Hierarchical relationships between landscape structure and temperature in a managed forest landscape

Management may influence abiotic environments differently across time and spatial scale, greatly influencing perceptions of fragmentation of the landscape. It is vital to consider a priori the spatial scales that are most relevant to an investigation, and to reflect on the influence that scale may have on conclusions. While the importance of scale in understanding ecological patterns and processes has been widely recognized, few researchers have investigated how the relationships between pattern and process change across spatial and temporal scales. We used wavelet analysis to examine the multiscale structure of surface and soil temperature, measured every 5 m across a 3820 m transect within a national forest in northern Wisconsin. Temperature functioned as an indicator – or end product – of processes associated with energy budget dynamics, such as radiative inputs, evapotranspiration and convective losses across the landscape. We hoped to determine whether functional relationships between landscape structure and temperature could be generalized, by examining patterns and relationships at multiple spatial scales and time periods during the day. The pattern of temperature varied between surface and soil temperature and among daily time periods. Wavelet variances indicated that no single scale dominated the pattern in temperature at any time, though values were highest at finest scales and at midday. Using general linear models, we explained 38% to 60% of the variation in temperature along the transect. Broad categorical variables describing the vegetation patch in which a point was located and the closest vegetation patch of a different type (landscape context) were important in models of both surface and soil temperature across time periods. Variables associated with slope and microtopography were more commonly incorporated into models explaining variation in soil temperature, whereas variables associated with vegetation or ground cover explained more variation in surface temperature. We examined correlations between wavelet transforms of temperature and vegetation (i.e., structural) pattern to determine whether these associations occurred at predictable scales or were consistent across time. Correlations between transforms characteristically had two peaks; one at finer scales of 100 to 150 m and one at broader scales of ^>300 m. These scales differed among times of day and between surface and soil temperatures. Our results indicate that temperature structure is distinct from vegetation structure and is spatially and temporally dynamic. There did not appear to be any single scale at which it was more relevant to study temperature or this pattern-process relationship, although the strongest relationships between vegetation structure and temperature occurred within a predictable range of scales. Forest managers and conservation biologists must recognize the dynamic relationship between temperature and structure across landscapes and incorporate the landscape elements created by temperature-structure interactions into management decisions.     

Effect of microclimate and nutrients on development of cucumber gray mold (Botrytis cinerea)

Infection of young parthenocarpic cucumber fruits byBotrytis cinerea begins in the petals. Removing petals or washing nutrients from the flower significantly reduced infection. Germination of conidia occurred at relative humidity (r.h.) above 92%, but when water deposition on artificial surfaces was prevented, germination did not occur even at 98% r.h. Germination of conidia on petals is promoted by deposition of an aqueous film not visible on the petal surface by the bare eye (but demonstrable by CoCl₂). Provided there is a film of water on the surface of the host, germination and the infection process occur at a wide range of temperatures up to 25 °C. Pre-exposure of cucumber plants at temperatures as high as 30 °C or as low as 8 °C, prior to their infection and incubation under conditions conducive to gray mold, resulted in greater severity of the disease on young fruits or leaves as compared with plants previously incubated at 10-25 °C. The relevance of these results to cultural control of gray mold is discussed.     

针阔混交林转为桉树林对森林小气候的影响

为了探讨针阔混交林改种桉树人工林对林内小气候的影响,以便为桉树造林的生态效应分析提供依据,对桉树人工林（2008年种植,08EU）和针阔混交林（MF）林内空气温湿度和表土温度进行了连续1 a的观测。结果表明:（1）两种林分林内空气日均温湿度以及日最大相对湿度差异不显著;（2）08EU表土温度和日最高气温的年均值比MF分别高1.5℃和1.4℃,日最低气温比MF低0.8℃,日气温极差比后者高2.2℃,日气温变异系数比混交林高40%;桉树林日最低相对湿度比混交林低6.7%,日湿度极差和变异系数的年均值比后者分别高16.4%和22.0%;（3）空气温湿度日极差与温湿度平均值呈显著正相关,与极小值呈显著负相关,与极大值相关不显著,秋冬季两种林分林内小气候差异最大;（4）桉树纯林对林内气象环境的缓冲保护作用弱于针阔混交林,其林内空气日最低温度和最小湿度的平均出现时间比混交林分别提前51 min和45 min。桉树人工林小气候的变化将会加快土壤水分散失和有机质分解速率。     

地膜不同覆盖方式对大棚秋季小气候及黄瓜生长和品质的影响

为探讨秋季地膜覆盖对大棚环境和黄瓜生长的影响,在大棚栽培条件下,通过畦面地膜覆盖（对照）、畦面覆膜畦沟铺稻壳和畦面畦沟全膜覆盖栽培黄瓜对比试验,研究不同覆盖方式对大棚空气温湿度、土壤温度、CO₂浓度变化以及对黄瓜生长、产量和品质的影响。结果表明：畦面覆膜沟铺稻壳的方式使土壤温度降低了1℃左右,大棚内空气湿度略有增加,霜霉病病情较重。畦面畦沟全膜覆盖明显提高了秋季大棚内的空气温度和土壤温度,空气湿度比对照降低4.9%,CO₂浓度增加了34%,霜霉病病情指数较低,产量和果实中维生素C、可溶性蛋白和游离氨基酸的含量增加。在夏秋高温季节使用畦膜沟铺稻壳的栽培方式,可以降低定植初期的土壤温度,有利于缓苗。在秋季以及秋延后的黄瓜栽培中,利用畦沟全膜覆盖方式可以明显提高产量,改善黄瓜品质。     

