三峡库区马尾松细根生产和周转及其影响因子

采用连续根钻法、分解袋法、分室通量模型法计算三峡库区马尾松细根的年生产量和周转率,分析细根生产量和周转率与各影响因子的关系.结果表明: 马尾松<0.5、0.5～1和1～2 mm细根年均生物量分别为0.29、0.59、0.76 t·hm^-2,细根年生产量分别为0.13、0.49、0.37 t·hm^-2,细根年周转率分别为1.49、1.01、0.40 a^-1.各影响因子对不同径级细根生产与周转的影响不同.土壤温度、土壤钙含量显著影响<0.5 mm细根生产量与细根周转,且土壤温度解释生产量和周转率32.8%和25.0%的变异,土壤钙含量解释65.6%和73.1%的变异;细根生物量与细根生产量呈显著正相关,细根生物量分别解释<0.5、0.5～1和1～2 mm细根生产量41.0%、41.1%和54.5%的变异;细根P、K含量与<0.5 mm细根生产量具有显著相关性,分别解释<0.5 mm细根生产量32.2%、39.2%的变异.<0.5 mm细根与各影响因子的关系最为密切,土壤温度、土壤钙含量是细根生物量的主要影响因子.     

三峡库区马尾松人工林细根生产和周转

2011年3-12月,采用连续根钻法和分解袋法,研究了三峡库区20年生马尾松人工林细根的季节动态,计算了细根的年生产量和周转率.结果表明:三峡库区马尾松人工林细根(＜2 mm)年均生物量为146.98 g·m-2,其中活细根年均生物量(102.92 g·m-2)远大于死细根生物量(44.06 g·m-2);不同径级细根现存量的时间动态不同,＜1 mm根系季节动态较为明显,整体呈单峰型曲线;马尾松人工林细根(＜2 mm)的年生产量为104.12 g·m-2·a-1,年周转率为1.05 a-1,其中＜1 mm和1～2 mm的年生产量分别为58.35和45.77 g·m-2·a-1,周转率为1.41和0.69 a-1.     

土壤增温、氮添加及其交互作用对杉木幼苗细根生产的影响

为了揭示杉木(Cunninghamia lanceolata)人工林地下部分对全球变暖和氮沉降的响应,在福建省三明市开展了杉木幼苗土壤增温和氮添加双因子试验,包括对照、增温、低氮、高氮、增温低氮、增温高氮6个处理,用微根管法探讨试验第1年土壤增温、氮添加及其交互作用对杉木幼苗细根生产量(以每根管细根一年总出生数量作为表征)的影响。结果表明:(1)土壤增温对细根生产量有显著影响;氮添加、土壤增温与氮添加交互作用对细根生产量并没有显著影响。(2)土壤增温、径级、土壤增温和径级的交互作用对细根生产量有显著影响;土壤增温显著增加了0–1 mm径级细根的生产量,表明小径级的吸收根对于增温的响应更具有可塑性。(3)土壤增温、季节、土壤增温和季节的交互作用,以及土壤增温、氮添加和季节三者的交互作用对细根生产量的影响均达到显著水平。春季,土壤增温、土壤增温和氮添加的交互作用对细根生产量有显著的促进作用;而在夏季,土壤增温、氮添加以及两者的交互作用对细根生产量有显著的抑制作用。(4)土壤增温、土层,以及土壤增温和土层的交互作用对细根生产量有显著影响,土壤增温仅对20–30 cm土层的细根生产有显著的促进作用,表明土壤增温促使细根向更深层土壤分布。由此可见:土壤增温促进了杉木幼苗细根生产,但其影响因径级、季节和土层而异;氮添加则对细根生产没有影响;土壤增温和氮添加仅在春季和夏季才存在显著的交互作用。     

施氮肥对水曲柳人工林细根生产和周转的影响

细根周转与土壤养分密切相关,但由于根系研究方法的差异以及研究对象的不同,土壤养分对细根周转影响的研究存在不一致的结论。本文以水曲柳（Fraxinus mandshurica）人工林为对象,应用3种方法研究施氮肥对细根生产和周转的影响。结果表明：施肥降低了活细根现存生物量,但施氮肥样地细根年生产量平均值（93．105g&#183;m^-2&#183;a^-1）与对照样地（93．505g&#183;m^-2&#183;a^-1）没有差异,不同方法得出施氮肥样地细根平均周转率（0．917次&#183;a^-1）大于对照样地（0．710次&#183;a^-1）;不同土层内细根的生产量显著不同,表层生产量最大,土层越深细根生产量越低,但细根周转率一般随土壤加深而加快;不同的研究方法得出细根的年生产量和周转率差异较大,分室模型法最高,其次是内生长土芯法,极差法和积分法最低。     

