Litterfall In Forest Research Articles

Enhanced accumulation and storage of mercury on subtropical evergreen forest floor: Implications on mercury budget in global forest ecosystems

AbstractForest ecosystems play an important role in the global cycling of mercury (Hg). In this study, we characterized the Hg cycling at a remote evergreen broadleaf (EB) forest site in southwest China (Mount Ailao). The annual Hg input via litterfall is estimated to be 75.0 ± 24.2 µg m−2 yr−1 at Mount Ailao. Such a quantity is up to 1 order of magnitude greater than those observed at remote temperate/boreal (T/B) forest sites. Production of litter biomass is found to be the most influential factor causing the high Hg input to the EB forest. Given their large areal coverage, Hg deposition through litterfall in EB forests is appropriately 9 ± 5 Mg yr−1 in China and 1086 ± 775 Mg yr−1 globally. The observed wet Hg deposition at Mount Ailao is 4.9 ± 4.5 µg m−2 yr−1, falling in the lower range of those observed at 49 T/B forest sites in North America and Europe. Given the data, the Hg deposition flux through litterfall is approximately 15 times higher than the wet Hg deposition at Mount Ailao. Steady Hg accumulation in decomposing litter biomass and Hg uptake from the environment were observed during 25 months of litter decomposition. The size of the Hg pool in the organic horizon of EB forest floors is estimated to be up to 2–10 times the typical pool size in T/B forests. This study highlights the importance of EB forest ecosystems in global Hg cycling, which requires further assessment when more data become available in tropical forests.

Litter Chemistry, Community Shift, and Non-additive Effects Drive Litter Decomposition Changes Following Invasion by a Generalist Pathogen

Forest pathogens have strong potential to shape ecosystem function by altering litterfall, microclimate, and changing community structure. We quantified changes in litter decomposition from a set of distinct diseases caused by Phytophthora ramorum, an exotic generalist pathogen. Phytophthora ramorum causes leaf blight and increased litterfall %N, but no mortality on California bay laurel (Umbellularia californica), a common overstory tree that accumulates high levels of infection. Lethal twig and bole cankers on tanoak (Notholithocarpus densiflorus) lead to the disease sudden oak death which creates canopy openings and alters litterfall in mixed-species forests dominated by redwood (Sequoia sempervirens) which is minimally susceptible. Species identity had the greatest effect on mass loss and N dynamics with the most rapid rates in bay laurel, slowest in redwood, and intermediate in tanoak. Decomposing litter from infected sources had increased N accumulation, and although these changes were of lower magnitude relative to species identity, the region-scale invasion of P. ramorum suggests that this effect could occur over an extensive area. Canopy mortality was a significant and slowing influence on litter N dynamics in all species and also dampened non-additive effects within mixed litter bags. Redwood—the lowest quality litter—demonstrated non-additive interactions with consistently lower C:N when decomposed in mixed litter bags, but this effect did not alter the entire mixture. Mortality and subsequent changes in community composition have the greatest magnitude effects on litter decomposition for sudden oak death, but our study implies that different and sometimes cryptic mechanisms will drive decomposition changes for other forest diseases.

Autochthonous microbial community associated with pine needle forest litterfall influences its degradation under natural environmental conditions

The slow natural degradation of chir pine (Pinus roxburghii) needle litterfall and its accumulation on forest floors have been attributed to its lignocellulosic complexities of the biomass. The present study offers a microbiological insight into the role of autochthonous microflora associated with pine needle litterfall in its natural degradation. The denaturing gradient gel electrophoresis (DGGE) fingerprinting indicated actinomycetes (Saccharomonospora sp., Glycomyces sp., Agrococcus sp., Leifsonia sp., Blastocatella sp., and Microbacterium sp.) as a dominant microbial community associated with pine needle litterfall with the absence of fungal decomposers. On exclusion of associated autochthonous microflora from pine litterfall resulted in colonization by decomposer fungi identified as Penicillium chrysogenum and Aspergillus sp., which otherwise failed to colonize the litterfall under natural conditions. The results, therefore, indicated that the autochthonous microbial community of pine needle litterfall (dominated by actinomycetes) obstructs the colonization of litter-degrading fungi and subsequently hinders the overall process of natural degradation of litterfall.

