Diurnal Variation of Volatile Organic Compounds in Recreational Forests and Its Relationship with Microclimate Factors

This study used the dynamic headspace adsorption(DHS) to collect volatile organic compounds(VOCs) released from the Fokienia hodginsii forest in summer, and analyzed the the composition and concentration of VOCs and their correlation with environmental factors. The results showed that: there were 165 types of VOCs in the Fokienia hodginsii forest;the diurnal variation of the concentration of total volatile organic compounds(TVOCs) was "W"-shaped, the concentration reached its peak at 13:00–15:00 and its trough at 1:00–3:00;VOCs beneficial to human health mainly appeared at 13:00, while VOCs harmful to human health chiefly occurred at 11:00–19:00. The correlation analysis between the concentration of VOCs and climatic factors indicated that the concentration of VOCs was basically proportional to the temperature and illumination intensity and inversely proportional to the humidity and wind speed. In other words, the diurnal variation of the concentration was consistent with the diurnal variation of temperature and illumination intensity.

Compound Planting of Bletilla striata under Forest in the Three Gorges Dam Area

[Objectives] The aim was to study the artificial cultivation of Bletilla striata to realize large scale and standardization planting. [Methods] The comparison tests were conducted on B. striata with different canopy densities of the Magnolia officinalis forests,different compound planting densities and different tending measures and management. [Results] When the stand canopy density was 0. 4-0. 6,the per unit yield of B. striata was 5. 4%,6. 8% higher than that at the canopy density of less than 0. 4 and more than 0. 6,respectively. When the planting density was 30 cm × 30 cm,the per unit yield increased by 16. 1%,12. 0%,13. 1% respectively compared with the planting density of 20 cm × 20 cm,25 cm × 25 cm,35 cm × 35 cm. When B. striata was planted from October to November,the per unit yield was 5. 6% higher than that planted from December to January of the following year,and 21. 3% higher than that from February to March of the second year. When farmyard manure was applied during the cultivation,the per unit yield was 31. 7% and 18. 4% higher than the application of chemical fertilizer and compound fertilizer. When weeding 4 times per year,the per unit yield increased by 240. 1%,137. 0% and 43. 9% respectively from that weeding 1 times,2 times,3 times per year. [Conclusions]When planting B. striata,the stand canopy density of 0. 4-0. 6 could make it receive absolutely shelters and the lighting conditions required for the growth,thereby bringing in high emergence rate,good growth potential and high yield. The best planting effect of B. striata could achieve by planting from October to November with the planting density of 30 cm × 30 cm,which can play the maximum benefit of individual plants. Moreover,weeding 4 times per year combined with the use of farmyard manure can promote the development and growth of tubers,which can greatly improve the yield of B. striata.

Changes in Chemical Composition of Soluble Organic Chemical Compounds during Litters Decomposition into Tropical Forest of Milletia laurentii De Wild

