[Objective]This study aims to explore the effects of different concentrations of graphene on the enzyme activities and microbial diversity in rhizosphere soil of Cunninghamia lanceolata seedlings,thus providing reference for the efficient cultivation of high-quality Cunninghamia lanceolata seedlings.[Method]Taking one-year-old Cunninghamia lanceolata clone“Yang 061” as the research object,a pot experiment was conducted on the basis of applying 30 g compound fertilizer to every treatment,the effects of 30（T1）,25（T2）,20 mg/L（T3） graphene on soil enzyme activities,as well as microbial diversity were analyzed,the correlation and RDA analysis were also performed.[Result]With the increase of graphene concentration,the activity of urease,nitrate reductase,nitrite reductase and glutaminase in rhizosphere soil of cunninghamia lcunninghamia seedlings was enhanced,which showed a trend of promoting low level and inhibiting high level.The activities of four enzymes in T3 treatment were 6.87%,59.32%,2.65% and 12.75% higher than those in the control respectively,which showed a pattern of T3＞T2＞CK＞T1,there was a significant difference in nitrate reductase activity among different treatments（P＜0.05）;After graphene treatment,the rhizosphere soil microbial diversity of cunninghamia lcunninghamia seedlings was generally higher than that of the control,the highest microbial diversity index was found in T3 treatment.Among them,the Shannon and Simpson indices of bacteria were not significantly different among different concentration treatments and controls（P＞0.05）,while the Shannon and Simpson indices of T3 and T2 treated fungi were increased by 18.39% and 11.53%,T1 was decreased by 14.75%,and the size order was T3＞T2＞CK＞T1,which was significantly different from the control（P＜0.05）.The Chao1 and Ace indices of bacteria except T1 were significantly different in the control（P＜0.05）.The effect of Graphene on fungal diversity was more significant than that on bacterial diversity. Correlation analysis showed that nitrate reductase activity was positively correlated with bacterial Chao1 and Ace indices.There was a significant positive correlation between urease activity and fungal Shannon index,and a significant positive correlation between nitrite reductase activity and fungal Shannon and Simpson index,and a significant or extremely significant correlation between nitrate reductase activity and fungal diversity index.Soil urease and nitrate reductase are important factors causing microbial diversity change.[Conclusion]20 mg/L graphene can improve the rhizosphere soil enzyme activity and microbial diversity of cunninghamia lcunninghamia seedlings,promote the turnover of nutrients,improve the uptake and utilization of nutrients,and ultimately promote the growth of cunninghamia lcunninghamia seedlings.

地形是影响土壤酸酸类物质含量及微生物结构组成的主要因子之一,研究酚酸物质在不同地形中的变化规律及其与微生物群落结构的关系,有助于更好地揭示不同地形下土壤微生物群落结构变化潜在调控机制.以往研究主要集中于地形对微生物群落结构影响,而关于地形对土壤酚酸物质累积及其微生物群落结构间相互影响的研究鲜有报道.以福建省南平市100 a年生杉木林为研究对象,测定西南坡地、西北坡地、山凹地和山洼地上酚酸物质含量和土壤理化性质,并结合16S和ITS技术分析不同地形中土壤细菌和真菌群落结构的变化规律.结果表明:(1)不同地形土壤酚酸物质含量大小规律总体表现为西北坡地>西南坡地>山凹地>山洼地;随着土层深度加深,酚酸物质含量总体呈下降趋势.(2)西南坡地细菌放线菌纲相对丰度较高,山凹地真菌粪壳菌纲相对丰度较高;随土层深度加深,微生物相对丰度总体上呈降低趋势.(3)高浓度酚酸物质对细菌类浮霉菌纲和α-变形杆菌纲相对丰度起促进作用,而对放线菌纲和 β-变形菌纲相对丰度起抑制作用;低浓度酚酸物质条件下真菌类粪壳菌纲和座囊菌纲相对丰度较高,而伞菌纲和定耳银纲相对丰度较低.(4)不同地形条件下,细菌群落结构表现较为分散,而真菌群落结构表现较为集中;土壤总孔隙度、土壤容重、水杨酸戊酯、有机质和阿魏酸对细菌群落影响显著,而全磷对真菌群落影响显著.不同地形导致土壤酚酸物质含量和微生物群落结构发生改变,酚酸物质对微生物具有双重作用,高浓度酚酸物质促进细菌菌类生长,而低浓度则会抑制真菌类生长.研究结果揭示土壤酚酸物质对微生物群落结构的影响,可为实现杉木林的长期生产力维持提供参考.