2004—2008年落叶松人工林细根生产和死亡的季节动态

2004—2008年,采用微根管(minirhizotron)技术,对落叶松人工林细根生产和死亡进行连续动态观测,同时测定了温度(大气温度和土壤10 cm温度)和水分(降雨量和土壤10 cm深处含水量)的变化,研究细根生产、死亡的动态及其与温度和水分的关系.结果表明:落叶松细根年根长生产量在0.20～0.78 mm.cm-2,死亡量在0.26～0.72 mm.cm-2;2004—2006年细根年根长平均生产量(0.67 mm.cm-2)和死亡量(0.59 mm.cm-2)均高于2007—2008年细根年根长平均生产量和死亡量(0.37和0.39 mm.cm-2);在生长季内(5—10月),落叶松春末至夏季(6—7月)的细根生产量占全年产量的51%～68%,秋末(10月)仅占全年的1%～4%;而夏末(8月)和秋季(9—10月)细根死亡量占全年的59%～70%,早春(5月)占全年的1%～5%.相关分析表明,大气温度变化可以解释细根生产量66%的变异,而土壤10 cm深处温度解释24%,降雨量解释27%.细根的死亡量与土壤10 cm深处温度呈指数正相关.     

2004—2008年落叶松人工林细根生产和死亡的季节动态

2004—2008年,采用微根管(minirhizotron)技术,对落叶松人工林细根生产和死亡进行连续动态观测,同时测定了温度(大气温度和土壤10 cm温度)和水分(降雨量和土壤10 cm深处含水量)的变化,研究细根生产、死亡的动态及其与温度和水分的关系.结果表明：落叶松细根年根长生产量在0.20～0.78 mm·cm^-2,死亡量在0.26～0.72 mm·cm^-2;2004—2006年细根年根长平均生产量(0.67 mm·cm^-2)和死亡量(0.59 mm·cm^-2)均高于2007—2008年细根年根长平均生产量和死亡量(0.37和0.39 mm·cm^-2);在生长季内（5—10月）,落叶松春末至夏季(6—7月) 的细根生产量占全年产量的51%～68%,秋末(10月)仅占全年的1%～4%;而夏末(8月)和秋季(9—10月)细根死亡量占全年的59%～70%,早春(5月)占全年的1%～5%.相关分析表明,大气温度变化可以解释细根生产量66%的变异,而土壤10 cm深处温度解释24%,降雨量解释27%.细根的死亡量与土壤10 cm深处温度呈指数正相关.     

中亚热带不同演替阶段的马尾松和米槠人工林的细根生产量研究

对不同演替阶段的树种细根生产动态及其对环境因子响应的差异目前仍缺乏了解。为此, 在福建省三明市选择了中亚热带演替前期的马尾松(Pinus massoniana)和演替后期的米槠(Castanopsis carlesii)两种人工林为研究对象, 采用微根管法对两种人工林的细根根长生产量及其动态进行了为期2年的观测, 并分析了细根生产量的径级和土层分布, 及月生产量动态与气温、降水、土壤温度、土壤含水率等环境因子间的关系。结果表明: 1)两种林分的细根生产量有显著差异, 马尾松人工林细根年根长生产量约为米槠人工林细根年根长生产量的4倍; 两种林分的细根生产量呈现显著的月变化, 峰值均出现在夏季, 且2年内总细根生产量以夏季的细根生产量最大。2)两林分均是直径0-0.3 mm的细根所占细根生产量比例最大; 土层分布上, 马尾松人工林0-10 cm土层细根所占生产量的比例最大, 米槠人工林30-40 cm土层细根所占生产量比例最大。3)偏相关分析表明, 两林分细根月生产量均与气温、土壤温度极显著相关或显著正偏相关, 与降水、土壤含水率的偏相关均不显著; 一元线性回归分析表明, 演替早期马尾松人工林细根月生产量与气温、土壤温度的相关性明显高于米槠人工林。该研究表明, 与演替后期的米槠人工林相比, 中亚热带演替早期的马尾松人工林细根生产量大, 且与温度间的相关性更高。     

