Spatial variability of O layer thickness and humus forms under different pine beech–forest transformation stages in NE Germany

Spatial variability of humus layer (O layer) thicknesses can have important impacts upon soil water dynamics, nutrient storage and availability, as well as plant growth. The purpose of the present study was to elucidate the impact of forest‐transformation practices on the spatial variability of O layer thicknesses. The study focused on the Kahlenberg forest area (NE Germany) with stands of Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica) of different age structures that form a transformation chronosequence from pure Scots pine stands towards pure European beech stands. Topsoil profiles including both, the O layer and the uppermost humic mineral soil horizon were excavated at intervals of 0.4 m along 15–20 m long transects, and spatial variability of O layer thicknesses was quantified by variogram analysis. The correlation lengths of total O layer thickness increased in the sequence consisting of pure pine stand (3.1 m) → older mixed stand (3.7 m) → pure beech stand (4.5 m), with the exception of the younger mixed stand, for which no correlation lengths of total O layer thickness could be determined. The degree of spatial correlation, i.e., the percentage of the total variance which can be described by variograms, was highest for the two monospecies stands, whereas this percentage was distinctly lower for the two mixed stands. A similar minimum for the two mixed stands was observed for the correlation lengths of the Oh horizon. These results suggest that the spatial structures of forest‐transformation stands may be interpreted in terms of a disturbance (in the form of the underplanting of beech trees). After this disturbance, the forest ecosystem requires at least 100 y to again reach relative equilibrium. These findings are in line with the results of other soil‐related investigations at these sites.     

海河低平原盐渍涝洼区表层土壤积盐影响因素通径分析

采用通径分析方法研究海河低平原盐渍涝洼区表层土壤积盐因素的主次关系结果表明 ,地下水埋深2～ 3m、表层土壤全盐量≤ 5 0g/kg、地表高差≤ 6 6cm地段 ,表层土壤盐渍度主要受心土层盐分状况和微地形因素支配 ,而 6个间接作用中亚表土层全盐量通过心土层全盐量对表层土壤盐分累积的作用最大。     

Influence of smoke exposure on soil enzyme activities and nitrification

Summary Soil was exposed to red phosphorous/butyl rubber (RP/BR) aerosols at various relative humidities in a recirculating environmental wind tunnel. Soil microbial and enzymatic activities were measured immediately after exposure and periodically thereafter for 56 days. The nitrification potential was significantly reduced in soil amended with ammonium sulfate and exposed to RP/BR smoke, and could be related to a decline in soil pH. The rate of nitrate formation in unamended soil with time was also reduced, but by 57 days postexposure, concentrations were similat to those of unexposed controls in all but the thinnest soil lense. Soil dehydrogenase and phosphatase enzyme activities were sensitive to RP/BR smoke and in some treatments no activity was detected. The measured activities did not recover within the 56-day postexposure period and in some cases declined. Soil lense thickness was the greatest factor controlling the degree of RP/BR effects, indicating that injury to soil microbial and enzymatic activities may be surficial. Deposition of smoke particles increased with increasing relative humidity, which had a significant impact on the activities measured.     

基于电阻率断层扫描技术探测林地土层厚度

土层厚度对林地生产力具有重要影响,是评价林地土壤质量的重要指标。为了对林地土壤的土层厚度进行调查,该文应用电阻率断层扫描技术对林地土壤土层厚度进行了研究,对其可适用性做出评价。通过在野外试验点对土壤电阻率的实地断层扫描,将其结果与实际测定得到的基岩特征电阻率相结合,预测土层厚度,并将预测值和实地基坑开挖数据进行比较。结果表明,研究区土层厚度多在小于2 m的范围内,电阻率断层扫描技术估测结果与实测结果相符(均方根误差为0.2678),初步表明该技术在估算林地土层厚度方面具有良好的适用性。该研究结果为土壤学方面相关研究提供重要手段,也将对土壤质量评价和土地利用等相关工作提供指导。     

北缘地区毛竹实生林生长与立地条件的关系

为了探讨北缘地区毛竹实生林生长发育与立地条件的关系,选用10 a生毛竹实生林地开展制约实生林生长的因素研究。结果表明：在种源和培育措施都相同的条件下,立地条件与毛竹胸径生长量有密切的关系,不同的立地条件对竹林的林分结构有着较为显著的影响,不同的土壤厚度是导致立竹径阶分布显著差异的主要因素。因此,毛竹实生苗造林立地条件的...     

不同净能水平日粮对育肥猪生长性能、背膘厚度及眼肌面积的影响

试验研究不同净能水平日粮对育肥猪生长、背膘及眼肌面积的影响。选择420头(38.5±0.5)kg丹系三元育肥猪,随机分为5组,每组6个重复,每个重复14头猪,公、母各半。试验A、B、C、D、E组饲粮净能水平分别为9.84、10.05、10.26、10.46和10.67 MJ/kg,预试期7 d,正式试验期97 d。结果显示,A组育肥猪0~97 d的平均日采食量显著高于E组(P<0.05)。A组、B组育肥猪0~97 d的料重比显著高于D组、E组(P<0.05),且A组显著高于C组(P<0.05)。A组均重110 kg育肥猪的眼肌面积显著高于E组(P<0.05)。A组、B组均重130 kg育肥猪的眼肌面积显著高于E组(P<0.05)。A组均重110 kg育肥猪的背膘厚度显著低于D组、E组(P<0.05)。A组130 kg育肥猪的背膘显著低于D组、E组(P<0.05)。试验表明,净能为9.84 MJ/kg日粮可以明显提高平均日采食量、眼肌面积,并且降低背膘厚度。     

