THE RELATIONSHIPS BETWEEN SNOW COVER AND CYCLONES IN THE EASTERN UNITED STATES

Snow cover extent is correlated with the latitude, pressure, and frequency of cyclones at every five degrees of longitude from 70° to 100° West, for the winter seasons 1971 to 1980. Each cyclone parameter is also lag correlated with snow cover extent to test relationships between snow cover extent of one week and cyclone variables of successive weeks. More extensive snow cover is related to cyclones traveling farther south, having higher central pressure, and becoming less frequent.     

THERMALLY DRIVEN SORPTION,DESORPTION, AND MOISTURE MIGRATION IN THE ACTIVE LAYER IN CENTRAL ALASKA

Combined observations of hourly soil temperature and electric potential, the latter converted to a relative index of soil-water solute concentration, yield information on the physical chemistry of near-surface frost effects. Solute concentration near the descending 0° C isotherm in the refreezing active layer above permafrost is divided into three distinct zones: (1) an ion-enriched zone in the unfrozen active layer that precedes the penetrating freezing front; (2) an ion-purified desorbed zone at the freezing front that is the source region of the downward-expelled ions and water; and (3) a hydrologically isolated subfreezing zone of enhanced solute concentration located above the freezing isotherm. High-frequency fluctuations superimposed on these general patterns are traceable to vapor migration driven by surface thermal fluctuations. These effects diminish at temperatures below about -0.4° C, as permeability decreases with soil-ice formation. The combined temperature-solute concentration time series is used to develop sorption curves for the frozen organic and mineral soils, and indicates that approximately half of the pore water present in the mineral soil at -0.4° C had not been converted to ice at -6° C. Gradual soil desiccation over winter appears to result from outward vapor diffusion, possibly through soil cracks. [Key words: Alaska, active layer, frozen ground, soil temperature, soil water, permafrost.]     

SPATIAL,SYNOPTIC, AND SEASONAL PATTERNS OF HEAVY RAINFALL IN THE SOUTHEASTERN UNITED STATES

This paper examines the synoptic climatology and seasonality of heavy rainfall across the southeastern United States. Frontal systems (particularly cold fronts) were found to be the dominant mechanism that induces heavy rainfall across the study area, but tropical disturbances and air-mass storms also contribute, especially at the more coastal locations. Annual regimes were found to vary dramatically from one site to another, and seven of the eight sites investigated exhibited statistically significant seasonality. Generally, peaks in heavy rainfall are bimodal in the western portion of the region, occurring in the transitional seasons. The central portion of the region peaks in late winter and spring, whereas the area east of the Appalachians (including Florida) has summer peaks. This spatial pattern is likely related to patterns of mid-tropospheric air flow and positions of the Bermuda High in summer, and the seasonality of cyclogenesis in North America. [Key words: synoptic climatology, seasonality, heavy rainfall, storms, southeastern United States.]     

云南省中部3种森林土壤含水率、容重和细根重及其垂直分布

根据27个土壤剖面的405个土壤样品,研究云南中部地区华山松林、旱冬瓜林、云南松林的土壤含水率、容重和细根重及其垂直分布特征。结果表明：3种森林100em深土壤的平均含水率分别是（28．79±11．98）％、（24．66±9．89）％、（14．11±5．84）％,差异极显著;平均容重分别是（1．14±0．20）g／cm3、（1．26±0．18）g/cm3、（1．42±0．12）g／cm3,差异极显著;平均细根重分别为（0．1956±0．2144）g／100cm3、（0．0706±0．1066）g／100cm3、（0．1381±0．2989）g／100cm3,在0．05水平上差异显著。华山松林林下土壤的物理性质最好,旱冬瓜林次之,云南松林最差。3种森林里,随着土壤深度增加,土壤含水率增加,土壤容重和土壤细根重减少。华山松林与云南松林平均容重与平均细根重均显著负相关,旱冬瓜林平均含水率与平均容重显著负相关。华山松林下土壤细根量最大,0～20cm层根系占根系总重量的83％。     

美国中东部温带稳定≥10℃积温

应用修订的康拉德公式计算美国中东部温带地区日均温稳定≥10℃积温,并同我国相应纬度地区作了对比。这一对比揭示出我国东部温带并非世界同纬度地带夏半年热量资源最丰富。     

云南省中部3种森林土壤含水率、容重和细根重及其垂直分布

根据27个土壤剖面的405个土壤样品,研究云南中部地区华山松林、旱冬瓜林、云南松林的土壤含水率、容重和细根重及其垂直分布特征.结果表明:3种森林100 cm深土壤的平均含水率分别是(28.79±11.98)％、(24.66 ±9.89)％、(14.11±5.84)％,差异极显著;平均容重分别是(1.14±0.20) g/em3、(1.26±0.18)g/cm3、(1.42±0.12)g/cm3,差异极显著;平均细根重分别为(0.1956±0.2144) g/100 cm3、(0.0706±0.1066)g/100 cm3、(0.1381±0.2989) g/100 cm3,在0.05水平上差异显著.华山松林林下土壤的物理性质最好,旱冬瓜林次之,云南松林最差.3种森林里,随着土壤深度增加,土壤含水率增加,土壤容重和土壤细根重减少.华山松林与云南松林平均容重与平均细根重均显著负相关,旱冬瓜林平均含水率与平均容重显著负相关.华山松林下土壤细根量最大,0 ～ 20 cm层根系占根系总重量的83％.     