Recent publication attested that in the urban forest of Brazzaville, litter decomposition is faster with almost 45% of initial weight loss than in the dry season, where an average loss of 26% in initial litter weight is noted (Ifo et al., 2018). This study was carried out in the urban forest of Brazzaville to follow the decomposition of some organic compounds/secondary metabolites (reducing Sugars, total Flavonoid and Polyphenols) of the leaves litters of two tropical species Antiaris toxicaria Lesch and Millettia laurentii De Wild. Thin-layer chromatography and spectrophotometric assay of these metabolites were used on the samples of litters collected in the field on various dates of follow-up of the decomposition (0 d, 14 d, 28 d, 42 d, 56 d, 72 d and 84 d). The chromatographic profile of initial litters shows a series of spots on yellow florescence materializing presence of flavonoids, green fluorescence revealing the presence of the acids phenols derived from the cinnamic acid. But the chromatographic profile of the two litters in decomposition after two weeks remains without structural information, being able to characterize the decomposition of the chemical families highlighted in the initial litters. Also, the analysis of quantitative total reducing sugar in the initial litters, gives average concentrations of 64.4, 58.6, 57.5 g EG/kg Ms respectively for the litters of Millettia laurentii De Wild, Antiaris toxicaria Lesch and the mixed litters (Millettia laurentii and Antiaris toxicaria). Comparatively with the other types of litters, the initial average concentrations in phenolic compounds (polyphenols and flavonoids totals) were the highest for the litters of Antiaris toxicaria Lesch (27.3 g EAG/kg Ms and 13.07 g EC/kg Ms) (P = 0.001). The losses of organic chemical compounds are more significant during the first two weeks of experiment than after this period. Antiaris toxicaria Lesch loses on average 43.8 g EG/kg Ms of reducing Sugars, 12.21 g EC/kg Ms of totals flavonoids and 26.4 g EAG/kg Ms of total polyphenols, equivalent to 30% of loss of the initial weight. Average losses of 45.7 g EG/kg Ms were obtained for reducing sugars, 1.5 g EC/kg Ms for totals flavonoids and 8.72 g EAG/kg Ms for totally phenols in for the litters of Millettia laurentii, comparable to 24% in initial weight loss. This study showed on the one hand, the direct link between rainfall and litters decomposition and the losses in weight of the litters resulted in dissolution in the water of the studied compounds.

Emissions of volatile organic compounds from heated needles and twigs of Pinus pumila

A study was conducted to explore the mechanism that emissions of volatile organic compounds（VOC） from heated needles and twigs（200°C,within 15 min） of Pinus pumila affect fire behaviours using the technology of Thermal Desorption-Gas Chromatography-Mass Spectrometry（TD-GC-MS）.The results indicated that the main components of VOC from heated needles and twigs are terpenoids.Most of these terpenoids are monoterpenes.Terpenoids account for 72.93% for the needles and 92.40% for the twigs of the total VOC,and their emission ratios are 61.200 μg·g-1 and 217.060 μg·g-1 respectively.Heated twigs can emit more terpenoids than heated needles because twigs had more volatile oils than needles.In actual fires,these large amounts of terpenoid emissions,especially the monoterpene emissions,have strong effects on fire behaviors that are not only in the initial stage but also in the fast propagation stage of fires.These flammable gases are capable of causing violent combustion and creating crown fires.In addition,if these gases accumulate in an uneven geographical area,there will be a possible for eruptive fires and/or fires flashover to occur.

面向喷染车间的挥发性有机物质量浓度预测方法及应用研究

以喷染车间挥发性有机物为研究对象,对喷染车间挥发性有机物(Volatile Organic Compounds, VOCs)质量浓度预测方法进行研究。首先,使用随机森林(Random Forest, RF)算法对影响喷染车间挥发性有机物质量浓度的特征变量进行权重分析。同时,构建基于长短期记忆神经网络(Long-Term and Short-Term Memory Neural Network, LSTM)的挥发性有机物质量浓度预测模型,并在此基础上引入麻雀搜索算法(Sparrow Search Algorithm, SSA)进行参数优化选择。最后,以浙江省杭州市某汽车喷染车间7月29日—10月28日的数据为样本,将温度、相对湿度、室内大气压、室外大气压作为模型输入变量,并与LSTM模型、随机森林-长短期记忆神经网络(Random Forest-Long Short-Term Memory neural network, RF-LSTM)模型、随机森林-反向传播神经网络(Random Forest-BP neural network, RF-BP)模型进行对比试验。结果显示,基于随机森林-麻雀搜索算法-长短期记忆神经网络(Random Forest-Sparrow Search Algorithm-Long Short-Term Memory neural network, RF-SSA-LSTM)模型的预测效果最佳,平均绝对误差、均方根误差和决定系数分别为2.812 2、3.457 4、0.988。同时,为验证RF-SSA-LSTM模型性能,通过不同时间步长实现对喷染车间VOCs质量浓度预测,结果显示预测误差较小,在可接受范围内。RF-SSA-LSTM预测模型提高了挥发性有机物质量浓度的预测精度,为减少挥发性有机物排放提供科学依据。