以1年生杉木优良无性系"洋061"作为试验材料,采用室内盆栽方法,在统一施同量复合肥的基础上,分析添加不同浓度石墨烯(30、25、20、0 mg·L-1)对杉木幼苗光合色素、叶绿素荧光特性及养分积累的影响.结果表明不同石墨烯处理下杉木幼苗养分含量均表现为叶显著高于根和茎,全磷和全钾含量随培育时间的增加呈下降趋势;20 mg·L-1石墨烯处理有利于杉木叶养分含量的积累,25 mg·L-1石墨烯处理有利于杉木茎养分含量的积累,30 mg·L-1石墨烯处理有利于杉木根养分含量的积累.不同浓度石墨烯处理下杉木叶绿素a(Chlorophyll a,Chla)、叶绿素b(Chlorophyll b,Chlb)、类胡萝卜素(Carotene,Car)含量,以及可变荧光值(variable fluorescence,Fv)、潜在活性(potential activity,Fv/Fo)均存在显著差异.与对照相比,石墨烯处理杉木光合色素和叶绿素荧光特性普遍较高,其中30 mg·L-1石墨烯处理的初始荧光值(minimal fluores-cence,Fo)、Fv和最大荧光值(maximal fluorescence,Fm)最高,20 mg·L-1石墨烯处理的Chla含量和Fv/Fo最高,25 mg·L-1石墨烯处理的Chlb、Car含量和光能转化效率(photochemical efficiency,Fv/Fm)最高.杉木幼苗全氮含量与全磷、全钾含量之间,Car含量与Chla、Chlb含量之间,Fo、Fm、Fv之间,呈极显著正相关(P<0.01),全磷含量与全钾含量之间,Chlb含量与Chla含量之间,Fv/Fo与Fm、Fv/Fm与全钾含量之间呈显著正相关(P<0.05).表明一定浓度的石墨烯有利于杉木幼苗的养分积累及光合作用.

[目的]探究石墨烯对杉木幼苗生长、根系形态及N素吸收利用的影响,为杉木高效培育奠定理论依据.[方法]以1年生杉木优良无性系"洋061"为试验材料,采用盆栽试验及15N示踪技术,测定不同浓度石墨烯(0、20、25、30 mg·L?1)处理的杉木幼苗生长、根系形态指标及15N分配率和利用率.[结果]在杉木幼苗的生长和根系形态指标中,除茎干质量和根体积外,其余指标均表现为25 mg·L?1石墨烯浓度的处理最大,但各处理间差异不显著;杉木全株15N利用率表现为25 mg·L?1>20 mg·L?1>30 mg·L?1>CK1,15N分配在杉木幼苗各器官表现为叶>茎>根;根15N分配率、全株15N利用率与根系形态的相关性显示,除根长、根体积、根15N分配率与根直径呈负相关外,其他各指标间均呈极显著正相关.[结论]一定浓度的石墨烯有利杉木幼苗生长,并能促进N素吸收利用.

