格氏栲天然林与人工林根际土壤微生物及其生化特性的研究

通过对格氏栲天然林（约１２０年生）和人工林（２８年生）根际土壤和全土微生物、生化活性、土壤养分的研究,结果表明：格氏栲天然林根际和全土土壤养分、土壤微生物区系、生理类群数量、土壤酶活性和生化作用强度均比相应人工林的大,格氏栲天然林根际土壤速效性养分相对富集,而人工林的则存在亏缺现象。格氏栲人工林的根际效应（Ｒ／Ｓ值）比天然林的明显。     

巨桉人工林地土壤微生物类群的生态分布规律

研究了四川省洪雅县巨桉人工林地土壤微生物数量及其类群分布规律.结果表明,洪雅县巨桉人工林地土壤微生物数量具有明显的季节变化,各样地均以秋季最多,达到17.42×10⁶CFU·g^-1,春季次之,夏季最少.土壤微生物主要集中在0～20cm的土层,随着土层的加深,微生物数量迅速减少;在0～60cm土层,同一类群微生物数量变动范围较大,其中好气性细菌0.31×10⁶～14.39×10⁶CFU·g^-1,放线菌0.06×10⁶～0.79×10⁶CFU·g^-1,真菌0.02×10⁶～0.07×10⁶CFU·g^-1,厌氧细菌0.07×10⁶～3.22×10⁶CFU·g^-1.巨桉人工林地微生物以细菌为主要类群,占微生物总数的92.83%以上,其次是放线菌和真菌,其微生物组成结构合理.与青冈次生林和农耕地相比,巨桉人工林地微生物数量远远高于青冈次生林地,有利于土壤微生物生长.细菌生理类群的Simpson多样性指数和Shannon-Wiener多样性指数分别达到0.773和1.896.     

连作对大豆根部土壤微生物的影响研究

研究了正茬与连作大豆根际及非根际土壤微生物区系的变化。结果表明,细菌总数占绝对优势,连作低于正茬。放线菌数量总体变化幅度不大,真菌数量有显著变化,连作明显高于正茬。连作使土壤pH、含水率和微生物主要生理类群数量明显下降,土壤肥力降低。无论细菌、放线菌和真菌,正茬及连作大豆根际微生物数量明显高于非根际。     

中亚热带地区两种森林植被类型土壤微生物群落结构

利用磷脂脂肪酸(PLFA)生物标记法分析了中亚热带地区罗浮栲天然林和相邻的杉木人工林土壤微生物群落结构特点.结果表明: 两种植被类型的磷脂脂肪酸总量、细菌特征脂肪酸、真菌特征脂肪酸、放线菌特征脂肪酸、革兰氏阳性菌和革兰氏阴性菌特征脂肪酸含量均为0～10 cm高于10～20 cm土层,罗浮栲天然林高于杉木人工林.在两种植被类型的两个土层中,细菌PLFAs含量均显著高于真菌PLFAs含量.两种植被类型中,细菌PLFAs含量约占PLFAs总量的44%～52%,而真菌仅占6%～8%,表明细菌在该地区两种植被类型土壤中处于优势地位.主成分分析表明,土壤微生物群落结构差异主要由植被类型差异引起,土层深度的影响相对较小.相关分析显示,革兰氏阴性菌、革兰氏阳性菌以及细菌的PLFAs含量与pH呈显著负相关,与含水量呈显著正相关;土壤微生物主要类群PLFAs含量与总氮、有机碳、C/N和铵态氮均呈显著正相关.     

塔克拉玛干沙漠腹地人工植被下土壤微生物的初步研究

在极端干旱的塔克拉玛干沙漠腹地利用矿化度为4～5 g/L的地下咸水灌溉,在风沙土上建立了人工绿地。对流沙和人工绿地中微生物三大类群（细菌、真菌和放线菌）进行了数量测定,结果显示：流沙上微生物数量很少,人工绿地的微生物数量显著增加;种植时间相同而植被类型不同的样地中的微生物数量有差异;微生物的组成中,细菌占绝大多数,达微生物总数的90%以上,其次是放线菌,真菌数量最少;表层微生物数量明显高于下层。人工绿地微生物数量的变化,说明风沙土已逐步向具有一定肥力水平的土壤方向演变。     