苹果等6种经济林不同时期果实BVOCs成分分析

为探究常见经济林树种不同时期果实在自然状态下释放植物源挥发性有机物(BVOCs)组成成分差异,并分析其香气类型,选取苹果、桃、李、梨、山楂和枣6种经济林树种为研究对象,采用动态顶空采集法收集释放的BVOCs,结合自动热脱附-气相色谱/质谱联用技术进行BVOCs分析。结果表明,6种果实膨大期和成熟期均检测出12类BVOCs,组分总数量前者(305)大于后者(275),2个时期果实释放烷烃类、烯烃类、芳香烃类、酯类和醛类BVOCs占比最大;不同时期6种果实有10种共有BVOCs为2,2,4,6,6-五甲基庚烷、正十九烷、a-柏木烯、正戊醛、庚醛、辛醛、天然壬醛、癸醛、苯乙酮和庚胺醇;苹果、桃、李和梨随着果实生长发育BVOCs成分数量减少;不同时期6种果实香韵涵盖香型有差异,并随果实生长发育,青草香、果香、檀木香、醛香和柑橘香占比明显增加。表明不同时期6种经济林植物果实释放BVOCs组成成分和相对含量差异明显,在果实成熟期,主要香气BVOCs成分相对含量较高,是果实香精开发的最佳时期。

九寨沟不同森林植被的芬多精成分及含量研究

为了解九寨沟不同森林林分芬多精的成分及相对含量,选择当地3种具有代表性的森林植被类型即油松林(Form.Pinus tabuliformis)、红桦林(Form.Betula albosinensis)和云杉林(Form.Picea asperata)作为研究对象,于2022年4—8月分别对3种森林类型的植物挥发性有机物(又称芬多精)进行采样,并带回实验室采用气相色谱-质谱成(GC/MS)联机法测定林分芬多精的成分及其相对含量,分析芬多精排放与环境因素的关系,以期为九寨沟森林养生游憩的推广和开展提供理论指导。结果表明:九寨沟林分芬多精的主要组成物质为萜烯类化合物,以云杉林含量最高,主要包括(+)-柠檬烯、α-蒎烯和莰烯,β-蒎烯偶有检出;3种林分排放的萜烯类物质相对含量与温度呈正相关,与相对湿度呈负相关。

杉木土壤酚酸物质对草珊瑚生长和品质的影响

【目的】探究杉木人工林土壤中含量较高的4种酚酸物质对草珊瑚生长和品质的化感效应,为杉木林下套种草珊瑚提供理论依据,同时为利用其化感效应指导生产提供参考。【方法】以3个月生草珊瑚为试验材料,分别施加20,40,60,80 mg/L的对羟基苯甲酸、阿魏酸、香草酸和没食子酸处理液,以清水处理为对照,探究其对草珊瑚幼苗生长(苗高增量、地径增量、地上生物量、地下生物量)、光合生理(光合色素含量、净光合速率、蒸腾速率、气孔导度、胞间CO_(2)浓度)和药用成分(异嗪皮啶、绿原酸、迷迭香酸、总黄酮)含量的影响,利用平均敏感指数、相关性分析和主成分分析进行综合评价。【结果】①与对照相比,20~60 mg/L对羟基苯甲酸、阿魏酸和没食子酸总体上对草珊瑚的苗高增量、地径增量、地上生物量、地下生物量以及异嗪皮啶、绿原酸、迷迭香酸和总黄酮单株含量表现出促进作用,而香草酸则仅在质量浓度为20~40 mg/L时表现出促进作用。②与对照相比,4种酚酸在质量浓度为20~40 mg/L时对草珊瑚叶片的净光合速率、气孔导度和蒸腾速率表现为促进作用;在20~60 mg/L时对叶绿素a、叶绿素b、总叶绿素及类胡萝卜素含量提升表现为促进作用;在质量浓度为80 mg/L时对胞间CO_(2)浓度表现为促进作用。③综合分析可知,酚酸处理下草珊瑚的光合生理指标与生长指标、药用成分之间有较强的相关性,说明在一定阈值内酚酸物质可通过增强草珊瑚植株的光合作用,进而促进草珊瑚生长及其体内药用成分的累积。【结论】4种杉木土壤酚酸物质对草珊瑚生长和品质整体呈现出低中质量浓度(20~60 mg/L)促进、高质量浓度(80 mg/L)抑制的化感效应,且20 mg/L阿魏酸、60 mg/L对羟基苯甲酸、40 mg/L的香草酸和没食子酸在促进草珊瑚生长和品质提升方面表现较优。