杉木种子园为培育高产稳产杉木良种提供重要保障,在林业生产中具有积极意义.通过试验研究,探究杉木3代种子园土壤养分丰缺情况、养分间的平衡规律,确定杉木种子园最佳肥料配比和施肥量,以期为闽北低山丘陵红壤分布区杉木种子园提供推荐施肥配方.采用"3414"配方施肥设计方案,对闽北第3代杉木种子园开展N、P、K、Ca、Mg、B、Mo等元素施肥试验.分别设计大量元素氮、磷、钾三因素施肥水平(并增设施用钼肥处理)、中微量元素钙、镁、硼三因素施肥水平,以球果数量(质量)、出籽率、种子产量、胸径等为评价指标,拟合肥料效应函数方程,研究各养分间的作用规律,并提出最佳施肥配比和施肥量.结果表明:种子园土壤N、P、K、Ca、Mg养分含量较低,B含量属于中等水平,而Mo含量较高;N、P、Mg以及N-K、Ca-B肥料联合对种子园产量的影响达到显著或极显著水平,而单施某一肥料效应较小,其中单施K、Ca、B几乎没有效果,而肥料联合施用效果较好.综合效应分析结果,得出种子园最大产量施肥量组合为:每株施尿素100 g+过磷酸钙897 g+氯化钾150 g+石灰150 g+硫酸镁105 g+硼砂75 g,并配施钼肥.N、P2O5、K2O、CaO、Mg、B、Mo的用量依次为46.0、107.7、90.0、75.0、31.4、2.3、5.0 g,其配比为N:P2O5:K2O:CaO:Mg:B:Mo=1.0:2.3:2.0:1.6:0.7:0.05:0.1.多元素配方施肥能很好地改善杉木种子园产量和质量,单株球果产量、球果单粒重、出籽率及种子园产量等指标均比不施肥的母树有大幅度提高.本研究施肥方案,理论上种子园产量可达45.99～95.65 g/株,大量元素施肥试验的产量达到理论产量的80％～86％,中微量元素施肥试验的产量为理论产量的70％左右.现实种子园平均产量大约是预测产量的40％,通过合理配方施肥有望大幅度提高杉木3代种子园产量.

以福建省南平市王台镇100年生人工杉木林为研究对象,分析4种地形(西南坡地、西北坡地、山凹地、山洼地)0～20、20～40、40～60 cm处的土壤理化性质及林下植被多样性的差异,采用方差分析法分析地形因素对两类指标的影响,采用相关性分析方法分析两类指标间的内在联系.结果表明:同一土层下非毛管孔隙度、全磷、速效磷和速效钾受地形影响显著,总孔隙度和有机质多无显著影响,且非毛管孔隙度、有机质、全氮和速效钾总体表现在西南坡地最高,速效磷在山凹地最高,全磷等理化性质均表现在山洼地最高,西北坡地的土壤理化性质相对较低.4种地形下林分土壤除容重、全磷和全钾外,含水率等理化性质多随土层加深呈下降的趋势;相较草本层,灌木层多样性指数变化更为明显,且灌木层及草本层均表现为西北坡地最高,其次是西南坡地和山凹地,山洼地最低;该林分土壤含水率、毛管孔隙度、全磷及速效钾与灌木层及草本层林下植被多样性关系密切,且存在显著或极显著相关.可见,不同地形下土壤理化性质和植被多样性受地形影响较大.

为探究不同C/N比对杉木凋落叶分解特性的影响,通过添加外源氮,采用分解袋法,分析林下植被保留和林下植被去除2种林分中不同C/N比值的杉木凋落叶分解300 d时细菌群落结构差异。研究显示:一定范围内,初始C/N比降低有利于杉木凋落叶分解和细菌群落多样性提升,过低的C/N比则具有抑制作用;相比于林下植被去除,林下植被保留管理措施更有利于杉木凋落叶的分解,且细菌群落多样性更高,但当初始C/N比值为20.3时,杉木凋落叶分解所受的抑制作用更为明显;在门水平上,变形菌门、放线菌门和浮霉菌门为杉木凋落叶中主要优势种群;在属水平上,慢生根瘤菌属、嗜酸栖热菌属和Singulisphaera属在杉木凋落叶中相对丰度较高;不同处理间的杉木凋落叶细菌群落结构具有显著差异,变形菌门、放线菌门和酸杆菌门等细菌门中的多类细菌相对丰度差异显著;在门分类水平上,杉木凋落叶C/N比值与主要细菌种群相对丰度的相关性最高,C/P比值与杉木凋落叶细菌群落结构变异的相关性最高;在属水平上,杉木凋落叶全碳含量、C/N比值和全钾含量与主要细菌种群相对丰度的相关性最高,全钾含量与杉木凋落叶细菌群落结构变异的相关性最高。结果表明初始C/N比的降低改变了杉木凋落叶细菌群落结构,进而作用于杉木凋落叶的分解。