中国亚热带森林转换对土壤呼吸动态及通量的影响

通过用静态碱吸收法对中国亚热带福建三明格氏栲自然保护区内的格氏栲天然林和33年生的格氏栲人工林及杉木人工林的土壤呼吸进行为期2a的定位研究,结果表明,3种森林土壤呼吸速率季节变化均呈单峰曲线,最大值出现在5月至6月份,最小值出现在12月至翌年1月份。格氏栲天然林、格氏栲人工林和杉木人工林土壤呼吸速率一年中变化范围分别在403.47～1001.12mgCO2m-2h-1、193.89～697.86mgCO2m-2h-1和75.97～368.98mgCO2m-2h-1之间。2002年土壤呼吸速率主要受土壤温度影响,但在极端干旱的2003年则主要受土壤湿度的影响。双因素关系模型(R=aebTWc)拟合结果优于仅考虑土壤温度或土壤湿度的单因素关系模型,土壤温度和土壤湿度共同解释不同年份不同森林土壤呼吸速率季节变化的80%～96%。杉木林土壤呼吸对气候变化敏感性高于格氏栲天然林和人工林。格氏栲天然林、格氏栲人工林和杉木人工林土壤呼吸年通量分别为13.742、9.439和4.543tC·hm-2·a-1,前者分别约是后二者的1.5倍和3.0倍。森林转换对土壤呼吸通量的影响可能与枯落物数量和质量、根系呼吸、土壤有机质数量和质量的变化有关。     

不同种植年限菜田土壤微生物区系的研究

采用稀释平板涂抹法对山东聊城周边地区不同种植年限的菜田土壤微生物数量、组成与养分状况及其相互关系进行了研究。结果表明：①该地区土壤微生物以细菌占绝对优势,其次为放线菌;②随着种菜年限的增加,土壤细菌和微生物总数表现出“低高低”的变化趋势,而真菌和放线菌则随种菜年限的增加而增加;③菜田土壤各类微生物主要集中在0～20cm的土层中,随着土层加深,其数量迅速减少;④菜田土壤放线菌组成复杂,共分离到了6个属的放线菌,但仍以链霉菌为主,其次为小单胞菌属和马杜拉放线菌属。链霉菌可分为9个类群,白孢类群占优势。种植1—2a的菜田土壤放线菌组成复杂,而链霉茼组成较简单;⑤蔬菜种类不同时,土壤微生物亦不同;⑥土壤养分含量与真菌和放线菌呈负相关,与细菌和微生物总数呈正相关。     

格氏栲天然林与人工林根系呼吸季节动态及影响因素

通过用挖壕沟 静态碱吸收法对福建三明格氏栲天然林及33年生格氏栲和杉木人工林的根系呼吸进行为期2a定位研究。不同森林根系呼吸速率季节变化均呈单峰曲线,最大值出现在春末或夏初,最小值出现在冬季。1年中格氏栲天然林、格氏栲人工林和杉木人工林根系呼吸速率变化范围分别在157.76~480.40mgCO2/(m2·h)、53.03~339.45mgCO2/(m2·h)和16.66~228.02mgCO2/(m2·h)之间。在近似正常气候状况的2002年,不同森林根系呼吸主要受土壤温度影响(R2=0.52~0.72);而土壤温度和土壤湿度共同则可解释根系呼吸速率季节变化的81%~90%。在极端干旱的2003年,根系呼吸受土壤温度或湿度的影响较小,土壤温度和土壤湿度共同仅能解释根系呼吸变化的24%~60%,这与根系在持续干旱期间长期处于近休眠状态有关。根系呼吸对土壤温度和土壤湿度的敏感性大小顺序均为杉木人工林>格氏栲人工林>格氏栲天然林。格氏栲天然林根系呼吸占土壤呼吸比例(47.6%)均高于格氏栲和杉木人工林的(42.5%和40.2%),不同森林根系呼吸占土壤呼吸比例均以冬季最低,而以5月或6月最高。格氏栲天然林、格氏栲人工林和杉木人工林根系呼吸年通量分别为6.537、4.013和1.828tC/(m2·h)。     

不同龄级速生杨人工林土壤微生物数量与养分动态变化

通过稀释平板法和常规化学分析法, 对伊犁河谷地区3种龄级(5年、10年、15年)的速生杨欧美黑杨(Populus × euramericana)人工林的土壤微生物数量、组成和土壤养分变化进行了研究。结果表明, 3种不同林龄林地土壤微生物集中分布在10-40 cm土层, 数量和种类组成随季节变化有明显差异。随着林龄的增长, 土壤微生物总数、细菌数量减少, 真菌和放线菌数量在10年生人工林最高, 这一规律随季节变化。三大类土壤微生物的组成比例相对稳定, 不随季节变化而变化。土壤有机碳、氮含量主要集中在0-20 cm土层, 随土壤深度的增加逐渐减少, 其含量及分布受季节和土壤深度不同程度的影响。土壤有机碳含量随林龄的增长而逐渐增高, 有机氮则先减后增。相关分析表明, 土壤微生物总数与土壤有机碳呈负相关, 真菌数量与土壤有机氮呈正相关。3种林地土壤有机C/N比与土壤细菌数量/真菌数量比例一致, 说明速生杨人工林在一定生长年龄内能提高土壤的固碳能力, 改善土壤肥力。     

