and enzyme activities significantly varied with the fungal species, while the N addition and litter types greatly affected fungal enzyme activities. The N treatments significantly increased lignin-rich needle decomposition by lignocellulose decomposers (Penicillium and Aspergillus) but did not affect their leaf decomposition. On the contrary, The N treatments stimulated leaf decomposition by cellulolytic species (Trichoderma) but did not affect its needle decomposition. Correlation analysis showed that lignin in the litter was the key component to affect litter decomposition. Activities of N-acetyl-β-glucosaminidase and phenol oxidase were both positively correlated to litter decomposition. The fungi (Penicillium and Aspergillus) with higher production of N-acetyl-β-glucosaminidase showed higher litter decomposition ability. The low N addition levels stimulated Penicillium and Aspergillus litter decomposition, but they still required more N source (e.g., litter N source) to support decomposition. Depressed fungal litter N uptake (lower N-acetyl-β-glucosaminidase activities) only occurred at the highest N addition level. Litter decomposition of Trichoderma depended more on external N and its litter decomposition capability was the lowest among the three species.     

计数模型在池塘养殖游憩服务价值评估中的应用

随着社会经济的快速发展,休闲渔业正在逐渐成为渔业产业经济发展的新方向。近十年来,上海地区加大了对休闲渔业的投入,使得该地区池塘养殖系统更加具有游憩服务价值。目前对池塘养殖游憩资源价值的研究相对较少,对相应的评估方法及其在池塘养殖游憩价值评估中的适用性也需进一步探讨。由于对评估方法研究的滞后,池塘养殖系统中的游憩服务价值往往得不到科学揭示。基于对青浦、嘉定、奉贤3区的实证调查结果,本文以上海市为例,使用计数模型的个人旅游成本法估算这3个地区的池塘养殖游憩价值,进而将泊松模型和负二项模型进行对比研究,并将本文得到的青浦地区池塘养殖游憩价值结果与前期研究成果进行比较,探讨两种模型在池塘养殖评价中的有效性及个人旅游成本(ITCM)与区域旅游成本(ZTCM)两种方法在此类评估中的稳定性。研究发现:①不同模型对池塘养殖游憩价值的评估结果存在差异,总体来看负二项模型优于泊松模型。②个人旅游成本法与区域旅游成本法估计结果比值为4.98︰1,分别以两种方法估算值作为养殖池塘系统游憩价值的上限值和下限值比较合适。③基于计数模型的个人旅行成本法评估青浦、嘉定和奉贤地区的池塘养殖游憩服务价值分别约为20 863.34元·hm 2·a 1、57 997.03元·hm 2·a 1和522.73元·hm 2·a 1。建议有关各方重新认识池塘养殖休憩价值,继续加大休闲渔业支持力度,保护该地区的池塘养殖生态系统,以促进旅游及池塘养殖产业的可持续发展,提高渔民收入水平。     

黄山市浅层地下水中氮污染特征研究

随着工业的发展、人口增多以及农业氮肥的施用,浅层地下水受到的氮污染越来越严重,该试验沿黄山市境内布设了23个浅层地下水采样点,结合单项组分评价与综合评价的方法,对4和9月份两期的水样进行检测分析,结果表明,黄山市4月份水质优良占30％,水质良好的占57％,水质较好的占0％,水质较差的占4％,水质极差的占9％;9月份水质优良的占26％,水质良好的占61％,水质较好的占4％,水质较差的占0％,极差水质的占9％.     

改进的简单竞争指标在单木生长模型中的应用1）

以湖南省攸县黄丰桥国有林场杉木中龄林为研究对象,改进简单竞争指标,采用多元逐步回归和非线性回归的方法建立以单木大小、竞争和立地条件为自变量,单木直径连年生长量为因变量的估算模型,实现单木直径生长量的预测。研究结果显示：单木大小因子平方（ D2）、竞争因子（ CI ）、立地条件（ SL、SLP、E）对模型都有较大的影响,改进后的直径生长模型的决定系数R2为0．763,显著高于改进之前的结果（ R2为0．710）。这说明简单竞争指标模型参数的指数为变量时,直径生长模型的拟合优度得到了显著提升,单木生长模型的预测效果更好。     