[目的]铁元素在植物生长发育过程中需求量最大,在植物光合作用、叶绿素合成以及呼吸过程等生理活动中起着重要的作用.但当铁浓度超过植物所需的正常水平时,会对植物产生胁迫作用,不利于其生长发育.探究不同供铁水平对杉木幼苗内在生理机制的影响,为杉木人工林的科学经营提供理论依据.[方法]以1年生杉木幼苗为研究对象,通过室内砂培盆栽试验,在改良霍格兰完全营养液:铁浓度分别为20 mg/kg(T1)、30 mg/kg(T2)、40 mg/kg(T3)条件下,以常规霍格兰完全营养液为对照(CK),测定其15,30,45,60 d时杉木幼苗叶片叶绿素含量、荧光参数、丙二醛含量和抗氧化酶活性的变化.[结果]随处理浓度增加,叶绿素b和叶绿素a+b含量呈现先升高后降低的趋势,而叶绿素a/b含量表现出先降低后升高.在45 d、60 d时,T1、T2、T3叶绿素a含量均与CK处理间达显著性差异(P<0.05).F0含量随着铁浓度的升高也不断升高,而Fm、Fv/Fm、Fv/F0和Fm/F0则呈现不断下降的趋势,在处理30 d时,T3处理下的Fm、Fv/F0、Fm/F0相较于CK处理而言降低最明显,且CK处理下的Fm、Fv/F0和Fm/F0与T1、T2、T3处理达显著性差异(P<0.05),F0和Fv/Fm含量未达显著差异(P>0.05).不同铁浓度处理下的丙二醛含量均高于CK处理,随着铁浓度升高,其含量整体呈现降低后升高的趋势.而超氧化物酶、过氧化氢酶和多酚氧化酶活性均以CK处理最高,过氧化氢酶随着铁浓度升高,其活性呈现先降低后升高的趋势,且在15 d时,不同处理酶活性与CK处理间存在显著性差异(P<0.05),而超氧化物歧化酶活性随处理浓度的提升不断降低,但各处理间差异未达到显著水平(P>0.05);多酚氧化酶和过氧化物酶在各个培养时间上,随铁浓度的升高其酶活性未呈现出规律的变化,且在试验期间差异均未达到显著水平(P>0.05).[结论]本研究中当年生叶为新叶,对铁的耐受性较低.营养液中铁处理浓度的增加使杉木幼苗叶片细胞膜系统受到损伤,叶绿素合成减缓,光合作用受阻.

