Effects of cereal cover crops on the main insect pests in Spanish olive orchards

In olive orchards, which are very common in the Mediterranean region, cover crops are becoming increasingly used to counter problems of erosion. Although such plant covers can provide food and shelter for beneficial insects, mites, and spiders, they may also attract pests. In order to determine their relationships with the main pests in olive orchards, an analysis was made of adult population levels and damage caused in five olive-cultivation zones, in olive orchards with cereal-crop covers and in olive orchards with conventional tillage. The effects of the cereal cover crops on insect pest populations were different and in some cases in opposite direction. Thus cereal cover crops had no impact on the different studied pests, including all those that spend part of their development cycle in the soil, such as Bactrocera oleae, Prays oleae, or Otiorrhynchus cribicollis. However, under certain conditions some pests did show an increase in abundance. Diverse trophic relationships should be investigated in this agroecosystem in future studies in order to develop appropriate crop-management policies.     

不同覆盖条件对陇东旱塬苹果园土壤水分及果实品质的影响

为了提高苹果园的水分利用效率和果实品质,以长富2号17年生苹果树为试材(基砧为山定子,中间砧为M26),覆盖条件共设覆黑膜+覆麦草(处理Ⅰ)、覆麦草(处理Ⅱ)、覆玉米秆(处理Ⅲ)、生草(处理Ⅳ)4种处理,以清耕为对照,就不同覆盖条件对苹果园土壤集雨保墒的影响情况进行了试验研究。结果表明:在5～7月干旱期的各测定日期,处理Ⅰ～Ⅲ这三种覆盖条件下土壤各层的绝对含水量均显著或极显著高于处理Ⅳ和对照;在干旱程度较重的6月中旬,不同覆盖条件下土壤全层(0～60 cm)的绝对含水量比生草处理Ⅳ和对照的提高13.54%～37.77%,其中0～20 cm土层的绝对含水量提高25.25%～55.92%,20～40 cm土层的绝对含水量提高了5.26%～26.13%,40～60 cm土层的绝对含水量提高了7.15%～33.82%,说明集雨保墒效果明显,但处理Ⅰ～Ⅲ这三种覆盖处理间保墒效果的差别不大。处理Ⅰ～Ⅲ的果实单果质量比处理Ⅳ和对照增加6%～10%;果实中的可溶性固形物含量,处理Ⅱ与对照接近,其他覆盖处理的均显著低于对照;果实去皮硬度,处理Ⅱ的最大,为10.69 kg·cm-2,极显著高于其他处理及对照。     

Analysis of soil moisture variation by forest cover structure in lower western Himalayas, India

Soil moisture affects various hydrological processes, including evapotranspiration, infiltration, and runoff. Forested areas in the lower western Himalaya in India constitute the headwater catchments for many hill streams and have experienced degradation in forest cover due to grazing, deforestation and other human activities. This change in forest cover is likely to alter the soil moisture regime and, consequently, flow regimes in streams. The effect of change in forest cover on soil moisture regimes of this dry region has not been studied through long term field observations. We monitored soil matric potentials in two small watersheds in the lower western Himalaya of India. The watersheds consisted of homogeneous land covers of moderately dense oak forest and moderately degraded mixed oak forest. Observations were recorded at three sites at three depths in each watershed at fortnightly intervals for a period of three years. The soil moisture contents derived from soil potential measurements were analyzed to understand the spatial, temporal and profile variations under the two structures of forest cover. The analysis revealed large variations in soil moisture storage at different sites and depths and also during different seasons in each watershed. Mean soil moisture storage during monsoon, winter and summer seasons was higher under dense forest than under degraded forest. Highest soil moisture content occurred at shallow soil profiles, decreasing with depth in both watersheds. A high positive correlation was found between tree density and soil moisture content. Mean soil moisture content over the entire study period was higher under dense forest than under degraded forest. This indicated a potential for soil water storage under well managed oak forest. Because soil water storage is vital for sustenance of low flows, attention is needed on the management of oak forests in the Himalayan region.     