Forest litterfall and its composition: a new data set of observational data from China

AbstractKnowledge of litterfall production and its allocation is important for understanding nutrient cycling and assessing productivity in forest ecosystems; however, available litterfall datasets are rare in China. Consequently, in the present study, data from published studies (1970–2014) on litterfall and its composition in forest ecosystems in China (excluding Hong Kong, Macao, and Taiwan) were collected, critically reviewed, and incorporated in a comprehensive forest litterfall data set for China. The data set included the following litterfall data: leaves, branches, reproductive parts (flowers and fruits), and miscellaneous. Moreover, associated information was also included, i.e., geographical location (latitude, longitude, altitude, aspect, and slope), climate [mean annual temperature (MAT) and mean annual precipitation (MAP)], stand description (forest type, dominant tree species, stand origin, stand age, mean DBH, mean tree height and stand density), and data collection regime (sample frequency and date, trap size, and number). The data set included 904 entries for 168 study sites, that were distributed in various climate zones with latitudes 18.26°–51.50° N, longitudes 82.25°–129.53° E and altitudes 0–4115 m above sea level (a.s.l.), covering broad climatic gradients (−5.4 to 25.4°C in MAT and 370 to 2800 mm in MAP). The data can be used to analyze spatio‐temporal dynamics of China's forest litterfall and its allocation, understand nutrient cycling and assess productivity in forest ecosystems. Finally, the data set is freely available for noncommercial scientific applications.

Temporal and spatial patterns of remotely sensed litterfall in tropical and subtropical forests of Taiwan

AbstractLitterfall is important for returning nutrients and carbon to the forest floor, and microbes decompose the litterfall to release CO2 into the atmosphere. Litterfall is a pivotal component in the forest biogeochemical cycle, which is sensitive to climate variability and plant physiology. In this study, we combined field litterfall estimates and time series (2001–2011) climate (the Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) and Tropical Rainfall Measuring Mission (TRMM) precipitations) and green vegetation (MODIS photosynthetically active vegetation cover (PV)) variables to estimate regional annual litterfall in tropical/subtropical forests in Taiwan. We found that time series MODIS LST‐ and PV‐derived metrics, the annual accumulated MODIS LST, and coefficient of variation of PV, respectively, but not the TRMM precipitation variables were salient factors for the estimation (r2 = 0.548 and p < 0.001). The mean (±standard deviation) annual litterfall was 5.1 ± 1.2 Mg ha−1 yr−1 during the observation period. The temporal dynamics of the litterfall revealed that typhoons and consecutive drought events might affect the litterfall temporal variation. Overall, the annual litterfall decreased along the elevation gradient, which may reflect a change in the vegetation type. The northeast and northwest facing slopes yielded the highest amount of annual litterfall (≥5.9 Mg ha−1 yr−1), which was in contrast with the southern aspect (5.1 Mg ha−1 yr−1). This variation may be associated with the dryness of the microclimate influenced by solar radiation. This study demonstrates the feasibility of utilizing time series MODIS LST and PV data to predict large‐scale field litterfall, which may facilitate large‐scale monitoring of biogeochemical cycles in forest ecosystems.

Litterfall and nutrient return in moist evergreen broad-leaved primary forest and mixed subtropical secondary deciduous broad-leaved forest in China

Litterfall plays an important role in carbon and nutrient cycling of a forest ecosystem which is generally affected by climate, vegetation, forest type and age. The majority of the subtropical forests of China are occurring in nutrient poor environment, and thus there is a need to understand the role of litterfall on the recycling of C and nutrients in these forests for their proper management. We measured litter production, and carbon and nutrient return in an evergreen broad-leaved primary forest (Mt. Ailao, SW China) and a deciduous broad-leaved secondary forest (Mt. Damei, East China). The annual litterfall productions were 1124 and 490 g m−2 at the primary evergreen forest and secondary deciduous forest, respectively. Carbon return in primary evergreen forest was approximately three times greater than that in secondary deciduous forest. Litter N concentrations in the secondary deciduous forest were higher than that of the primary evergreen forest and consequently, the use efficiency of N of the secondary deciduous forest was lower than the primary evergreen forest. This reflects a stronger nutrient conservation mechanism in the primary evergreen forest than in the secondary forest.

