米槠人促更新林与杉木人工林叶片及凋落物溶解性有机物的数量和光谱学特征

选取中亚热带米槠人促更新林(CCF)和杉木人工林(CLP)内的鲜叶、未分解层(L层)和半分解层(F层)凋落物为研究对象进行室内淋溶,对其淋溶液中的溶解性有机碳(DOC)、溶解性有机氮(DON)和溶解性有机磷(DOP)含量,紫外吸收值(SUVA),腐殖化指标(HIX)和红外光谱(FTIR)等进行了比较分析,以揭示其淋溶液中溶解性有机物(DOM)的数量和光谱学特征。结果表明:随着淋溶时间的增加,不同样品的DOM含量呈现先上升后下降,或者有波动的上升的趋势,这是因为DOM的释放和反吸附共同控制着DOM的含量。两林分中,F层凋落物DOM的SUVA值显著高于鲜叶和L层凋落物(P0.05);从鲜叶到L层到F层凋落物,其HIX逐渐变大并且三者荧光强度最大值对应的波长由短波向长波移动,这是腐殖化程度越来越高、电子共轭体系逐渐增大的体现。两个林分6种样品的红外光谱显示了5个相似的吸收谱带,但不同样品各吸收带的相对比例不同,强度最大的吸收来自于H键键合的—OH的伸缩振动;同一林分内3种样品之间红外吸收的差异证明了鲜叶到L层再到F层凋落物,其DOM的芳香类物质含量逐渐升高,化学键力常数变小。总体上,与杉木人工林相比,米槠人促更新林的DOM养分含量更高,结构更复杂,因而更有利于有机质的积累。     

马尾松与芒萁鲜叶及凋落物水溶性有机物的溶解特征和光谱学特征

为探讨福建省三明市马尾松人工林淋溶液中水溶性有机物(DOM)的溶解特征和光谱学特征,以马尾松(Pinus massoniana)和芒萁(Dicranopteris dichotoma)鲜叶、未分解层(L层)和半分解层(F层)凋落物为研究对象进行室内淋溶,对淋溶液中的水溶性有机碳(DOC)、水溶性有机氮(DON)与水溶性有机磷(DOP)含量和紫外光谱(SUVA)、荧光光谱指标和红外光谱(FTIR)等特征进行研究。结果表明,在24 h内,随着淋溶时间的延长,DOM含量呈现有波动的上升趋势;芒萁除鲜叶的DOC含量显著高于马尾松外(P0.01),其余DOM含量均小于马尾松。两植物F层DOM的SUVA值和腐殖化指标(HIX)都显著高于鲜叶和L层(P0.05),表明F层的芳香性化合物含量和腐殖化程度越来越高。DOM的同步荧光峰值显示淋溶液中含有类蛋白和类富里酸荧光团。两植物的红外光谱显示有5个相似的吸收谱带,强度最大的吸收来自于H键键合的-OH的伸缩振动,同一植物3种样品之间红外吸收的差异证明从鲜叶-L层-F层凋落物的共轭体系逐渐增大,结构更复杂。因此,随分解进程两植被DOM的化学结构越来越复杂;马尾松较芒萁含有更多的DON和DOP,这一方面为微生物提供了更多的养分,另一方面又增加了底物分解的难度。     