杉阔异龄混交模式的初步研究

为了研究不同杉阔异龄混交方式对珍贵阔叶树种生长情况的影响,通过带状混交、均匀混交和纯林3种造林方式,在国有七坡林场杉木成熟林中混交香合欢(Albiziaodoratissima)、红椿(Toonaciliata)、交趾黄檀(Dalbergia cochinchinensis Pierre)、红锥(Castanopsis hystrix)、楠木(Phoebe bournei)、金丝李(Garcinia paucinervis Chun et How)等珍贵阔叶树种,以混交后2.5年生珍贵树种的树高、胸径和单株材积为评价指标,开展杉木异龄混交珍贵树种不同模式的对比试验。结果显示:纯林模式的珍贵树种单株材积大于混交模式,其中香合欢的生长速度最快;混交模式中交趾黄檀的生长速度最快;2种混交模式中以带状混交的珍贵树种单株材积为最大,带状混交、均匀混交分别以15 m带宽、80%间伐强度的珍贵树种长势为最好。综上所述,树种选择和混交方式是影响林下复合经营短期成效的关键,短期来看,杉木林复层改造的优良树种和优良模式分别是交趾黄檀和带状混交;另外,香合欢的生长速度虽非常快,但不适合林下种植。

杉木林下药用植物淋出物对林木枯落物分解及土壤酶活性的影响

以浙江丽水松阳县杉木Cunninghamia lanceolata林林下7种常见药用植物三叶崖爬藤Tetrastigma hemsleyanum、多花黄精Polygonatum cyrtonema、蒲公英Taraxacum mongolicum、薄荷Mentha canadensis、蕺菜Houttuynia cordata、白及Bletilla striata、灵芝Ganoderma lucidum为对象,通过水浸法提取其茎叶淋出物浸提液,并将其配制成浓度为85 mg·mL^(-1)浸提液,使用喷雾器每次喷浇250 mL浸提液于培养钵中的林木枯落物,每隔2周喷浇一次,喷浇周期分别为1个月、3个月、6个月,研究药用植物淋出物对杉木枯落物分解的影响,以及通过土壤酶活性检测研究对其存在的潜在化感影响。结果表明:蒲公英、薄荷、鱼腥草浸提液对杉木枯落物处理后,其养分碳、氮、磷、钾、铜、锌、锰残余留量均有升高趋势,表明这三种植物抑制了杉木枯落物分解、延长其分解周转期,土壤酶(蔗糖酶、羧甲基纤维素酶、β-葡糖苷酶、脱氢酶、多酚氧化酶、蛋白酶、磷酸酶)活性显著降低,其他4种植物淋出物均能够显著加速分解残留物及提升土壤酶活性,因此建议杉木林下应该尽力避免种植蒲公英、薄荷、鱼腥草,同时通过降低套种密度减少药材植物的化感影响。

