潞江坝胡椒种植面积严重萎缩原因分析及发展建议

自20世纪80年代起,云南保山潞江坝胡椒种植面积逐渐萎缩,经调查分析,该地区冬春季节低温干旱的气候条件、管理粗放、连作障碍等导致胡椒旱衰和死亡是种植面积大幅萎缩的主要原因;作者在此基础上提出了该区胡椒产业发展的建议。     

The decline of Austrocedrus chilensis forests in Patagonia, Argentina: soil features as predisposing factors

The forests of Austrocedrus chilensis in southern Argentina suffer mortality from “mal del ciprés”, whose causes remain unknown. The purpose of this work was to establish the relation of soil features with the occurrence of the disease. In Río Grande Valley, Chubut Province, Argentina, 14 areas with “mal del ciprés” were selected for study. The spatial pattern of the decline varied among the different areas and was classified as aggregated and disaggregated. In each area, symptomatic and asymptomatic plots were established and characterized by 11 edaphic and topographic variables. Three forest areas where the disease was totally absent were also included. Site features were related to the occurrence of the decline using principal component analysis and cluster analysis. Results indicated that soil properties related to poor internal drainage, such as the proximity to water streams, non-allophanized soils of fine textures, and redoximorphic features, act as predisposing factors to the development of “mal del ciprés”. Poor soil drainage was strongly associated not only with the occurrence of the disease, but also with its spatial pattern. Symptomatic and asymptomatic plots presented similar edaphic features in areas with a disaggregated distribution of the decline and were grouped together in the multivariate analysis. This result suggests that large areas with such a pattern are prone to develop the decline.     

认识和重视-类病害——森林衰退病

本文就“森林衰退病”(Forest decline)理论的概念、意义,森林衰退病病原,“衰退病”(Decline,Dicline disease)模式,以及诱发因素(Predisposing factors)、激化因素(Inciting factors)和促进因素(Contributing factors)之间的相互关系作了综述介绍,并看重强调了运用这一新的植物病理学理论,认识和指导我国林业及热作生产的重要现实意义。     

The process of decline of an endangered tree species,Pinus armandii Franch. var.amamiana (Koidz.) Hatusima, on the southern slope of Mt. Hasa-dake in Yaku-shima Island

The process of decline of an endangered tree species,Pinus armandii var.amamiana, was monitored on the southern slope of Mt. Hasa-dake in Yaku-shima Island from 1994 to 1998. There are 163 trees ofP. armandii var.amamiana over 1.3 m in height. They are distributed on steep ridges and rocks with a thin soil layer mostly consisting of friable granite. During the monitoring period, 21 trees ofP. armandii var.amamiana died and the mortality rate was 12.9%. Dead trees were categorized into three types: standing, uprooted and landslide. The uprooted- and landslide-typed dead trees were found only after a severe typhoon struck Yaku-shima Island. This suggests that the combination of fragile site conditions and severe typhoons play an important role in the process of decline ofP. armandii var.amamiana. The standing-typed dead trees were presumed to have been killed by pine wilt disease, accounting for 71.4% of the dead trees. However,Bursaphelenchus xylophilus, the cause of pine wilt disease, was not detected from any of the wood chips or branch samples from the standing-typed dead trees ofP. armandii var.amamiana. This might indicate that some factor(s) other than pine wilt disease could be responsible for the standing-typed death ofP. armandii var.amamiana in natural habitats. A part of this paper was presented at the 109th Meeting of the Japanese Forestry Society.     

中国城市水土流失的现状、对策及研究展望——以广东省深圳市为例

[目的]总结城市水土流失的概念、危害、成因、特点和防治对策,分析城市水土保持工作存在的问题和未来研究方向,旨在为中国城市水土流失治理及研究工作提供参考依据。[方法]根据多年的研究工作经验和文献资料,综合分析国内外城市水土流失及水土保持研究的成果。[结果](1)城市水土流失的概念蕴涵自然和人为两种动力,水和土两个流失主体,城市和周边及地表与地下两类分布空间;(2)城市水土流失危害主要包括管道淤积、风沙扬尘、水源污染、资源衰退、环境破坏等多方面;(3)城市水土流失防治对策主要包括法律、机制、宣传、监管、兼治和科研等6个方面。[结论]人们对城市水土流失的认识尚存不足,城市水土保持理论、技术及法规体系有待完善。城市水土流失及城市水土保持工作应从理论研究、应用优化以及经验推广等方面深入开展。     

瑞丽柠檬园红蜘蛛消长规律及药剂防治研究

在云南省瑞丽市进行了柠檬园红蜘蛛的消长规律及药剂防治研究。结果表明:柠檬红蜘蛛主要在11月至次年1月发生,其发生量在1月中旬达到高峰(2500~3000头/株);红蜘蛛在树冠北方、南方的发生量较多;柠檬园红蜘蛛的发生和为害与温度、湿度、食料、施肥、施药等因素关系密切;在7种供试药剂中,以4%螺螨酯悬浮剂、1.8%阿维菌素乳油和73%炔螨特乳油对红蜘蛛的防治效果较好,且对柠檬的嫩梢、花和幼果安全无害。     

Range fidelity: The missing link between caribou decline and habitat alteration?

