池杉林分生长量定期调查与研究

于１９８８年和１９９３年，对金湖县池杉标准地进行重复调查，研究林分生长量的变化。结果表明：池杉在２２年生时材积生长尚未达数量成熟，材积年均生长量为１６．８ｍ＾３／ｈｍ＾２，比１７年生时增长６０％。     

Forest Re-growth Since 1945 in the Dadia Forest Nature Reserve in Northern Greece

The Dadia forest complex, in the Evros prefecture, in north eastern Greece was designated as a nature reserve in 1980 in order to protect the black vulture (Aegypius monachus) and other raptors. In this paper, the impacts of the protection on the forest growth were assessed using geographic information system (GIS) technologies. The major requirement for almost all research needed for sustainable forest management is extensive and intensive monitoring. GIS is a convenient tool for integrating remotely sensed data and various other kinds geo-referenced data. Detailed spatial and temporal change patterns of the land uses in the area were quantified by interpreting aerial photographs of the years 1945 and 1973 and a satellite image of 2001. The results showed that the rate of forest growth is significantly larger during the second period (1973–2001) than during the earlier one (1945–1973). This is mostly due to the introduction, in 1980, of a protection regime, including two high-protection core areas, and a buffer zone. From 1945 to 2001 the openings which are important as hunting biotopes for raptors were significantly decreased. Apart from the protection of the area that was played an important role in the forest changes the effects of various landscape parameters (elevation, slope, distance from the roads and urban areas, aspect, soil depth, geology, erosion and forest density) on these changes were examined.     

遥感技术在森林资源连续清查中的应用——以利用遥感技术分析森林植被、地类的动态变化为例

通过遥感技术在第六次连清工作中的应用实践,文章就利用遥感技术分析森林资源动态变化的空间分布,寻找森林资源动态变化的原因;利用卫星遥感数据从新的角度分析森林资源动态变化等方面进行了有益的探索。     

紫花苜蓿对镉胁迫的生理响应及积累特性

采用盆栽的方法研究紫花苜蓿(Medicago sativa)对镉(Cd)胁迫的生理响应及积累特性。结果表明,Cd浓度低于25 mg·kg-1可以促进紫花苜蓿地上部和地下部的生长。随着Cd浓度提高,紫花苜蓿相对电导率和叶绿素含量降低,脯氨酸含量呈现先增大后减小的趋势,且在25 mg·kg-1时达到最高。Cd在紫花苜蓿体内表现为地下部地上部,随着Cd浓度增大,紫花苜蓿地上部和地下部Cd含量逐渐增大,转运指数和耐性指数先增大后减小。Cd浓度为25和100 mg·kg-1时,地上部和地下部Cd积累量最大,每盆分别为42.5和26.11μg。综合分析紫花苜蓿的生长、生理变化及富集能力表明,紫花苜蓿适用于浓度小于25 mg·kg-1的Cd污染土壤修复。     

Linking Land Cover Changes in the Sub‐Alpine and Montane Belts to Changes in a Torrential River

Channel changes are the consequence of changes in sediment yield from the slopes and in the connectivity between slopes and channels because of distinct land use and climate impacts. In this study, we investigated the characteristics and evolution of a short reach in the headwater of the Ijuez River, central–southern Pyrenees. Assessment of a series of sedimentary and geomorphic structures confirmed major changes to the valley bottom, mainly related to changes in the intensity of human activity. The oldest sedimentary structure is a terrace level located 3 to 4 m above the current alluvial plain. General deforestation, overgrazing and recurring fires in the montane belt (1100–1600 m a.s.l.) have led to increased soil erosion and connectivity, and to the triggering of debris flows that have been deposited on the fluvial terrace. Woody fragments from within the debris flows were dated using accelerator mass spectrometry ¹⁴C radiocarbon techniques (AMS), yielding ages between 100 and 115 cal years bp , which coincides with the period of maximum deforestation and human density in the Pyrenees. Depopulation and farmland abandonment since the beginning of the 20th century has resulted in generalized natural and artificial reforestation, a shrinkage of the eroded areas and a decline in connectivity between slopes and the channel. The most important consequence has been channel incision and narrowing, and the development of a sediment armour layer. Active sediment transport is continuing, although there has been a decrease in sediment yield from the slopes. Copyright © 2014 John Wiley & Sons, Ltd.     