两个园林树种的芬多精含量及其日动态变化

植物芬多精可增强人体免疫力,抑制癌细胞生长,具有较为特殊的医学功能,同时具有一定调节血压、缓解精神障碍、降低血糖、缓解疼痛、抗痉挛的保健作用。随着近年来我国森林康养产业的迅速发展,森林芬多精的研究与开发利用日益受到学者们的重视。探究森林康养植物所释放的挥发性有机物中芬多精的组成成分、相对含量及日动态变化特征,可为森林康养活动的开展和康养时间与地点的优化选择提供参考依据。以国家级森林康养基地中两个特色的森林康养植物鸡爪槭(Acer palmatum)和肉桂茶树(Camellia sinensis)为研究对象,使用动态顶空吸附采样法(dynamic headspace collection)定时定量进行样品采集,采用Entech7200预浓缩和Agilent 7890B/5977GC-MS联用仪进行分析,鉴定鸡爪槭和茶树(肉桂)这两个特色植物VOCs中芬多精的组成成分、相对含量及日动态变化特征。结果表明:两种森林康养植物的芬多精组成成分主要以烷烃类、醇类、芳香烃类、酮类、醛类、萜烯类六种挥发性有机物为主,其中占比相对较高的为烷烃类(鸡爪槭20.6%,茶树25.92%)和芳香烃类(鸡爪槭15.26%,茶树11.93%)。2种植物芬多精的重要成分萜烯类物质的相对含量鸡爪槭较高于茶树(高出0.18%),且2种植物萜烯类相对含量均表现出相同的日变化特征,即上午8:00和下午16:00的萜烯类相对含量较高,而中午12:00的相对含量最低。因此,在森林康养基地建设和森林康养植物选择时可优先选择具体高观赏价值和较高芬多精含量的鸡爪槭,且森林康养活动开展的时间于上午8:00和下午16:00的时间段开展较为适宜。

千岛湖马尾松次生林抚育改造种群结构变化研究

为分析马尾松次生林抚育改造的林分密度、树种结构及其空间布局的动态变化,评估马尾松次生林改造成效。以千岛湖的5块马尾松天然次生林改造典型样地为研究对象,2008年在实施林分改造前布设每个30 m×30 m大小的样地,同年冬季间伐、次年春节补植,至2023年进行复位监测,调查林分改造前后样地的林分生长情况,求得树种重要值,分析直径、树高构成以及群落混交度、大小比数、角尺度等空间结构。结果表明:①千岛湖区马尾松次生中龄林间伐并补植阔叶树种,经过14年生长,林分密度提高72.88%;②林分改造后马尾松的重要值从61.308下降至26.754,同时其他常绿针叶树种重要值也同步下降,而常绿、落叶阔叶树树种均有一定程度上升,木荷、石栎的重要值提高6.81%;檵木、短柄枹之类灌木、阔叶小乔木的重要值增幅高达84.81%;③马尾松抚育补植第14年的群落直径分布特征呈“L”形,高度级个体数呈塔型,下层幼树较多,复层结构明显;④平均混交度抚育前为0.42,抚育后混交程度提高至0.72。受优势木增加且补植阔叶树生长的影响,群落的大小比数分化明显。群落的平均角尺度从抚育前的0.59下降至抚育后的0.356,由聚集分布向均匀分布转变。指出了马尾松次生林间伐并补植阔叶树种有利于改善林分结构,提高林分生产力和生物多样性,未来千岛湖马尾松次生林或将以针阔叶树种混交并与小乔木、灌木共同构建复层林方向演替为常态。

沈阳城市森林群落的树种组合选择

通过对沈阳市建成区公园树木的调查分析 ,获得各树种的综合表现排序 ,并利用Jaccard定量修正系数进行树种间关联性分析 .结果表明 ,沈阳市建成区城市森林群落的最佳树种组合为 5组 ,参考树种组合 3组 ,且选择树种与各树种的综合表现评价相一致 ;对沈阳城市森林的树种进行选择分析 ,提出沈阳城市森林的参考骨干树种和基调树种 ;分析了沈阳市建成区公园树种分布的现状 ,并提出其发展建议 .