细根对降水变化响应的meta分析

细根对土壤水分含量变化十分敏感, 增加和减少降水直接影响土壤水分含量。为探索细根对降水变化的响应, 该文从48篇已发表的国内外研究论文中搜集到202组数据, 通过meta分析的方法揭示细根生物量、生产量、周转率、根长度密度、比根长及细根分解对增加和减少降水的一般响应规律, 用加权响应比评价降水对细根各指标的影响效应, 降水变化对细根分解的影响用土壤微生物生物量碳的响应比衡量。结果表明: 1)不同类型植物的细根对降水变化的响应程度不同, 灌木细根的响应强于乔木。2)细根各指标对降水变化的响应存在土层空间异质性, 并且降水变化量为50%时细根响应最显著。降水增加50%时, 显著增加20-40 cm土层的细根生物量和0-10 cm土层的细根比根长, 降水减少50%时, 显著减少20-40 cm土层的细根生产量和增加0-10 cm土层的细根根长度密度。3)降水变化实验持续时间的长短会影响细根的响应程度, 短期实验中细根通过形态适应对降水变化做出应对, 而长期实验中细根通过重新分配生物量对降水变化做出响应。4)增加降水促进了细根养分归还, 致使土壤微生物得到了充足的底物资源, 提高了自身活性, 使细根分解加快。     

干旱区琵琶柴群落细根周转对土壤有机碳循环的贡献

尽管干旱区生态系统的脆弱性受到了广泛的关注, 但目前关于干旱区植物细根有机碳与土壤碳循环关系的研究还比较少见。在2010年整个生长季节内, 采用土钻法和内生长法, 对新疆干旱区的琵琶柴(Reaumuria soongorica)群落土壤特性、细根的生物量月动态、生产量和周转进行了研究。结果表明: 琵琶柴群落表层土壤含水量最低, 土壤含水量表现出从浅层到深层逐渐增加的趋势; 而表层土壤的有机碳含量最高, 随着土壤深度的加深, 有机碳含量逐渐降低。细根生物量的月平均值为54.51 g·m^-2, 群落细根生产量在82.76-136.21 g·m^-2·a^-1之间, 琵琶柴群落的细根周转率为2.08 times·a^-1, 通过细根死亡进入土壤中的有机碳为17 g·m^-2·a^-1。这些结果表明: 由于灌丛细根高的周转速率, 细根是干旱区土壤有机碳输入的重要部分。     

Response of fine roots to precipitation change: A meta-analysis

细根对土壤水分含量变化十分敏感, 增加和减少降水直接影响土壤水分含量。为探索细根对降水变化的响应, 该文从48篇已发表的国内外研究论文中搜集到202组数据, 通过meta分析的方法揭示细根生物量、生产量、周转率、根长度密度、比根长及细根分解对增加和减少降水的一般响应规律, 用加权响应比评价降水对细根各指标的影响效应, 降水变化对细根分解的影响用土壤微生物生物量碳的响应比衡量。结果表明: 1)不同类型植物的细根对降水变化的响应程度不同, 灌木细根的响应强于乔木。2)细根各指标对降水变化的响应存在土层空间异质性, 并且降水变化量为50%时细根响应最显著。降水增加50%时, 显著增加20-40 cm土层的细根生物量和0-10 cm土层的细根比根长, 降水减少50%时, 显著减少20-40 cm土层的细根生产量和增加0-10 cm土层的细根根长度密度。3)降水变化实验持续时间的长短会影响细根的响应程度, 短期实验中细根通过形态适应对降水变化做出应对, 而长期实验中细根通过重新分配生物量对降水变化做出响应。4)增加降水促进了细根养分归还, 致使土壤微生物得到了充足的底物资源, 提高了自身活性, 使细根分解加快。     