格氏栲天然林与人工林凋落物数量、养分归还及凋落叶分解(英文

通过对中亚热带格氏栲天然林(natural forest of Castanopsis kawakamii。约150年生)、格氏挎和杉木人工林(monoculture plantations of C．kawakamii and Cunninghamia lanceolata,33年生)凋落物数量与季节动态、养分归还及凋落叶分解与其质量的关系为期3a的研究表明。林分年均凋落量及叶所占比例分别为：格氏栲天然林11．01t／hm^1。59．70t／hm^2;格氏栲人工林9．54％。71．98％;杉木人工林5．47t／hm^2。58．29％。格氏栲天然林与人工林凋落量每年只出现1次峰值(4月份)。而杉木林的则出现3次(4或5月份、8月份和11月份)。除杉木林的Ca和格氏栲人工林的Mg年归还量最大外。N、P、K及养分总归还量均以格氏栲天然林的为最大。杉木人工林的最小。分解la后格氏栲天然林中格氏栲叶的干重损失最大(98．16％)。杉木叶的最小(60．78％)。C／N及木质素／N比值与凋落叶分解速率呈显著负相关。而N、水溶性化合物初始浓度与分解速率呈显著正相关。与针叶树人工林相比,天然林的凋落物数量大、养分归还量高、分解快。具有良好自我培肥地力的能力。因此。保护和扩大常绿阔叶林资源已成为南方林区实现森林可持续经营的重要措施之一。     

杉木和米槠凋落叶DOM对土壤碳矿化的影响

DOM(Dissolved organic matter)是土壤微生物呼吸的重要底物,凋落物淋溶的DOM对土壤碳矿化具有重要影响。选择中亚热带地区具有代表性的杉木(Cunninghamia lanceolata)和米槠(Castanopsis carlesii)凋落叶作为研究对象,通过两个月的短期室内培养,把不同凋落叶浸提出的DOM添加到培养瓶中,定期测定土壤碳矿化速率,计算土壤碳累积矿化量,探讨两种等浓度等量DOM添加对土壤碳矿化的影响,并分析DOM化学性质在土壤碳矿化过程中的重要性。结果表明:米槠凋落叶浸提得到的DOC(Dissolved organic carbon)和DON(Dissolved organic nitrogen)浓度均显著高于杉木凋落叶的(P0.05),而杉木凋落叶浸提得到的DOM的UV吸收值(SUVA_(254))和HIX(Humification index)均显著低于米槠凋落叶的(P0.01)。添加等浓度等量杉木和米槠凋落叶DOM到土壤中均显著增加了土壤碳矿化速率,在第1天内分别比对照高198%和168%,3d后下降到61.8%和44.1%,14d后基本处于平稳状态,表明外源有机物添加对土壤碳矿化的前期影响较大。培养过程中,添加杉木和米槠凋落叶DOM的土壤碳矿化累积量均能采用双因素指数模型进行拟合(r~2=0.99),但添加两者凋落叶DOM后土壤碳矿化累积量没有显著差异。     

米槠常绿阔叶次生林和杉木人工林穿透雨和树干径流可溶性有机质浓度和质量的比较

以中亚热带米槠常绿阔叶次生林和杉木人工林为研究对象,定位观测了穿透雨和树干径流中可溶性有机质(DOM)浓度的变化,分析了DOM腐殖化程度和芳香性特征.结果表明: 研究区米槠次生林穿透雨可溶性有机碳(DOC)浓度的变化幅度明显高于杉木人工林,且前者DOC浓度显著高于后者,相比大气降水DOC浓度,分别增加了7.2和3.2倍.杉木人工林树干径流DOC浓度约为米槠次生林的2.5倍,且两种林分树干径流DOC浓度均呈现旱季高于雨季的趋势.相关分析结果显示:米槠次生林和杉木人工林树干径流DOC浓度均与其相应的水量呈极显著负相关.米槠次生林穿透雨DOM腐殖化程度和芳香性均显著高于杉木人工林;相反,杉木人工林树干径流DOM腐殖化程度和芳香性均显著高于米槠次生林.说明米槠次生林穿透雨中DOM结构较复杂且具有较多的芳香族化合物,而杉木人工林树干径流中DOM结构复杂于米槠次生林.米槠次生林和杉木人工林穿透雨和树干径流的DOM数量和质量具有明显差异,对土壤有机碳的积累可能产生重要影响.     

