平原粉沙淤泥质海岸防护林土壤渗透特性的研究

探讨了淤泥质海岸防护林土壤的渗透特性 ,指出同一林分土壤渗透速率差异较大 ,不同样地间土壤渗透速率的差异也十分显著。林地初渗速率大 ,在降雨初期能吸收大量降雨 ,稳渗时渗透速率未必比光板地大。林地土壤渗透过程符合对数曲线 ,相关系数达极显著水平 ;渗透速率大小主要取决于土壤有机质含量和非毛管孔隙率     

塔里木河流域白杨农田防护林蒸散量计算模式研究

在综合分析气候、植物生物学特性和土壤湿度三方面因素的基础上,利用多年的白杨农田防护林试验资料,建立了塔里木河流域白杨农田防护林蒸散量的计算模式,并利用白杨林实际蒸散量的测量值,对模式进行了验证。结果表明,该模式计算精度较高,可以作为计算塔里木河流域白杨农田防护林蒸散量的一种方法而使用。     

Changes in stem taper for birch plants growing in tree shelters

Plantings with pendula (Betula pendula Roth) and pubescent (Betula pubescens Ehrh.) birches were studied on five localities (Lat. 57–60 ° N) in Sweden. Seedlings were planted in 1988 or 1989. The experiment contained 50 plants per parcel and five replications per treatment. Among treatments harrowed area and birches covered with tree shelter were included. In spring 1993 five plants growing on harrowed area, with and without tree shelter, respectively were randomly chosen on each parcel. A total of 25 birches per treatment, species and locality were used. The trial was replicated in 1994 and 1995. The plant height was estimated and diameter at 20 and 60% of tree height was measured each year for 4 yr. The stem taper was calculated by the quotient D₆₀/D₂₀. The stem taper for birches without tree shelter was 0.5 for both species on all localities. The quotients for birches, which have grown in tree shelter, were 0.6–0.75 the first years of the trial. Then the quotients decreased and 2–3 years later they were on the same level as for birches planted without tree shelters. The results of the studies indicate that tree shelters should be removed two to three years after the plant has reached the top of the shelter. The height of the tree shelter might be shortened to 0.8–1.0 m to stabilise the plant earlier than with the conventional shelter height of 1.2 m.     

基于MLR和人工神经网络的新疆杨日蒸腾量估算

为解决当前旱区防护林主要树种新疆杨日蒸腾量（T_r）估算值的精确度低、估算模型泛化能力差等问题，采用7种气象因子（日照时长、风速、相对湿度、饱和水蒸气压差、最低温、最高温和日均温）的8种组合作为模型输入，构建了传统多元线性回归模型（MLR）和人工神经网络模型（BP和Elman），估算2020年生长季新疆杨T_r值，并对3种模型不同输入组合的估算结果进行比较与评价；同时基于Garson算法量化各气象因子对T_r估算值的相对贡献率。结果显示，BP和Elman模型对T_r估算值的精确度超过73.66%，在不同输入组合下人工神经网络模型估算精确度比MLR模型提高了8.45%~31.33%，其中拓扑结构为6-4-4-1的Elman模型估算值的精确度最高；气象因子饱和水蒸气压差对T_r估算值的相对贡献率最大，相对湿度次之，不同温度变量对T_r估算值的相对贡献率依次为：日均温>最低温>最高温。结果表明，所构建的新疆杨日蒸腾量的估算神经网络模型可提高对干旱地区防护林蒸腾量的估算精确度。     

不同防控技术对秋延后避雨与保温栽培辣椒 烟粉虱的防效评价

摘要：为了有效防控洞庭湖区秋延后大棚避雨与保温栽培辣椒的烟粉虱，探究新的减药增效防控技术， 采用6种不同组合防治措施：黄板＋性诱剂、黄板＋性诱剂＋噻虫嗪、黄板＋吡虫啉、黄板＋性诱剂＋异丙 威、黄板＋性诱剂＋噻虫嗪＋异丙威、黄板＋吡虫啉＋异丙威等，比较分析其对辣椒烟粉虱的田间防治 效果。结果表明：6种防治措施对烟粉虱防治均有一定效果；从虫口减退率分析，药后7 d，黄板＋性 诱剂＋噻虫嗪处理达到最大值（90.8%），药后14 d降至77.9%；药后1 d，黄板＋性诱剂＋异丙威处理达 到最大值（97.6%），虫口数量大幅下降，药后14 d 仍维持在74.1%；从校正防效持久性分析，黄板＋性 诱剂＋噻虫嗪和黄板＋性诱剂＋噻虫嗪＋异丙威的防效较好，在药后14 d仍保持在89.2%以上；从产量分 析，黄板＋性诱剂＋噻虫嗪的产量最高。本着减量增效的原则，黄板＋性诱剂＋噻虫嗪防控技术为洞庭 湖区辣椒秋延后避雨与保温栽培烟粉虱防控最优组合。     

Formation mechanisms and remediation techniques for low-efficiency artificial shelter forests on the Chinese Loess Plateau

The construction of artificial shelter forests (ASFs) has resulted in substantial ecological, economic, and societal benefits to the Chinese Loess Plateau (CLP). However, the health and benefits of ASFs are being increasingly threatened by the formation of low-efficiency artificial shelter forests (LEASFs). In this study, LEASFs are systematically analyzed in terms of their status, formation mechanisms, and developmental obstacles. The key restoration techniques and schemes were summarized to improve the quality and efficiency of LEASFs. LEASFs are formed by relatively complex mechanisms, but they arise mainly due to poor habitat conditions, improper tree species selections, mismatch between stands and habitat, extensive forest management measures, and human interferences. The restoration and improvement of LEASFs are hindered by water deficits, mismatch between stands and habitat, single management purpose, and low efficiency. LEASFs are becoming more complex due to their wide range, the challenges associated with their restoration, and insufficient technological measures for their restoration. The key techniques of the quality and efficiency improvement of LEASFs include basic forest tending methods, near-natural restoration, multifunction-oriented improvement, and systematic restoration. An understanding on the formation mechanisms of LEASFs and a scientific approach toward their restoration are urgently needed and critical for the ecological protection and high-quality development of LEASFs on the CLP. Based on these analyses, we recommend strengthening the monitoring and supervision of LEASFs, considering the bearing capacity of regional water resources, implementing multiple restoration techniques, promoting multifunction-oriented ecological development, and exploring new management concepts to achieve the sustainable development of ASFs on the CLP.     

河套灌区农田防护林网内土壤季节性冻融过程及水盐运移

为了解内蒙古河套灌区农田防护林内冻融期土壤水盐状况及运移规律,在2020年10月至2021年4月实测土壤水分、盐分、温度及相关气象数据,并进行相关分析.结果 表明:土体表层温度波动较大,随土层深度加深土体温度变化逐渐平缓.冻结期气温下降速率低于消融期气温回升速率,加之土壤温度变化的滞后性,冻结期比消融期长10天左右.季...