黄河流域旱涝年夏季蒸发计算及其变化

根据我国北方的热量平衡观测资料,地立了计算感热—潜热比的经验模式,用于计算黄河流域旱涝年(1972、1975、1986、1988年)及一般年(1971、1974、1985、1987年)夏季陆面蒸发,并分析其变化特点以及与旱涝的关系。     

甘肃榆中县水土资源利用系统的建模与调控

以系统论，生态学、耗散结构理论为基础，分析研究了榆中县水地资源利用系统的结构特点，认为节水改土是合理开发利用水土资源，提高水资源利用率和土地资源生产率的关键；提出了走开源节流、节水改土、水旱并举的道路，建设引水改土型水土资源利用系统，农业节水改土先行的设想；给出了榆中县区域水土资源利用系统的模型。最后，从用新技术节水改土的战略思想出发，提出了具体可行的节水改土对策和相应的技术措施。     

广东鹤山赤红壤坡地林茶利用模式的水土保持效应

野外观测试验于1997年在广东省鹤山茶叶科技研究所的赤红壤坡地上进行，试验设计了人工林下地表覆盖（A）、人工林下地表裸露（B）、等高梯田种植茶树（C）和等高梯田裸地对照（CK）4个处理，采用自制的径流收集器分别测定了各处理4场降雨的径流深度、径流系数、水土流失量和侵蚀量等指标，结果表明，CK的平均径流深度高产田3.72mm/10mm，降水流失率为37.2%，平均每10mm降雨的土壤侵蚀量为43.6kg.hm^-2，年土壤侵蚀模数为7.42t.hm^-2；其它3个不同植被覆盖处理的地表径流量比裸地对照降低2.20%-67.08%，平均土壤侵蚀量减少43.81%-90.83%；林下地表覆盖处理的保土效果果好，等高梯田种植茶树处理的保水效果最好。     

伊犁河谷农用土地资源开发利用的若干问题

本文对伊犁河谷农用土地资源开发利用的现实意义了分析，对农用土地资源开发利用战略、开发结构。开发规模和开发布局作了探讨和研究。提出了长远的战略、合理的结构、适度的规模和切实的布局。     

西双版纳土地利用/覆盖格局的热环境效应研究

利用Landsat TM/ETM＋数据的热红外波段,通过单通道算法,反演了中国热带西双版纳地区的地表温度,并对西双版纳地表温度演变的规律进行了分析,结果显示：（1）研究期间,西双版纳土地利用/覆盖发生了剧烈变化,有林地面积不断减少,旱地、灌木林、茶园与橡胶园面积不断增加;（2）旱地、荒草地、茶园、建设用地的地表真实温度的平均值较高,水体和有林地的平均温度较低;（3）旱地、灌木林、有林地、荒草地和橡胶园对区域的热效应贡献较大,水体、水浇地、建设用地、滩涂和水体的热效应贡献较小;有林地的热单元权重有不断减少的趋势,灌木林与旱地的热单元权重有不断增加的趋势;（4）西双版纳土地利用/覆盖的剧烈变化改变了区域地表温度的分布格局,最终可能会导致地方气候变化。需要进一步开展西双版纳地区LUCC—气候—生态系统耦合研究,深入研究区域LUCC特别是橡胶园的时空变化过程及其气候/生态效应、气候变化与LUCC过程的互馈机制,为实现区域可持续发展提供科学依据。     

COUNTIES,STATES, SECTIONS,AND PARTIES IN THE 1984 PRESIDENTIAL ELECTION

County scale cartographic analysis of Ronald Reagan's reelection landslide of 1984 shows the geographical core of his electoral strength to be in the Interior West, non-ethnic areas of the South, and suburbs across the nation. Examination of spatio-temporal variations using factor analysis at a state scale shows this to be a continuation and reinforcement of recent electoral-geographical cleavages. T-mode factor analysis traces the emergence of a contemporary Conservative Normal Vote during the past several presidential elections and the manifestation of this cleavage in the election of 1984.     