Differential plant damage due to litterfall in palm-dominated forest stands in a Central Pacific atoll – CORRIGENDUM

An abstract is not available for this content. As you have access to this content, full HTML content is provided on this page. A PDF of this content is also available in through the ‘Save PDF’ action button.

Annual litterfall dynamics and nutrient deposition depending on elevation and land use at Mt. Kilimanjaro

Abstract. Litterfall is one of the major pathways connecting above- and below-ground processes. The effects of climate and land-use change on carbon (C) and nutrient inputs by litterfall are poorly known. We quantified and analyzed annual patterns of C and nutrient deposition via litterfall in natural forests and agroforestry systems along the unique elevation gradient of Mt. Kilimanjaro. Tree litter in three natural (lower montane, Ocotea and Podocarpus forests), two sustainably used (homegardens) and one intensively managed (shaded coffee plantation) ecosystems was collected on a biweekly basis from May 2012 to July 2013. Leaves, branches and remaining residues were separated and analyzed for C and nutrient contents. The annual pattern of litterfall was closely related to rainfall seasonality, exhibiting a large peak towards the end of the dry season (August–October). This peak decreased at higher elevations with decreasing rainfall seasonality. Macronutrients (N, P, K) in leaf litter increased at mid elevation (2100 m a.s.l.) and with land-use intensity. Carbon content and micronutrients (Al, Fe, Mn, Na) however, were unaffected or decreased with land-use intensity. While leaf litterfall decreased with elevation, total annual input was independent of climate. Compared to natural forests, the nutrient cycles in agroforestry ecosystems were accelerated by fertilization and the associated changes in dominant tree species.

Litterfall, carbon and nitrogen cycling in a southern hemisphere conifer forest dominated by kauri (Agathis australis) during drought

Under future climates, droughts will be more frequent and severe in parts of New Zealand, but the impact of drought has not been studied in New Zealand forests. Litterfall is one of the major fluxes of forest carbon. We explored seasonal and annual patterns of litterfall, carbon and nitrogen cycling in wet (2012) and dry (2013) years at Huapai Scientific Reserve, west Auckland. During 2012, rainfall was close to average with a wet summer, while the summer rainfall in the period from January to April 2013 was only 1/3 of the volume that fell during the same period in 2012, causing significant reductions in soil moisture. For the wet year, total annual litterfall was 9.00 ± 0.44 t ha−1, while during the dry year, there was a 72 % increase to 15.46 ± 0.85 t ha−1. Kauri constituted 80 % of the basal area of the plot and also contributed 80 % of the litter. The majority additional litter in the dry year was kauri leaves and twigs. Drought impacted slightly more heavily on the C cycle (with an 85 % increase during the drought year) than the N cycle (with a 69 % increase during the drought year) because concentrations of N in kauri leaves were lower during the drought period, due to nutrient reabsorption. Drought clearly enhances litterfall in this forest, stimulating the carbon and nitrogen cycles. These results have implications for forest C and N budgets as well as fire management practices due to the build-up of dry litter during drought.

