Diversity of street tree populations in larger Danish municipalities

Healthy and sustainable tree populations require a high diversity of genera and species. This study examined the occurrence and contents of tree inventories in Denmark's 30 largest municipalities. 59% of the municipalities had a tree inventory for street trees, but only about half of these were complete and updated. Only one municipality had a registration for trees other than street trees. Based on data from the tree inventories, the diversity of road side trees was analyzed at genus level and species level. A total of 82,072 street trees are part of the study. 11 different genera account for 92% of the total street tree stock, and 2–6 genera account for 40–80% of the street tree stock in the individual municipalities. Tilia was the most dominating genera (26%). 12 species account for 73% of the total street tree stock. The 6 most common species account for almost 50% of the total tree population. The species representing the largest numbers were Tilia × europaea (12%), Acer platanoides (10.9%), Platanus × acerifolia (7.2%), Tilia cordata (7.2%), Fraxinus excelsior (6.2%) and Sorbus intermedia (5.9%). The four most urbanized municipalities had a surplus of non-native species, but all municipalities apart from one had most street trees belonging to native species. The concluding recommendation of this study is that tree managers need to start working more strategic with their tree stock, in order to reduce the vulnerability, due to potential attacks from pests or diseases and climate change effects. A risk spreading system for the urban tree population is proposed, suggesting that no genera should account for more than 10% and no species for more than 5% of the tree population.     

A citywide survey of the pine processionary moth Thaumetopoea pityocampa spatial distribution in Orléans (France)

There is a growing recognition that urban trees provide various valuable benefits and services such as enhanced human wellbeing. However, they also have a cost in terms of public health either directly (allergies) or by harboring species representing health risk for humans. This paper focuses on such a forest insect species, the pine processionary moth Thaumetopoea pityocampa. Its caterpillars develop gregariously during winter in a conspicuous silk nest in coniferous hosts. When disturbed, the larvae release urticating hairs that cause human or animal serious health problems. The purpose of our survey was to (1) inventory all individual trees belonging to potential host species and estimate the density of T. pityocampa (2) assess the spatial pattern of the insect population at the city scale. We conducted an exhaustive inventory of potential coniferous host trees in five municipalities (ca. 5000 ha) in the north of Orléans, France. Each tree was identified, geo-referenced and the number of moth nests it hosted was counted. A total of 9321 urban trees representing 11 coniferous taxonomic units were investigated. The distribution of T. pityocampa exhibited a marked spatial structure citywide. Geostatistics allowed to draw risk maps revealing strong patchiness. We provide the first estimate of T. pityocampa host tree preference in an urban context and found that Pinus nigra, P. pinaster and P. sylvestris were the most attacked trees. We also report numerous cases of T. pityocampa occurrence on the exotic ornamental Himalayan cedar Cedrus deodara. The management implications of our findings are two-fold: (1) risk maps constitute a useful framework for communication and public information, and can help developing control strategies; (2) some species frequently used for ornamental purposes are poor quality hosts regarding T. pityocampa and should therefore be preferred in public place usually frequented by vulnerable people (schools, nurseries, hospitals).     

樟树幼林生物化学参数与高光谱遥感特征参数相关分析

高光谱遥感在植被研究中的应用使定量估算植被的生物化学参数和生物物理参数成为可能.分析了樟树幼林生物化学参数与高光谱特征变量之间的相关关系.结果表明:樟树幼林的大部分生物化学参数(叶绿素a含量、叶绿素b含量、叶绿素总含量、类胡萝卜素含量和总磷含量)与高光谱遥感特征参数(蓝边内最大的一阶微分、绿峰反射率、红边位置、蓝边面积、绿峰反射率和红谷反射率构成的比值与归一化植被指数、红边面积和蓝边面积构成的比值和归一化植被指数)之间的相关系数达到了0.01极显著性检验水平;纤维素、总氮含量与高光谱特征参数的相关系数没有达到显著性检验水平.因此,可以利用相关系数达到了0.01极显著性检验水平的高光谱特征参数建立樟树幼林生物化学参数的高光谱遥感估算模型.     

果树在园林植物造景中的应用

本文分析了果树在园林植物造号中利用率低的原因,阐述了果树在各类绿地园林植物造景中的选择配置与应用,以及果树作为园林植物造景树种应注意的问题,并简要介绍了园林绿化或造景中几种常见的果树。     

旅游区人为干扰对森林群落物种多样性的影响

研究人为干扰对湖北省梭布垭石林针阔混交林森林群落物种多样性的影响。结果表明,人为干扰对乔木层马尾松Pinus massoniana和杉木Cunninghamia lanceolata优势种的主体地位和作用没有根本性的改变,但使群落平均胸径（或地径）和平均树高降低,群落种类组成发生变化。重度干扰和中度干扰降低了群落乔木层阔叶树种和灌木层优势种的作用和地位,重要值降低,但增加了群落物种多样性水平。不同干扰类型的群落,在垂直高度1.0 m以下,Shannon-Weiner多样性指数较大,1.1 ~ 3.0 m高度达最大,以后随高度升高,多样性指数降低,在9.1 m以上的高度层,树种单一,多样性为０。图3表3参13     