饲料营养对林麝麝香产量和品质的影响

上海地区引种林麝取得成功后，首次进行了饲料营养对麝香产量和品质影响的研究。试验麝饲养在上海市郊崇明岛东平林场，进行分期对比试验。分别用青绿饲料、青绿饲料加低蛋白饲料、青绿饲料加高蛋白饲料、配合饲料饲喂受试麝，考察饲料营养对麝香产量和质量的影响。结果表明，饲料营养显著影响麝香产量和品质。单独饲喂青绿饲料不能满足泌香的营养需要，平均产香量３．２１ｇ，麝香色深而湿、品质差。提高营养水平后，麝香产量显著提高，品质也有所改善，其中以配合饲料效果最好。使用配合饲料不仅产香量提高，品质好，而且个体间差异小。初次泌香的一龄个体产香量达到１４．４ｇ，群体平均产量达到１３．４７５ｇ，在试验前的基础上提高３１９．７８％，分别比安徽、陕西和四川饲养群提高１４．９７％、６４．３３％和８．５８％。使用配合饲料来提高林麝麝香产量潜力很大。

松突圆蚧林间化学防治效果的研究

对6种复配化学药剂对松突圆蚧的林间防治效果进行研究。结果表明，6种复配剂中毒死蜱与杀扑磷（11：25）400～800倍液、毒死蜱与扑虱灵（11：20）400～800倍液、啶虫咪与吡虫啉（1：1）3000倍液等在林间对松突圆蚧的毒杀力较强，持续效果好。

北京西山春季侧柏游憩林内挥发物成分及其日变化规律

The research adopts open sampling method and TCT-GC/MS(Thermodesorption Cold Trap-Gas Chromatography/Mass Spectrometery) apparatus to collect and analyze the volatile organic compounds(VOCs) of Platycladus orientalis forest,with the intention of researching the compounds and diurnal variation of VOCs of P.orientalis forest in natural state in Beijing Western Hills in spring.The results are as follows:(1) There are 160 kinds(11 categories) of volatile organic compounds,containing Alkyl Hydrocarbon,Ketone,Alcohol,Acid,Aldehyde,Alkene,Ester,Aromatic hydrocarbon,Ether,Hydroxybenzene and Amide.The content of Alkyl Hydrocarbon,Ketone,Acid and Aldehyde occupy a greater percentage among all compounds.(2) The diurnal variation curve of total volatile organic compounds(TVOC) is characterized as "one peak at 11:00(36.44%) and one vale at 3:00(12.76%)".Generally,the concentration at daytime is higher than that of night,and higher in morning than in afternoon,with the maximum at noon.(3) The change of Alkyl Hydrocarbon concentration is greater in the morning and about midday,less in the afternoon and night.The diurnal variation curve of Ketone concentration appears as "three peaks and three vales".1:00,5:00—7:00 and 11:00 are peak time,3:00,9:00 and 17:00 are vale time.As to Acid,its concentration appears two obvious phases: the higher phase is from 9:00 to 17:00,with the maximum at 11:00,and the lower phase is from 19:00 to 7:00,with the minimum at 5:00.Concerning Aldehyde concentration,17:00 and 19:00 are the higher phases and also has obvious difference with other time,while the lower phrase has no obvious difference with each other.(4) Alkene is the most important compound to human health.Its concentration appears as "one peak" at 15:00,which has obvious difference with other time.Totally,its content at daytime is higher than that at night,and higher in afternoon than in morning.