[目的]通过探究不同地形下杉木老龄林土壤活性铝形态特征,为杉木人工林生态系统铝毒害的精细化治理提供理论依据.[方法]以福建省南平市百年杉木林为研究对象,测定了该林分西南坡、西北坡、山凹部和山洼地共4类地形土壤的pH值、全铝、交换性铝、单聚体羟基铝、酸溶无机铝和腐殖酸铝含量.[结果]该林分土壤pH值范围为4.72～5.09,活性铝主要形态为腐殖酸铝和酸溶无机铝,其含量占全铝含量的25.52％～60.35％.随着土层深度的增加,土壤铝活化程度逐渐降低,土壤pH值、全铝和腐殖酸铝含量不断增加,交换性铝、单聚体羧基铝和酸溶无机铝含量则不断减少.4类地形土壤pH值总体表现为山洼地>西南坡>山凹部>西北坡,全铝含量表现为山凹部>西北坡>山洼地>西南坡,全铝中活性铝所占比例以及交换性铝和酸溶无机铝含量表现为西北坡>西南坡>山凹部>山洼地,腐殖酸铝含量表现为西北坡>山凹部>西南坡>山洼地,单聚体羧基铝含量表现为山凹部>西南坡>西北坡>山洼地,山洼地土壤各形态活性铝含量普遍显著低于西北坡.地形和土层对于腐殖酸铝的含量具有显著的交互作用.主成分分析表明西南坡和山凹部之间、西北坡和山洼地之间土壤活性铝形态分布较为相似;相关性分析表明土壤pH值与交换性铝、腐殖酸铝和酸溶无机铝含量具有显著负相关关系,交换性铝、酸溶无机铝和腐殖酸铝含量三者间具有显著正相关关系.[结论]该杉木老龄林4类地形中以西北坡土壤活性铝积累现象最为明显,其次为西南坡和山凹部,山洼地最低.

为探讨绿肥对植烟土壤细菌的影响,以烤烟K326为研究对象,设置CK(不翻压绿肥)、T1(翻压光叶苕子)、T2(翻压黑麦草)和T3(翻压紫云英)等4个处理.结果 表明,与CK相比,T2处理土壤细菌在种分类水平上丰度增加得最多;T1、T2、T3处理明显提高土壤细菌α多样性;旺长期土壤细菌丰度超过2％的属分别是浮霉状菌属(Planctomyces)、假丝酵母菌属(Candidatus Solibacter)、罗丹菌属(Rhodanobacter)、红游动菌属(Rhodoplanes),成熟期土壤细菌丰度超过2％的属为水恒杆菌属(Mizugakiibacter)、Planctomyces、普雷沃氏菌属(Prevotella_9);冗余分析结果表明,旺长期土壤速效钾含量解释了细菌23.50％的变化,成熟期土壤有机质含量解释了细菌群落23.50％的变化;T1、T2、T3处理在旺长期均能显著降低烟草青枯病致病菌(Ralstonia)丰度,T3处理显著增加了旺长期和成熟期土壤中苯基杆菌属(Phenylobacterium)、固氮螺菌属(lnquilinus)、贪铜菌属(Cupriavidus)等3个固氮菌属丰度.说明翻压绿肥可以在一定程度上改善植烟土壤细菌结构.

为探究不同绿肥翻压对植烟土壤酶活性及烤烟的影响,设置了CK(不翻压绿肥)、T1(翻压光叶苕子)、T2(翻压黑麦草)、T3(翻压紫云英)4个处理,结果表明,T1、T2、T3处理的土壤过氧化氢酶活性与CK相比,分别提高了13.39％ ～ 30.65％、4.48％ ～ 38.71％、3.29％ ～ 30.43％,土壤多酚氧化酶活性分别提高了7.92％～61.71％、10.60％ ～ 90.70％、29.41％ ～ 60.68％;烤烟总生物量分别提高了4.83％、1.21％、3.32％,产量分别提高了4.19％、2.40％、3.59％;T1处理更有利于改善团棵期烟株农艺性状,T2处理有利于提高烟株茎围,T3处理提高了烟株中后期最大叶长和最大叶面积;T1、T2处理均提高了B2F(上桔二)与C3F(中桔三)还原糖含量、总钾含量、糖碱比、氮碱比,T3提高了B2F(上桔二)烟碱含量、总糖含量、还原糖含量、总氮含量、两糖比.综上所述,翻压绿肥可以提高植烟土壤酶活性、烤烟生物量与产量,改善烤烟农艺性状与品质.