新城疫单抗ELISA试剂盒监测免疫鸡群中新城疫强毒

应用新城疫（ND）单抗ELISA试剂盒对2个免疫鸡群中ND强毒感染情况及个体感染强毒后排毒动态跟踪监测，并平等测定其HI抗体效价。共采集泄殖腔棉拭子和血液对应样品2317份。结果表明：HI效价2－14之间的个体均可检出强毒，其中HI效价在6以下和11以上的个体强毒检出率都较高。HI效价在6以上的个体仍角感染强毒，强毒感染导致HI抗体水平上升，且感染前低者上升速度较快，幅度亦较大；并且发现排毒个体的高水平抗体是强毒感染所致。个体感染强毒后排毒过程可长达3周，而且感染前抗体水平低者排毒时间相对较长。强毒一旦侵入鸡群便可在群内巡回传播，长期维持下来。     

Spatial variability of enzyme activities in a 100-year old long-term field experiment

We attempted to clarify the importance of obtaining representative soil samples for microbiological purposes by comparing results from composite samples and individual cores taken at a depth of 30 cm from four different treatments at the Static Fertilisation Experiment in Bad Lauchstädt, Germany. As enzyme activities can be related to microbiological activities, we analysed alkaline phosphatase, -glucosidase and protease activities from the composite and individual samples. When comparing both kinds of samples, protease activity was found to be the most and -glucosidase activity the least variable parameter. Comparing just the individual cores, the greatest variation was found for alkaline phosphatase and the lowest variation for -glucosidase activity; however, the latter enzyme activity also showed significantly different values. Thus, care should be taken when sampling in the field for microbial purposes.

奶山羊的繁育与管理技术要点

奶山羊养殖是农村最广泛的一项养殖项目。我国现养殖的奶山羊品种主要是莎能奶山羊与本地山羊杂交培育的后代。种羊选择要根据当地的品种资源、区域性优势及价格,灵活实施。根据养殖需要合理饲养种公羊、母羊和羔羊。母羊要选择有明显乳用家畜的楔形体型,发育状况良好、体格强健、健康无病、外貌匀称,且乳房容积大、外形好看、产奶量高的优良个体。种公羊要选择品种优良、体质健壮、发育良好、反应灵敏、精力充沛、食欲旺盛、健康无病、雄性特征明显的优良个体。加强奶山羊的繁育管理,注意观察母羊的发情表现,做好发情鉴定,及时配种。注意做好母羊的妊娠管理、分娩接产和护理工作。     

川金丝猴幼仔全人工哺育技术及其个体行为观察

本文记述１例笼养川金丝猴幼仔“粒粒”，从出生至１６９日龄成功地放归笼养群体的全人工哺育技术，同时对幼仔个体行为与母乳哺育幼仔进行了对比观察，结果表明：（１）以优质人工乳哺育金丝猴幼仔，补加适量维生素和活性钙，于１１１日龄添加固体食物以后，随着日龄增长哺乳量递减，固体食物的种类、数量逐渐增加，２０６日龄断奶，幼仔健康成活；（２）主要护理技术为育幼期严格调控育幼箱内温、湿度，适度通风、日照，严格消毒和保育人员的精心爱抚：（３）２０日龄开始社群行为驯化，１４５日龄开始放归训练，并逐渐延长放归时间，１６９日龄顺利放归笼养群体，为其同类所接纳，到１８０日龄摆脱对保育员的依赖，习惯于群体生活；（４）全人工哺育金丝猴幼仔与母乳哺育者相比，个体行为发育２０日龄前差异不显著，２０日龄后全人工哺育幼仔行为发育较迟缓。     

天然麻栎单木地上生物量模型研究

通过对铜陵叶山林场麻栎样木地上生物量调查,以胸径、树高为自变量,地上总生物量、树干、树枝、树叶生物量为因变量,选择相对生长式、幂函数式和多项式为生物量回归模型,拟合各模型参数、相关指数、回归剩余离差,并计算生物量估测误差。结果表明:麻栎树干、树枝、树叶和地上总生物量与胸径、树高存在显著幂函数关系,其方程分别为:树干W=6.571×10-4D1.8473H2.411、树枝W=1.163×10-4D2.9497H1.3223、树叶W=0.0032D1.5148H0.8821、总生物量W=9.354×10-4D2.0825H2.1154。树干与总生物量的预估精度均达90%以上。