广西主要人工林凋落物分解过程及其对淋溶水质的影响

为探讨不同人工林各组分凋落物分解过程特征及其释放物质对淋溶水质的影响,恒温(28 ℃)培养条件下,在室内人工定期淋水模拟自然环境中凋落物的淋溶过程,对1年生和4年生尾巨桉、7年生杂交相思、13年生马尾松以及软阔林5种人工林的凋落叶、凋落枝、凋落皮进行255 d的模拟淋溶.结果表明：1年生和4年生尾巨桉各组分凋落物分解0～105 d的淋溶液色度和化学需氧量（COD）、总N和总P含量显著高于杂交相思、马尾松、软阔林,淋溶液pH值显著低于其他3种林分人工林;至255 d,1年生和4年生尾巨桉凋落叶淋溶液的COD累积量（193.9和212.8 g·kg^-1）分别是杂交相思、马尾松、软阔林的4.2、4.0、4.3倍和5.3、4.4、4.7倍;1年生尾巨桉凋落叶质量损失率、N和P淋失率显著大于杂交相思、马尾松和软阔林,凋落皮显著大于马尾松,而凋落枝与后三者基本相当.1年生尾巨桉凋落叶和凋落皮比4年生尾巨桉更易被分解淋溶,但凋落枝差异不显著.5种林分凋落物不同组分间,凋落叶最易被分解淋溶,凋落枝难于被分解淋溶.尾巨桉凋落物淋溶液pH值与色度、COD含量呈显著负相关,COD与色度、总N和总P呈显著正相关.     

雪被期川西高山林线交错带凋落物可溶性有机碳的淋失特征

凋落物可溶性有机碳(dissolved organic carbon,DOC)是土壤DOC的主要来源之一,同时,凋落物DOC的淋失过程是生态系统碳循环的重要环节。本文采用凋落物分解袋法,于2012年10月—2013年5月,以川西高山林线交错带12种代表性植物的凋落物为材料,研究了冬季雪被期凋落物DOC在暗针叶林森林、高山林线和高山草甸3种分解生境中的淋失特征。结果表明:1)凋落物初始DOC含量为22.78~178.8 g·kg-1,物种间差异显著;2)经过一个雪被期(182 d),凋落物DOC淋失率为18.92%~62.33%,各物种DOC的淋失率对分解生境的响应差异较大;3)分解生境差异对凋落物DOC的淋失产生了显著影响,暗针叶林生境中凋落物DOC的淋失率显著高于林线和高山草甸生境;4)雪被是影响冬季高山林线交错带凋落物DOC淋失的主要环境因素。因此,高山林线交错上雪被期DOC淋失的空间变异性主要是景观尺度分布的雪被差异造成的,分解生境中较厚的雪被更利于凋落物DOC的淋失。     

中亚热带森林转换对土壤可溶性有机质数量与光谱学特征的影响

选取中亚热带福建三明格氏栲天然林及其转换而成的木荷、锥栗及福建柏等3种人工林表层土壤(0—10 cm)可溶性有机质(DOM)为对象,对其数量和光谱学特征进行了研究,以探讨森林转换对土壤DOM的影响。结果表明,天然林转换成上述3种人工林后,0—5 cm土壤可溶性有机碳(DOC)浓度显著降低(P0.05),降低程度分别为66.1%,69.9%及29.4%,可溶性有机氮(DON)浓度也有所下降;除福建柏外,其余两种人工林5—10 cm土壤DOC及DON浓度均低于天然林。各林分0—5 cm土壤DOC及DON浓度均高于5—10 cm土层。两个土层中,天然林土壤DOM的芳香化及腐殖化程度均显著高于人工林(P0.05),但荧光效率值低于人工林;荧光光谱图显示,天然林土壤DOM在芳香性脂肪族及木质素类复杂结构荧光基团处的吸收大于人工林;各林分土壤DOM傅里叶红外光谱出现吸收谱带的位置相似,其中吸收强度最大的为形成氢键的—OH的伸缩振动,此外还有芳香性CC伸缩振动、有机羧酸盐COO-反对称伸缩振动、碳水化合物中烷氧基C—O的振动等,人工林土壤DOM中碳水化合物的比例增加是其结构简单的主要原因。土壤DOM中结构复杂、分子量大的组分不易向下迁移;天然林与人工林间土壤DOM数量及光谱学特征的差异主要与凋落物输入及营林措施的干扰有关;本研究所涉及的3种人工林中,福建柏更有利于土壤养分的累积。     