毛乌素沙地南缘沙丘生物结皮中微生物分布特征

为探明半干旱沙区生物结皮中微生物分布特征,对毛乌素沙地南缘沙丘生物结皮中微生物数量进行了测定。结果表明:微生物总数从丘顶到丘间地呈递增趋势,除丘顶与迎风坡、迎风坡与背风坡结皮层微生物总数差异不显著外,其他各地貌部位结皮层微生物数量之间差异显著。同一地貌部位结皮层、0～5和5～10cm土层微生物垂直分布有变化,其变化规律为:除迎风坡放线菌数量呈先增加后递减、迎风坡微生物总数、细菌、真菌和丘顶真菌数量随剖面的加深呈递减外,其他各地貌部位微生物数量均呈先降低,后增加的趋势。微生物类群的组成表现为细菌最多,放线菌次之,真菌最少。在丘间地细菌所占微生物总数的比例与丘顶相比有所增加,而放线菌和真菌的比例有所减少。结皮下0～5和5～10cm土层微生物分布与土壤含水量的变化同步,说明土壤水分可能是影响微生物垂直分布的重要因子。     

苞箭竹根际土壤微生物数量与酶活性

缺苞箭竹是四川西部亚高山针叶林下层重要的优势植物种群。对缺苞箭竹根际土壤微生物数量与酶活性进行了研究。结果表明,各龄级缺苞箭竹根际土壤细菌、真菌数量显著高于非根际土,而放线菌数量无显著差异,土壤酶活性比值(R/S值)平均分别为2.36、2.08和1.08。各龄级缺苞箭竹根际土壤酸性磷酸酶、蛋白酶、蔗糖酶、脲酶、过氧化氢酶以及多酚氧化酶等酶活性均显著高于非根际土,R/S值平均分别为1.48、1.57、2.14、1.37、1.98和1.67。各龄级缺苞箭竹间相比较,根际土壤中的细菌、真菌数量及各土壤酶活性总体上表现3、5、7龄>9、11、13龄>1龄竹,而放线菌数量在各龄级之间无显著变化,即箭竹在幼龄阶段(1~5龄)随竹龄增加根际微生物数量与酶活性逐渐增加,以后随竹龄老化,根际微生物数量和酶活性逐渐降低。     

辽东山区不同林龄日本落叶松人工林土壤微生物、养分及酶活性

对辽宁省抚顺市大孤家林场11、20、34和47年生日本落叶松人工纯林表层土壤(0~5 cm)微生物群落结构、养分及酶活性进行了研究.结果表明: 土壤微生物、养分及酶活性各项指标基本呈现11或47年林龄较高,而20或34年林龄较低.随林龄增加,土壤地力呈现衰退趋势,土壤微生物群落结构及酶活性变化对地力衰退呈现响应趋势,不同林龄真菌群落结构的差异较细菌显著.典范对应分析(CCA)表明,土壤养分含量及pH值对微生物群落结构的季节变化没有影响,但对在不同林龄间微生物的变化有影响.土壤全氮、有机碳、C/N、速效氮和pH值对不同林龄细菌分布影响较大,土壤速效磷、全钾、交换性镁离子和pH值对真菌分布影响较大.细菌与真菌群落主要的T RFs片段与氮、磷的相关性都较高,而真菌群落与有机碳、钾的相关性高于细菌群落.11和47年林龄微生物群落与土壤养分、酶活性的相关性高于20与34年.因此,土壤微生物(尤其是土壤真菌)可以敏感地指示土壤肥力的变化.     