红树林碳储量及碳汇效能研究的发展趋势和特征

为了解红树林碳储量及碳汇效能研究的发展趋势和特征,使用文献计量分析方法对基于Web of Science和中国知网(CNKI)数据库检索获得的文献进行统计分析。有关红树林碳汇效能研究的发文量逐年增加。美国和澳大利亚是该研究领域的两大强国,占据领先地位;这两个国家在世界排名前10位机构和作者上均占据明显的优势,其中发文量前10名机构中有5个来自美国,有3个来自澳大利亚,并且排列前4名的机构均来自美国和澳大利亚;国际上发文量超过10篇的作者中有2个来自美国,有3个来自澳大利亚,并且发文量前3名的作者中有2个来自澳大利亚。另外,高被引论文前10名中有4篇的作者来自美国,说明其在该领域具有较强的科研实力和较高的影响力。我国有关红树林碳汇效能研究的论文发文量逐年增加,在发文量前10名国家中排列第4,但总被引频次和篇均被引频次均较低。我国在国际排名前10位机构、发文量前10名作者和高被引论文前10篇中均占有一席之位,说明近年来我国在该领域发展迅速,科研实力不断增强,但在今后的发展中还需加强科研经费投入,引进高水平人才,加强国际合作,大力推动我国红树林碳汇的研究,提高我国在国际上的影响力。     

Modelling the impacts of cover crop management strategies on the water use,carbon exchange and yield of olive orchards

Cover crops have long been proposed as an alternative soil management for minimizing erosion rates in olive stands while providing additional ecosystem services.However,the trade-off between these benefits and the competition for water with the trees makes the definition of optimal management practices a challenging task in semiarid climates.This work presents an improved version of OliveCan,a process-based simulation model of olive orchards that now can simulate the main impacts of cover crops ...     

Farming carbon: an economic analysis of agroforestry for carbon sequestration and dryland salinity reduction in Western Australia

The widespread removal of native trees from the agricultural zone and replacement with annual crops and pastures is a major cause of dryland salinity in Australia. It has been recognised that a large proportion of the landscape needs to be replanted to trees to prevent further salinisation. However, for much of the agricultural zone, agroforestry is not an option due to lack of species that can viably generate the products currently demanded by the market. The emerging carbon market may provide a new agroforestry option for landholders, through carbon sequestration. This analysis assesses the viability of growing trees for the purpose of selling carbon credits, from a landholder’s perspective. Benefits of trees in preventing the onset of dryland salinity are accounted for. Two regions in Western Australia; a low rainfall (330 mm/year) region and a medium rainfall (550 mm/year) region, are analysed. At the expected carbon price of A$15/tCO₂-e, growing trees for carbon is not a viable alternative for landholders in the low rainfall region, due to low sequestration rates. In the medium rainfall region, growing trees for carbon and timber is a viable alternative; however the opportunity costs of land mean the carbon price would still need to be higher than expected for growers to choose this alternative. Accounting for the salinity prevention benefits makes growing trees a more attractive investment for landholders in both regions. However in both regions, even after accounting for salinity benefits, the price of carbon would need to be A$25–A$46/tCO₂-e higher than expected to make growing trees a worthwhile investment.     

优质短枝比例对红富士苹果产量品质的影响

通过对红富土苹果短枝量与其产量、品质之间关系的调查分析,得出了红富土苹果要获得优质、高产所应具备的最佳短枝量范围和二者之间的相关方程。     

中国CDM林业碳汇项目的管理政策研究

气候变化是当前全球面临的共同挑战,《京都议定书》规定了三种灵活机制,以促进发达国家在2008~2012年的第一承诺期内率先采取行动来缓解气候变暖趋势。其中,实施清洁发展机制(CDM)下的造林再造林碳汇项目是发达国家和发展中国家共同应对气候变化的一种选择。文章介绍了林业碳汇项目产生的背景,阐述了国内外对林碳汇概念的不同表述,分析了在我国对林业碳汇政策的研究,提出了我国林业碳汇管理政策的不足。     

红富士苹果总枝量对其产量和品质的影响

通过对红富土苹果总枝量与其产量、品质之间关系的调查分析,得出了红富土苹果要获得优质、高产所应具备的最佳枝量范围和二者之间的相关方程。     

土壤含水量对盆栽红富士苹果叶片光合特性的影响

以10 a生盆栽红富士苹果为试材,研究了不同土壤含水量对红富士苹果叶片光合特性的影响。结果表明,随着土壤含水量的降低,红富士苹果叶片净光合速率、蒸腾速率、气孔导度呈逐渐下降趋势,而细胞间隙CO2浓度逐渐上升。适当降低灌水量对盆栽红富士苹果的光合特性影响不大,80%灌水量下峰值的净光合速率为正常灌水量93.4%。     

酸性土壤铝的形态、迁移特征及林木根系的影响

采用孔洞根系生长法，研究了土壤中不同形态铝含量的变化及对杉木、马尾松根系生长的影响。结果表明：土壤中加入铝离子后，土壤pH下降，活性铝含量明显增加，孔洞中林木根系表现为明显的铝中毒症状；加入钙离子后，土壤pH升高，土壤中活性铝含量显著下降，根系生长得到改善，1a后，与原孔洞中土壤相比，土壤中总铝含量降低，交换态铝含量有所降低，腐殖质铝含量升高。     

