春天防止君子兰烂根

春天防止君子兰烂根春季是君子兰生长旺盛季节，但是由于水肥管理不当很容易出现烂根现象，究其原因主要以下几个。一是水浇大了。不论是小苗还是大花，水都不能浇过量，水一大，温度一高，通风再不良，君子兰肯定要烂根。二是土太生。不论是用腐叶土不是马粪土、草炭土配...     

不同栽培基质对辣木农艺性状的影响

对草炭、河沙、谷壳不同配比的栽培基质,以土壤为对照进行辣木栽培试验,结果表明,基质栽培对辣木农艺性状的影响优于对照,其中草炭∶河沙∶谷壳为3∶1∶1的基质处理,鲜叶产量极显著高于其它处理和对照,比对照增产67.34%。     

芍药促成栽培品种对比试验

选择13个芍药品种进行促花栽培;并以大富贵芍药为试材,进行了不同栽培基质试验,不同容器试验,不同浓度生根粉浸根试验及不同浓度抑制剂施用试验。结果表明:芍药适宜盆花促成栽培的品种有:大富贵、莲台、白玉冰、铁杆紫、金带围。适宜的栽培基质是草炭土+珍珠岩,容器是窗纱网袋+周转箱。合理的生根粉浸根浓度为0.005%。以前期每株根施2g多效唑,后期喷施0.015%的多效唑或缩节胺控制株型效果最好。     

不同配方基质对绿巨人生长的影响

选择松树皮、花生壳、污泥和丹麦草炭为原料复配,栽培绿巨人幼苗,分析不同配方基质对绿巨人生长的影响。结果表明:树皮和丹麦草炭的复配基质更适于栽培绿巨人,花生壳也是绿巨人适宜栽培基质原料之一。试验中绿巨人最佳栽培基质为草炭50%+树皮50%,栽培8个月后与纯丹麦草炭相比,株高增加22.1%,冠幅增加19.6%,平均叶面积增大34.6%,叶片数相当。     

赏食兼用型盆栽草莓无土栽培方法研究初报

以"燕香"草莓品种为试验材料,通过营养液浇灌和基质栽培两种模式,探究赏食兼用型盆栽草莓的栽培技术,结果表明:从食用性和观赏性两方面综合考虑,以河沙+蛭石为固定基质并使用山崎草莓专用配方的营养液循环浇灌为较佳的营养液栽培模式,以进口泥炭+蛭石+珍珠岩为栽培基质并施以复合肥为较佳的基质栽培模式。     

杜促移植茵纵劈繁殖法

杜仲以实生繁殖为主，但种子紧缺已成为育苗户共同焦虑的问题。在杜仲育苗生产上，根颈粗度在0.7cm以下的小苗常常需要留囿移植，继续培育，年后方可造森。西北林学院马惠玲等于1992年对杜促小苗进行了纵劈繁殖试验。     

菇类的覆土栽培技术

菇类的覆土栽培技术那崇贵，金若忠（东港市林场１１８３００）（辽宁省林科院）菇类的覆土栽培技术多指双孢菇（Ａｇａｒｉｃｕｓｂｒａｎｎｅｓｃｅｎｓ）等菇类，在栽培过程中，为保护菌丝体在基质中顺利生长，于基质表面覆盖一层湿上材料（或草炭等）的栽培技术．因菌...     

杜仲移植苗纵劈繁殖法

<正> 杜仲以实生繁殖为主,但种子紧缺已成为育苗户共同焦虑的问题。在杜仲育苗生产上,根颈粗度在0.7cm以下的小苗常常需要留移植,继续培育,年后方可造林。西北林学院马惠玲等于1992年对杜仲小苗进行了纵劈繁殖试验。     

不同栽培基质对鼠尾草扦插繁殖的影响

用园土、园土+有机肥、草炭+蛭石、草炭+沙子等4种材料为试验栽培基质,观察它们对鼠尾草扦插繁殖的影响。结果表明:园土处理的植株现蕾、开花时间均比其它基质处理的延迟,花朵凋谢的时间与之相反,其余处理的植株现蕾、开花、花朵凋谢的时间差别不大。不同基质处理间的植株成活率没有差异。在开花期,园土处理的株高、花序长度、花梗长度、叶片长度、叶片宽度都比其它处理的小,叶片数也比其它处理的少,其它处理的花序长度、叶片数、叶片长度、叶片宽度之间没有显著差异。植株鲜重、干重以园土+有机肥处理的最大,园土处理的最小。可见园土+有机肥、草炭+蛭石、草炭+沙子的混合基质都可用于鼠尾草的扦插繁殖生产。     

