Association of brook trout and Oncorhynchus spp. with large wood jams in a Lake Superior tributary in a northern old‐growth watershed

Wood in streams functions as fish habitat, but relationships between fish abundance (or size) and large wood in streams are not consistent. One possible reason for variable relationships between fish and wood in streams is that the association of fish with wood habitat may depend on ecological context such as large‐scale geomorphology. We studied the relationship between salmonid assemblages and large wood jams (LWJ) in four settings that differed geomorphically at the scale of the stream corridor along a tributary to Lake Superior in old‐growth conifer–hardwood forest in northern Michigan. The focal fish species of this study were brook trout (Salvelinus fontinalis), which were wild in the stream. Relocation efforts for coaster brook trout (an adfluvial life history variant of brook trout) were ongoing in the study stream. We measured fish abundance and length in pairs of pools of similar size and substrate, but varying in the presence of LWJ; this allowed us to evaluate associations of fish simply with the presence of LWJ rather than with other channel or flow‐shaping functions of LWJ. The length of Oncorhynchus spp. and young introduced brook trout was not strongly correlated with LWJ presence; however, the presence of LWJ in pools was positively correlated with larger wild brook trout. We also found that the correspondence of LWJ with the abundance of salmonids appears to be moderated by the presence of alternative habitat in this relatively natural, old‐growth forest stream.     

5个椰子品种形态特征的比较研究

对5个椰子品种茎、叶、花的23个形态特征进行了比较研究。结果表明:有15个数量性状和5个质量性状在5个品种间有显著性差异,而小叶形状、小叶边缘颜色和小叶边缘形状这3个性状在品种间无显著性差异。通过综合分析这20个性状,可以将供试品种进行初步区分。     

基于生态理念的蚌埠黑虎山景区规划探析

城市边缘风景名胜区是城市大环境绿化的龙头,对改善城市生态环境具有重要意义。以蚌埠黑虎山景区规划为例,在概述黑虎山景区现状及发展优劣势的基础上,提出了基于生态理念的城市边缘风景名胜区的规划思想和方法,以期为城市边缘风景名胜区的建设和发展提供思路。     

The Standardization of an Apparatus for the Mixing of Soil Samples for Nematode Extractions

Quantitative determination of nematode populations in soils frequently necessitates the mixing of representative soil samples to form a homogeneous, compound sample from which the nematodes are extracted. A mixing apparatus was developed and standardized with the aid of a spectrophotometric technique by which the dispersion of a dye through the soil during mixing could be determined. It was found that the mixer is most suitable for use on sandy loam soils. Optimal mixing is obtained at a speed of 15 rpm for 2 minutes. Under these conditions mechanical damage to nematodes during mixing is minimal.     

庐山自然保护区秋色叶树种观赏特性及其园林造景应用

介绍庐山保护区秋色叶树种观赏特性,从造景的角度,探讨秋色叶树种在园林中的应用,并提出开发对策。     

信阳茶园假眼小绿叶蝉发生特点及危害损失研究

本文通过系统调查研究信阳茶园假眼小绿叶蝉的发生规律，并利用网罩法测定了不同虫口密度对茶叶产量损失的影响。结果表明：假眼小绿叶蝉在信阳地区每年出现2个发生高峰，第1个出现在6月下旬至7月上中旬，第2个出现在9月上中旬；建立了不同虫口密度与产量损失的关系式为Y=0．2303X-0．5026和Y=0．2854X-0．8795（Y-产量损失；X-百叶虫数）。研究结果能为我们制定信阳地区假眼小绿叶蝉的预报预警和防控防治措施提供借鉴。     

Basic handling characteristics of wood fuels: Angle of repose,friction against surfaces and tendency to bridge for different assortments

Basic handling characteristics were measured for sawdust, fuel pellets, fuel chips, hog fuel and chunkwood. The aim was to find relations between the basic handling characteristics and easily measurable fuel properties to facilitate the design of feeding systems in heating plants. The angle of repose was 25–55° and increased with the increasing ratio of particle length to thickness and with the increasing content of hooked or long particles. The angle of static friction, 10–40°, was affected more by the kind of surface than the fuel and followed the ascending order: coated plywood, urethane rubber, particle board, stainless steel, concrete and rubber belt conveyor. The tendency to bridge varied considerably and increased with greater content of hooked or long particles, a deeper fuel bed depth over the opening and a higher moisture content. The results indicate that more attention should be paid to the particle shape.     

中幼龄林抚育质量与效果分析

文章主要阐述了五台山国有林管理局中幼龄林抚育的基本情况、抚育方法和调查方法及目的,总结了调查结果和结论,建议进行不同强度的抚育试验,不同年龄的抚育试验,以期寻求最佳的技术要点。     

台湾中部地区短延时降雨强度初步探讨

台湾地区在经历1999年的921地震后,山坡地土体松动严重,仅仅短延时的降雨即有机会引起土石流的发生,而近年微小的降雨条件下即有可能触动土石流发生,因此将台湾中部地区14个测站所测得的台风降雨资料,依照台风降雨强度进行水文频率分析,分析方法采用对数常态分布法、极端值第一类分布法、皮尔逊第三类分布法及对数皮尔逊第三类分布法等4种方法,计算短延时重现期距并绘成降雨强度-延时-频率之分析曲线,再整合各区域土石流潜势溪流的分布情况,分析台风降雨对台湾中部地区所造成之影响.     

栽培基质及配方施肥对虎雪兰‘霞光’的生长影响试验

通过盆栽方式，采用不同体积混合配比的泥炭、椰糠、陶粒、树皮基质试验，以N、P、K3元素3水平设置了正交施肥试验，测定植株的生长状况、叶片养分及发病情况，分析了不同栽培基质和施肥处理对‘霞光’生长特性的影响。结果表明，混合栽培基质对虎雪兰‘霞光’的生长较单一的基质效果好，以1／4树皮4-1／4泥炭＋1／4椰糠＋1／4陶粒混合基质植株的株高、假鳞茎、叶面积和根系生长效果最佳；外施氮、磷、钾肥最佳组合为N1P2K3，即NH4N03、NaH2P04和KCl含量分别为1．25mmol／L、0．456mmol／L和2．62mmol／L，有利于虎雪兰‘霞光’植株的营养生长，且设施栽培中发病率较低。