探讨杉木在连栽杉木林土壤培养下,其优良无性系根际与非根际土壤酶活性以及根际和根尖酚类物质含量的变化特征及其相互关系,揭示杉木优良无性系对不同连栽代数土壤培养的响应机理,以不同连栽代数杉木人工林土壤为培养基质,栽植杉木无性系幼苗2 a后,采用抖落法取根际和非根际土壤测定相关酶活性和根际酚类物质含量,并剪取0～2 cm根尖测定酚酸类物质含量.结果 表明,在杉木根际土壤和非根际土壤中的脲酶、蔗糖酶、过氧化氢酶及酸性磷酸酶活性总体上随连栽代数增加呈下降的变化趋势,而多酚氧化酶活性呈上升的变化趋势.杉木优良无性系根际土壤中共鉴定出11种酚类物质,其中阿魏酸、没食子酸和咖啡酸相对含量较高,是最主要的酚类物质.没食子酸相对含量随连栽代数增加而增多,阿魏酸含量表现为先降后升,但均高于对照,而咖啡酸则表现为先升后降,其含量均低于对照,且三者在三代林中的含量均高于一代林;杉木根尖中共鉴定出8种酚类物质,其中儿茶素、奎尼酸和山奈酚相对含量较高.儿茶素含量逐代下降,二代林和三代林中其含量均高于对照;山奈酚含量逐代增加,而不同连栽代数中其含量均低于对照;奎尼酸含量表现为先升后降,而不同连栽代数中其含量均高于对照.相关性分析表明,鞣花酸、奎尼酸与酸性磷酸酶呈显著负相关,龙胆酸与酸性磷酸酶呈极显著正相关,芦丁、龙胆酸与多酚氧化酶呈显著负相关,鞣花酸与多酚氧化酶呈显著正相关,没食子酸与脲酶呈显著负相关;槲皮素、芦丁和香草酸与脲酶呈显著正相关,对香豆酸和山奈酚与蔗糖酶呈显著正相关.综上所述,杉木连栽可能会通过改变杉木根尖和根际土壤中酚类物质的积累来影响土壤酶的活性,进而影响杉木对养分的吸收利用,最终导致杉木连栽障碍的发生.

To reveale the response mechanisms of different allelopathy types of Chinese fir clones on continuous cropping soil, Chlorophyll content[Chla, Chlb, Chl(a+b), Chla/Chlb], chlorophyll fluorescence parameters(Fo, Fm, Fv, Fv/Fm, Fv/Fo), antioxidant enzymes ( SOD, CAT, POD, PPO) activity and malondialdehyde ( MDA) content was investigated in different planting generations of Chinese fir plantation soil medium which was cultivated 1-year-old Chinese fir clones through pot experiment method. The results showed:(1) Compared with the CK, Chla, Chlb, Chl(a+b), Fm, Fv, Fv/Fm, Fv/Fo of Chinese fir clones declined with the increasing successive rotation, Chla/Chlb, Fo , antioxidant enzyme activity and MDA rose with the increasing successive rotation. (2) In the same forest types of soil, the value of endurance clones was higher than sensitive clones in chlorophyll content, chlorophyll fluorescence, however, endurance clones was lower than sensitive clones in antioxidant enzyme activity and MDA. Different Cunninghamia lanceolata clones existed significant difference in the same stand′s soil. ( 3) Correlation analysis between chlorophyll content and chlorophyll fluorescence parameters of Cunninghamia lanceolata showed that Chla, Chlb and Chl(a+b) was negatively correlated with Fo , significantly positive correlated with Fv/Fo;Chla/Chlb was negatively correlated with Fv , Fv/Fm , Fv/Fo .

