中国引种的柏科树种概况

自２０世纪以来我国先后从国外引进柏科树种大约５属５２种１１变种，至今保存２属５２种４变种。表现最好且在生产上有较大栽培面积的主要是柏木属、扁柏属和圆柏属的１０余个种：日本扁柏和日本花柏已成为长江中下游各省（区）中高山地带的优良造林树种；墨西哥柏和绿柏已成为我国中亚热带中、低山地区的优良造林树种；铅笔柏在北亚热带和暖温带湿润地区栽培较广；欧洲刺柏和辅地柏在北方一些城市广泛用作园林树种；铅笔柏在北亚热     

中国红豆杉中主要紫杉烷类物质的分布研究

对中国红豆杉[Taxus chinensis(Pilg.)Rehd.]中的紫杉烷类化合物紫杉醇及两种重要前体巴卡亭III(B III)和10-脱乙酰巴卡亭III(10-DAB)的分布进行了研究.结果表明,紫杉醇的含量在同一棵树中的分布依主干皮、根皮、侧枝树皮、种子、须根、嫩枝、叶的次序递减,并发现侧枝茎中紫杉醇在横截面方向呈梯度分布,且紫杉醇含量最高部位是在次生木质层.10-DAB和B III在叶中含量最高,在须根中含量最低,叶子中10-DAB的含量达0.02%～0.03%,高于B III的含量.在2～3 a生的小树枝、叶中未检测到紫杉烷类物质,提示其合成可能与植株发育有关.紫杉醇在30 a 树龄的当年生嫩叶中春季高于秋季,而10-DAB在当年生和多年生的叶中积累都较多,且秋季比春季含量高.     

Genotypic variation in water relations and gas exchange of urban trees in Detroit,Michigan, USA

Increasing tree species diversity has become a key underpinning for communities to improve resilience of urban and community forests. Increasingly, urban forestry researchers are examining physiological traits to aid in selecting trees for urban sites. Knowledge of physiological responses also has implications for understanding species’ resilience to increased stresses associated with climate change. Here, we compare growth, leaf SPAD chlorophyll index, water relations, and gas exchange of seven genotypes of shade trees planted in two locations in downtown Detroit, MI, USA. Genotypes included Redpointe® maple (Acer rubrum ‘Frank Jr.’), Flashfire® maple (Acer saccharum ‘JFS-Caddo2′), Pacific Sunset® maple (Acer truncatum x platanoides ‘Warrenred’), Emerald City® tulip tree (Liriodendron tulipifera ‘JFS-Oz’), Chanticleer® pear (Pyrus calleryana ‘Glen’s Form’), swamp white oak (Quercus bicolor), and Emerald Sunshine® elm (Ulmus propinqua ‘JFS-Bieberich’). Trees were planted in either Lafayette Plaisance Park (Park), a large urban greenspace, or on the median of St. Aubin Avenue (Median), a nearby major thoroughfare. Tree height growth and leaf SPAD index were higher for trees planted in the Park location than on the Median. However, genotypic variation was larger than the effects of location or the interaction of Genotype × Location for most traits. Across measurement dates, midday leaf water potential was lowest for Pyrus trees and highest for Ulmus and Liriodendron trees. Pyrus and Quercus trees had relatively high rates of net photosynthesis (A) and stomatal conductance (g_s) while Liriodendron, Acer saccharum, and Ulmus trees had low rates of A and g_s. Liriodendron trees closed their stomata rapidly as leaf water potential (Ψ_w) declined (isohydric response), while Pyrus and Quercus trees maintained g_s across a range of leaf Ψ_w (anisohydric response). Liriodendron trees also had the highest relative growth rates, suggesting that drought stress avoidance through isohydry is a viable drought tolerance mechanism in urban trees.     