Litterfall and nutrients return in Nothofagus antarctica forests growing in a site quality gradient with different management uses in Southern Patagonia

We evaluated the annual litterfall and nutrients return in primary forests of Nothofagus antarctica growing at three different site classes (SC) (III, IV and V) and compared two of these forests with adjacent stands under silvopastoral use (thinned 40 years ago), in Patagonia, Argentina. Traps were installed in each stand and sampled monthly during the litterfall over 10 years. Sample from the five stands was ground for further analyses of nutrients (N, P, K, Ca, Mg and S). The litterfall varied significantly between SC, but not between years, from 1,306 to 1,972 kg ha−1 in the best site. The nutrients return from litterfall did not change neither between site classes and years in most nutrients. Comparing primary forests with silvopastoral stands, in SCIV, significant differences among uses occurred for litterfall production and nutrients return, being higher in primary forest. While, in SCV, the litterfall and nutrients return practically did not change among uses. The results showed the incidence of site quality and forest use on the litterfall and nutrients return in N. antarctica forests.

Differential plant damage due to litterfall in palm-dominated forest stands in a Central Pacific atoll

Abstract:High densities of palms are common in many tropical forests. In some cases, the dominance of palms has been associated with a depauperate understorey and high rates of native seedling mortality. A variety of different potential mechanisms has been suggested to explain the sustained palm dominance in the understorey and canopy of these forests. Working in a Cocos nucifera-dominated wet tropical forest at Palmyra Atoll in the central Pacific, we examine how litterfall from this pantropical, and economically important palm, impacts seedling survival. We compare rates of litterfall, and rates of litterfall-associated damage, between forest stands dominated by C. nucifera (coconut palm) and forest stands with low abundance of C. nucifera. To assess litterfall damage we survey damage to both artificial seedlings (n = 711), outplanted real seedlings of two species (with and without protection via caging; n = 204), and standing rates of litterfall damage. We find that rates of large-litterfall damage were an average of five times higher in sites with high densities of C. nucifera. Associated with these increases we observe that levels of physical damage to artificial model seedlings caused by litterfall over a 4-mo period increased from 4.9% in sites with low abundance of C. nucifera to 16.1% in sites with high abundance of C. nucifera. Extrapolated to annual rates, litterfall damage of this magnitude exceeds the average levels observed in other published studies. Living native seedlings also showed more than 300% higher levels of mortality in forest stands with high densities of C. nucifera, a difference that was greatly reduced when protected by caging from litterfall. In contrast, uncaged C. nucifera seedlings actually had slightly higher survivorship in habitats dominated by conspecifics. We suggest that litterfall damage may be an important mechanism by which this tropical palm reaches and maintains near monodominance in many coastal and insular habitats.

Allometric relationships among different components of forest litterfall in China

Aims Litterfall is a measure of the metabolic product of forest plants during their growth. It plays an important part in the fluxes and recycling of matter and energy. The metabolic theory of ecology posits that there exist al- lometric relationships among different organs of a plant. However, all these scaling relationships do not take into account the potential contribution of litterfall, and hence much remains unknown about the allometric relation- ships among the different components of litterfall. In this study, we analyze the allometric relationships between component as well as the allometric relationships of the total litterfall with different components. Methods We compiled data on forest litterfall from the literature published in Chinese journals and divided these data into evergreen forests and deciduous forests for analysis of the allometric relationships between components as well as the allometric relationships of the total litterfall with different components.Important findings We found that the average amount of litterfall was 3 810.34 kg·hm–2·a–1, 1 019.07 kg·hm–2·a–1, and 767.95 kg·hm–2·a–1as leaves, branches, and propagules, respectively. Compared with precipita- tion and stand age, temperature had a greater effect on forest litterfall production. An isometrical relationship was observed between leaves and the total litterfall, as LL ∝ LT 0.96(LL, leaf litterfall; LT, total litterfall); whereas an allometric relationship was found between the propagules and the total litterfall as LP ∝ LT 1.84(LP, propagule lit- terfall), and between the branches and the total litterfall as LB ∝ LT 1.61(LB, branch litterfall), respectively. Signifi- cant allometric relationships were also observed among different components, with exponents all less than 1.0 in each case. Allometric relationships of the total litterfall with different components were approximately the same between the evergreen forests and the deciduous forests. The allometric relationships found in this study provide valuable insights into the investigation and estimation of forest productivity.

