中国介质蝴蝶兰输美检疫监管工作初探

介质种苗的检疫问题一直以来是该产品的出口瓶颈,美国一直都限制携带介质的种苗直接输入境。但随着《中国介质兰花输往美国工作计划》及相关法案的发布,中国大陆介质兰花输往美国有望在近期成为现实。本文分析了介质蝴蝶兰出口存在的检疫风险、中美双方存在的监管差异,并提出措施以帮助我国出口企业顺利打开美国市场。     

生物炭改良林地土壤研究进展

中国是世界上人工林面积最大的国家,同时也是林地土壤质量退化最为严峻的国家。如何减缓人工林地力衰退和维持人工林长期生产力等问题,已成为当今中国乃至世界林业科学最为关注的话题。近年来生物炭作为一种新型有效的土壤改良剂被世界各国广泛研究和利用,然而目前对生物炭的土壤改良作用研究多限于农地土壤,对林地土壤改良的综述性报道还不多见。文中从生物炭影响土壤物理学、化学及生物学特性等方面综述了生物炭在改良农林地土壤方面的研究进展,提出了生物炭研究存在的问题及今后的研究方向,以期为生物炭在农业及林地的应用提供理论参考,为改进传统的森林经营措施和实现人工林可持续经营提供借鉴。     

栽培密度与穴栽苗数对水稻产量的影响

采用不同栽培密度与穴栽苗数对水稻产量的影响进行研究。结果表明,不同栽培密度与穴栽苗数对水稻产量均存在极显著影响,咸宁市水稻种植采用宽窄行,即宽行30.00 cm、窄行16.67 cm、株距16.67 cm,密度为25.8万穴/hm2,每穴栽插2粒谷苗产量最高,达10 588.7 kg/hm2。     

Validation of an efficient visual method for estimating leaf area index in clonal Eucalyptus plantations

Leaf area index (LAI) is a key ecophysiological parameter in forest stands because it characterises the interface between atmospheric processes and plant physiology. Several indirect methods for estimating LAI have been developed. However, these methods have limitations that can affect the estimates. This study aimed to evaluate the accuracy and applicability of a visual method for estimating LAI in clonal Eucalyptus grandis × E. urophylla plantations and to compare it with hemispherical photography, ceptometer and LAI-2000^® estimates. Destructive sampling for direct determination of the actual LAI was performed in 22 plots at two geographical locations in Brazil. Actual LAI values were then used to develop a field guide with photographic images representing an LAI range of 1.0–5.0 m² m^?2 (leaf area/ground area). The visual LAI estimation guide was evaluated with 17 observers in the field. The average difference between actual LAI and visual LAI estimation was 12% and the absolute difference between the two methods was less than or equal to 0.5 m² m^?2 in 77% of plots. Pearson’s correlation coefficients were high between actual LAI and hemispherical photographs (0.8), visual estimation (0.93) and LAI-2000^® (0.99) and low for the ceptometer (0.18). However, absolute values differed among methods, with the average difference between the actual and estimated LAI of [12]% for visual estimation, 28% for the LAI-2000^®, 37% for the ceptometer and ?43% for hemispherical photographs. The LAI-2000^® and ceptometer overestimated LAI in all plots, whereas hemispherical photographs underestimated the values in all measurements, showing that these methods need calibration to be used. No differences were observed between actual LAI and visual estimates across stand ages of 2–8 years and LAI of 1.5–5.3 m² m^?2 (P > 0.05). The results show that visual estimation of LAI in Eucalyptus stands is a practical method that is unaffected by atmospheric characteristics and can be used on an operational scale.     