Valuing urban trees: A hedonic investigation into tree canopy influence on property values across environmental and social contexts in Baltimore,Maryland

Urban tree canopy yields numerous environmental and social benefits. This study investigates whether the marginal contribution of tree canopy cover to home values depends on certain characteristics of a property and its location. We address this using a hedonic property analysis with data from Baltimore, Maryland. Both Ordinary Least Square and Spatial Lag models were conducted, all including interaction terms between tree canopy cover and various site factors. Our results indicated that, on average, the amount of tree canopy in the 100–400 zone around a single-family property is positively associated with home price. We also find that the marginal impact of canopy on property price increases for properties that are larger in lot size and closer to downtown Baltimore. Model results were mixed in terms of the interactive effects of crime and proximity to major roadway with tree canopy. We suggest that the benefits that tree canopy provides in the form of added privacy, reduced urban heat, noise and pollution may influence these price increases. These findings may signal concerns about the potential for urban greening to contribute to gentrification. In a competitive housing market, those with the capacity to afford to pay more for urban tree canopy and the benefits it provides such as a cooler downtown environment, privacy on larger lots, or reduced noise and pollution from a major roadway may price out those who are unable to pay this urban tree canopy premium. There is, therefore, the potential for unequal increases in home equity across neighborhoods following tree planting and urban greening in Baltimore.     

橡胶树棒孢霉落叶病病原菌的生物学特性

通过对橡胶多主棒孢进行生物学特性研究,结果表明:菌丝生长的适宜温度范围为25～30℃,最适温度为30℃;最适pH范围为4～8;菌丝在以麦芽糖为碳源和以KNO3为氮源的培养基上生长最好。分生孢子萌发的适宜温度范围为20～35℃,最适温度为25℃;水滴是孢子萌发的必要条件;在不同的pH条件下分生孢子萌发无明显差异;分生孢子在果糖中萌发率最低。     

基于探地雷达杂波抑制与偏移成像的树木根系定位方法

探地雷达在果树和古树名木养护管理领域具有广阔的应用前景。针对探地雷达采集的B-scan图像中杂波影响根系定位精度的问题,提出了基于鲁棒深度自动编码器(RDAE)、直接最小二乘法(DLS)和频率-波数域偏移(FKM)相结合的树木根系定位方法。首先,通过RDAE将零点校正后的B-scan图像分解为表示杂波的低秩分量和表示根系目标回波的稀疏分量,保留稀疏分量完成杂波抑制;然后使用DLS拟合目标回波形成的双曲线估算土壤的相对介电常数;最后,根据土壤的相对介电常数计算得出偏移速度作为频率-波数域偏移的输入进行偏移成像,获取根系的半径和深度信息从而完成根系定位。实验结果表明：RDAE方法在仿真和实测数据上的杂波抑制效果对比均值减法(MS)、奇异值分解(SVD)和鲁棒主成分分析(RPCA)有着更高的信杂比和改善因子,通过DLS估计的土壤相对介电常数均方根相对误差为3.84%,根系定位的最大半径相对误差和最大深度相对误差分别为8.5%、8.7%,能够完成根系位置标定,满足根系无损检测的需求,可为树木健康管理和移植提供决策支持。     

白花泡桐树冠结构、生长性状的选择对于形改良的影响*

为了改良白花泡桐的干形，对树冠结构，生长性状与干形的遗传相关进行了剖析和通径分析，计算出主要树冠性状、生长性状对于干形的６３个选择指数方程。结果表明，胸径、小枝数、分枝总长、冠表面积和树高对形数，圆满度的决定系数在０．４０５～０．９４０和０．４２６～１．０６４之间。由以上５性状和形数或圆满度组成的综合选择指数方程效果最好。对形数选择遗传进度，相对效率分别为０．１５５和１５９．０１５７％。对圆满度选     

不同气体成分对冬枣贮藏的影响

根据冬枣的呼吸生理特点,冬枣气凋贮藏试验采用了4种不同的O2和CO2气体成分．通过比较各种试验处理的贮藏效果,确定了冬枣气调贮藏最佳气体成分为：O2含量为3％,CO2含量为2％。