森林粗木质物残体（CWD）的研究进展

森林粗木质物残体（CWD）在保持森林生态系统的完整性方面发挥着重要的生态功能,影响着系统内外相关的生物和非生物过程,不仅为微生物、节肢动物、鸟类以及哺乳动物提供栖息环境,也是生态系统中重要的碳库和养分库,而且在减少土壤侵蚀和森林水文生态方面具重要的作用．文章总结了CWD的研究历史及状况,系统地阐述了CWD的形成和来源、贮量、分解、碳元素和营养元素的贮藏功能以及CWD对森林的更新作用、对生物多样性的维持和水文生态功能等．对今后CWD研究的重点及方向提出了建议．     

中国森林粗木质残体储量及其影响因素

 粗木质残体（CWD）是森林生态系统的重要组成部分,在森林生态系统结构组成和功能发挥中扮演重要角色。在收集整理文献资料数据的基础上对长白山、小兴安岭、秦岭、武夷山、鼎湖山、哀牢山等地不同森林生态系统粗木质残体储量的研究结果进行了初步统计和分析。初步结果认为：中国南、北方森林生态系统的粗木质残体储量存在差异,北方的粗木质残体储量是针叶林＞针阔混交林;南方的粗木质残体储量是阔叶林＞针阔混交林＞针叶林。海拔、林分结构、年平均降水量、自然灾害、人为干扰均是影响粗木质残体储量的因子,枯立木和倒木是中国原始林粗木质残体储量的主要贡献者。研究结果可为中国森林生态系统粗木质残体的进一步深入研究及相应的合理保护和利用提供依据。图2表2参47     

长白山地区红松和紫椴倒木呼吸研究

该文采用静态箱-气相色谱技术,对红松和紫椴倒木呼吸及其与腐烂等级、温度、含水量等因子间关系进行了研究,并对长白山阔叶红松林内倒木总呼吸进行了估算。结果显示,倒木呼吸存在较大的季节变化(0.7～13.6 mg/(m2·h)),呼吸速率与倒木含水量、腐烂等级和温度显著相关(P0.05)。其中,基于倒木温度变化的指数拟合方程解释了超过67%的呼吸变化。不同腐烂等级倒木Q10值变幅为2.41～2.95,Q10计算值与选用的温度区间有关。林内倒木呼吸总量为(26.9±5.1) g/(m2·a),约占林地CO2排放总量的3%、年净交换量的15%。      

水溶性酸浆果多糖提取工艺的研究

对水溶性酸浆果多糖的提取工艺进行了研究,采取单因素试验和L9（3^4）正交试验研究了料液比、提取时间、提取温度、乙醇浓度对水溶性酸浆果多糖提取效果的影响。结果表明,影响多糖得率的因素依次为料液比、乙醇浓度、提取时间、提取温度,水溶性酸浆果多糖最佳提取工艺条件为料液比1：40,提取时间4h,提取温度90℃,90％乙醇沉淀。在此工艺条件下水溶性酸浆果多糖的得率为5．46％。     

冬小麦雪腐病苗期抗病性鉴定方法及抗病种质资源筛选

为了筛选冬小麦雪腐病人工接种抗病性鉴定方法及抗病种质资源,采用正交试验设计,比较了喷雾法、涂抹法和灌根法对冬小麦雪腐病苗期抗病性的鉴定效果以及不同材料的抗病性.结果表明,三种方法比较,采用喷雾法,于冬小麦1叶期,以浓度为105个孢子·mL-1进行接种,为冬小麦雪腐病苗期抗病性鉴定最适宜的方法.利用该鉴定方法以及9株雪腐病菌对8份冬小麦材料进行了抗病性鉴定,发现供试材料间以及同一材料对不同菌株间的抗病性均存在差异.8份冬小麦材料中,冬麦1号抗病性最强,对菌株Gn-rh2免疫,对其他8个菌株均表现为抗病;抗病性最弱的为东农冬麦377;其他品系的抗病性介于两者之间.9个菌株的致病力也存在差异,菌株Gn-rh4毒力最强,Gn-rh2毒力最弱.     

Examining changes in participation in recreational fisheries in England and Wales

Abstract Inland fisheries in England and Wales have high economic and social values. Managing participation to maximise fishery performance is key to maintaining this status. The capital value of fishing rights for migratory salmonid fisheries is €165 million. Coarse fisheries contribute €1030 million to the economy. The central tenet to increasing participation in recreational salmonid fisheries is that an increase in stock size will result in more anglers accessing the fishery. This was examined for salmon on the rivers Usk and Lune where exploitation restrictions increased the number of salmon available to anglers. On the River Lune, the number of salmon available post‐intervention increased by 66%. There was no significant increase in catch while the number of anglers decreased by 16.3%. On the River Usk, the closure of the net fishery potentially resulted in an additional ～1200 salmon being available. Following closure, there was no significant change in rod catch or in the number of anglers. Increased participation is dependent less upon stock manipulation for coarse fisheries and more upon facilitating the activity. In recent years, urban fishery development programmes have provided improved access to local fishing opportunity. Also, new anglers have been targeted through campaigns such as Get Hooked on Fishing and the Scout Angler Badge.     