根系在凋落物层生长对凋落叶分解及酶活性的影响

根系向凋落物层生长是森林生态系统存在的普遍现象,研究根系存在对凋落物分解的影响对理解森林生态系统的养分物质循环具有重要意义。在福建三明市楠木和格氏栲林进行1年的凋落叶分解试验,设置有根处理和无根处理(对照),研究根系生长对凋落叶分解速率、养分释放和酶活性的影响。结果表明: 在分解360 d后,有根处理楠木和格氏栲凋落叶干重残留率比对照分别降低8.4%和19.7%;根系在分解前期(90~180 d)对凋落叶分解影响最为显著。在分解360 d后,与对照相比,有根处理凋落叶碳、氮、磷残留率在楠木人工林分别降低6.0%、19.1%和20.6%,在格氏栲人工林分别降低21.3%、23.2%和20.5%。在整个分解过程中,根系生长对凋落叶水解酶活性无显著影响;在分解180 d时,楠木和格氏栲有根处理凋落叶过氧化物酶活性比对照显著升高111.4%和92.4%。碳、氮、磷残留率与纤维素水解酶、β-葡萄糖苷酶、酸性磷酸酶和过氧化物酶活性呈显著负相关。根系在凋落物层生长会通过养分吸收和刺激氧化酶活性来加速凋落叶分解和养分释放过程。     

格氏栲天然林与人工林凋落叶分解过程中养分动态

通过对中亚热带格氏栲天然林 (natural forest of Castanopsis kawakamii, 约150a)、格氏栲和杉木人工林 (monoculture plantations of C. Kawakamii and Cunninghamia lanceolata,33年生) 凋落叶分解过程中养分动态的研究表明,各凋落叶分解过程中N初始浓度均发生不同程度的增加后下降;除格氏栲天然林中其它树种叶和杉木叶P浓度先增加后下降外,其它均随分解过程而下降;除杉木叶外,其它类型凋落叶的Ca和Mg浓度呈上升趋势;凋落叶K浓度均随分解过程不断下降.养分残留率与分解时间之间存在着指数函数关系xt=x0e-kt.凋落叶分解过程中各养分释放常数分别为N(kN) 0.678～4.088;P (kP) 0.621～4.308;K(kK) 1.408～4.421;Ca (kCa) 0.799～3.756;Mg (kMg) 0.837 ～ 3.894.除杉木叶外,其它凋落叶分解过程中均呈kK>kP>kN>kMg>kCa的顺序变化.各林分凋落叶的年养分释放量分别为N 10.73～48.19kg/(hm2·a),P 0.61～3.70kg/(hm2·a),K 6.66～39.61kg/(hm2·a),Ca 17.90～20.91kg/(hm2·a),Mg 3.21～9.85kg/(hm2·a).与针叶树人工林相比,天然阔叶林凋落叶分解过程中较快的养分释放和较高的养分释放量有利于促进养分再循环,这对地力维持有重要作用.     

