Evaluating the efficiency of sampling methods in assessing soil macrofauna communities in arable systems

The soil fauna is often a neglected group in many large-scale studies of farmland biodiversity due to difficulties in extracting organisms efficiently from the soil. This study assesses the relative efficiency of the simple and cheap sampling method of handsorting against Berlese–Tullgren funnel and Winkler apparatus extraction. Soil cores were taken from grassy arable field margins and wheat fields in Cambridgeshire, UK, and the efficiencies of the three methods in assessing the abundances and species densities of soil macroinvertebrates were compared. Handsorting in most cases was as efficient at extracting the majority of the soil macrofauna as the Berlese–Tullgren funnel and Winkler bag methods, although it underestimated the species densities of the woodlice and adult beetles. There were no obvious biases among the three methods for the particular vegetation types sampled and no significant differences in the size distributions of the earthworms and beetles. Proportionally fewer damaged earthworms were recorded in larger (25 × 25 cm) soil cores when compared with smaller ones (15 × 15 cm). Handsorting has many benefits, including targeted extraction, minimum disturbance to the habitat and shorter sampling periods and may be the most appropriate method for studies of farmland biodiversity when a high number of soil cores need to be sampled.     

Development of an appropriate procedure for estimation of RUSLE EI30 index and preparation of erosivity maps for Pulau Penang in Peninsular Malaysia

Pluviographic data at 15 min interval from 6 stations in Pulau Penang of Peninsular Malaysia were used to compute rainfall erosivity factor (R) for the revised universal soil loss equation (RUSLE). Three different modelling procedures were applied for the estimation of monthly rainfall erosivity (EI₃₀) values. While storm rainfall (P) and duration (D) data were used in the first approach, the second approach used monthly rainfall for days with rainfall ≥ 10 mm (rain₁₀) and monthly number of days with rainfall ≥ 10 (days₁₀). The third approach however used the Fournier index as the independent variable. Based on the root mean squared error (RMSE) and the percentage error (PE) criteria, models developed using the Fournier index approach was adjudged the best with an average PE value of 0.92 and an average RMSE value of 164.6. Further, this approach was extended to the development of a regional model. Using data from additional sixteen stations and the Fournier index based regional model, EI₃₀ values were computed for each month. ArcView GIS was used to generate monthly maps of EI₃₀ values and also annual rainfall erosivity (R). The rainfall erosivity factor (R) in the region was estimated to vary from 9000 to 14,000 MJ mm ha^− 1 h^− 1 year^− 1.     

Excess Nickel Modulates Oxidative Stress Responsive Enzymes in Groundnut

Groundnut plants exposed to excess nickel (Ni) produced visual symptoms of toxicity that intensified with increasing level and duration of metal supply. Decreased concentrations of pigments along with a marked increase in the activities of anti-oxidative enzymes such as superoxide dismutase, ascorbate peroxidase, and peroxidase suggest strong induction of oxidative stress due to excess Ni. The decreased activity of catalase may suggest interference of excess nickel in iron metabolism of plants. The appearance of metal specific toxicity is a likely result of damage predominantly due to enhanced generation of reactive oxygen species (ROS) at higher (300–400 μM) nickel supply. The threshold of toxicity (10% growth reduction) and toxicity (33% growth reduction) values of Ni in groundnut were 26 and 72 μg g^?1 in leaves, 17 and 94 μg g^?1 in stem and 45 and 240 μg g^?1 in roots respectively.     

Development of an algorithm identifying maximally diverse core collections

The development of a core collection, one which represents the genetic diversity of a crop with minimal redundancy and increases utility of the collection as a whole, is especially important as the funding for germplasm collections decreases. With limited resources, it is difficult to manage large germplasm collections and disperse genetically diverse germplasm to plant breeders. An algorithm was developed to assist in selection of core collections based on estimates of genetic distance. The criteria for selection of the maximum genetically diverse set were based on rankings of genetic distance between an accession with respect to all other accessions. Depending on the size core which a user wished, a zone around each selected accession was determined and no other accession within these limits was selected. The premise for the algorithm was that the genetic variability represented in the core must be representative of the distribution of genetic distances within the population of interest. In the present study, the algorithm was used with RAPD-marker-based estimates of genetic distance for 270 Theobroma cacao L. accessions and 134 Capsicum accessions that chose a set representing 18.5% of the population and representing the breadth of RAPD-based variation.     

基于土地利用变化的江苏省生态服务价值新评估

利用1996—2004年江苏省地籍数据,计算分析江苏省8年间生态服务价值变化,并提出了生态服务价值对经济发展的响应指标EG值。结果表明:江苏省生态服务价值由1996年的2 080.66亿元下降到2004年2 007.29亿元,下降了3.53%,减少了73.37亿元,下降的主导因素是湿地大面积直接或间接转变为耕地、水产养殖和建设用地。1996—2004年苏南生态服务价值增长,苏中、苏北下降。8年间江苏省每年EG值都小于0,说明江苏省经济增长对生态服务价值主要是负影响。苏南EG值变化范围较小,表示苏南地区人均GDP对生态服务价值的影响较小。苏中EG值2002—2004年呈增长趋势,说明人均GDP增长消耗的生态服务价值变小。苏北EG值从1998年开始呈现下降趋势,说明经济增长消耗的生态服务价值越来越多。     