树皮替代草炭对鸟巢蕨生长的影响

为了探索树皮替代草炭栽培鸟巢蕨的可行性,选择树皮与丹麦草炭的复配基质进行鸟巢蕨盆栽试验,以100％泥炭处理为对照,分析不同配方基质物理性状及其对鸟巢蕨的株高、冠幅、叶片数以及叶面积的影响.结果表明:草炭与树皮按一定比例复配后的基质密度、孔隙度、持水力介于两者之间,其栽培鸟巢蕨优于或接近单一使用草炭的效果,最佳配比为草炭80％+树皮20％,上盆8个月后,比使用纯草炭的株高增加4.5％,叶片数增加8.6％.     

Beobachtungen zu einer Schlaffsuchterkrankung der Fichtengespinstblattwespe,Lyda hypotrophica Htg. (Cephaleia abietis L.) im Latenzstadium und während der Fraßperiode in den Kronen

Zusammenfassung Beobachtungen von Kalamit?ten der FichtengespinstblattwespeLyda hypotrophica Htg. (Cephaleia abietis L.) in den letℨten beiden Jahrzehnten in ?sterreich ergaben unter den biotischen Faktoren des Umweltwiderstandes auch das Aufscheinen einer Kernpolyedrose, die vor allem das Fettgewebe, teilweise aber auch das Mitteldarmgewebe ergriff. Die Bedeutung der Erkrankung lag vor allem in den nun erstmalig festgestellten epidemischen Ausbrüchen w?hrend der Fra?periode der Afterraupen in den Kronen. Es wurden dadurch Fra? sch?den weitgehend gemildert und das Abbaumen zahlreicherer vollentwickelter Larven zu den B?den verhindiert. Die reduzierende Wirkung der Erkrankung auf die Latenzlarven in den B?den war von geringerer Bedeutung; sie lag nach vorgenommenen Probegrabungen zwischen 0 und 27%.

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Summary Observations on an atony disease of the false spruce webworm,Lyda hypotrophica Htg. (Cephaleia abietis L.) in the stage of latency and during its feeding period in tree crowns. Observations on outbreaks of the false spruce webwormLyda hypertrophica Htg. (Cephaleia abietis L.) during the last two decades in Austria revealed, among biotic factors of environmental resistance, the occurrence of a nuclear polyhedrosis attacking mainly the fatty tissue but partly also the mesenteric tissue. The importance of the disease consisted chiefly in epidemie outbreaks during the larvae's (pseudo-caterpillars') feeding period in the tree-crowns. Damages by the larvae's feeding were greatly reduced by this way, and the descent of numerous larvae from trees to the ground prevented. The reducing effect of the disease on larvae in the stage of latency (diapausis) in soils was of less importance varying between 0% and 27% in sample diggings.

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Résumé Observations sur une atonie de Lyda Hypotrophica Htg. (Cephaleia abietis L.)en diapause et pendant la periode de pature dans les cimes d'arbres. Les observations sur des gradations deLyda hypertrophica Htg. (Cephaleia abietis L.) pendant les deux dernières décennies en Autriche ont révélé, parmi les facteurs biotique de la résistance ambiante, l'apparition d'une polyédrose nucléaire attaquant avant tout le tissu adipeux, mais encore en partie le tissu mésentérique. L'importance de la maladie consistait avant tout en irruptions épidémiques pendant le période de pature des larves (pseudochenilles) dans les cimes d'arbres. Les dégata par pature en furent considérablement modérés et la descente par terre de nombreuses larves vivant sur les arbres fut empêchée. L'éffet réduisant de la maladie sur les larves en diapause dans les sols était de moindre importance, avec une variation entre 0% et 27% dans les déterrements d'échantillonnage.