果园微气候及土壤养分对灰枣果实矿物元素含量的影响

为了遴选出影响灰枣果实矿物元素形成的关键因子,分别设计了树体阴阳面、遮阳、喷水及地表覆盖物等果园微气候处理方式,就不同处理下的气象因子及土壤碱解氮(N)、速效磷(P)、速效钾(K)、有机质(OM)及酸碱度(p H)对灰枣果实中的钙(Ca)、镁(Mg)、铁(Fe)、锌(Zn)、锰(Mn)和铜(Cu)等矿物元素的影响情况进行了试验,并采用显著性、通径系数及线性回归等分析方法,探究了枣果中矿物元素含量与气象因子及土壤养分因子之间的关系。结果表明:在一定范围内,p H值的升高,有利于枣果中Mg和Mn含量的增加;平均湿度相对较高,对枣果中Fe的含量有促进作用。土壤N含量能有效增加枣果中Cu的含量;枣果Ca含量的影响因素依次为平均湿度差、OM、N、平均最低温度及平均最小湿度,Ca含量与OM和平均最低温度间均有负相关,而与其他指标间均呈正相关;影响枣果Zn含量的因素依次为N、平均最低温度、平均湿度差、平均温度差和OM,其中Zn含量与N和OM间均存在负相关,而与上述其余各指标间均呈正相关。     

黄冈市城区绿地小气候效益计量

基于2009年黄冈城区典型样地单位附属绿地、道路绿地、居住区绿地、生产绿地、防护绿地6种类型绿地面积计算小气候效益,结果表明:改善小气候效益分别为:防护绿地34.84万元/hm2.a>公园绿地16.07万元/hm2.a>道路绿地6.33万元/hm2.a>单位附属绿地6.30万元/hm2.a>生产绿地6.26万元/hm2.a>居住区绿地2.51万元/hm2.a。使用便携式气象仪Kestrel NK4000测定其空气温度,计算城市森林夏季降温和冬季增温的效益,通过货币化的方式直观的反映黄冈城区绿地改善小气候的效益。以此为实例进行森林生态效益相关问题的探讨,提高人们对城市森林,改善居住环境重要性的认识。     

三亚春季豇豆防虫网覆盖栽培小气候研究初报

研究了三亚春季防虫网覆盖栽培对豇豆生长小气候环境（温度、光照强度、湿度）的影响。结果表明：防虫网覆盖栽培能降低豇豆生长环境的温度,减弱光照强度,对空气湿度影响小。     

覆盖方式对旱作水稻后期冠层生理生态特性及产量的影响

以超级杂交稻组合P88S/1128为材料,设置地膜覆盖、稻草覆盖和液体膜覆盖3个处理,以裸地为对照,研究了不同覆盖方式对旱作水稻群体生理生态特性的影响。研究表明,覆盖方式对旱作水稻群体微气象因子和水稻的个体生长都有明显影响,表现为覆盖显著降低了高温季节特别是高温时段水稻冠层的温度,提高了相对湿度,营造了群体内部良好的微气象环境。覆盖处理的叶片蒸腾作用增强,叶片的温度降低,叶片的抗高温胁迫能力提高,从而光合速率显著提高。覆盖栽培下产量构成各因子均有明显优化,其中地膜覆盖栽培下的每穗粒数和结实率最高,产量较对照增加16.81%;稻草覆盖处理的有效穗增多,较对照增产9.59%。但液体膜覆盖的增产效果不明显,产量构成因子与对照相比差异不显著。     

浚单20不同密度群体冠层微生境研究

在90000、75000、60000株/hm~2种植密度条件下,研究了浚单20吐丝期、灌浆期群体冠层的微生境变化及叶斑病发生情况.结果表明,在吐丝期,冠层上层风速与种植密度呈负相关,且大于中、下层风速;在灌浆期,中、下层风速不同种植密度间差异不明显.在玉米不同生育时期,不同种植密度群体的上层光照强度差异均不显著,但中、下层尤其是中层穗位处的光照强度差异较大,表现为光照强度与种植密度呈负相关.在吐丝期,上层的温度表现为高、中密度大于低密度,在灌浆期不同种植密度间差异不明显,中层和下层的温度在吐丝期和灌浆期午后13:00左右时低密度高于中、高密度.群体湿度与种植密度呈正相关,且下层湿度依次高于中层和上层.玉米叶斑病随着种植密度的增加而加重.结合产量分析表明,浚单20种植密度以75000株/hm~2较为适宜.     

渭北旱地苹果园生草小气候效应研究

采用定位观测的方法,对渭北旱地苹果园生草气温、相对湿度等小气候因子进行了测定,同时以清耕果园为对照进行同步观测。结果表明,生草调节了苹果园近地层的大气温度、增加相对湿度,调节土壤温度;在牧草的不同发育阶段上述调节作用不同,且调节程度与草种的种类关系密切,旱地苹果园种植白三叶调节小气候效果优于种植黑麦草。