Drivers of Mangrove Litterfall within a Karstic Region Affected by Frequent Hurricanes

AbstractTropical storms can shape the structure and productivity of mangrove forests. In this study, we compared current litterfall with historical tropical storm disturbance in the karstic Yucatan Peninsula (YP). We also explored the relationship between litterfall and the fresh/seawater mixture of floodwater. Our hypotheses were that litterfall peaks at moderate perturbations and in sites where seawater dominates the floodwater mixture, and thus, where soil total phosphorus (TP) is relatively high. Litterfall was sampled for 2 yr, from eight mangrove forests around the YP. At each site, forest structure, interstitial salinity, TP, nitrogen, carbon, pH, and bulk density were measured. Our results show that mangrove forest from northeast YP are historically impacted by stronger and more frequent tropical storms compared with those in northwest and southeast YP, where tropical storm intensity is moderate and mild, respectively. Litterfall was higher in northwest YP (≥3 g/m2 d) compared with northeast and southeast (≤ 2 g/m2 d), mimicking a subsidy‐stress gradient where highest productivity is reached at moderate perturbations. Neither salinity nor forest structure alone satisfactorily explained litterfall variability. Soil TP followed a similar geographical pattern as the disturbance gradient: highest concentrations in the northwest YP (≥0.05%) and lowest in the northeast and southeast (≤ 0.03%). Thus, it is likely that TP, and not tropical storm disturbance, is the main driver of litterfall in mangrove forests of the YP. Alterations in TP availability (e.g., sea level rise and aquifer contamination) have the potential to modify mangrove productivity in the region.

Soil carbon release enhanced by increased tropical forest litterfall

Enhanced tropical forest productivity, facilitated by increasing carbon dioxide concentrations, could act as a substantial carbon sink. However, a long-term field experiment shows that increased leaf-litter inputs to the soil as productivity rises could stimulate the release of significant amounts of soil carbon, partially offsetting predicted gains in carbon storage.

Foliar nutrient dynamics in tidal and non-tidal freshwater forested wetlands

Foliar nutrient dynamics were studied at 8 forest stands (three non-tidal and five tidal) along the lower 30 km of the Apalachicola River system in Florida, USA, during 2008. At each site, we sampled canopy foliage and litterfall from three to four trees representative of the dominant overstory species. Foliage and litterfall were analyzed for a variety of elements including N and P and these data were used to examine differences in element concentrations, nutrient ratios (C:P, C:N, and N:P), nutrient use efficiency, and nutrient proficiency. Measurements of tree diameter at basal height (DBH) at each plot were used with species allometric equations to estimate forest litterfall dry weight and N and P flux in non-tidal and tidal wetlands. Both non-tidal and tidal wetlands showed evidence of P limitation based on N:P ratios, but absolute levels of P were determined to be extremely low in tidal wetlands based on higher nutrient use efficiencies (measures of both P resorption efficiency and proficiency). Differences in P concentrations and fluxes between tidal and non-tidal wetlands are probably related to longer inundation and hydrologic export observed in tidal wetlands. Using estimations of annual litterfall dry weight and nutrient concentrations, N and P flux in non-tidal swamps were 2–4 times greater than in tidal wetlands. This study demonstrates the change in nutrient dynamics as wetlands shift from tidal to non-tidal conditions.

The structure and dynamics of litterfall in forest stands in the Słowiński National Park in 2003-2005

Struktura i dynamika opadu organicznego w wybranych drzewostanach Słowińskiego Parku Narodowego w latach 2003-2005

