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1.
厚朴不同种源及家系种子性状的变异 总被引：5，自引：0，他引：5
研究厚朴自然分布区内8个省份19个种源的种子长、种子宽、种子厚、种子长宽比及种子百粒重等性状的变异及趋变模式.结果表明:种源间种子长、种子宽、种子厚、种子长宽比等性状的差异均达到极显著水平;种源内不同家系种子长、种子宽、种子厚等性状的差异也均达到极显著水平;种源间种子百粒重变异远远高于种源内家系间变异,前者种子百粒重变异幅度为14.147～24.547 g,后者种子百粒重变异幅度为15.003～17.357 g;种子宽、种子厚和种子百粒重等性状受积温和热量因子控制作用极为明显. 相似文献
2.
《福建林业科技》2016,(4)
采用标准样地法对色季拉山急尖长苞冷杉在海拔3700~4200 m阴坡与阳坡处种子特征、种子饱满率、种子发芽率及天然更新幼苗状况进行研究。结果表明:同一坡向随着海拔的升高种子带翅长度、种子去翅长度、种子宽度、种子厚度、千粒重、种子饱满率及种子发芽率均呈现先升高后降低的趋势,天然更新幼苗数量亦然;不同坡向同一海拔处,种子带翅长度、种子去翅长度、种子宽度、种子厚度、千粒重、种子饱满率及种子发芽率阳坡优于阴坡,幼苗数量阴坡比阳坡丰富;阴坡、阳坡在海拔3800 m或3900 m处种子带翅长度、种子去翅长度、种子宽度、种子厚度、千粒重、种子饱满率及种子发芽率均出现最优值,此海拔处天然更新效果相对较好。 相似文献
3.
4.
对短萼仪花群落中5个优良单株的荚果长、荚果宽、荚果长宽比、种子长、种子宽、种子长宽比及种子单粒质量等性状进行测定分析,发现单株间种子表型性状差异均达到极显著水平;变异最大的为种子单粒质量,其变异系数为20.41%;种子表型性状间具有一定的相关性。 相似文献
5.
温度对植物种子萌发机制的影响 总被引：1，自引：0，他引：1
温度作为环境因子,在种子萌发的过程中起着重要的作用。文章主要从温度对种子萌发特征的影响和对种子萌发生理过程的影响两大方面进行了综述。其中对种子萌发特征的影响体现在种子萌发率、萌发速率及种子芽长、胚根长的变化;对种子萌发生理过程的影响体现在种子的酶促反应过程、呼吸作用及种子的抑制物质的变化。 相似文献
6.
很多林木种子存在难萌发、天然更新不良的现象，而种子际是直接影响种子萌发的土壤区域，种子际微生物会对天然更新的植物产生有益或有害的影响，并对解释根际微生物群落的建立具有重要的意义。文中主要从种子际微生物多样性、对种子和幼苗生长发育的影响、种子际微生物群落变化的影响因素以及种子际微生物的自身调节行为等4方面来概述种子际微生物研究现状，分析种子际微生物研究中存在的问题，提出未来林木种子际微生物的研究展望，旨在为林木种子建立共生萌发机制及为濒危物种野生居群的生态恢复提供参考。 相似文献
7.
分析马尾松种子园无性系种实性状的变异,结果表明①种子园无性系的平均种子潜能为132,平均种子效率为40.66%;②球果长、宽在无性系间、无性系内均存在极显著差异;每个球果饱满种子数、种子千粒重/种子潜能/种子效率在无性系间存在极显著差异,无性系内差异不显著;③球果长和宽、种子千粒重的重复力分别为0.144,0.179和0.139;球果饱满种子数、种子潜能、种子效率的重复力分别为0.652,0.626和0.745;重点讨论了现有种子园种子生产潜力及提高产量的着眼点. 相似文献
8.
9.
《林业实用技术》2015,(9)
通过收集和测量来自麻栎自然分布区的北京、安徽、江西、河北、山东、河南、云南、四川、重庆、陕西等10个省15个地理种源的种子,运用SPSS 18.0软件进行统计分析,探讨了不同种源麻栎种子各性状的变异及原因。结果表明:麻栎种子的种子长、种子宽、种子长宽比、单果重等性状差异均达到极显著水平(p<0.01);种子宽与种子长宽比呈显著负相关(p<0.05);单果重与种子长宽比呈显著负相关(p<0.05);种子宽与单果重呈极显著正相关(p<0.01);而种子其它性状间均未达显著性相关水平(p≥0.05);单果重与7月均温呈显著正相关(p<0.05),其他生态因子与种子性状相关性不显著(p≥0.05);聚类分析显示15个种源的麻栎可聚为3类。 相似文献
10.
11.
Else Jahn 《Journal of pest science》1967,40(10):145-152
Summary The present paper reports on an outbreak of the False Pine Webworm (Acantholyda erythrocephala L.) in the Steinfeld of Lower Austria, from its detection in July 1964 up to swarming of wasps in April 1967. The course
of gradation and resulting damages are described, and data obtained on development, manner of life, and mortality given. In
plantations of predominant Austrian Black Pine (Pinus nigra ssp.austriaca) and Scots Pine(Pinus silvestris) the former, too, was attacked though to a considerably lesser extent than the latter. Among mortality factors observed, most
important was a nuclear polyhedrosis, which, during the first year of outbreak, killed numerous pseudocaterpillars, but sensibly
diminished in lethal effect in the further course of calamity. In connection with the outbreak ofAcantholyda erythrocephala, some other pest occurrences in the plantations are mentioned. A possible competition effect of a previous outbreak ofNeodiprion sertifer, lasting several years, and one ofDendrolimus pini L., lasting two years, resulting in inhibitions of a more precocious development of the outbreak ofAcantholyda erythrocephala, and in prevention of a nascent gradation ofPanolis flammea by the multiplication ofAcantholyda taking its course, is particularly referred to. Control experiments were done with the fumigant “Kerfex-Nebelk?rper/rd. An
effective control by this product, too, must be carried out soon after emerging of young larvae.