[Objective]The responses of soil microbes to decomposition of Chinese fir-Michelia macclurei litter with different compositions were analyzed to provide scientific basis for the sustainable management and development of Chi-nese fir plantations in South China.[Method]In 4-,15-and 32-year Chinese fir plantations in typical southern acid rain region,Shaowu,Fujian,five litter decomposition treatments were set:Chinese fir leaf(C),M. macclurei leaf(M),Chi-nese fir leaf:M. macclurei leaf=2:1(C2M1),Chinese fir leaf:M. macclurei leaf=1:1(C1M1)and Chinese fir leaf:M. macclurei leaf=1:2(C1M2). The difference in soil microbial biomass carbon content(SMBC),soil microbial biomass nitrogen content(SMBN)and soil microbial biomass carbon-to-nitrogen ratio(SMBC/SMBN)of soil at 0-5 cm layer were studied by net bag method.[Result]SMBC of 4-and 15-year Chinese fir plantations were at the peak in C2M1 and C1M1 treatments respectiverly,and the contents were significantly higher than single composition treatments C and M(P<0.05, the same below). For 32-year Chinese fir plantation,differences in SMBC among treatmemnts changed as time passed. For 4-, 15-and 32-year Chinese fir plantations, difference of SMBN between mixed litter and single litter altered as time varied. SMBC/SMBN of different plant ages changed greatly at different decomposition periods,and reached the mini-mum on day 120 and 240 of decomposition. Soil temperature and moisture content had significant effects on SMBC and SMBN in the 4- and 15-year Chinese fir plantations,but had insignificant influence on 32-year Chinese fir plantation. SMBC and SMBN of different plant ages were significantly correlated with soil pH. Variance analysis indicated that,in-fluenced by plant age,Chinese fir leaf-M. macclurei litter composition and decomposition time,SMBC and SMBN of each plantation presented wave shape variation during the whole decomposition procedure. SMBC reached the peak on day 60 and 240 after decomposition,and SMBN reached the top on day 120 and 240.[Conclusion]The improvement of young and middle age Chinese fir plantation can be mixed with Chinese fir-M. macclurei 2:1 and 1:1 respectively. In actual planting,the selection of Chinese fir-M. macclurei composition should take plant ages,soil pH,soil temperature, moisture content and seasonal variation into consideration.

In the 4-,15-and 32-year artificial forest of Cunninghamia laneolata,the net bags of different ratio C.laneolata and Michelia macclurei litterfalls and blank control plots were conducted.Biolog technique was used to analyze the microbial diversity index and the carbon metabolism diversity in 0～ 5 cm soil layer under different proportioned litterfalls,and to study the effects of different proportioned litterfalls on the carbon source utilization and microbial diversity of soil microbes.The result showed that the total soil microbial metabolic activity (average well color development,AWCD) was 32 a＞ 15 a＞4 a.The total metabolic activity under C1M2 treatment in the 4-year topsoil was the highest than other treatments.The difference of Shannon and Simpson index in topsoil was not significant,and the effect of C1M2 (P=0.001) on McIntosh index of soil microbial was significant.The main types of carbon source utilization in those plantations were carbohydrate,polymer and amino acid,which was under C2MI and C treatments were clustered into one group,but under C1M2, C1M1 and M treatments in the 15-,32-year stands were clustered into another group.

以宁化县紫色土区不同林龄马尾松人工林、杉木人工林及阔叶林3种森林类型为研究对象,在调查生长量及林下植被的基础上,分析了不同森林类型土壤理化性质的差异.结果表明:随着土层深度的增加,紫色土区不同森林类型土壤非毛管孔隙度、毛管孔隙度、有机质、全N、速效K、有效P含量均呈下降趋势,而土壤容重呈上升趋势;随着林龄的增加,马尾松人工林土壤非毛管孔隙度、毛管孔隙度、有机质含量、全N含量及有效P含量呈现先增加后降低的趋势,杉木人工林则呈降低的趋势.就不同林分类型土壤化学性质差异而言,在中林龄阶段,土壤pH值及有效P含量表现为:马尾松人工林>阔叶林>杉木人工林,有机质含量及全N含量表现为:马尾松人工林>杉木人工林>阔叶林,速效K含量表现为:阔叶林>马尾松人工林>杉木人工林;在成熟林阶段,土壤有机质含量、全N含量、速效P含量表现为:马尾松人工林>阔叶林>杉木人工林,速效K含量表现为:阔叶林>杉木人工林>马尾松人工林.