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Резюме Наблюдения на заб олевании от атони и слового пилильщика — ткач а (Lyda hypotrophica Htg. [Cephaleia abietis L.]) в диапаузе и в п ериод поедания в к ронах. Доцент Др. Эльза Ян Наблюдения на гра дациях слового пи лильщикаткача Lyda hypertrophica Htg. (Cephaleia abietis L.) в последние два де сятиетия в Австри и показали между биотически ми факторами отпо ра внешной среды и появление ядрового полиэдр оза, поражавлиего прежде всего жирн ую ткань, но частич но и средне кишечную т кань (mesenteron). Значение заболевания сост ояло прежде всего в эпидемических в спышках во время п ериода поедания личинок (ложных гу сениц) в кронах. Так им образом повреж дения от поедания были значительно умерены, а спуску м ногочисленных ли чинок от деревьев на землю было поставлено п репяствие. Уменьшительное д ействие заболева ния на личинок в ди апаузе в почвах бы ло более незначит ельно, колебаясь по испо лненным пробным в ыкопаниям между 0 и 27%.

     

Die Tannenwickler

Summary In Central Poland in Saint Cross Mountains (Góry Swiętokrzyskie) from 1948 takes place a mass appearance of fir budwormChoristoneura murinana Hb. on the area of 2168 ha (8700 acres). Morever it accures over thereErnarmonia (Zeiraphera) rufinitrana HS,Eucosma (Epiblema) nigricana HS and others. The author performed from 1957 detailed investigations concerning these pests. In the present paper he discussed history of present attacks of the pests in Poland, as well as causes of mass appearance and economic significance of damages, listed species of accompanying insects as well as methods of prognosis. On the area of mass appearance the author conducted investigations concerning biology and ecology of the pests, inquired conditions of development of mass increase and experiments of chemical and biological fight. On this area there are conducted also pedological, typological, phenological and biometric studies. The task of these studies is to explain the causes of rise of mass appearance of these insects and elaboration of preventing means.

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Résumé Dans le territoire de la Pologne Centrale sur le terrain des Monts Sainte Croix a lieu à partir de l'année 1948 la gradation (apparition en masse) de la tordeuse du sapin(Choristoneura murinana Hb.) sur la surface de 2168 hectares. L'Ernarmonia (Zeiraphera) rufimitrana H. S., l'Eucosma (Epiblema) nigricana H. S. et autres y paraissent aussi. A partir du 1957 l'auteur conduit des recherches détaillées sur ce nuisible insecte. Il a discute dans un article l'histoire des gradations précédentes de ces insectes en Pologne, causes des origines des gradations, importance économique par rapport aux dommages occasionnés, ainsi que les espéces des insectes accompagnat les tordeuses du sapin et les méthodes de la prognose. Dans les terrains de la gradation l'auteur fait des observations concernant la biologie et l'écologie des insectes précites, explore les conditions des origines des gradations, fait des expériments de la lutte chimique pour les détruire complètement. On y conduit aussi des études du sol, ainsi que les études typologiques, biometriques, fénologiques et autres. Ces études ont pour but de pouvoir approfondir les causes d'origine des gradations ainsi que l'élaboration des mesures préventives.

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Краткое содерж ание В сре дней Польше, на терри тории Свенто кшиских гор, имеет место, начин ая с 1948 г. массовое появление пихтовых листо верток, выступа ющих на площади 2168 га. Главным вредителем являетсяChoristoneura murinana Hb. — Кроме того появляютсяErnarmonia (Zeiraphera) rufimitrana H. S.,Eucosma (Epiblema) nigricana H. S. и другие. Автор ведет с 1957 г. подробнье иссле дования этих вре дителей. В своей статье даетист ориюпоя влений в Польше этих вредителей, имевших место до того времени, причины возникн овениям ассовых появлений, хозяйст венное значение причинен ныхубытков, роды насек омых, сопутст вующихл истоверткам, равно как метод прогноза ихпоявления. Автор ведет на террит ории массовото появления вредителей наблюдения над биологией и экологиейв редителей, изучает усл овия возникнове ниямассовых появлений, ведет опыты над химическойи биологи ческой борьбой с ними. На месте проводятся одновре менно исследо ванияпочвы, типологи ческие, биометри ческие, фенолог ическиеи другие испытания. Все привед енныеиспы тания имеют целью определить причинывоз никновения массовых появлений вредителейи разработать предохранит ельные меры. —

     