The effect of soil texture and organic amendment on the hydrological behaviour of coarse-textured soils

To gain more insight into the hydrological behaviour of coarse-textured soils, the physical properties of artificially created soil mixtures with different texture were determined. The mixtures were prepared according to the specifications of the United States Golf Association (USGA) for constructing putting greens. In addition, the effect of 10 vol.% organic matter addition was studied. The soil moisture retention and hydraulic conductivity relationships of the different mixtures were determined and their hydrological behaviour was studied using the numerical model SoWaM. Both texture and organic matter addition substantially affected the hydraulic properties. Hydraulic conductivity significantly increased with increasing coarseness while moisture retention decreased. On the other hand, organic matter addition reduced saturated hydraulic conductivity by a factor of 10 to 100 and distinctly increased moisture retention capacity. The amounts of total available water were increased by the addition of organic matter between 144% (slightly coarse texture) and 434% (very coarse texture). Results indicate that the mixtures can contain only 2–16% plant available water and therefore need frequent irrigation to maintain plant growth. Addition of organic matter seems a good solution to reduce the irrigation water requirements but it increases the risk of ponding or runoff because of large reductions in the saturated hydraulic conductivity sometimes to below the rate of 3.6 m/day recommended by the USGA.     

Transect relascope sampling for assessing coarse woody debris: The case of a π/2 relascope angle

In transect relascope sampling, a wide‐angle relascope is used along survey lines for selecting a sample of objects that extend linearly in the plane, e.g. downed logs. The method is closely related to line intersect (intercept) sampling. In this article, a special case of the transect relascope technique is studied. Using a π/2 radian relascope angle, the method becomes invariant to the orientation of the line objects in the population. The reason is that the area of inclusion around objects, through which a survey line should pass for an object to be included, turns out to be circular. In analytical studies and Monte Carlo simulations, the cost‐efficiency of transect relascope and line intersect sampling is evaluated. It is found that transect relascope sampling is a competitive alternative to line intersect sampling in inventories of the total volume of coarse woody debris (in the form of downed logs) in forest compartments.     

CerealBeta-Amylases

Cerealbeta-amylases are perhaps best known in terms of the vital role they play in releasing easily fermentable sugars from cereal grain starch to fuel the production of alcohol by yeast in brewing. The extent to which they have been investigated is indeed largely due to their significance in this economically important industry. However, cerealbeta-amylases are also, or could be, employed in many other aspects of the food industry and the analysis of starch, and they constitute valuable markers in cereal assessment and breeding studies. Quite apart from their practical significance, they are rewarding objects of biochemical and physiological research. They are interesting models for the study of enzyme polymorphism, post-translational modification and the differential expression of isoenzymes. In spite of their often high activitiesin situand all that is known about their generation, they are an enigma in that their physiological function, or even necessity, remains unclear. It has been recently recognised that there are two different categories of cerealbeta-amylases which exhibit different tissue and taxonomic specificities and physiological developmental patterns. The «classical»beta-amylases present at high activities in cereal seeds appear to be limited to the endosperm of the species of the Triticeae tribe of the Festucoideae subfamily of the Gramineae (wheat, barley and rye), whereas all cereals exhibit a different, tissue-«ubiquitous» form of the enzyme which is present at much lower activity levels. The physiological phenomenology and the usage of cerealbeta-amylases are discussed in relation to these two categories of enzyme.     

Effects of grazing strategy on limiting nitrate leaching in grazed grass‐clover pastures on coarse sandy soil

Urinations of ruminants on grazed pastures increase the risk of nitrate leaching. The study investigated the effect of reducing the length of the grazing season on nitrate leaching from a coarse sandy, irrigated soil during 2006–2007 and 2007–2008. In both years, precipitation was above the long‐term mean. The experiment was initiated in a 4‐yr‐old grass‐clover sward in south Denmark. Three treatments were as follows grazing only (G), spring cut followed by grazing (CG) and both spring and autumn cuts with summer grazing (CGC). Nitrate leaching was calculated by extracting water isolates from 80 cm depth using ceramic suction cups. Because of considerable variation in measured nitrate concentrations, the 32 installed suction cups per treatment were insufficient to reveal differences between treatments. However, weighted nitrate leaching estimations for G, CG and CGC showed estimated mean nitrate N concentrations of 23, 19 and 13 mg/L for an estimated proportion area occupied by urine patches of 0.33, 0.26 and 0.16, respectively. Thus, N concentrations in G and CG exceeded the EU limit of 11.3 mg N/L. Under the prevailing conditions, the time of urination did not appear important. The estimated background leaching calculated from suction cups presumably not situated under urine patches resulted in mean nitrate N concentrations of 2.6 mg/L.