共查询到19条相似文献，搜索用时 244 毫秒
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为实现落叶松采伐剩余物的多级、高值利用及炭化还林、改良土壤提供理论依据,探究了落叶松不同器官(树干边材、树枝、树皮、树叶和松果)材料的主要化学组分,分析了其热解特性及其生物炭的基本理化性质,分离并测定落叶松各器官纤维素、半纤维素、木质素、苯醇抽提物和灰分含量,并表征各器官材料的热稳定性。将落叶松不同器官材料分别在500、700、900℃下炭化并表征各生物炭的理化性质。落叶松树干边材中综纤维素含量最高、松针中木质素和灰分含量最高、树枝中苯醇抽提物含量最高。落叶松的热解过程分为干燥、快速热降解和煅烧3个阶段,主热解反应发生在200～400℃,热重结果及炭得率分析均表明,松针的残炭率最高。同一组织器官的生物炭产率和表面官能团种类均随炭化温度的升高而逐渐减少;而同一组织器官生物炭的pH值随炭化温度上升而逐渐升高。5种生物炭的比表面积情况为：树皮炭>树干炭>松果炭>松针炭>树枝炭。落叶松边材的纤维素含量最高,适宜用作造纸制浆等原材料,松针的木质素含量较高,适宜用于提取化学品。树干边材、树皮和树枝适合炭化还林,其中树皮炭的炭得率较高、比表面积较大,pH值呈强碱性且化学性质比... 相似文献
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矮化密植苹果园土壤养分对果实品质的影响 总被引：2，自引：0，他引：2
以"金世纪"苹果为试材,对昆明市西山区团结街道办事处4个矮化密植苹果园的土壤养分状况、果实品质进行了调查、测定和分析。结果表明:4个矮化密植苹果园的土壤pH值平均为5.99;土壤有机质、碱解氮、速效磷、速效钾含量偏低,且果园之间各肥料的施用水平存在较大差异。土壤有机质与土壤各养分间均呈正相关,pH值与土壤各养分间呈负相关;不同土壤养分与果实品质也存在着相关性,其中单果质量与土壤有机质、全氮、全磷、全硼、碱解氮、速效磷、速效钾均呈正相关,与土壤pH值呈极显著负相关,可溶性固形物与pH值、有机质、全氮、速效钾呈正相关。 相似文献
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李海飞徐国锋闫震沈友明高贯威 《中国果树》2022,(11):52-56
2017—2020年连续4年对山东省栖霞市常规管理模式下苹果园不同土层土壤电导率和pH值进行定点研究,探明苹果园土壤电导率和pH值在时间和空间上的变化趋势,以期为苹果园的土壤改良和合理施肥提供科学的依据。结果表明,在苹果园0～80 cm土层,土壤电导率和pH值均呈现对数正态分布,全距呈下降趋势,变幅逐渐减少,最大变幅出现在0～20 cm土层,电导率和pH值的变异系数均呈现中等变异。在时间维度上,随着种植年限的延长,苹果园土壤电导率和pH值均呈上升的变化趋势;在垂直剖面方向上,土壤电导率整体呈“下降”型分布,最大值0.35 mS/cm出现在0～20 cm土层,存在明显的表聚现象;土壤pH值在0～40 cm土层的表现为下降趋势,40～80 cm土层又呈现上升趋势,最大值为5.93,出现在60～80 cm土层,整体呈“V”形变化趋势。相关性分析结果表明,在0～20 cm土层,种植年限与土壤电导率存在显著的正相关,与pH值呈负相关,在20～80 cm土层,种植年限与土壤电导率存在显著的正相关,而与pH值虽然呈正相关但随土层深度的增加相关性逐渐变弱至无相关性,说明苹果园耕作层土壤电导率和pH值的... 相似文献
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以不同配比的悬铃木(Platanus)树叶和加拿大杨(Populus canadensis Moench)树叶为试材,研究了树木落叶生物基质对城市园林绿地土壤容重、有机质含量、pH值及N、P、K含量的影响.结果表明:利用悬铃木和加杨落叶制作的生物基质来改良绿地土壤效果显著.处理1、处理2、处理3都能有效地降低土壤容重,改善土壤结构;有效地提高土壤的有机质含量,降低碱性土壤的pH值,提高肥力的有效性,改善植物根系生长环境;显著地提高土壤N、P、K的含量和有效性. 相似文献
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桃褐腐病是桃树上的一种重要病害,导致桃果经济损失严重。本文对不同产区桃褐腐病菌的生物学特性进行了研究。来源不同产区的桃褐腐菌株总体在PDA培养基、25℃、pH值6.0~7.0及每天光照12h条件下生长最好;菌丝生长最适碳源和氮源分别是淀粉和牛肉浸膏。褐腐菌株分生孢子平均在25℃、pH值7.0及每天光照12h条件下萌发率最高。不同产区褐腐菌株间存在生物学差异,表明病菌存在丰富的生理生化多样性。研究结果表明,不同的营养、温度、光照、pH值等环境条件对桃褐腐病菌菌丝生长和孢子萌发有显著影响。 相似文献
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草莓果实成熟过程中Ca~(2+)-ATPase活性变化及酶学特性 总被引：8，自引：1，他引：8
以不同成熟度的草莓果实为试材,研究了草莓果实成熟过程中Ca2+-ATPase活性变化规律、最适pH值、动力学参数Km值和Vmax值。研究结果表明,草莓果实从开始成熟时(绿熟期)Ca2+-ATPase活性不断升高,果实完全成熟时(粉红期)达到最大值,随着成熟后的不断衰老,其活性逐渐降低;该酶的最适pH值为7.0;不同成熟阶段果实Ca2+-ATPase反应所需的Ca2+浓度有所不同,EGTA对各成熟阶段草莓果实的Ca2+-ATPase活性的抑制作用存在明显的差异。经对Ca2+-ATPase的动力学分析表明,不同成熟度果实Ca2+-ATPase的Km值和Vmax值不同,从果实开始成熟Km值逐渐降低,衰老时又逐渐上升,变化趋势与酶活性变化趋势相反;Vmax值变化趋势与酶活性变化趋势相同。2+ 相似文献
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秸秆还田方式对设施土壤盐分的影响 总被引：1，自引：0，他引：1
在设施栽培条件下,研究不同秸秆还田方式对土壤盐分空间运移的影响,通过测定分析不同秸秆还田方式处理对不同深度土壤全盐、电导率、硝酸盐、pH值,比较不同处理盐分指标的差异,并对不同盐分指标进行相关性分析。结果表明:2 000kg/667m2行下秸秆反应堆处理之间差异不明显,但与无秸秆处理相比,不同行下秸秆反应堆处理能够降低0~10cm土层土壤全盐20.16%~21.75%,降低10~20cm土层土壤全盐13.25%~24.40%;能够降低0~10cm土壤硝酸盐25.00%~25.80%,降低20~30cm土层土壤硝酸盐22.41%~24.75%;土壤全盐与土壤硝酸盐极显著正相关,土壤全盐与土壤pH值极显著负相关。 相似文献
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城市的行道树作为城市绿化系统的重要组成部分,对城市的生态环境的改善起着重要的作用。本文对昆明市五华区24条不同等级道路行道树进行实地调查,结果表明:昆明市五华区行道树共有21科、26属、31种,存在种类单一,乡土树种应用较少,特色不明显;行道树布局结构单调,缺乏变化等问题。针对以上问题提出了合理配置行道树和提高行道树管养水平的建议。 相似文献
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天山桦（Betu Iatianschanica Ruprecht）,主要分布在我国新疆天山,生长在海拔1300～2500m的林缘、疏林地或者混交林中。喜光,对气候、土壤适应性很强,耐寒,能耐极端低温－50℃。天山桦树冠卵形,树皮洁白、树体高大、枝叶繁茂、秋季树叶金黄,是良好的植树造林及城市绿化树种,也可用于公园、行道树,具有较高的欣赏价值。天山桦种了,颗粒小,幼苗生长缓慢,播种育苗难度大。 相似文献
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The application of de-icing salts for winter road maintenance is recognized as a major contributor to the decline of urban trees. We conducted a long-term monitoring program across several locations in the City of Edmonton (Alberta, Canada) to evaluate the impact of roadway salt application on tree species widely planted in boulevards and right-of-ways: Ulmus americana, Fraxinus pennsylvanica, Pinus contorta, and Picea glauca. Soil and leaf samples were collected from a total of 16 sites over six years. There were four sites selected for each tree species: three mid- to high- traffic roadside