"VALUING THE TROPICS": DISCOURSES OF DEVELOPMENT IN THE FARM AND FOREST SECTORS OF FRENCH INDOCHINA, circa 1900–40

The paper examines how land and forest management policies were elaborated in French Indochina circa 1900–40. It places their development in the context of a scientific and economic discourse about the value of land and forest resources, the most appropriate ways in which they might be exploited and the relationship between colonial science and indigenous knowledge. By focusing on debates and laws relating to the development of small‐scale and plantation farming systems (Land Code legislations) and forest management and exploitation (Forest Code legislations) the paper seeks to ground arguments about Western conceptions of the “tropics” within a discussion of national policy development and impacts. Focusing primarily on Cochinchina and Annam (southern and central Vietnam) and drawing on materials from French archives, the paper shows how changes in both attitudes and legislation have had lasting consequences on systems of property rights in forest management and on the place and status of indigenous peoples in Indochina.     

FLORISTIC PATTERNS ON AVALANCHE PATHS IN THE NORTHERN ROCKY MOUNTAINS,USA

Avalanche paths in the northern Rocky Mountains have transverse zones of plant physiognomic types representing major exogenous environmental gradients related to topography. Species composition was analyzed among these transverse zones. Forty plots on two paths in Montana, USA, were ordinated by detrended correspondence analysis, giving ordination axes for both plots and species. The results of the ordination of the plots did not correspond to their differentation in physiognomic zones. Dominant species of similar physiognomy were widely separated in the ordination of species. Endogenous spatial processes are suggested to explain the more complex floristic pattern. (Keywords: avalanche, floristic patterns, Rocky Mountains, vegetation)     

MESSAGE IN THE PLAZA: LANDSCAPE,LANDSCAPING, AND FOREST DISCOURSE IN HONDURAS*

ABSTRACT. As visible, material expression of human activities and goals, the landscape communicates as well as reflects. Specific landscapes communicate specific messages within the public sphere of which they are a part. In Honduras, many plaza landscapes have seen recent changes in form and in what they communicate. Once open, treeless spaces, many Honduran plazas are now filled with trees. These trees often support signs announcing the virtues of forests, linking the trees themselves to the official discourse on forest issues and illuminating the role of public‐space landscapes in influencing public perception. This article points out the links between such iconographic landscapes and the complex, multitiered environmental issues that are part of environmental conditions and their perception by local actors.     

云南元谋干热河谷土地退化及其防治对策*

本文探讨了云南元谋干热河谷土地退化的特点、分布及其危害,提出了加强基础教育、控制人口增长、改革耕作制度、继续农业基础设施建设、因地制宜发展林业和农业等于热河谷土地退化防治对策。     

长白山岳烨林带泥炭沼泽孢粉分析及其意义

长白山岳桦林带赤池泥炭沼泽堆积开始于3400aBP.前后,其周围植被有过针叶林和岳桦林的交替过程.长白山地区于3400a B .P.前气温已开始下降;3400～2200a B.P.为相对温暖时期;2200a B.P.之后气温下降加快;1800a B P.以后气温冷暖交替变化.     

新疆巩乃斯河流域季节性积雪中硫酸盐的时空分布与来源

１９９６￣１９９７年冬季,一次针对巩乃斯河流域季节怀积雪化学成分的调查与研究工作和以开展,期间共采集了约１００个新、老雪样。经室内分析发现巩乃斯河流域季节性积雪中含有相对丰富的硫酸盐。本文主要分析了该流域季节性积雪的ＳＯ４＾２－离子以及与之有关的Ｋ＾＋＋Ｎｚ＾２＋和Ｃａ＾２＋离子的时间与海拔分布特征,并重点讨论了硫酸酸盐类物质的来源．     

中国华南地域结构的形成、演变与优化研究

伴随着世界地缘政治格局的转换,边缘地区由军事对抗渗透逐步向多方经济合作,交错方向发展。改革开放这后,中国华南地区利用毗邻港澳优越的地缘环境,以华人文化为纽带,吸引了洪澳台的大量资金投入珠江三角洲及边缘地区,形成了日益典型的核心边缘模式。阐述了中国华南地域结构的形成,组成结构,演化规律及地域功能设计,以此基础上提出了华南地域结构优化的途径。     

北极中心海域海冰特征,积雪及变质过程

根据我国首次北极地区的考察观察观测资料，分析了北冰洋８８°Ｎ￣９０°Ｎ考察路段上海冰形态和雪层剖面特征，划分出３种冰形态类型和相应的积雪分布形式，指出了不同积雪分布形式下雪深测量、雪层剖面观测以及雪坑采样的适宜性。海冰上覆积雪的积消过程表现为缓慢的积累和快速的消融，雪深空间分布与降水来源有极大的关系。遥感监测和雪层剖面观证明北冰海洋冰上覆积雪无明显“年积累”大于“年消融”的区域，属于季节性积雪。