The effect of afforestation on soil carbon dioxide emissions in blanket peatland in Ireland

We studied the effect of afforestation on soil CO₂ emissionsin blanket peat. The study sites were as follows: two undrainedblanket peatland sites, six sites which had been drained andafforested 3, 19, 23, 27, 33 and 39 years previously, and twoforest sites which were clearfelled in summer 1996. Soil CO₂emissions were measured using the soda-lime method during 13sampling campaigns throughout 1997. Each campaign consistedof two consecutive 24-h measurements. Comparison of the averageannual CO₂ emission revealed no clear pattern in relation tosoil type and suggests that afforestation does not always leadto an increase in soil CO₂ emissions. In the most recently forestedsite, CO₂ emissions were 1.7 t C ha^–1 a^–1 and drainagehad failed to lower the water-table sufficiently to cause alarge increase in CO₂ emissions. In the 19-, 23-, 27- and 33-year-oldsites soil CO₂ emissions were 1.0–1.4 t C ha^–1 a^–1and were similar to, or lower than, levels in the undrainedsites. In the 39-year-old site average CO₂ emissions were 2.6t C ha^–1 a^–1. In the clearfelled sites CO₂ emissionswere lower at between 1.4 and 1.6 t C ha^–1 a^–1.Root respiration appears to account for a large proportion ofCO₂ emissions, and blanket peat, despite drainage, is resistantto decay. It is concluded that losses of soil C are compensatedby C uptake by the trees.     

长枝比例对红富士苹果产量品质的影响

通过对红富士苹果长枝量与其产量、品质之间关系的调查分析,得出了红富士苹果要获得优质、高产所应具备的最佳长枝量范围和二者之间的相关方程。     

木炭的土地利用及碳汇效应

在土壤中施入木炭颗粒,不仅能提高土壤的透气、透水、保水性能,提高土地的生产力及产品的品质,而且阻断了木炭本身成为碳源的通道。同时,通过提高植物的生长量,可更多地吸收大气中的CO2,提高碳汇效应。     

不同立地、土壤类型对土壤含水量和苹果新梢生长的影响

为了给苹果园土壤水分管理提供依据,以‘长富2’苹果为试材,选取粘壤土平地、粘壤土梯田、壤土平地、壤土梯田、沙土平地、沙土梯田、上层壤土、下层尾矿砂平地7种不同立地、土壤类型苹果园,研究其对土壤含水量及苹果新梢生长的影响。结果表明:不同时期粘壤土平地的土壤含水量均极显著高于沙土平地、沙土梯田、上层壤土下层尾矿砂平地的土壤含水量,沙土平地、沙土梯田的土壤含水量均极显著低于其他立地、土壤类型。各立地、土壤类型长、中、短新梢均只有一次生长,迅速生长期基本一致,在4月初到5月底;除沙土平地和沙土梯田类型外,其他5种立地、土壤类型徒长新梢均出现了二次生长,第1次迅速生长期与其他新梢一致,第2次生长期在7月至8月。不同立地、土壤类型土壤含水量与苹果各类新梢长度均呈正相关,达到显著相关水平的时期多出现在新梢生长高峰期,其中,4月22日至5月13日,壤土梯田、沙土平地的土壤含水量与长梢长度的相关系数分别为0.968、0.966,5月14日至5月31日,壤土梯田的土壤含水量与徒长新梢长度的相关系数为0.986,壤土平地的土壤含水量与长梢长度的相关系数为0.980。     

陕西渭北地区苹果园黑蚱蝉的产卵危害及其控制研究

选取渭南市白水县具有代表性的苹果园,对黑蚱蝉Cryptotympana atrata (Fabriciu)在果树枝条上的产卵危害规律进行了调查分析.结果表明:该地区苹果园最大受害株率可达94％,且受害株率与树龄成正相关;果树不同方位枝条受害程度与栽培走向密切相关;间作不同的果园受害差异不显著.黑蚱蝉趋向于在直径2.6～6.1 mm幼嫩枝条上产卵,产卵部位长度在5.8 ～35.2 cm之间,产卵部位基部与枝梢顶端的距离为10.8～56.2 cm;单枝平均刻槽数为35.1个,单刻槽平均卵量为6.8粒,单枝平均卵量为241.3粒.产卵枝条直径、产卵部位长度、单枝刻槽数和单枝总卵量两两之间均存在极显著相关性.应结合黑蚱蝉产卵规律,通过科学修剪、冬季深翻园土、喷施药剂等综合措施有效降低黑蚱蝉卵及若虫的数量,逐步控制该害虫对果园的危害.