sites that received regular winter maintenance and one non-serviced site (control). Sampling was performed three times per year from late spring to late summer. Airborne salinity was assessed in four locations at different distances from the road. In 50% of the roadside sites, soil electrical conductivity (EC) values exceeded 2 dS m−1. Soil pH in all of the roadside sites was also significantly higher than in the control sites, with values ranging from 7.6 to 8.5. In all four species, trees growing in sites with high soil EC had increased leaf Na concentrations and reduced leaf chlorophyll concentrations. Among the airborne monitoring sites, Na deposition in high traffic locations was over four-fold higher than those measured in the control location. Furthermore, Na levels remained relatively high at 20–50 m from the main road. Our data suggest that while soil salinity is among the main stressors affecting roadside trees in Edmonton, salt spray deposition may also have a significant impact on trees located close to high vehicle traffic areas and dense road networks. Our study highlights the importance of collecting data over several years and from multiple locations to account for the spatial and temporal heterogeneity of the urban environments in order to better evaluate the impact of road salt application on urban trees. 相似文献
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Roads destroy natural habitats. To reduce erosion, support wildlife and decorate surroundings, ornamental trees are planted near the roadside. However, it is inadequately understood how roads influence fruit production of trees and birds that consume their fruits, within urban landscapes. During the autumn and winter of 2012–2013, we studied the extent to which birds used the fruit from rowanberry trees (Sorbus aucuparia), in two cities along a 700 km latitudinal gradient in Finland. In matched pair design (total of 35 pairs), we compared roadside trees (approximately 8 m from main roads) with trees grown away from roads (control trees; approximately >80 m from the roads). During the autumn, each rowanberry tree pair was photographed, and frugivorous birds were surveyed twice per month until all of the rowanberry fruit-crop was consumed. There was no difference in fruit crop size between roadside trees and control trees. A total of eight frugivorous bird species and 960 individuals were observed foraging in roadside trees. The three most abundant species were Bohemian waxwing (Bombycilla garrulus, 56.4%), Pine Grosbeak (Pinicola enucleator, 28.9%) and Fieldfare (Turdus pilaris, 10.5%). Total abundance and species richness of frugivorous birds were lower around roadside trees than control trees during most of the study period. Fruits were consumed later from roadside trees than from control trees, probably due to human-caused disturbance. Therefore, roadside rowanberry trees extended the period when frugivorous birds stayed in urban habitats. Later consumption of fruits in northern areas than in southern areas was related to earlier peak abundance of frugivorous birds in south than in north. Our results indicated that rowanberry is a suitable ornamental tree for urban and roadside landscaping and may additionally benefit birds and other frugivorous wildlife. 相似文献
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Heritage trees in a city, echoing factors conducive to outstanding performance, deserve special care and conservation. To understand their structural and health conditions in urban Hong Kong, 30 defect-disorder (DD) symptoms (physical and physiological) subsumed under four tree-position groups (soil-root, trunk, branching, and crown-foliage) and tree hazard rating were evaluated. The surveyed 352 trees included 70 species; 14 species with 233 trees were native. More trees had medium height (10–15 m), medium DBH (1–1.5 m) and large crown (>15 m). In ten habitats, public park and garden (PPG) accommodated the most trees, and roadside traffic island (RTI) and public housing estate (PH) had the least. Tree dimensions and tree habitats were significantly