Controls on the release of dissolved organic carbon and nitrogen from a deciduous forest floor investigated by manipulations of aboveground litter inputs and water flux

Although dissolved organic matter (DOM) released from the forest floor plays a crucial role in transporting carbon and major nutrients through the soil profile, its formation and responses to changing litter inputs are only partially understood. To gain insights into the controlling mechanisms of DOM release from the forest floor, we investigated responses of the concentrations and fluxes of dissolved organic carbon (DOC) and nitrogen (DON) in forest floor leachates to manipulations of throughfall (TF) flow and aboveground litter inputs (litter removal, litter addition, and glucose addition) at a hardwood stand in Bavaria, Germany. Over the two-year study period, litter manipulations resulted in significant changes in C and N stocks of the uppermost organic horizon (Oi). DOC and DON losses via forest floor leaching represented 8 and 11% of annual litterfall C and N inputs at the control, respectively. The exclusion of aboveground litter inputs caused a slight decrease in DOC release from the Oi horizon but no change in the overall leaching losses of DOC and DON in forest floor leachates. In contrast, the addition of litter or glucose increased the release of DOC and DON either from the Oi or from the lower horizons (Oe + Oa). Net releases of DOC from the Oe + Oa horizons over the entire manipulation period were not related to changes in microbial activity (measured as rates of basal and substrate-induced respiration) but to the original forest floor depths prior to manipulation, pointing to the flux control by the size of source pools rather than a straightforward relationship between microbial activity and DOM production. In response to doubled TF fluxes, net increases in DOM fluxes occurred in the lower forest floor, indicating the presence of substantial pools of potentially soluble organic matter in the Oe + Oa horizons. In contrast to the general assumption of DOM as a leaching product from recent litter, our results suggest that DOM in forest floor leachates is derived from both newly added litter and older organic horizons through complex interactions between microbial production and consumption and hydrologic transport.     

Dissolved Organic Carbon Leaching from a Coniferous Forest Floor -- A Field Manipulation Experiment

Leaching of dissolved organic carbon (DOC) from the O layer is important for the carbon cycling of forest soils. Here we study the role of the Oi, Oe and Oa horizons in DOC leaching from the forest floor in field manipulations carried out in a Norway spruce forest stand in southern Sweden. The manipulations involved the addition and removal of litter and the removal of Oi, Oe and Oa horizons. Our data suggest that both recent litter and humified organic matter contribute significantly to the leaching of dissolved organic matter from the O layer. An addition of litter corresponding to four times annual litterfall resulted in a 35% increase in DOC concentrations and fluxes although the specific UV absorbance remained unchanged. The removal of litterfall and the Oi horizon resulted in a decreased DOC concentration and in a significant increase in the molar UV absorptivity. The DOC concentration under the Oa horizon was not significantly different from that under the Oe horizon and there were no increase in DOC flux, but rather a decrease, from the bottom of the Oe horizon to the bottom of the Oa horizon, suggesting that there is no net release of DOC in the Oa horizon. However, significant leaching of DOC occurred from the Oa horizon when litterfall and the Oi and Oe horizons were removed. This indicates that there is both a removal of DOC from the Oi and Oe horizons and a substantial production of DOC in the Oa horizon. Quantitatively, we suggest that the Oi, Oe and Oa horizons contributed approximately 20, 30 and 50%, respectively, to the overall leaching of DOC from the O layer.     

Leaching of dissolved organic carbon,dissolved organic nitrogen,and other solutes from coarse woody debris and litter in a mixed forest in New York State

Coarse woody debris (CWD) may play a role in nutrient cycling in temperate forests through the leaching of solutes, including dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), to the underlying soil. These fluxes need to be considered in element budget calculations, and have the potential to influence microbial activity, soil development, and other processes in the underlying soil, but studies on leaching from CWD are rare. In this study, we collected throughfall, litter leachate, and CWD leachate in situ at a young mixed lowland forest in NY State, USA over one year. We measured the concentrations of DOC, DON, NH₄⁺, NO₃⁻, dissolved organic sulfur, SO₄²⁻, Cl⁻, Al, Ca, K, Mg, Na, and P, estimated the flux of these solutes in throughfall, and measured the cover of CWD to gain some insight into possible fluxes from CWD. Concentrations of DOC were much higher in CWD leachate than in throughfall or litter leachate (15 vs. 0.7 and 1.6 mM, respectively), and greater than reported values for other leachates from within forested ecosystems. Other solutes showed a similar pattern, with inorganic N being an exception. Our results suggest that microsite scale fluxes of DOC from CWD may be An high relative to throughfall and litter leaching fluxes, but since CWD covered a relatively small fraction (2%) of the forest floor in our study, ecosystem scale fluxes from CWD may be negligible for this site. Soil directly beneath CWD may be influenced by CWD leaching, in terms of soil organic matter, microbial activity, and N availability. Concentrations of some metals showed correlations to DOC concentrations, highlighting the possibility of complexation by DOM. Several solute concentrations in throughfall, including DOC, showed positive correlations to mean air temperature, and fewer showed positive correlations in litter leachate, while negative correlations were observed to precipitation, suggesting both biological and hydrologic control of solute concentrations.     