Effect of mixed rearing of barrows and gilts on backfat thickness and serum metabolite profiles of the Kagoshima-Kurobuta (Berkshire) pig

We investigated the effect of mixed rearing of barrows and gilts on the backfat thickness and the serum metabolite profiles of Kagoshima-Kurobuta (Berkshire) pigs. A total of 149 pigs with an average body weight of 35 kg were divided into the following groups: 100%, 90%, 70%, 50%, 30%, 10%, and 0% groups consisting of 10 barrows (1 pen), 9 barrows + 1 gilt (3 pens), 7 barrows + 3 gilts (2 pens), 5 barrows + 5 gilts (3 pens), 3 barrows + 7 gilts (2 pens), 1 barrow + 9 gilts (3 pens), and 9 gilts (1 pen), respectively. All pigs were raised to a shipping weight of 120 kg. Mixed rearing significantly reduced (p < 0.001) backfat thickness, and the optimum mixing ratio of barrows and gilts was 7:3 (the 70% group). Four types of circulating sex steroids were found in both the barrows and gilts in the 50% group but were not detected in barrows from the 100% group. These results indicated that mixed rearing of barrows and gilts was effective for reducing the backfat thickness of barrows, and induced sex steroid hormones may influence the backfat thickness of barrows in mixed-reared groups.     

氯前列醇钠、产前背膘厚及便秘对后备母猪同期分娩效果的影响

试验旨在研究氯前列醇钠、产前背膘厚、便秘对后备母猪同期分娩集中度和生产性能的影响,并进一步探讨母猪同期分娩的最优方案。选取后备母猪共295头,根据妊娠期110 d时P2点处的背膘厚,随机分为3组：对照组（CON组：0.9%生理盐水）、低剂量氯前列醇钠组（LPG组：0.1 mg氯前列醇钠）、高剂量氯前列醇钠组（HPG组：0.2 mg氯前列醇钠）,于妊娠期114 d进行阴户部注射诱导分娩。结果表明,与对照组相比,高、低剂量氯前列醇钠均可显著缩短母猪从注射到分娩的时间间隔（P<0.05）,且两试验组间差异不显著（P>0.05）。但是,LPG组后备母猪在注射氯前列醇钠后48 h内的分娩率高达95%,并且白天分娩率达75.7%。此外,LPG组后备母猪的产仔间隔也显著短于CON组（P<0.05）。同时本研究发现,背膘厚在16~20 mm范围内的后备母猪从注射到分娩的时间间隔显著短于背膘厚≤15 mm的后备母猪（P<0.05）;便秘指数0~1.0组后备母猪的产程和产仔间隔均显著大于便秘指数1.1~2.0组及2.1~3.0组的后备母猪（P<0.05）。进一步回归分析发现,母猪背膘厚分别与产程、总产仔数、活仔数存在极显著线性相关（P<0.01）,母猪便秘指数分别与产程、产仔间隔、总产仔数、活仔数存在极显著线性相关（P<0.01）。综上所述,在妊娠期114 d对后备母猪阴户部注射0.1 mg氯前列醇钠诱导分娩,不仅可显著加快母猪分娩的进程,而且还可大大节约药物成本。此外,母猪产前背膘厚和便秘均会影响母猪同期分娩的效果,应使母猪分娩前保持最佳的背膘厚（16~20 mm）,且避免母猪便秘,方可保证同期分娩的顺利实施。     

土壤耕层深度和施肥深度对桔梗根部主要农艺性状的影响

[目的]探索优质高产的桔梗栽培方法。[方法]在15、20、30、40cm的耕深和不施肥、全层施肥、深层施肥（30～40cm）的3个施肥深度条件下,调查桔梗根的主要农艺性状。[结果]在耕深试验中,30cm耕深条件下的主根长最长、根粗最粗、单根鲜重最重,但侧根数也最多;施肥效果为深层施肥的效果好于全层施肥和不施肥。[结论]试验结果对山区、半山区桔梗栽培体系的建立有一定的参考价值。     

鲤头长、体厚、体高性状的QTL定位及遗传效应分析

用174个SSR、41个EST、345个SNP标记对以镜鲤良种后代为祖父母本所培育的杂交F2群体的68个个体进行基因型检测,运用JoinMap4.0软件包构建遗传连锁图。利用MapQTL5.0区间作图法(interval mapping,IM)和多QTL区间定位法(MQM mapping,MQM)进行QTL检测,通过置换实验(1000次重复)确定连锁群显著性水平阈值。在对体高、头长、体厚的区间定位中,共检测到6个与体高性状相关的QTLs区间,分布在LG1(SNP1339-SNP1490)、LG10(HLJE469-SNP1491)、LG12(SNP0922-HLJ1316)、LG13(SNP0937-HLJ328)、LG25(SNP1041-HLJ594)、LG35(SNP1425-SNP0389)等6个连锁群上,解释表型变异范围为20.0%～43.3%。其中,SNP1339-SNP1490区间LOD值最大为3.64,解释表型变异35.4%。6个与头长相关的QTLs,分布在LG1(SNP1339-SNP1490)、LG12(HLJ071-HLJ336)、LG13(SNP0937-HLJ328)、LG24(SN...