落叶松和水曲柳人工林细根生长、死亡和周转

 细根周转是陆地生态系统碳分配格局与过程的核心环节,而细根周转估计的关键是了解细根的生长和死亡动态。该研究以18年生落叶松(Larix gmelinii)和水曲柳(Fraxi nus mandshurica)人工林为对象,采用微根管（Minirhizotron）技术对两树种0～40 cm深度的细根生长和死亡动态进行了为期1年的观测,研究了两树种细根在不同土层深度的生长与死亡动态、细根周转以及与土壤有效氮含量、土壤温度、大气温度和降水的关系。结果表明：1） 落叶松平均细根生长（Root length density production, RLDP）0.0045 mm•cm^－2•d^－1）明显低于水曲柳RLDP（0.0077 mm•cm^－2•d^－1）。两个树种细根平均RLDP在表层（0～10 cm）最大,而底层（30～40 cm）最小 ,两树种平均细根死亡（Root length density mortality, RLDM）也表现同样规律 。水曲柳春季生长的细根占41.7%,夏季占39.7%,而落叶松细根生长分别是24.0%和51.2%,水曲柳细根死亡主要发生在春季（34.3%） 和夏季（34.0%）,而落叶松细根死亡主要发生在夏季和秋季（分别占28.5%和32.3%）,两 树种细根生长与死亡在冬季均较小;2）落叶松细根年生长量（0.94 mm•cm^－2•a^－1）和年死亡量（0.72 mm•cm^－2•a^－1）明显低于水曲柳（1.52和1.21 mm•cm^－2•a^－1）,两树种细根表层年生长量和年死亡量均最高,底层最低。落叶松细根年周转为3.1次•a^－1（按年生长量计算）和2.4次•a^－1（按年死亡量计算）,相比较,水曲柳细根年周转分别为2.7次•a^－1和2.2次•a^－1;3）土壤有效氮含量、土壤温度、大气温度和降水综合作用影响细根生长和死亡动态,可以解释细根生长80%的变异和细根死亡95%以上的变异。     

Estimation of fine root production, mortality and turnover with Minirhizotron in Larix gmelinii and Fraxinus mandshurica plantations

Fine root turnover is a major pathway for car-bon and nutrient cycling in forest ecosystems. However, to estimate fine root turnover, it is important to first understand the fine root dynamic processes associated with soil resource availability and climate factors. The objectives of this study were: (1) to examine patterns of fine root production and mortality in different seasons and soil depths in the Larix gmelinii and Fraxinus man-dshurica plantations, (2) to analyze the correlation of fine root production and mortality with environmental factors such as air temperature, precipitation, soil temperature and available nitrogen, and (3) to estimate fine root turn-over. We installed 36 Minirhizotron tubes in six mono-specific plots of each species in September 2003 in the Mao'ershan Experimental Forest Station. Minirhizotron sampling was conducted every two weeks from April 2004 to April 2005. We calculated the average fine root length, annual fine root length production and mortality using image data of Minirhizotrons, and estimated fine root turnover using three approaches. Results show that the average growth rate and mortality rate in L. melinii were markedly smaller than in F. mandshurica, and were high-est in the surface soil and lowest at the bottom among all the four soil layers. The annual fine root production and mortality in F. mandshurica were significantly higher than in L. gmelinii. The fine root production in spring and summer accounted for 41.7% and 39.7% of the total annual production in F. mandshurica and 24.0% and 51.2% in L. gmelinii. The majority of fine root mortality occurred in spring and summer for F. mandshurica and in summer and autumn for L. gmelinii. The turnover rate was 3.1 a-1 for L. gmelinii and 2.7 a-1 for F. mandshurica. Multiple regression analysis indicates that climate and soil resource factors together could explain 80% of the varia-tions of the fine root seasonal growth and 95% of the seasonal mortality. In conclusion, fine root production and mortality in L. gmelinii and F. mandshurica have dif-ferent patterns in different seasons and at different soil depths. Air temperature, precipitation, soil temperature and soil available nitrogen integratively control the dynamics of fine root production, mortality and turnover in both species.     

Soil fertility and fine root dynamics in response to 4 years of nutrient (N,P, K) fertilization in a lowland tropical moist forest,Panama

The question of how tropical trees cope with infertile soils has been challenging to address, in part, because fine root dynamics must be studied in situ. We used annual fertilization with nitrogen (N as urea, 12.5 g N m^?2 year^?1), phosphorus (P as superphosphate, 5 g P m^?2 year^?1) and potassium (K as KCl, 5 g K m^?2 year^?1) within 38 ha of old‐growth lowland tropical moist forest in Panama and examined fine root dynamics with minirhizotron images. We expected that added P, above all, would (i) decrease fine root biomass but, (ii) have no impact on fine root turnover. Soil in the study area was moderately acidic (pH = 5.28), had moderate concentrations of exchangeable base cations (13.4 cmol kg^?1), low concentrations of Bray‐extractable phosphate (PO₄ = 2.2 mg kg^?1), and modest concentrations of KCl‐extractable nitrate (NO₃ = 5.0 mg kg^?1) and KCl‐extractable ammonium (NH₄ = 15.5 mg kg^?1). Added N increased concentrations of KCl‐extractable NO₃ and acidified the soil by one pH unit. Added P increased concentrations of Bray‐extractable PO₄ and P in the labile fraction. Concentrations of exchangeable K were elevated in K addition plots but reduced by N additions. Fine root dynamics responded to added K rather than added P. After 2 years, added K decreased fine root biomass from 330 to 275 g m^?2. The turnover coefficient of fine roots <1 mm diameter ranged from 2.6 to 4.4 per year, and the largest values occurred in plots with added K. This study supported the view that biomass and dynamics of fine roots respond to soil nutrient availability in species‐rich, lowland tropical moist forest. However, K rather than P elicited root responses. Fine roots smaller than 1 mm have a short lifetime (<140 days), and control of fine root production by nutrient availability in tropical forests deserves more study.     