Concentration and Fluxes of Dissolved Organic Carbon (DOC) in Three Norway Spruce Stands along a Climatic Gradient in Sweden

Leaching of dissolved organic carbon (DOC) from the forest floor and transport in soil solution into the mineral soil are important for carbon cycling in boreal forest ecosystems. We examined DOC concentrations in bulk deposition, throughfall and in soil solutions collected under the O and B horizons in three Norway spruce stands along a climatic gradient in Sweden. Mean annual temperature for the three sites was 5.5, 3.4 and 1.2 °C. At each site we also examined the effect of soil moisture on DOC dynamics along a moisture gradient (dry, mesic and moist plots). To obtain information about the fate of DOC leached from the O horizon into the mineral soil, ¹⁴C measurements were made on bulk organic matter and DOC. The concentration and fluxes of DOC in O horizon leachates were highest at the southern site and lowest at the northern. Average DOC concentrations at the southern, central and northern sites were 49, 39 and 30 mg l⁻¹, respectively. We suggest that DOC leaching rates from O horizons were related to the net primary production of the ecosystem. Soil temperature probably governed the within-year variation in DOC concentration in O horizon leachates, but the peak in DOC was delayed relative to that of temperature, probably due to sorption processes. Neither soil moisture regime (dry, mesic or moist plots) nor seasonal variation in soil moisture seemed to be of any significance for the concentration of DOC leached from the O horizon. The ¹⁴C measurements showed that DOC in soil solution collected below the B horizon was derived mainly from the B horizon itself, rather than from the O horizon, indicating a substantial exchange (sorption–desorption reactions) between incoming DOC and soil organic carbon in the mineral soil.     

中亚热带不同类型米槠林凋落枝溶解性有机质动态及光谱学特性

以中亚热带不同类型米槠林为对象,研究了米槠天然林、次生林和人工林凋落枝在生产量持续增加阶段、高峰阶段、持续减少3种生产阶段溶解性有机质的动态及光谱学特性。结果表明:凋落枝生产阶段和森林类型显著影响米槠凋落枝溶解性有机质含量及光谱学特征。米槠天然林在凋落枝生产量持续减少阶段溶解性有机碳(DOC)含量较高,溶解性有机质在254、260和280 nm处的特征紫外吸光值(SUVA₂₅₄、SUVA₂₆₀、SUVA₂₈₀)较低,表明该阶段天然林凋落枝质量较高,具有较高的以溶解性有机质为载体的物质循环效率。米槠人工林在凋落枝生产量高峰阶段具有较高的总氮(TN)、总磷(TP)、溶解性总氮(TDN)和溶解性总磷(TDP)含量以及较低的DOC∶TDP和TDN∶TDP值,但次生林凋落枝溶解性有机质含量及其光谱学特征在各阶段无显著差异。米槠天然林和次生林凋落枝DOC、TDN和TDP与气温和降水量呈负相关,人工林凋落枝TDN、TDP与气温和降水量呈正相关。人工林凋落枝生产量在高峰阶段具有较高的养分含量,可能具有相对快速的物质循环效率,天然林在凋落枝生产量下降阶段以凋落枝溶解性有机质为载体的物质循环效率相对较高。     