By mixing thoroughly litters of Cunninghamia lanceolata and Michelia macclurel from acid rain region in different propor-tions ( A 1:0,B 0:1,C 1:1,D 1:2,E 2:1) , litter decomposition rate and enzyme activity of litter and topsoil were measured. The results showed that after 300-day decomposition, decomposition rates of litters in different proportions increased as follows: B (27.93%)>D(25.99%)>E(24.55%)>C(21.78%)>A(21.07%), and enzyme activities of litters were always higher than those of topsoil. The cellulose activity of litters peaked on day 180 and hit bottom on day 300, while there was no obvious tendency in the variations of other enzyme activities. The enzyme activity of topsoil varied significantly during decomposition period, with acid phos-phatase minimizing on day 120 and peaking on day 300. Cellulose and sucrose activities decreased along decomposition time, and reached the lowest level on day 300. The litter decomposition rate was positively correlated with litter polyphenol oxidase and acid phosphatase activity, and negatively correlated with cellulase activity and sucrase activity in both litter and topsoil.

The dynamics of soil base cations content in different-age Chinese fir plantations in acid rain region were analyzed to study the dynamic law of soil base cations under the background of acid rain. The results showed as follows. The soil base cations were closely related with seasons, forest ages, soil depth. In different seasons, the content of K+and Na+had significant differences in different seasons as those were higher in summer and autumn than in spring and winter (P<0.05) at the same soil depth in the same forest age, while the content of Ca2+and Mg2+were higher in spring or summer than in autumn and winter. In the same season, the content of K+ and Na+ increased from 1 to 5 a, then decreased from 5 to 15 a and increased again from 15 to 20 a, and the content of Ca2+ and Mg2+showed the different trend that rose from 1 to 10 a, and declined from the 10 to 20 a at the same soil depth. With the increase of the soil depth, the content of soil base cations in different age Chinese fir plantations tended to decrease.

在测定土壤理化性质的基础上,应用Biolog-ECO技术,分析杉木1代(FCF)、连栽2代(SCF)、连栽3代(TCF)人工林和楠木人工林(PBP,对照)4种林分类型土壤微生物群落总碳源利用动力学特性、微生物多样性指数及多样性指数与土壤理化性质的相关关系.结果显示:4种林分类型的土壤微生物丰富度(Shannon指数)、优势度(Simpson指数)、均匀度(McIntosh指数)均达到了显著差异(P＜ 0.05);PBP土壤微生物总体活性(AWCD)、Shannon指数、Simpson指数及McIntosh指数值均高于其他3种类型;土壤微生物生物量碳(C)含量、氮(N)含量、Shannon指数、Simpson指数与AWCD值的相关性达到了显著水平(P＜0.05);其中AWCD值、土壤pH、全C、全N、土壤微生物生物量C、N的大小顺序为PBP＞ FCF＞ SCF＞ TCF.本研究表明,随着杉木连栽代数的增加,土壤微生物群落总体活性逐代下降.

Seasonal dynamics of the chronosequence soil enzyme activities in different tree ages of Cunninghamia lanceolata planta-tion in acid rain area was investigated .In addition, the correlation between nutrients and enzyme activities in soil was also analyzed . The results indicated as follows .( 1 ) The soil pH increased with the depth of soil .Soil nutrient contents and enzyme activities declined with the depth of soil.(2) The activities of polyphenol oxidase , peroxidase, catalase in the mature plantation were higher than those in the middle plantation and young plantation , and the tend of sucrase activity firstly increased and then decreased with the tree ages.(3) The activities of sucrase, polyphenol, oxidase in spring, winter and autumn were higher than those in summer;the activity of urease in autumn was higher than that in spring , summer and winter; the activity of catalase showed the following trend:summer>autumn>spring and winter , with non-significant difference between spring and winter;the activity of peroxidase in autumn was significantly lower than that in winter , spring and summer.(4) Soil enzyme activities had significant negative correla-tion with soil pH, and had significant positive correlation with soil total nitrogen , total phosphorus, hydrolyzable nitrogen, available phosphorus , available potassium , organic matter content .