Gas exchange responses of <Emphasis Type="Italic">Eucalyptus</Emphasis>, <Emphasis Type="Italic">C. africana</Emphasis> and <Emphasis Type="Italic">G. robusta</Emphasis> to varying soil moisture content in semi-arid (Thika) Kenya

A dramatic decline in forest cover in eastern Africa along with a growing population means that timber and poles for building and fuelwood are in short supply. To overcome this shortage, the region is increasingly turning to eucalyptus. But eucalyptus raises environmental concerns of its own. Fears that it will deplete water supply, affect wildlife and reduce associated crop yields have caused many countries in the region to discourage farmers from planting this exotic. This paper is part of a series of investigations on the growth and water use efficiency of faster growing eucalyptus hybrids, which was introduced from South Africa to Kenya. The hypothesis is that the new hybrids are more efficient in using water and more suitable for the semi-arid tropics than existing eucalyptus and two popular agroforestry species. Gas exchange characteristics of juvenile Eucalyptus grandis (W. Hill ex Maiden), two eucalyptus hybrids (E. grandis × Eucalyptus camaldulensis Dehnh.), Grevillea robusta (A. Cunn) and Cordia africana (Lam) was studied under field and pot conditions using an infrared gas analyzer was used to measure photosynthetic active radiation (PAR), net photosynthetic rate (A), stomatal conductance (g _s) and transpiration rate (E) at CO₂ concentrations of 360 μmol mol⁻¹ and ambient humidity and temperature. A, E and g _s varied between species, being highest in eucalyptus hybrid GC 15 (24.6 μmol m⁻² s⁻¹) compared to eucalyptus hybrid GC 584 (21.0 μmol m⁻² s⁻¹), E. grandis (19.2 μmol m⁻² s⁻¹), C. africana (17.7 μmol m⁻² s⁻¹) and G. robusta (11.1 μmol m⁻² s⁻¹). C. africana exhibited high E values (7.0 mmol m⁻² s⁻¹) at optimal soil moisture contents than G. robusta (3.9 mmol m⁻² s⁻¹) and eucalyptus (5.3 mmol m⁻² s⁻¹) in field experiment and G. robusta (3.2 mmol m⁻² s⁻¹) and eucalyptus (4.2 mmol m⁻² s⁻¹) in pot-grown trees. At very low soil moisture content, extremely small g _s values were recorded in GC 15 and E. grandis (8 mmol m⁻² s⁻¹) and G. robusta (14 mmol m⁻² s⁻¹) compared to GC 584 (46.9 mmol m⁻² s⁻¹) and C. africana (90.0 mmol m⁻² s⁻¹) indicating strong stomatal control by the species. Instantaneous water use efficiency ranged between 3 and 5 μmol mmol⁻¹ and generally decreased with decline in soil moisture in pot-grown trees but increased with declining soil moisture in field-grown trees.     

Gegenwärtige Hauptprobleme der landwirtschaftlichen Schädlingsforschung in Finnland

Zusammenfassung Einige der wichtigsten gegenwärtigen Probleme hinsichtlich der landwirtschaftlichen Schädlinge in Finnland sind folgende:Bei Getreide die Schäden durchCalligypona pellucida am Hafer sowie die Schäden durch die Fritfliege(Oscinella frit) an Saat von Winter- und Sommergetreide, die durch Blasenfüßer(Thysanoptera) u. a. Arten verursachte Weißährigkeit und Schmachtkörnigkeit, deren Bekämpfung noch nicht befriedigend entschieden ist. — Beim RotkleePhytonomus nigrirostris, Apion apricans undA. assimile, Sitona spp. undDitylenchus dipsaci, deren Biologie und Bekämpfung weiterhin fortgesetzt werden, — Bei ÖlpflanzenCeuthorrhynchus assimilis undC. quadridens sowieDasyneura brassicae, deren Bekä mpfung zu ermitteln ist. — Bei Zuckerrübe sowie einigen anderen Kulturpflanzen Bedeutung und Bekä mpfung vonLygus-Arten (besondersL. rugulipennis undL. pratensis). Bekämpfung der Rübenfliege(Pegomyia hyoscyami) bei Zuckerrübenkulturen. — Bei den Wurzelschädlingen von Gemüse und Hackfrüchten Klären von Biologie und Bekämpfung der Kohlfliegen (Hylemyia brassicae undH. floralis), der Fliegenschädlinge von Zwiebeln (Hylemyia antiqua, Eumerus tuberculatus undE. strigatus) und der Möhrenfliege. — Die Wirkung der Spritzungen in Obstgärten auf die wichtigsten Schä dlinge(Metatetranychus pilosus, Doralina pomi, Psylla mali, Carpocapsa pomonella, Argyresthia conjugella) und ihre wirksamsten Feinde.— In Beerengärten bei den ArtenTarsonemus fragariae, Eriophyes ribis undPachynematus pumilio sowie in Obstgärten bei der ArtAnisandrus dispar Intensivierung der Bekä mpfung. — Älchen(Anguillulidae), besondersdas Kleeälchen und Klärung von Lebensbedingungen und Bekämpfung desKartoffelälchens. — Bedeutung und Bekämpfung der Wühlmäuse (besondersMicrotus agrestis, M. arvalis undArvicola terrestris). — Untersuchung der Bedeutung von virusverbreitenden Insektenarten. — Erforschung der Nachteile von Bekämpfungsmitteln für die Pflanzen.     