焉耆盆地气候变化和人类活动对生态系统服务 价值的影响研究

环境变化下的生态服务功能研究,对生态环境与社会经济持续发展具有重要的科学意义和应用价值。本文以新疆焉耆盆地作为研究对象,基于Landsat遥感影像数据、DEM数据和气象要素数据,运用非参数气候变化突变点检验(MK,Mann-Kendall-Sneyers test)、趋势分析方法(Mann-Kendall,MK),通过计算生态服务价值(ESV)和土地利用/覆盖变化(LUCC)动态度,对新疆焉耆盆地近40 a(1973—2014年)生态服务功能的变化及其驱动因素进行了分析。结果显示:1)生态系统服务价值和功能的变化是气候变化和人类活动共同作用的结果;2)山区冰川面积的缩小是山区生态服务价值减少的主要原因;3)平原区的生态系统服务价值以2004年为转折点呈现先减少后增加的趋势,整个研究区的生态服务价值分别为1973年85.86×108元、1977年94.46×108元、1994年84.15×108元、2004年89.40×108元和2014年96.47×108元,这与降水量和蒸发量变化趋势吻合。人类活动如长期开垦、扩大绿洲面积和有益的气候变化支撑(降水量增加、蒸发量减少)是平原区生态服务价值增加的主要原因。在山区,生态服务价值随着降水量、蒸发量的变化而变化,在绿洲区生态服务价值的变化是人类开荒耕地、还林、还耕,以及人工栽培芦苇等活动和气候变暖共同作用的结果。     

Laboratory vs. in situ resin‐core methods to estimate net nitrogen mineralization for comparison of rotation and tillage practices

Properly estimating soil nitrogen (N) mineralization as a consequence of different agronomic practices would result in better soil N fertility management. In this study, we tested the differences between laboratory and in situ resin‐core incubation methods for estimating soil net N mineralization for long‐term burley tobacco (Nicotiana tobacum L .) tillage and rotation systems. The laboratory incubation method used crushed, homogenized, litter‐free soil samples, and the in situ resin‐core incubation method used an intact soil core with the inclusion of any plant residue below or above ground. Comparisons showed that no‐tillage had significantly increased soil net N mineralization compared to conventional tillage with the laboratory incubation method, while there was no significant difference between tillage methods with the in situ resin‐core method. This indicates that soil pretreatment in the laboratory incubation method can create an “artificial tillage effect” for soil previously managed with no‐tillage, resulting in overestimated soil net N mineralization. The rotation comparison showed that different crop sequences had no impact on measured net N mineralization with the laboratory incubation method. However, a preceding soybean crop did significantly increase net soil N mineralization compared to preceding corn when measured with the in situ resin‐core method. This suggests that discarding plant residue in the laboratory incubation method can neglect the potential effect of plant residue on soil N mineralization. Therefore, it is important to be aware that soil pretreatment may influence soil N mineralization estimates, potentially resulting in flawed decisions for soil N fertility management.     

1976-2011年博斯腾湖小湖区湿地生态系统服务价值变化分析

以1976年、1990年、2002年和2011年4期的遥感影像资料为基础,结合野外实地调查及其他相关资料,研究了1976-2011年博斯腾湖小湖区湿地面积和生态系统服务价值变化及其影响因素.结果表明:(1)近40年间小湖区湿地面积变化呈波动性趋势.其中1976年湿地面积最大为3 813.12 hm2;2002年和2011年湿地面积分别减少为3 138.12,2 285.53 hm2.(2)在整个研究时段博斯腾湖小湖区湿地生态系统服务价值的变化整体上呈减少趋势:其中在1976 1990年,年平均减少2.67％;而在1990-2002年,年平均增长2.63％;2002年以后不断减少,减少速度比前15年明显加快.从研究区各生态功能服务价值对总的生态系统服务功能价值的贡献来看,废弃物处理、水涵养和气候调节功能服务价值的贡献率较大,且在整个研究时段呈增加的趋势.在研究期间,博斯腾湖小湖区湿地面积和生态系统服务价值的变化与流域自然和人为因素密切相关,应重视近年来人类活动的负面影响,对绿洲经济活动进行合理规划和控制.     

Optimum nutrient levels in a container growing medium determined by a saturated aqueous extract

Abstract

Red pine (Pinus resinosa Ait.) seedlings were grown for 15 weeks over a range of nutrient regimes to calibrate a test procedure used for monitoring nutrient status of a common container growing medium. The test was based on a saturated aqueous extract of the growing medium, obtained by suction displacement. Seedling growth and nutrition exhibited typical responses of deficiency, sufficiency, luxury consumption and toxicity over the range of substrate fertility examined. Water extractable nutrients of the growing medium were related to yield and nutrient uptake of the seedlings. Ranges of nutrient levels associated with maximum dry matter production were selected as provisional values for optimum growth of containerized red pine seedlings. The following critical nutrient levels were considered optimum for red pine seedlings managed under similar cultural conditions: 15–65 ppm N (as NH₄ ⁺), 35–95 ppm P, 25–115 ppm K, 30–60 ppm Ca, 15–35 ppm Mg, and electrical conductivity of 1.0–2.2 dS/m.