associated. The associations between the 2831 DD and tree-position groups, tree habitats and tree hazard rating were analyzed. Fourteen trees from Ficus microcarpa, Ficus virens and Gleditsia fera had high hazard rating, 179 trees from 22 species moderate rating, and 159 trees from 55 species low rating. RTI, roadside tree strip (RTS), roadside tree pit (RTP), roadside planter (RP) and stone wall (SW) had more moderate hazard rating, and PPG, roadside slope (RS) and government, institutional and community land (GIC) more low rating. Redundancy analysis showed that DD were positively correlated with RTS, RTP, RP and SW, but negatively correlated with PPG, RS and GIC (p < 0.05). The DD significantly increased tree hazard rating and failure potential. Future management implications for heritage-tree conservation and enhancement focusing squarely on critical tree defect-disorder in urban Hong Kong were explored, with application to other compact cities. 相似文献
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An analysis of tree health in urban greeneries exposed to winter road salt contamination was carried out in the cities of Alytus and Kaunas, Lithuania, during spring and summer 2009–2014. Trees were assessed for crown dieback, crown defoliation and foliage discolouration. In addition, the prevalence of saprotrophic pathogenic fungi that cause sooty mold disease was assessed in street and recreational plantings. Tilia cordata Mill. (small-leaved lime) was found to be the most common tree species among urban deciduous trees. Summarising the tree foliage results, saprotrophic fungi were detected on 16 species plants belonging to 13 genera. Three species of fungal pathogens belonging to two genera, two families, two classes, and two divisions, and 12 species of anamorphic fungi from nine genera were isolated and identified from Tilia cordata leaves. The most frequent sooty mold disease agents were Aspergillus brasiliensis and Cladosporium herbarum. Nonetheless, a weak correlation between salt contamination and lime tree damage by sooty mold was found. 相似文献
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Understanding the potential dynamics of tree pests and pathogens is a vital component for creating resilient urban treescapes. Epidemiologically relevant features include differences in environmental stress and tree management between street and garden trees, and variation in the potential for human-mediated spread due to intensity of human activity, traffic flow and buildings. We extend a standard spatially explicit raster-based model for pest and pathogen spread by dividing the urban tree population into roadside trees and park/garden trees. We also distinguish between naturally-driven radial spread of pests and pathogens and human-mediated linear spread along roads. The model behaviour is explored using landscape data for tree locations in an exemplar UK town. Two main sources of landscape data were available: commercially collated aerial data, which have high coverage but no information on species; and, an urban tree inventory, with low, non-random, coverage but with some species data. The data were insufficient to impute a species-specific host landscape accurately; however, by combining the two data sources, and applying either random or Matérn cluster point process driven selection of a subset of all trees, we create two sets of potential host landscapes. We find that combining the two mechanisms of dispersal has a non-additive effect, with the enhanced linear dispersal enabling new foci of infection to be established more rapidly than with radial dispersal alone; and clustering of trees by species slows down the expansion of epidemics when compared with random distribution of tree species within known host locations. 相似文献