帽儿山温带落叶阔叶林细根生物量、生产力和周转率

细根在森林生态系统能量流动与物质循环中占有重要地位,但其生物量、生产和周转测定尚存在很大的不确定性,而且局域尺度空间变异机制尚不清楚。本研究分析了帽儿山温带天然次生林活细根生物量和死细根生物量在0～100 cm剖面的垂直分布与0～20 cm细根的季节动态、生产力和周转率,对比了采用连续根钻法(包括决策矩阵法和极差法)和内生长袋(直径3和5 cm)估测细根生产力和细根周转率,并探讨了可能影响细根的林分因子。结果表明: 76.8%的活细根生物量和62.9%的死细根生物量均集中在0～20 cm土层,随着深度增加,二者均呈指数形式减少。活细根生物量和死细根生物量的季节变化不显著,可能与冬季几乎无降雪而夏季降雨异常多有关。2种直径内生长袋估计的细根生产力无显著差异;对数转换后决策矩阵、极差法和内生长法估计的细根生产力和细根周转率差异显著。随着土壤养分增加,活细根生物量和死细根生物量比值显著增加,死细根生物量显著减少,但活细根生物量、细根生产力和细根周转率均无显著变化;细根周转率与前一年地上木质生物量增长量呈显著正相关,但与当年地上木质生物量增长量无显著相关关系。     

树木根系碳分配格局及其影响因子

根系作为树木提供养分和水分的“源”和消耗C的“汇”,在陆地生态系统C平衡研究中具有重要的理论意义。尽管20多年来的研究已经认识到根系消耗净初级生产力占总净初级生产力较大的比例,但是,根系（尤其是细根）消耗C的机理以及C分配的去向一直没有研究清楚。主要原因是细根消耗光合产物的生理生态过程相当复杂,准确估计各个组分消耗的C具有很大的不确定性,常常受树种和环境空间和时间异质性、以及研究方法的限制。综述了分配到地下的C主要去向,即细根生产和周转、呼吸及养分吸收与同化、分泌有机物、土壤植食动物,及有关林木地下碳分配机理的几种假说,分析了地下碳分配估计中存在的不确定性。目的是在全球变化C循环研究中对生态系统地下部分根系消耗的C以及分配格局引起重视。     

Soil [N] modulates soil C cycling in CO2‐fumigated tree stands: a meta‐analysis

Under elevated atmospheric CO₂ concentrations, soil carbon (C) inputs are typically enhanced, suggesting larger soil C sequestration potential. However, soil C losses also increase and progressive nitrogen (N) limitation to plant growth may reduce the CO₂ effect on soil C inputs with time. We compiled a data set from 131 manipulation experiments, and used meta‐analysis to test the hypotheses that: (1) elevated atmospheric CO₂ stimulates soil C inputs more than C losses, resulting in increasing soil C stocks; and (2) that these responses are modulated by N. Our results confirm that elevated CO₂ induces a C allocation shift towards below‐ground biomass compartments. However, the increased soil C inputs were offset by increased heterotrophic respiration (Rh), such that soil C content was not affected by elevated CO₂. Soil N concentration strongly interacted with CO₂ fumigation: the effect of elevated CO₂ on fine root biomass and –production and on microbial activity increased with increasing soil N concentration, while the effect on soil C content decreased with increasing soil N concentration. These results suggest that both plant growth and microbial activity responses to elevated CO₂ are modulated by N availability, and that it is essential to account for soil N concentration in C cycling analyses.     

