危害沙棘的围连环夜蛾生物学特性及防治

围连环夜蛾在我国多有分布，但看见其幼虫的还是很少，因资料中寄主不祥，笔者经室内外观察。发现其危害多种植物的叶片，更喜欢危害沙棘树的叶片，笔者经2a的室内外观察得知。其生物学特性在辽宁西部每年1代，以蛹越夏及冬。对沙棘树危害较重，对栽植的大果沙棘危害尤为严重，在5a生的沙棘树上有100多头幼虫危害，成虫善飞翔。     

“大树进城”为何刹而不止？——兼谈加强树木采挖移植管理的政策措施

概述了“大树进城”之风形成的背景，对“大树进城”的弊端与危害进行了归纳，分析了“大树进城”之风难以遏止的原因，提出了“控两头、掐中间”、多管齐下、综合治理的基本思路和具体措施。     

刈割次数对林下黑麦草产量与品质的影响

林下种草养禽是一种复合型生态农业模式,为了优化林下牧草的刈割方式,获得较高产量的优质牧草。以林下黑麦草为试验材料,设置不同刈割次数处理(1、2、3、4、5次),比较不同刈割次数对其生长性状、干物质累积、产量和品质的影响。结果表明:刈割4次处理,林下黑麦草鲜草和干草产量最高,分别为86.53 t/hm~2和11.83 t/hm~2,刈割5次处理,鲜草和干草产量分别下降10.27%和7.79%。随着刈割次数的增加,林下黑麦草粗蛋白、粗脂肪和粗灰分等营养成分含量有上升趋势,粗纤维含量有下降趋势。另外,各处理以第2茬和第3茬黑麦草干草产量和品质较高。与非林下黑麦草比较,林下黑麦草产量和品质稍有下降。本试验条件下,林下黑麦草刈割4次可兼顾高产与优质,并且适当延长第2茬和第3茬生长时间,有利于产量和品质提高。     

香港行道树管理优化探讨

结合实际情况，分析香港市区行道树安全管理在综合管理措施、规划设计建设、种植养护技术等方面存在的不足，其管理观念及技术已经不符合当前绿化生态的理念及发展。继而针对性提出健全管理机构、优化技术措施、加强各部门的宏观协作等建议。     

层次分析法在庆阳市行道树选择中的应用

结合庆阳市立地条件与能源化工基地建设,运用层次分析法构建了庆阳市行道树综合评价体系,进行定性与定量相结合评价。评价结果表明,在庆阳市行道树的选择中以生态效益较好的法国梧桐、臭椿、银杏、国槐、桑树等为主,以常绿针叶树种侧柏、刺柏等为辅。     

不同林龄杉木林下套种阔叶树对土壤磷组分的影响

套种是杉木人工林经营的重要措施,磷是南方森林生态系统中主要限制性养分元素之一,但套种模式对土壤磷素的影响尚不明确。以亚热带杉木人工林表层(0-10 cm)土壤为对象,研究套种林(杉阔套种幼林、杉阔套种成熟林)和杉木幼林土壤理化性质和土壤各形态磷含量差异,分析套种对杉木人工林土壤磷含量的影响。结果表明:(1)不同套种林显著改变土壤总磷、土壤总无机磷、土壤总有机磷、土壤微生物生物量磷(MBP)和土壤酸性磷酸酶活性(APA),大小顺序均为杉阔套种成熟林>杉阔套种幼林>杉木幼林。(2)土壤各磷组分中活性磷含量较低,其中NaHCO3-Po在活性组分中占主导;土壤NaOH-Po是中等活性磷的主要组分,杉阔套种成熟林尤为显著;闭蓄态磷(Residual-P)在总磷含量中最高。(3)与杉木幼林相比,杉阔套种成熟林显著增加了树脂提取态磷(Resin-Pi)、碳酸氢钠提取态有机和无机磷(NaHCO3-Pi、NaHCO3-Po)、氢氧化钠提取态有机和无机磷(NaOH-Pi、NaOH-Po)、氢氧化钠残留提取态有机磷(NaOHu.s-Po)、盐酸提取态磷(HCl-Pi)和闭蓄态磷(Residual-P)含量;土壤总无机磷、NaHCO3-Po、HCl-Pi、NaHCO3-Pi、NaOHu.s-Pi和Residual-P对杉阔套种幼林的响应不敏感。(4)除含水率外不同林龄下杉阔套种林土壤磷形态与土壤理化性质(土壤总碳氮、土壤可溶性有机氮、土壤微生物生物量磷、酸性磷酸酶)呈正相关性(P<0.05)。冗余分析表明,土壤磷组分的变化主要受MBP调控,且MBP与有机磷组分(NaOHu.s-Po、NaOH-Po)和HCI-Pi呈显著正相关。总之,套种林的土壤磷素有效性高于杉木幼林,土壤养分状况更佳。     