7种杀菌剂和避雨栽培对林下三七圆斑病的防治效果

圆斑病是三七生产上的一种重要毁灭性病害,为筛选防治三七圆斑病的有效防治措施,本研究评估分析了7种杀菌剂和避雨培栽对林下三七圆斑病防治效果估。结果显示,10%苯醚甲环唑水分散粒剂1500倍、430克/升戊唑醇悬浮剂4000倍、400克/升氟硅唑乳油8000倍、450克/升咪鲜胺乳油1500倍、80%代森锰锌可湿性粉剂600倍、60%唑醚.代森联水分散粒剂1000倍和30%肟菌.戊唑醇悬浮剂1000倍防治效果分别为89.26%、87.26%、86.30%、87.82%、78.80%、81.58%和85.66%,10%苯醚甲环唑水分散粒剂1500倍的防治效果最好,避雨栽培的防治效果最高可达86.66%,7种杀菌剂和避雨栽培对三七圆斑病均有不同程度的防治效果,对三七生长无不良影响,在生产上可以推广使用,研究结果为三七病害的有效防治奠定了科学基础。     

Effects of converting natural grasslands into planted grasslands on ecosystem respiration: a case study in Inner Mongolia,China

With increasingly intensifying degradation of natural grasslands and rapidly increasing demand of high quality forages, natural grasslands in China have been converted into planted grasslands at an unprecedented rate and the magnitude of the conversion in Inner Mongolia is among the national highest where the areal extent of planted grasslands ranks the second in China. Such land-use changes(i.e., converting natural grasslands into planted grasslands) can significantly affect carbon stocks and carbon emissions in grassland ecosystems. In this study, we analyzed the effects of converting natural grasslands into planted grasslands(including Medicago sativa, Elymus cylindricus, and M. sativa+E. cylindricus) on ecosystem respiration(F_(eco)) in Inner Mongolia of China. Diurnal F_(eco) and its components(i.e., total soil respiration(F_(ts)), soil heterotrophic respiration(F_(sh)) and vegetation autotrophic respiration(F_(va))) were measured in 2012(27 July to 5 August) and 2013(18 July to 25 July) in the natural and planted grasslands. Meteorological data, aboveground vegetation data and soil data were simultaneously collected to analyze the relationships between respiration fluxes and environmental factors in those grasslands. In 2012, the daily mean F_(eco) in the M. sativa grassland was higher than that in the natural grassland, and the daily mean F_(va) was higher in all planted grasslands(i.e., M. sativa, E. cylindricus, and M. sativa+E. cylindricus) than in the natural grassland. In contrast, the daily mean F_(ts) and F_(sh) were lower in all planted grasslands than in the natural grassland. In 2013, the daily mean F_(eco), F_(ts) and F_(va) in all planted grasslands were higher than those in the natural grassland, and the daily mean F_(sh) in the M. sativa+E. cylindricus grassland was higher than that in the natural grassland. The two-year experimental results suggested that the conversion of natural grasslands into planted grasslands can generally increase the F_(eco) and the increase in F_(eco) is more pronounced when the plantation becomes more mature. The results also indicated that F_(sh) contributed more to F_(eco) in the natural grassland whereas F_(va) contributed more to F_(eco) in the planted grasslands. The regression analyses show that climate factors(air temperature and relative humidity) and soil properties(soil organic matter, soil temperature, and soil moisture) strongly affected respiration fluxes in all grasslands. However, our observation period was admittedly too short. To fully understand the effects of such land-use changes(i.e., converting natural grasslands into planted grasslands) on respiration fluxes, longer-term observations are badly needed.     

祁连山西水林区灌木林降雨截留特征

基于2014年5—9月的野外试验数据,采用野外观测与统计分析相结合方法,研究了祁连山排露沟流域5种典型灌丛:吉拉柳(Salix gilashanica)、箭叶锦鸡儿(Caragana jubata)、金露梅(Potentilla fruticosa)、鲜黄小檗(Berberis diaphana)和甘青锦鸡儿(Caragana tangutica)灌丛降雨截留特征,分析了降雨量对灌丛穿透雨量和截留量的影响。结果表明:研究期间共观测到降雨40次,年降雨总量为292.4mm,其中2~10mm的降雨事件出现次数最多;5种灌丛穿透雨量、截留量分别为吉拉柳灌丛183.5,108.9 mm;甘青锦鸡儿灌丛174.3,73.5 mm;箭叶锦鸡儿灌丛168.8,123.6mm;金露梅灌丛166.1,106.4mm;鲜黄小檗灌丛165.7,82.1mm;5种灌丛穿透雨量和截留量与降雨量均呈显著线性正相关(p0.001);而穿透率和截留率与降雨量均以对数函数拟合较好(p0.001)。     