Responses of fine roots and soil N availability to short-term nitrogen fertilization in a broad-leaved Korean pine mixed forest in northeastern China

Knowledge of the responses of soil nitrogen (N) availability, fine root mass, production and turnover rates to atmospheric N deposition is crucial for understanding fine root dynamics and functioning in forest ecosystems. Fine root biomass and necromass, production and turnover rates, and soil nitrate-N and ammonium-N in relation to N fertilization (50 kg N ha(-1) year(-1)) were investigated in a temperate forest over the growing season of 2010, using sequential soil cores and ingrowth cores methods. N fertilization increased soil nitrate-N by 16% (P<0.001) and ammonium-N by 6% (P<0.01) compared to control plots. Fine root biomass and necromass in 0-20 cm soil were 13% (4.61 vs. 5.23 Mg ha(-1), P<0.001) and 34% (1.39 vs. 1.86 Mg ha(-1), P<0.001) less in N fertilization plots than those in control plots. The fine root mass was significantly negatively correlated with soil N availability and nitrate-N contents, especially in 0-10 cm soil layer. Both fine root production and turnover rates increased with N fertilization, indicating a rapid underground carbon cycling in environment with high nitrogen levels. Although high N supply has been widely recognized to promote aboveground growth rates, the present study suggests that high levels of nitrogen supply may reduce the pool size of the underground carbon. Hence, we conclude that high levels of atmospheric N deposition will stimulate the belowground carbon cycling, leading to changes in the carbon balance between aboveground and underground storage. The implications of the present study suggest that carbon model and prediction need to take the effects of nitrogen deposition on underground system into account.     

Estimating Fine Root Turnover in Tropical Forests along an Elevational Transect using Minirhizotrons

Growth and death of fine roots represent an important carbon sink in forests. Our understanding of the patterns of fine root turnover is limited, in particular in tropical forests, despite its acknowledged importance in the global carbon cycle. We used the minirhizotron technique for studying the changes in fine root longevity and turnover along a 2000-m-elevational transect in the tropical mountain forests of South Ecuador. Fine root growth and loss rates were monitored during a 5-mo period at intervals of four weeks with each 10 minirhizotron tubes in three stands at 1050, 1890, and 3060 m asl. Average root loss rate decreased from 1.07 to 0.72 g/g/yr from 1050 to 1890 m, indicating an increase in mean root longevity with increasing elevation. However average root loss rate increased again toward the uppermost stand at 3060 m (1.30 g/g/yr). Thus, root longevity increased from lower montane to mid-montane elevation as would be expected from an effect of low temperature on root turnover, but it decreased further upslope despite colder temperatures. We suggest that adverse soil conditions may reduce root longevity at high elevations in South Ecuador, and are thus additional factors besides temperature that control root dynamics in tropical mountain forests.     

Estimation of fine root production, mortality and turnover with Minirhizotron in Larix gmelinii and Fraxinus mandshurica plantations

Fine root turnover is a major pathway for carbon and nutrient cycling in forest ecosystems. However, to estimate fine root turnover, it is important to first understand the fine root dynamic processes associated with soil resource availability and climate factors. The objectives of this study were: (1) to examine patterns of fine root production and mortality in different seasons and soil depths in the Larix gmelinii and Fraxinus mandshurica plantations, (2) to analyze the correlation of fine root production and mortality with environmental factors such as air temperature, precipitation, soil temperature and available nitrogen, and (3) to estimate fine root turnover. We installed 36 Minirhizotron tubes in six mono-specific plots of each species in September 2003 in the Mao’ershan Experimental Forest Station. Minirhizotron sampling was conducted every two weeks from April 2004 to April 2005. We calculated the average fine root length, annual fine root length production and mortality using image data of Minirhizotrons, and estimated fine root turnover using three approaches. Results show that the average growth rate and mortality rate in L. melinii were markedly smaller than in F. mandshurica, and were highest in the surface soil and lowest at the bottom among all the four soil layers. The annual fine root production and mortality in F. mandshurica were significantly higher than in L. gmelinii. The fine root production in spring and summer accounted for 41.7% and 39.7% of the total annual production in F. mandshurica and 24.0% and 51.2% in L. gmelinii. The majority of fine root mortality occurred in spring and summer for F. mandshurica and in summer and autumn for L. gmelinii. The turnover rate was 3.1 a⁻¹ for L. gmelinii and 2.7 a⁻¹ for F. mandshurica. Multiple regression analysis indicates that climate and soil resource factors together could explain 80% of the variations of the fine root seasonal growth and 95% of the seasonal mortality. In conclusion, fine root production and mortality in L. gmelinii and F. mandshurica have different patterns in different seasons and at different soil depths. Air temperature, precipitation, soil temperature and soil available nitrogen integratively control the dynamics of fine root production, mortality and turnover in both species. Transtlated from Journal of Plant Ecology, 2007, 31(2): 333–342 [译自: 植物生态学报]