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Exotic coniferous trees in forests adjacent to spa towns and in parks within spa towns are increasingly being attacked by outbreak populations of native bark beetles in western Bohemia (Central Europe). In the 12 localities in western Czech Republic the current study, we detected a total of 19 native bark beetle species infesting more than 10 % of exotic tree species in the genera Abies, Picea, Pinus, and Pseudotsuga in 1 year. Several exotic tree species were identified as new hosts for native European bark beetles. We also identified three non-native bark beetles, including Phloeosinus aubei, a species that transmits the pathogens that cause cypress canker disease.The numbers of infested trees in the localities were not correlated with the distance from surrounding bark beetle outbreak sites in commercial forests, because all forests adjacent to spas and all forests in spa towns (i.e., “urban forests”) are close to commercial forests with infested trees. Infestations were greater in spa towns than in the forests adjacent to spa towns. We therefore assume that trees within spa towns will be further attacked due to the increasing abundance of native bark beetles. 相似文献
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Urban forest managers must balance social, economic, and ecological goals through tree species selection and planting location. Ornamental trees are often popular in tree planting programs for their aesthetic benefits, but studies find that they have lower survivability and growth compared to larger shade trees. To maximize ecosystem services within these aesthetic preferences, it is important to select species carefully based on their ability to grow in each particular climate. However, little locality-specific and species-specific data exist on urban trees in many regions. This study examines the growth, survival, and vigor of three common ornamental street trees in San Francisco’s three different microclimate zones after over 16 years since planting. While we found over 70% survival for all three species throughout the city, there were significant differences in health and vigor among microclimates for each species, likely due to differences in drought-tolerance. While Arbutus had the greatest proportion of healthy trees in the Fog Belt and Sun Belt zones, Prunus cerasifera had the greatest proportion in the Sun Belt, and Prunus serrulata had the greatest proportions in the Transition and the Sun Belt zones. This species-specific and climate-specific information will better equip urban foresters to target both planting and tree-care of these popular species appropriately to maximize the benefits provided by these street trees while still maintaining a diverse canopy. Finally, we argue that simple survival calculations can mask more complex differences in the health and ability of different urban tree species to provide ecosystem services. 相似文献
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The level of tree species diversity in urban tree populations can have serious implications for urban forest resilience and has a direct impact on ecosystem functioning at the local level. Few studies have measured the relationship between tree species diversity and vulnerability in UK urban forests. This study analysed the species composition, species diversity and the vulnerability to pests and diseases of 10,149 public trees in the London borough of Westminster across three land use types: housing, parks, and highways. Tree species diversity was significantly different across these land use types (Shannon’s diversity index (H) was 2.47 for housing sites, 1.63 for parks and 0.83 for highways) and we found that higher diversity appears to result in reduced vulnerability, evidenced by negative correlations between tree species diversity and susceptibility to pests and diseases. A stronger negative correlation was found between vulnerability and species richness than between vulnerability and Gini-Simpson’s diversity index. Our study reinforces the role of biodiversity indices in establishing and monitoring baseline levels of UK urban tree diversity. Our findings may inform future tree planting projects, help to ensure that development does not negatively affect urban tree diversity and inform proactive strategies for urban trees to contribute to wider biodiversity conservation. 相似文献