Fungi in ectomycorrhizal associations of silver fir (Abies alba Miller) in Central Italy

 Naturally occurring ectomycorrhizas of silver fir (Abies alba Miller) were studied in two stands, one natural and one artificial, situated in Central Italy. A total of 25 mycorrhizal types was classified, for eight of which the mycobiont was identified at the species level. Analysis of macroscopic and microscopic features and matching of field-collected carpophores with associated mycorrhizas led to the tentative identification of several other types encountered during this study, at least at the genus level. No significant differences were noticed between natural and artificial stands in the relative richness of mycorrhizal types found on A. alba, indicating the maturity of the artificial stand with regard to succession of ectomycorrhizal fungi. Confocal laser scanning microscopy was used for visualization of mycorrhizal structures formed by Lactarius spp., without the need for specific staining with a fluorochrome, thanks to latex autofluorescence. This technique allowed observation of several structures in greater detail than with conventional light microscopy. Accepted: 13 February 1998     

Not only light quality but also mechanical stimuli are involved in height convergence in crowded Chenopodium album stands

? In crowded stands, height is often similar among dominant plants, as plants adjust their height to that of their neighbours (height convergence). We investigated which of the factors, light quality, light quantity and mechanical stimuli, is primarily responsible for stem elongation and height convergence in crowded stands. ? We established stands of potted Chenopodium album plants. In one stand, target plants were surrounded by artificial plants that were painted black to ensure that the light quality was not modified by their neighbours. In a second stand, target plants were surrounded by real plants. In both stands, one-half of the target plants were anchored to stakes to prevent flexing by wind. The target plants were lifted or lowered by 10?cm to test whether height convergence was affected by the different treatments. ? Stem length was affected by being surrounded by artificial plants, anchoring and pot elevation, indicating that light quality, light quantity and mechanical stimuli all influenced stem elongation. Height convergence did not occur in the stand with artificial plants or in anchored plants. ? We conclude that light quality and mechanical stimuli are important factors for the regulation of stem growth and height convergence in crowded stands.     

湿地松混交林地土壤养分、微生物和酶活性的研究

1　引　　言土壤养分、微生物和酶是森林生态系统的重要组成成分 .土壤养分含量对林木生长有重要影响 .土壤微生物参与土壤的物质循环和能量转化[16] ,而土壤酶参与土壤的许多重要的生物化学过程和物质循环[18] ,二者一起推动着土壤的代谢过程 ,影响着林木生长 .长期以来 ,有关森林土壤养分、微生物和酶的研究受到广泛重视[4 ,6～ 2 0 ] .黎蒴栲 (Ｃａｓ ｔａｎｏｐｓｉｓｆｉｓｓａ)、红荷 (Ｓｃｈｉｍａｗａｌｌｉｃｈｉｉ)和湿地松 (Ｐｉｎｕｓｅｌ ｌｉｏｔｔｉｉ)是我国南方重要的用材树种 ,但是关于黎蒴栲×湿地松及红荷×湿地松混交…     

黄土高原人工油松林地土壤微生物的分布特征

研究了黄土高原不同树龄的油松人工林地土壤微生物的分布特征.结果表明：土壤细菌、放线菌和真菌的数量随树龄的变化不显著,而随土壤深度的变化极为显著;细菌数量随土壤深度的变化规律符合Quadratics Ratio模型,放线菌和真菌数量则随土壤深度呈现指数衰减变化.与油松＋紫穗槐混交林、撂荒地相比,油松人工林地土壤细菌含量小于混交林,而大于撂荒地,这为黄土高原地区营造混交林提供了依据.     

自然与人工恢复对川西高山采伐迹地植物群落特征的影响

以天然林为对照,选取自然恢复(40年)与人工恢复(30、40和50年)下川西高山采伐迹地,研究不同恢复途径下川西高山采伐迹地的植物群落特征。结果表明: 采伐迹地经过40年的自然恢复演替成为高山绣线菊次生灌丛,人工恢复后成为川西云杉林,与天然林群落相似性分别为极不相似(0.19)和中等不相似(0.28~0.49)。自然与人工恢复采伐迹地的灌木层物种多样性均低于天然林,而草本层高于天然林。随着恢复年限的增加,人工林胸高断面积、蓄积量、径级幅度、物种多样性指数及与天然林群落的相似性均呈现增加的趋势,而林分密度逐渐减小。人工林面临林分密度较高、结构不合理、同龄纯林和林下更新差等问题。     