Diets of endangered silver chub (Macrhybopsis storeriana,Kirtland, 1844) in Lake Erie and implications for recovery

Silver chub (Macrhybopsis storeriana, Kirtland, 1844) is a native Cyprinid in Lake Erie, one of the Laurentian Great Lakes of North America. It is listed as endangered by the US state of New York and Canada, which has a recovery plan, and as special concern by the state of Michigan. Silver chub faces a potential threat to recovery from control efforts for invasive Grass carp (Ctenopharyngodon idella, Valenciennes 1844). Among the knowledge gaps for protection and restoration is current diet data. I describe the diet of silver chub from western Lake Erie in 2014, and I compare it to past studies to assess changes in diet through time. Silver chub captured in bottom trawls May–September 2014 were frozen in the field, and stomach contents were preserved in ethanol. Diet taxa were identified to the lowest practical taxonomic unit, then dried and weighed. Frequency of occurrence in silver chub diets was highest for Hexagenia spp. mayflies (79%). Dreissena spp. and Hexagenia spp. were both 41% of the diet by dry weight. Analysis of δ¹³C isotopes identified Hexagenia spp. as the primary source of carbon in silver chub. Compared to past studies, Dreissena spp. have mostly replaced Sphaeriidae and Gastropoda in silver chub diets. There also have been seasonal shifts in relative amounts of shelled organisms and Hexagenia spp. This study and past research suggest a functional link between silver chub and Hexagenia spp. abundance. Maintenance and recovery of silver chub may be dependent on maintaining Hexagenia spp. populations.     

日本落叶松与天然萌芽阔叶树人工混交培育效果的分析

通过对日本落叶松与天然萌生阔叶树人工混交林的调查分析,结果表明:日本落叶松与天然萌芽阔叶树人工混交培育降低了培育成本,提高了生态效益,混交林培育28a后,林分生长稳定,生产力较高;混交林中的植物种类丰富,数量较多,各层次的物种多样性指数均好于人工营造的日本落叶松与白桦针阔混交林和日本落叶松纯林;日本落叶松与天然萌生阔叶树人工混交林,对恢复森林生态原始林貌有一定促进作用。     

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...     

Effects of arrangement of surge-rootirrigation emitters on growth,yield andwater use efficiency of apple trees

Six-year old apple trees were selected for field experiment. The objective of this study was to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards. There were three factors: the buried depth H( 25,40,55 cm),the horizontal distance L( 30,40,60 cm) between the emitters and the trunk of the experimental tree,and the number of the irrigation emitters N( 1,2,4). The effect of the arrangement of surge-root irrigation emitters on the growth,yield and irrigation water use efficiency( IWUE) of apple trees were studied in Northern Shaanxi where the irrigation quota takes 60%-75% of the field water capacity. The results showed that the arrangement of emitters for surge-root irrigation had a significant effect on apple tree yield and IWUE,especially,the yield and IWUE reached 28 388. 17 kg/hm2 and 16. 83 kg/m3 in treatment T3,respectively. At the same L and N levels( T1,T2,and T3),the yield and IWUE in treatment T3 were the highest,and the yields in treatments T1 and T2 were decreased by 26.22% and 31.48%,while IWUE is reduced by14.02% and 18.12% compared with T3,respectively. At the same H and N levels( T3,T4,and T5),the yield and IWUE of apple trees were decreased with increasing L level. Especially,when L was 30 cm( T3),the yield and IWUE were the highest. The same L and H levels( T3,T6,and T7) could promote the growth of apple trees when N was 2( T3). Compared with treatment T3,it was found that the increment of new shoots was decreased by 8.07%-18.71%,and the fruit diameter was decreased by 5.41%-9.11%. Therefore,two emitters should be arranged symmetrically on both sides of an apple tree,each was buried at a 40 cm depth and 30 cm away from the trunk of the tree to effectively improve the yield and IWUE of the apple tree in mountainous areas in Northern Shaanxi.