晋北丘陵风沙区不同植被恢复模式的土壤化学特征与生态恢复效应

通过对山西省右玉县从高家堡乡至右卫镇的公路两侧乔木林(小叶杨、樟子松、油松和华北落叶松)、灌木丛(沙棘、柠条和乌柳)及各种乔木、乔灌混交林的土壤化学特征分析,评价了乔、灌恢复模式的生态恢复效应。结果表明:(1)不同植被恢复模式的生态恢复效应差异显著,混交林生态恢复效果优于纯林;(2)灌木沙棘、柠条、乌柳在本区生态恢复中的作用突出,特别是豆科植物柠条的生态恢复效果优于其他非豆科植物;(3)乔木种樟子松、油松,灌木种沙棘、柠条、乌柳耐旱、耐寒,生态适应性强,在本区生态修复中作用明显,可用于本区人工植被恢复的植被重建优先物种;(4)本区土壤洁净,适宜发展有机农业。     

不同砧木对日光温室秋冬茬嫁接西瓜产量品质及叶绿素荧光特性的影响

为筛选适宜日光温室秋冬茬嫁接西瓜生产的耐低温弱光砧木品种,试验采用7种不同类型西瓜嫁接砧木与设施西瓜主栽品种‘华铃’嫁接,研究不同砧木对日光温室秋冬茬嫁接西瓜产量、品质及叶绿素荧光特性影响。通过隶属函数综合评价不同砧木嫁接西瓜产量及果实品质,发现以葫芦型砧木‘甬砧5号’嫁接后西瓜坐果最早,产量最高,达2 660.2 kg·667m~(-2),中心糖及边糖含量最高,综合表现最佳。分析7种砧木接穗叶片叶绿素荧光参数发现,以‘甬砧5号’为砧木接穗叶片光合原初反应激发能分配最优,非光化学淬灭最少,在秋冬茬低温弱光逆境下叶片光化学效率最高。综上所述,‘甬砧5号’砧木在秋冬茬日光温室嫁接西瓜坐果性、果实品质、产量及植株叶绿素荧光特性等方面表现最佳,更适合作为日光温室秋冬茬西瓜嫁接砧木。     

长沙市城乡交错带4种人工林土壤养分及其相关性研究

以长沙市城乡交错带4种人工林为研究对象,对各林分林下土壤理化性质进行比较分析,揭示了土壤养分间的相互关系,结果表明:土壤物理性质指标垂直分布规律明显,同一林分内土壤容重基本上随土层深度增加而增大,毛管孔隙度、总孔隙度和自然含水率相反;土壤容重与毛管孔隙度、总孔隙度呈极显著的负相关(P<0.01),与自然含水率呈显著的负相关(P<0.05);毛管孔隙度与总孔隙度呈极显著的正相关(r=0.943,P<0.01);自然含水率与总孔隙度呈显著正相关(P<0.05),与毛管孔隙度呈极显著正相关(r=0.815,P<0.01);各林分内不同土层土壤各化学性质指标垂直分布规律明显,基本上随土层深度增加而减小;土壤pH值与土壤养分因子的相关系数值均为负数,与速效氮含量显著负相关(r=-0.661,P<0.05),土壤有机质与全氮、全磷、全钾、速效钾含量相关性显著(P<0.05),与速效氮呈极显著正相关(r=0.760,P<0.01);土壤全量养分与有效养分间均呈显著的正相关。