Die vorliegenden Beobachtungen der derzeit noch weiter laufenden Kalamit?t schlie?en mit der Flugperiode 1967 ab. Von H. Schmutzenhofer werden bzw. wurden weitere Untersuchungen zum Auftreten dieses Sch? dlings besonders zur Erlangung kritischer Ei- und Larvenzahlen, zur Kl?rung des Problems des überliegens und Auffindung wirksamer Bek?mpfungsmittel durchgeführt. 相似文献
Résumé Le présent mémoire rend compte d'une pullulation de la Lyde bleue du Pin (Acantholyda erythrocephala L.) au Steinfeld en Basse-Autriché, à partir de sa découverte au mois de Juillet 1964 jusqu'à l'essaimage des guépes au mois d'Avril 1967. Le cours de la gradation et ses effets nuisibles sont caracté risés avec des données obtenues sur le développement, la manière de vivre et la mortalité de l'insecte. Dans les plantations où dominaient le Pin noir d'Autriche (Pinus nigra ssp.austriaca) et le Pin sylvestre(Pinus silvestris), le Pin noir a aussi été attaqué, mais à un bien moindre degré que le Pin sylvestre. Parmi les facteurs relevés de mortalité le plus important a été une maladie cubique nucléaire, faisant dépérir de nombreuses fausses chenilles pendant la première année de la calamité, mais ne déployant que peu d'activité pernicieuse au cours ultérieur de la gradation. En rapport avec cette gradation deAcantholyda erythrocephala on mentionne quelques autres apparitions d'insectes nuisibles dans les plantations. On met spécialement en relief des effets possibles de compétition de la part d'une précédente calamité de plusieurs années deNeodiprion sertifer et d'une autre, de deux années, deDendrolimus pini L., par rapport à un ralentissement du développement de l'attaque massive del'Acantholyda erythrocephala et à l'empéchement d'une gradation naissante dePanolis flammea par ie déroulement de la gradation deAcantholyda. Des essais de lutte ont été entrepris avec le fumigant ?Kerfex-Nebelk?rper?. Si la lutte doit être efficace, il faut l'exécuter peu de temps après l'eclosion finie des jeunes larves.
Резюме Настоящая статья доносит о массовом размножении красноголового общественного пилильщика — ткача,Acatholyda erythrocephala L., в Штейнфельде (Нижняя Австрия), от его открытия в июле 1964г. до роения ос в апреле 1967г. Характеризуются ход градащии и вредные действия так как приводятся информации о развитии, способе жизни и смертности. В культурах, составленных преимущестнно из сосен австрийской (Pinus nigra ssp. austriaca) и обыкновенной (P. silvestris) была поражена и австрийская, хотя в значительно менышей степени, чем обыкновенная. Среди действующих факторов смертиности была важнейшим ядерная полиэдровая болезнь, которая убила в первом году бедствия многочисленных лжегусениц, а в далышем ходу показывала уже мало смертного действия. В связи с градацииAcantholyda erythrocephala упомнаются и другие появления вредителей в культурах. Указывается особенно на возможные конкуренцийные действия предшествующей долголетной градацииNeodiprion sertifer и двухлетной таковойDendrolimus pini L. по отношению к торможениям более ранного развития массового появленияAcontholyda erythrocephala и препятствованию возникающей градацииPanolis flammea протекающим размножением акантолиды. Попытки борьбы были установлены фумигантом ?Керфекс -Небелькерпер?. Борьбу, если должна быть успешной, нужно проводить и этим средством скоро после вылупляния молодых личинок.
Die vorliegenden Beobachtungen der derzeit noch weiter laufenden Kalamit?t schlie?en mit der Flugperiode 1967 ab. Von H. Schmutzenhofer werden bzw. wurden weitere Untersuchungen zum Auftreten dieses Sch? dlings besonders zur Erlangung kritischer Ei- und Larvenzahlen, zur Kl?rung des Problems des überliegens und Auffindung wirksamer Bek?mpfungsmittel durchgeführt. 相似文献
12.
E. Jahn 《Journal of pest science》1962,35(7):99-102
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%.
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.
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.
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%.相似文献
13.
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. 相似文献
14.
Veikko Kanervo 《Journal of pest science》1960,33(1):1-5
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. 相似文献
15.
K. Gadek 《Journal of pest science》1963,36(5):67-70
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.
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.
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. —相似文献
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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-. 相似文献
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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＾ 相似文献
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Tomohito Sano Takashi Hirano Naishen Liang Ryuichi Hirata Yasumi Fujinuma 《Forest Ecology and Management》2010
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 (Pmax) 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. 相似文献
20.
Nitrogen leaching in response to increased nitrogen inputs in subtropical monsoon forests in southern China 总被引：1，自引：0，他引：1
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. 相似文献