植被覆盖对科尔沁沙地土壤生物结皮及其下层土壤理化特性的影响

为了解不同植被覆盖对沙地土壤生物结皮及其下层土壤的影响,于2006年调查了科尔沁沙地冷蒿、小红柳、杨树和樟子松等植被封育区土壤生物结皮及结皮下0～5 cm土壤的理化特性.结果表明：经过15年的封育保护和植被建设,科尔沁沙地天然植被和人工植被下流动沙地大部分被生物结皮所覆盖,其结皮覆盖度可达60%～80%,厚度1～2 cm;在调查的几种植被中,小红柳植被区的土壤结皮厚度、硬度、粘粉粒、有机质和养分含量最高,其次是樟子松林地,杨树林地和冷蒿植被区相对较差;几种植被区的苔藓结皮的结皮厚度、硬度、粘粉粒、有机质和养分含量均优于地衣结皮;与流动沙地相比,结皮下0～5 cm土壤的理化特性有明显改善,改善程度苔藓结皮强于地衣结皮,小红柳和樟子松植被区强于杨树林地和冷蒿群丛;土壤结皮及结皮下表土理化特性的变化既受植被覆盖类型的影响,也受制于土壤结皮的发育.由于枝叶繁茂的中、高植被有利于降风滞尘和产生较多的凋落物,因而更能促进沙地结皮发育和土壤改良,而苔藓结皮较地衣结皮更有利于其下层土壤理化特性的改善.     

Effects of stand age, wildfire and clearcut harvesting on forest floor in boreal mixedwood forests

Carbon (C) in the forest floor (FF) of the boreal region is an important reservoir of terrestrial C. We examined the effects of stand age and disturbance type (clearcutting vs. wildfire) on quantity and quality of organic C of FF in a boreal mixedwood forest of central Canada. Forest floor samples were collected from 6 post-fire (2- to 203-year-old) and 3 post-harvest age classes (2- to 28-year-old) on mesic sites, each randomly replicated three times. Samples were analyzed to determine the physical and chemical properties and the C quality was assessed by quantifying C fractions as easily labile, moderately labile and recalcitrant. Bulk density, total organic C concentration, N concentration and the cation exchange capacity increased with stand age and peaked at 85-year-old sites. Soil pH and concentration of P and K decreased with stand age. In post-fire stands, the depth of FF, total organic C, and labile C fractions increased with stand age in the 2- to 85-year-old stands, while recalcitrant C was lower in 2-year-old stands than older stands. In stands ≤28 years old, post-harvest sites had significantly higher concentration of total organic C and the three C fractions than post-fire sites in 2-year-old stands. No or marginal difference occurred between the two stand origins in 10- and 28-year-old stands. The relative proportions of C fractions did not differ with stand age or stand origin. Our results showed that the quantity of organic C in FF of boreal mixedwoods increased with stand development till 85 years and then slightly decreased in older stands, and post-harvest stands had a higher amount of organic C than post-fire stands immediately after disturbance, but the effect of two disturbances on C in FF converged shortly (within 10 years). The quality of organic C remains the same through stand development and between the two studied stand origins.     

Biomass and nutrient concentrations of sporocarps produced by mycorrhizal and decomposer fungi in Abies amabilis stands

Summary Sporocarps and sclerotia were collected for a one-year period in 23- and 180-year-old Abies amabilis stands in western Washington. All sporocarps were classified and chemically analyzed for N, P, K, Ca, Mg, Na and Fe. Lactarius sp. and Cortinarius sp. contributed the largest proportion of the total annual epigeous sporocarp production in both stands. Annual epigeous production was 34 kg/ha in the young stand and 27 kg/ha in the mature stand. Hypogeous sporocarp production increased from 1 kg ha^-1 yr^-1 to 380 kg ha^-1 yr^-1 with increasing stand age. High sclerotia biomass occurred in the young (2,300 kg/ha) and mature (3,000 kg/ha) stands. Peak sclerotia and epigeous sporocarp biomass in the young stand and epigeous and hypogeous sporocarp biomass in the mature stand coincided with the fall peak of mycorrhizal root biomass.In the young stand, sporocarps produced by decomposer fungi concentrated higher levels of Ca and Mn than those produced by mycorrhizal fungi. In the mature stand, sporocarps of decomposer fungi concentrated higher levels of N, P, Mn, Ca and Fe than sporocarps of mycorrhizal fungi. Epigeous and hypogeous sporocarps concentrated higher levels of N, P, and K than sclerotia or mycelium. The highest concentration of N (4.36%), P (0.76%), K (3.22%) and Na (1,678 ppm) occurred in epigeous sporocarps. Highest Mn (740 ppm) and Ca (20,600 ppm) concentrations occurred in mycelium, while highest Mg (1,929 ppm) concentrations were in hypogeous sporocarps and highest Fe (4,153 ppm) concentrations were in sclerotia.