黄河小浪底库区山地栓皮栎人工林土壤呼吸的季节动态

[目的]分离并量化土壤自养呼吸和异养呼吸,探讨各自贡献率及其随季节变化的动态特征。[方法]采用壕沟法和气体红外分析法,研究黄河小浪底库区山地栓皮栎人工林土壤总呼吸、自养呼吸和异养呼吸速率的季节动态变化、贡献率和环境影响因子。[结果]表明:栓皮栎人工林总土壤呼吸、自养呼吸和异养呼吸均呈夏季速率高、冬季速率低。栓皮栎土壤总呼吸、自养呼吸及异养呼吸速率与5 cm土壤温度均呈极显著指数相关,温度敏感性系数Q_(10)值大小为自养呼吸(3.40)异养呼吸(2.90)土壤总呼吸(2.45);栓皮栎土壤总呼吸、自养呼吸、异养呼吸速率与0 10 cm土壤体积含水量均显著线性相关;土壤总呼吸、自养呼吸速率与0 10 cm土壤电导率显著相关。土壤总呼吸和异养呼吸的温度敏感系数Q_(10)值均在冬季最大,夏秋季最小;而自养呼吸的Q_(10)值则呈相反的变化趋势。栓皮栎人工林自养呼吸和异养呼吸对土壤总呼吸的月贡献率为13.23%37.33%和62.67%86.76%,且自养呼吸的贡献率与土壤温度的季节变化规律相似。土壤总呼吸、异养呼吸与自养呼吸的CO2年通量分别为1 616.41、1 199.39、417.02 g·m~(-2)·a~(-1)。[结论]经过区分与定量化土壤总呼吸及其组分,确定异养呼吸为本研究区栓皮栎人工林土壤总呼吸的主要组分,作用于异养呼吸的生物与非生物因子均能显著影响整个森林生态系统表层CO_2总排放通量的大小,进一步为该研究区森林生态系统碳循环与能量流动的进一步量化研究提供参考。     

Below-ground root yield and distribution in natural and replanted mangrove forests at Gazi bay, Kenya