桉树枝瘿姬小蜂对不同桉树品系及颜色的选择

在室内条件下,研究桉树枝瘿姬小蜂Leptocybe invasa雌成虫对不同桉树品种(系)气味及颜色的行为趋性,并在室外条件下研究了该虫对各桉树品个(系)产卵选择情况。结果表明:①桉树枝瘿姬小蜂对13个桉树品种(系)挥发性气味的趋性存在明显的差异,其中对10个品种(系)有不同程度的正趋性,尤其是对尾赤桉Eucalyptus urophylla×E.camaldulensis DH201-2的趋性最强,而对韦赤桉E.wetarensis×E.camaldulensis GL3和大花序桉E.cloeziana则表现出负趋性或不选择性;②不同色卡对桉树枝瘿姬小蜂的引诱效果差异明显,其中纯白色(RAL9010)和信号黄(RAL1003)引诱效果较好,选择系数分别为0.29和0.28;③不同桉树品种(系)上的桉树枝瘿姬小蜂产卵刻痕数明显不同,每叶平均产卵刻痕数由大到小依次为尾赤桉DH201-2,巨桉E.grandis QG3,尾巨桉E.urophylla×E.grandis DH32-29,尾叶桉E.urophylla U6,巨尾桉E.grandis×E.urophylla GL9,尾巨桉DH32-26,邓恩桉E.dunnii,尾巨桉DH32-28,尾细桉E.urophylla×E.tereticornis M1,柳桉E.saligna,巨桉JG1。其中尾赤桉DH201-2上的产卵刻痕数明显大于其他品种(系),而韦赤桉GL3和大花序桉2个品种上没有发现产卵刻痕。

不同郁闭度林茶复合模式对茶树光合日变化的影响

茶叶的产量和品质与生长环境关系非常密切,为探明林分不同郁闭度对茶树光合日变化的影响,本研究以不同郁闭度的栾树(Koelreuteria paniculata)-茶(Camellia sinensis)复合系统中茶树为材料,纯茶园为对照(CK),利用便携式LI-6400光合作用测定仪研究茶树分别在0.3(T1)、0.6(T2)和0.9(T3)郁闭度条件下的光合作用参数日变化。结果表明:随郁闭度增加,茶树光合有效辐射(PAR)和叶片温度(Tl)日均值和差值呈递减趋势,日变化呈单峰曲线;茶树净光合速率(Pn)日均值随郁闭度增加呈递减趋势,均表现双峰型曲线;CK和T1的蒸腾速率(Tr)和气孔导度(Gs)日变化午间受到明显的抑制且呈双峰曲线,T2和T3呈单峰型曲线。

太行山核桃林药材间作试验

太行山核桃林分布广泛,林下土地空闲率高,光照条件良好,适宜间种多种经济作物,林药间作成为理想的经营模式。为了筛选适宜的药材种类,引进射干、知母、桔梗、菊花、瓜蒌、天南星、黄芩、荆芥、土贝母、土木香和丹参共11种中药材,在河北省涉县索堡乡南沟村的核桃林地进行了间种栽培试验,对其生物生态学习性和物候期进行了调查与分析,并针对引种地春季干旱的气候条件,以降低核桃与药材间的竞争强度和提高林地收益为目标,选择育苗难易程度、抗旱性、株高、根系分布深度和经济效益这5项指标进行了综合评价。结果表明：土贝母、知母、菊花、射干、桔梗这5种药材适宜在核桃结果初期（核桃树龄为10~12 a）间种,而荆芥、丹参、土木香这3种药材适宜在核桃幼树期（核桃树龄为3~4 a）种植。

乔木在城市森林建设中的重要作用

城市森林对光、热、气、水、土等生态因子具有重要的调节作用,对城市的生态环境保护起着不可替代的作用。目前,我国城区生态建设所使用的树种普遍比较单一,造成城市绿化景观的单调。在城市森林建设中,要重构人与自然的关系,按照复合生态系统理论,以人为本,林水结合。选择城市乔木树种时,要按照适地适树的原则,尽可能应用乡土及野生树种,利用乔木尽快占领城镇空间,保证生态环境安全。提高枝下高到8m左右,就可营造出夏天降温,冬天充分享受阳光的公共场所。在城区广场的绿化中,要引入一些高大乔木,形成巨大的伞状树冠,以乔木为主组成乔、灌、藤、草结合的近似天然林,充分向空间要生态效益,是一条行之有效的捷径,还要增加攀缘植物的绿化比重。攀缘植物有较强的适应性、耐旱性和吸附攀缘能力,不仅是荒漠化土地、荒山、沟壑恢复植被的先锋植物,而且也是城市绿化、桥梁美化、道路护坡的优良绿化植物。