Environmental Factors Controlling Soil Organic Carbon Stocks in Two Contrasting Mediterranean Climatic Areas of Southern Spain

Managing soil carbon requires accurate estimates of soil organic carbon (SOC) stocks and its dynamics, at scales able to capture the influence of local factors on the carbon pool. This paper develops a spatially explicit methodology to quantify SOC stocks in two contrasting regions of Southern Spain: Sierra Norte de Sevilla (SN) and Cabo de Gata (CG). Also, it examines the relationship between SOC stocks and local environmental factors. Results showed that mean SOC stocks were 4·3 kg m⁻² in SN and 3·0 kg m⁻² in CG. Differences in SOC in both sites were not significant, suggesting that factors other than climate have a greater influence on SOC stocks. A correlation matrix revealed that SOC has the highest positive correlation with clay content and soil depth. Based on the land use, the largest SOC stocks were found in grassland soils (4·4 kg m⁻² in CG and 5·0 kg m⁻² in SN) and extensive crops (3·0 kg m⁻² in CG and 5·0 kg m⁻² in SN), and the smallest under shrubs (2·8 kg m⁻² in CG and 3·2 kg m⁻² in SN) and forests soils (4·2 kg m⁻² in SN). This SOC distribution is explained by the greatest soil depth under agricultural land uses, a common situation across the Mediterranean, where the deepest soils have been cultivated and natural vegetation mostly remains along the marginal sites. Accordingly, strategies to manage SOC stocks in southern Spain will have to acknowledge its high pedodiversity and long history of land use, refusing the adoption of standard global strategies. Copyright © 2015 John Wiley & Sons, Ltd.     

Histological alterations in the hepatopancreas of Penaeus monodon Fabricius (1798) given aflatoxin B1-incorporated diets

Aflatoxin is a toxic contaminant produced by toxigenic fungi of the genus Aspergillus during the processing and storage of feeds and feed ingredients. Aflatoxins can cause abnormalities such as poor growth, physiological imbalances and histological changes that result in a reduction in the yield and profitability of shrimp culture. Histological changes in Penaeus monodon sub-adults fed different doses of aflatoxin B₁ were studied. The doses of aflatoxin B₁ administered in the diets were 50, 100, 150, 500, 1000 and 2000 ppb. At the end of the fourth and the eighth weeks of the experiment, the shrimps were sampled and the cephalothorax was observed for histological changes. Significant changes were observed in the different treatment groups at the fourth and eighth weeks. The severity of pathological changes was proportional to the increase in the concentration of aflatoxin fed to the shrimps. Histological changes in the hepatopancreas were loss of structure of the cells and tubules, nodule formation, cell elongation, desquamation, rounding of cells, fibrosis, necrosis, haemocytic infiltration and cellular inflammation.     

不同加热温度对三穗鸭肉品质的影响

以三穗鸭胸肉和腿肉为原料,对不同温度处理的鸭胸肉和腿肉的色泽、保水性、蒸煮损失、剪切力、质构和微观结构的变化情况进行研究.结果显示:不同部位间色泽变化不大,而保水性、蒸煮损失、剪切力、质构指标等存在显著差异;相同部位随加热温度的不同L*值与a*值显著呈正相关,保水性与蒸煮损失呈负相关.随加热温度升高三穗鸭肉保水性降低,蒸煮损失逐渐升高,剪切力在70℃时降至最低后显著升高.相同处理间不同部位的质构变化差异显著.加热使三穗鸭肉肌束膜溶解,温度上升对溶解效果影响显著,70℃以上加热使三穗鸭肉机械强度降低,肉质变软.     

新疆地区制度变迁对经济增长的影响研究

基于新疆经济的发展与该地区制度变迁密不可分这一假设,设计并实现对制度变迁的量化,定量估算了新疆地区制度变迁对经济增长的贡献度,验证了制度创新与经济增长的关系。最后,通过进一步的分析和比较,指出西向开放的大背景下新疆地区要促进经济发展所要进行的体制改革的重点和难点。     

春植蔗生长季降水变化及其影响

[目的]了解广西来宾市甘蔗生长季降水特征及其变化趋势。[方法]运用农业气象统计分析方法,结合春植蔗阶段需水特点,分析了广西来宾市甘蔗种植区1965～2007年3～11月逐月降水资料。[结果]广西来宾市有2／3的年份降水不能满足甘蔗需水,特别是9～10月几乎年年发生干旱,甘蔗生长季月降水变率大,春植蔗生长季总降水有随年份减少趋势,但主汛期6—7月降雨量随年份增加,这将导致来宾市春植蔗易发生干旱,特别是秋旱,且干旱发生机率和强度变大,同时也存在着主汛期6—7月发生局地渍涝灾害的风险。最后提出了相应的生产对策与建议。[结论]该研究对科学安排蔗田灌溉与人工增雨作业,提高甘蔗生产应对气候变化的能力具有一定指导意义。