Estimation of total biomass in woody ecosystems is important because of its relevance to nutrient turnover and the potential to store carbon. Most work on mangrove biomass, particularly in the Western Indian Ocean Region, has concentrated on the above-ground component; comparatively little is known on below-ground biomass. The current study was conducted at Gazi bay on the southern coast of Kenya. The objective was to determine the below-ground biomass of three species of mangrove, Rhizophora mucronata Lamarck, Avicennia marina (Forsk.) Vierh and Sonneratia alba J. Smith, in natural and replanted stands. The effects of distance from the tree base and of soil depth on root biomass and size distributions were also studied using coring. Live below-ground biomass (mean ± S.E.) ranged from 7.5 ± 0.4 t/ha to 35.8 ± 1.1 t/ha, 48.4 ± 0.7 t/ha to 75.5 ± 2.0 t/ha and 39.1 ± 0.7 t/ha to 43.7 ± 1.7 t/ha for R. mucronata, S. alba and A. marina, respectively, depending on the age of the stand. Including dead roots produced total biomass values of 34.9 ± 1.8–111.5 ± 5.6 t/ha, 78.9 ± 3.3–121.5 ± 7.3 t/ha and 49.4 ± 1.1–84.7 ± 5.4 t/ha for R. mucronata, S. alba and A. marina. These values imply carbon contents of live roots ranging between 3.8 ± 0.2 C t/ha and 17.9 ± 0.6 C t/ha, 24.2 ± 0.4 C t/ha and 37.7 ± 1.0 C t/ha and 19.5 ± 0.4 C t/ha and 21.9 ± 0.9 C t/ha for R. mucronata, S. alba and A. marina stands, respectively, and 17.4 ± 0.9 C t/ha and 55.7 ± 2.8 C t/ha, 39.4 ± 1.7 C t/ha and 60.7 ± 3.6 C t/ha and 24.7 ± 0.6 C t/ha and 42.4 ± 2.9 C t/ha for R. mucronata, S. alba and A. marina stands, respectively if dead roots are included. Stand densities were 4650 ± 177 stems/ha, 3800 ± 212 stems/ha and 3567 ± 398 stems/ha for R. mucronata 6-year old, 12-year-old and natural stands respectively. Mean stem diameter, and basal area were highest in the 12-year-old plantation while below-ground root biomass increased with age. Stand density for S. alba, was highest in the 12-year-old plantation (7900 ± 141 stems/ha) while the 9-year-old stand had trees with the largest diameter (7.7 ± 0.9 cm). Below-ground biomass was highest in the 12-year old (75.5 ± 2.0 t/ha) and lowest in the natural stand (48.4 ± 0.7 t/ha). Stand density for A. marina was highest in the 12-year-old plantation (4300 ± 919 stems/ha) while mean stem diameter (7.9 ± 0.7 cm) and basal area (16.2 ± 2.1 m²/ha) were highest in the natural stand. Below-ground biomass in the 12-year-old (43.7 ± 1.7 t/ha) and natural stands (39.1 ± 0.7 t/ha) was similar. Root densities decreased with soil depth and with distance from the base of trees for all species and stands. Fine roots (diameter <5 mm) constituted between 24% and 45% of the total stand live root biomass. The information generated is important in establishing the total biomass and thus the potential amount of carbon sequestered by mangroves in the study area.     

重庆酸雨区缙云山典型林分冠层酸雨淋洗特征

选取重庆缙云山的针阔混交林、常绿阔叶林、毛竹林、灌木林4种典型林分,观测酸性降水过程中林外雨、穿透雨及干流等林内水分转换分量中的主要离子含量变化,分析林分冠层对雨水化学组成的影响,结果表明:(1)降雨中的离子当量浓度大小依次是SO42-＞Ca2+＞ NH4+＞Mg2+＞K+＞Na+＞NO3-;(2)降雨经过林冠层后pH值降低,干流的酸化程度增加最大;(3)降雨经林冠层后离子浓度明显增加(除灌木林),穿透雨中通量增加最大的阴离子和阳离子分别为SO42-(2.19×103～6.47×103 eq·hm-2)和Ca2+(1.41×103～3.39×103 eq-hm-2),离子来源主要为大气沉降和植物分泌物或淋出;(4)同一离子在不同林分的干流和穿透雨中的通量变化不同,反映出不同林分冠层的离子交换性差异.在针阔混交林中,林下降雨净淋溶量大小顺序为SO42-＞Ca2+＞ NO3-＞K+＞NH4+＞Mg2+＞ Na+;常绿阔叶林为SO42-＞ Ca2+＞ K+＞NO3-＞ NH4+＞ Mg2+ ＞Na+;毛竹林为Ca2+＞ SO42-＞ K+＞NO3-＞ NH4+＞Na+＞Mg2+;灌木林为Ca2+＞ NO3-＞ K+＞ Na+＞Mg2+＞ NH4+＞ SO42-.     