Climate change and Cognettia sphagnetorum: effects on carbon dynamics in organic soils

1. A microcosm experiment was performed to test the impacts of Cognettia sphagnetorum on carbon leaching in a cambic stagnohumic gley soil.
2. Leaching of dissolved organic carbon (DOC) was significantly enhanced by C.sphagnetorum, with the greatest effect being found in the upper, 0–6 cm, soil layers. The ratio of DOC to dissolved organic nitrogen (DON) in the leachate decreased in faunated systems, indicating that the enchytraeids were mobilizing carbon from organic matter with a low C to N ratio.
3. The vertical distribution of the enchytraeids had an effect on the production of DOC, and this vertical distribution is affected strongly by climate. It is proposed that increases in DOC found in a field soil-warming experiment with the same soil are largely a result of changes in the vertical distribution of these organisms.     

杉木凋落物对土壤有机碳分解及微生物生物量碳的影响

利用¹³C稳定同位素示踪技术,研究了杉木凋落物对杉木人工林表层(0～5 cm)和深层(40～45 cm)土壤有机碳分解、微生物生物量碳和可溶性碳动态的影响.结果表明: 杉木人工林中深层土壤有机碳分解速率显著低于表层土壤,但其激发效应却显著高于表层土壤.杉木凋落物添加使土壤总微生物生物量碳和源于原有土壤的微生物生物量碳均显著增加,但对土壤可溶性碳没有显著影响.深层土壤被翻到林地表层,可能加速杉木人工林土壤中碳的损失.     

Detrital Controls on Soil Solution N and Dissolved Organic Matter in Soils: A Field Experiment

We established a long-term field study in an old growth coniferous forest at the H.J. Andrews Experimental Forest, OR, USA, to address how detrital quality and quantity control soil organic matter accumulation and stabilization. The Detritus Input and Removal Treatments (DIRT) plots consist of treatments that double leaf litter, double woody debris inputs, exclude litter inputs, or remove root inputs via trenching. We measured changes in soil solution chemistry with depth, and conducted long-term incubations of bulk soils from different treatments in order to elucidate effects of detrital inputs on the relative amounts and lability of different soil C pools. In the field, the addition of woody debris increased dissolved organic carbon (DOC) concentrations in O-horizon leachate and at 30 cm, but not at 100 cm, compared to control plots, suggesting increased rates of DOC retention with added woody debris. DOC concentrations decreased through the soil profile in all plots to a greater degree than did dissolved organic nitrogen (DON), most likely due to preferential sorption of high C:N hydrophobic dissolved organic matter (DOM) in upper horizons; percent hydrophobic DOM decreased significantly with depth, and hydrophilic DOM had a much lower and less variable C:N ratio. Although laboratory extracts of different litter types showed differences in DOM chemistry, percent hydrophobic DOM did not differ among soil solutions from different detrital treatments in the field, suggesting that microbial processing of DOM leachate in the field consumed easily degradable components, thus equalizing leachate chemistry among treatments. Total dissolved N leaching from plots with intact roots was very low (0.17 g m⁻² year⁻¹), slightly less than measured deposition to this very unpolluted forest (~s 0.2 g m⁻² year⁻¹). Total dissolved N losses showed significant increases in the two treatments without roots whereas concentrations of DOC decreased. In these plots, N losses were less than half of estimated plant uptake, suggesting that other mechanisms, such as increased microbial immobilization of N, accounted for retention of N in deep soils. In long-term laboratory incubations, soils from plots that had both above- and below-ground litter inputs excluded for 5 years showed a trend towards lower DOC loss rates, but not lower respiration rates. Soils from plots with added wood had similar respiration and DOC loss rates as control soils, suggesting that the additional DOC sorption observed in the field in these soils was stabilized in the soil and not readily lost upon incubation.