果树无病毒研究进展

结合国内外研究,介绍了当前果树生产上应用的4类主要的无病毒技术,即物理疗法、化学疗法、微茎尖法和转基因技术的操作过程和特点,指出脱毒药品开发和抗病毒转基因的研究,将是今后无病毒技术研究的主要领域。     

不同基质对苹果幼树生长发育及叶片生理特性的影响

本研究旨在筛选出适合苹果幼树栽培的基质配方。以2 年生富士芽苗为试材,采用玉米秸杆、园土、草炭土、珍珠岩和牛粪为基质原料,研究不同基质配方对苹果幼树的生长、生物量、根系形态特性和叶片生理特性等参数的影响。研究结果表明：T3（园土:草炭土:牛粪:珍珠岩=2:3:1:1）和T4（园土:玉米秸秆:牛粪:珍珠岩=2:3:1:1）基质最佳,其理化性质理想,栽培的苹果幼树生长量（苗高、茎粗、新梢长、新梢粗、地上部干物质重）、根系发育情况（根系总长、根表面积、根体积、根尖数）和叶片生理特性（净光合速率、蒸腾速率、气孔导度和胞间CO2浓度）等指标都显著高于对照,根冠比和根平均直径则显著低于对照。因此,腐熟后的玉米秸杆完全可代替草炭土在苹果幼树容器栽培中使用,T4 基质可作为培育苹果容器大苗的优良基质在生产上推广应用。     

淳化县泥河沟流域果林发展与综合效益遥感动态研究

利用不同时期遥感信息资源、结合实地调查测绘，编制不同时期果林类型图，经过叠合比较，建立动态分类系统，获得果林类型动态图，以此分析淳化县泥河沟流域１９８６￣１９９５年果林面积的动态变化与综合效益。     

不同新型作用机制杀菌剂对梨树主要病菌毒力及防治流程应用

 为明确多种新型作用机制杀菌剂与引起梨树褐斑病、黑星病、白粉病等病原菌的有效对靶关系及制定梨树主要病害防治流程,采用菌丝生长速率法、离体叶片法与田间药效方法研究新型杀菌剂对靶标病原菌的毒力、对靶标病害的防效及其田间有效应用,建立替代梨树主要病害传统化学杀菌剂的防治流程技术。结果显示,双胍三辛烷基苯磺酸盐在离体叶片法下对褐斑病的防效大于85%,田间药效验证3次用药后7 d防效大于85%、30 d防效大于80%、90 d防效仍大于60%,兼治轮纹病菌其毒力EC₅₀值均小于1 μg·mL^-1。双胍三辛烷基苯磺酸盐、辛菌胺醋酸盐、吩嗪α-2羧酸在离体叶片法下对黑星病防效大于90%且毒力EC₅₀值小于1 μg·mL^-1;田间药效验证1次用药后7 d防效大于80%、30 d防效仍大于75%。噻肟菌酯、硝苯菌酯、丙硫菌唑在离体叶片法下对白粉病的防效大于85%;田间药效验证3次用药后7 d铲除效果大于70%、30 d仍大于60%。丙硫菌唑对黑斑、轮纹病菌毒力EC₅₀值均小于1 μg·mL^-1;吩嗪α-2羧酸同时对褐斑、黑斑、轮纹病菌毒力EC₅₀值小于1 μg·mL^-1。针对梨树主要病害发生期,选用新型杀菌剂替代传统杀菌剂制定防治技术流程,其综合防效达到88.94%。不同新型作用机制杀菌剂在防治梨树主要病害上的应用,能够降低抗药性产生,同时达到有效防治的目的。     

滴灌施肥周期和毛管布设方式对苹果树细根直径时空分布的影响

为探明不同滴灌施肥策略对苹果树细根直径的调控效应,于2019—2021年开展二因素二水平完全组合设计田间试验,毛管布设方式设置一行一管和一行两管,施肥周期设置15 d和30 d,采用微根管原位监测技术,分苹果树正南、正西及东北3个方位和0～19、19～38、38～57、57～76 cm不同深度土层,持续观测苹果树活跃生长期内细根直径的动态变化,分析了苹果树细根直径对毛管布设方式和施肥周期的响应。结果表明：细根直径主要集中在0.5～1.5 mm范围内,约占90%,0～0.5 mm和1.5～2.0 mm直径的细根占比很少。在夏季之前,直径≤1.0 mm的细根增多;夏季之后,细根直径加粗,直径>1.0 mm的细根迅速增加。相较于施肥周期15 d,施肥周期30 d在2020年6—11月和2021年4—7月均能增加细根直径;在大部分土层中,施肥周期30 d会增加细根直径,施肥周期15 d会减小细根直径;在2020年正南和东北方向上,施肥周期15 d会减小细根直径,施肥周期30 d会增加细根直径。一行一管较一行两管在2020年和2021年8月均能增加细根直径;在浅中层土壤(0～38 cm土层...