广州市酸雨对不同森林冠层淋溶规律的研究

１９９８年４月至１９９９年３月对广州市白云山马尾松林和常绿阔叶林、广州市龙眼洞马尾松林两试验点进行了酸雨的监测,并测定和分析了林内穿透雨物理量及化学量,旨在探讨酸雨对不同森林冠层养分淋溶规律的影响。结果表明：（１）广州市酸雨占次数的７９．７％或占降雨量的９５．１％。（２）酸雨通过林冠层后,ｐＨ值明显增加。（３）在马尾松林和常绿阔叶林中,某些单次降雨出现ＳＯ４＾２－、ＮＯ３＾－、ＮＨ４＾＋Ａｌ＾３＋、Ｎａ＾＋的负淋溶现象,说明森林对这些离子（特别是ＮＯ３＾－、Ａａ＾３＋）具有吸收作用;阔叶林全年的ＮＯ３＾－和Ａｌ＾３＋净淋溶为负值,说明阔叶林比马尾松林对这两种离子具有更强的吸收能力。（４）雨水酸度增加（即ｐＨ值减小）,明显提高阳离子Ｃａ＾２＋、Ｍｇ＾２＋、Ｋ＾＋和Ｎａ＾＋冠层淋溶面分率。（５）ＮＨ４＾＋、ＳＯ４＾     

Carbon dioxide exchange of a larch forest after a typhoon disturbance

A typhoon event catastrophically destroyed a 45-year-old Japanese larch plantation in southern Hokkaido, northern Japan in September 2004, and about 90% of trees were blown down. Vegetation was measured to investigate its regeneration process and CO₂ flux, or net ecosystem production (NEP), was measured in 2006–2008 using an automated chamber system to investigate the effects of typhoon disturbance on the ecosystem carbon balance. Annual maximum aboveground biomass (AGB) increased from 2.7 Mg ha⁻¹ in 2006 to 4.0 Mg ha⁻¹ in 2007, whereas no change occurred in annual maximum leaf area index (LAI), which was 3.7 m² m⁻² in 2006 and 3.9 m² m⁻² in 2007. Red raspberry (Rubus idaeus) had become dominant within 2 years after the typhoon disturbance, and came to account for about 60% and 50% of AGB and LAI, respectively. In comparison with CO₂ fluxes measured by the eddy covariance technique in 2001–2003, for 4.5 months during the growing season, the sum of gross primary production (GPP) decreased on average by 739 gC m⁻² (64%) after the disturbance, whereas ecosystem respiration (RE) decreased by 501 gC m⁻² (51%). As a result, NEP decreased from 159 ± 57 gC m⁻² to −80 ± 30 gC m⁻², which shows that the ecosystem shifted from a carbon sink to a source. Seasonal variation in RE was strongly correlated to soil temperature. The interannual variation in the seasonal trend of RE was small. Light-saturated GPP (P_max) decreased from 30–45 μmol m⁻² s⁻¹ to 8–12 μmol m⁻² s⁻¹ during the summer season through the disturbance because of large reduction in LAI.     

Nitrogen leaching in response to increased nitrogen inputs in subtropical monsoon forests in southern China

Dissolved inorganic nitrogen (DIN) (as ammonium nitrate) was applied monthly onto the forest floor of one old-growth forest (>400 years old, at levels of 50, 100 and 150 kg N ha⁻¹ yr⁻¹) and two young forests (both about 70 years old, at levels of 50 and 100 kg N ha⁻¹ yr⁻¹) over 3 years (2004–2006), to investigate how nitrogen (N) input influenced N leaching output, and if there were differences in N retention between the old-growth and the young forests in the subtropical monsoon region of southern China. The ambient throughfall inputs were 23–27 kg N ha⁻¹ yr⁻¹ in the young forests and 29–35 kg N ha⁻¹ yr⁻¹ in the old-growth forest. In the control plots without experimental N addition, a net N retention was observed in the young forests (on average 6–11 kg N ha⁻¹ yr⁻¹), but a net N loss occurred in the old-growth forest (−13 kg N ha⁻¹ yr⁻¹). Experimental N addition immediately increased DIN leaching in all three forests, with 25–66% of added N leached over the 3-year experiment. At the lowest level of N addition (50 kg N ha⁻¹ yr⁻¹), the percentage N loss was higher in the old-growth forest (66% of added N) than in the two young forests (38% and 26%). However, at higher levels of N addition (100 and 150 kg N ha⁻¹ yr⁻¹), the old-growth forest exhibited similar N losses (25–43%) to those in the young forests (28–43%). These results indicate that N retention is largely determined by the forest successional stages and the levels of N addition. Compared to most temperate forests studied in Europe and North America, N leaching loss in these seasonal monsoon subtropical forests occurred mainly in the rainy growing season, with measured N loss in leaching substantially higher under both ambient deposition and experimental N additions.