Conservation of forest-dwelling caribou (Rangifer tarandus caribou) is of great concern across most of its range. Anthropogenic disturbances, primarily logging activities, have been identified as the most important cause of caribou decline, although the mechanisms underlying this decline are not fully understood. Caribou commonly display fidelity to calving sites or seasonal ranges, but the potential role of this life-history trait has been largely overlooked in research and conservation planning. This is surprising because sites and ranges with high inter-annual use should have high conservation value. We investigated the relationship between habitat disturbances and home-range fidelity of forest-dwelling caribou across three study sites in Québec, Canada, using a broad range of natural and anthropogenic disturbances. Between 2004 and 2007, we tracked 47 adult female caribou using GPS collars. Home-range fidelity varied between seasons, being higher during calving and summer, and lower during winter. Caribou reduced fidelity following natural and anthropogenic disturbances, the latter having a stronger negative influence. Anthropogenic disturbances had a strong negative impact on home-range fidelity during annual, summer and winter periods, whereas natural disturbance was the dominant factor during calving. Despite this negative influence on fidelity, caribou tended to demonstrate range fidelity even in study sites most impacted by human activities. Habitat disturbances could produce two possible outcomes for caribou conservation: (1) a trend for females to reduce home-range fidelity which could translate into lower calf and female caribou survival through reduced familiarity with food distribution, escape cover and predation risk and (2) a global tendency to maintain range fidelity even in a drastically modified landscape which could turn into an ecological trap, particularly for calves when predation risk increases due to increased black bear density in early successional forests. Taking range fidelity behavior into consideration during forest management planning could direct conservation efforts toward the best available sites and therefore facilitate caribou persistence in managed landscapes.     

Vitality rating of picea abies by defoliation class and other vigour indicators

The study was made to assess the relationship between visually estimated defoliation class and a number of other variables depicting the vitality of Norway spruce (n=50). Variables characterizing crown size and condition were determined on the standing trees. Electrical impedance (an indication of the physiological status of a tree) was measured in the inner bark tissue of the living trees. Shoot growth and needle variables were determined from the detached sample branches. Negative correlations were found between defoliation class and the growth parameters (5‐year height, radial and volume growth of the trunk). Positive correlations were observed between the needle loss class and the abundance of branch damage, secondary shoots and impedance values. 18 variables (defoliation excluded) describing tree size and vitality were summarized in a factor analysis incorporating 5 factors. These were interpreted as 1) vitality, 2) foliage discoloration, 3) tree size, 4) needle number and 5) needle size factors. The tree‐specific score values for the first factor were interpreted as “vitality indices”;. The rank correlation between these score values and defoliation degree was 0.835. This result suggests that the defoliation class and vitality parameters contributing to the first factor give a consistent estimate of the tree condition.     

Influences of Forest Decline on Various Properties of Soils at Mt. Hirugatake, Tanzawa Mountains, Kanto District, Japan

At Mt. Hirugatake in the Tanzawa Mountains, Kanto district, Japan, the deciduous broadleaved forests have rapidly declined. In our previous studies, we reported that the amount of soil organic matter had significantly decreased at the early and final stages of forest decline, and that the soil microbial biomass also showed a large decrease at these stages, suggesting that the composition of soil organic matter might have also changed with forest decline. To clarify the influences of forest decline on the composition of soil organic matter, the amount of humic substances, optical properties of humic acid, and the amount of soil carbohydrates in surface soils at different stages of forest decline were investigated. The amounts of humic acid and fulvic acid decreased to a lesser extent at the early and middle stages of forest decline, and showed a significant decrease at the final stage. As the amount of humin significantly decreased at the early stage, it was plausible that the distinct decrease in the total carbon content of the soil surface horizons at the early stage of forest decline was induced by the decrease in the amount of humin, and at the final stage, by the decrease in the amounts of humic acid and fulvic acid. The amount of soil carbohydrates did not change appreciably with forest decline although the soil organic matter content markedly decreased. It was suggested that most of the carbohydrates in the soil surface horizons were in a stabilized form consisting of complexes with humic substances, metals, and minerals, and would not be affected by the environmental changes associated with forest decline.     

Potential role of soil calcium in recovery of paper birch following ice storm injury in Vermont, USA

In recent years, an increased number of mature paper birch (Betula papyrifera Marsh.) and heart-leafed paper birch (B. papyrifera var. cordifolia (Regel) Fern.) in northeastern United States forests have exhibited decline symptoms including foliar loss, reduced fine branching, and tree mortality. We assessed crown health, radial growth, and available soil cations in 2006 as a preliminary assessment of factors that may be influencing paper birch decline. Tree rings began to decrease in width in 1998—the year of a severe region-wide ice storm. All trees (regardless of their current decline status) experienced reduced growth starting in 1998 and tree growth continued to decrease for two years following the ice storm. After this generalized growth decrease, trees that now have vigorous crowns showed a marked increase in growth, whereas trees that now have low crown vigor did not rebound in growth, but instead exhibited a significantly higher incidence of locally absent annual rings. Extractable soil-aluminum (Al), a phytotoxic element mobilized by acid deposition, was significantly higher in soils associated with declining trees compared to those adjacent to vigorous trees. Higher soil calcium (Ca) availability was associated with both vigorous crowns and increased radial growth following the 1998 ice storm. Furthermore, increased soil Ca availability was negatively correlated to the percentage of declining trees, and positively related to increased radial growth, whereas elevation was not significantly associated with either parameter. Although previously overlooked as a factor influencing paper birch recovery from injury, we found that available soil Ca was linked to crown vigor and rebounds in growth following an inciting event.