High litterfall in old-growth and secondary upper montane forest of Costa Rica

Tropical upper montane forests usually comprise trees of small stature with a relatively low aboveground productivity. In contrast to this rule, in the Cordillera de Talamanca (Costa Rica), tall trees (>35 m in height and more than 60 cm in diameter) are characteristic for the upper montane old-growth oak forests which are growing at an altitude of almost 3,000 m close to the alpine timberline. For these exceptional forests, productivity data are not yet available. In this study, we analyzed litterfall and its components (tree leaves, litter of epiphytic vascular and non-vascular plants, mistletoes, twigs and other canopy debris) in three forest stands belonging to different successional stages and related seasonal changes in litterfall to micrometeorological variables. The studied stands were early-successional forest (10–15-year-old), mid-successional forest (40-year-old), and old-growth forest. The stands are dominated by Quercus copeyensis and are located at 2,900-m altitude. Total litterfall was highest in the mid-successional forest (1,720 g m−2 y−1), and reached 1,288 g m−2 y−1 in the old-growth forest and 934 g m−2 y−1 in the early-successional forest. Litter mass was dominated by leaves in all stages (56–84% of total litterfall). In the old-growth forest, however, twigs and small canopy debris particles (33%), epiphytes (6%), and mistletoes (5%) also contributed substantially to litter mass. Leaf litterfall showed a clear seasonal pattern with a negative correlation to monthly precipitation and highest values in the dry season (January–April). However, the strongest correlation existed with minimum air temperature (negative), probably because temperatures already dropped at the end of the rainy season, when precipitation had not yet declined and leaf shedding already increased. In contrast, litterfall of epiphyte mass, and twigs and other debris was mostly dependent on occasional strong winds. We conclude that the upper montane oak forests of the Cordillera de Talamanca are exceptional with respect to the large tree size and the relatively high productivity as indicated by litterfall. Litter mass was especially high in the mid-successional and old-growth forests, where the observed annual totals are among the highest recorded for tropical forests so far.

Increased Litterfall in Tropical Forests Boosts the Transfer of Soil CO2 to the Atmosphere

Aboveground litter production in forests is likely to increase as a consequence of elevated atmospheric carbon dioxide (CO2) concentrations, rising temperatures, and shifting rainfall patterns. As litterfall represents a major flux of carbon from vegetation to soil, changes in litter inputs are likely to have wide-reaching consequences for soil carbon dynamics. Such disturbances to the carbon balance may be particularly important in the tropics because tropical forests store almost 30% of the global soil carbon, making them a critical component of the global carbon cycle; nevertheless, the effects of increasing aboveground litter production on belowground carbon dynamics are poorly understood. We used long-term, large-scale monthly litter removal and addition treatments in a lowland tropical forest to assess the consequences of increased litterfall on belowground CO2 production. Over the second to the fifth year of treatments, litter addition increased soil respiration more than litter removal decreased it; soil respiration was on average 20% lower in the litter removal and 43% higher in the litter addition treatment compared to the controls but litter addition did not change microbial biomass. We predicted a 9% increase in soil respiration in the litter addition plots, based on the 20% decrease in the litter removal plots and an 11% reduction due to lower fine root biomass in the litter addition plots. The 43% measured increase in soil respiration was therefore 34% higher than predicted and it is possible that this ‘extra’ CO2 was a result of priming effects, i.e. stimulation of the decomposition of older soil organic matter by the addition of fresh organic matter. Our results show that increases in aboveground litter production as a result of global change have the potential to cause considerable losses of soil carbon to the atmosphere in tropical forests.

Caracterização da matéria orgânica do solo em fragmentos de mata atlântica e em plantios abandonados de eucalipto

A compreensão da dinâmica da matéria orgânica (MO) nos ecossistemas de Mata Atlântica é necessária para o manejo eficiente e conservação de vegetações nativas. A natureza química das substâncias húmicas (SHs) reflete os processos de gênese e uso do solo e pode ser usada como indicador da qualidade da MO. O objetivo deste estudo foi usar a qualidade da MO como sinalizador do ambiente edáfico em áreas de mata nativa, sobre Gleissolo Háplico Tb distrófico, argissólico e Cambissolo Háplico Tb distrófico, e em plantios abandonados de eucalipto de diferentes idades, sobre Argissolo Vermelho-Amarelo distrófico latossólico, localizados na Reserva Biológica União, RJ. Para isso, foram avaliadas as distribuições da MO humificada e os ácidos húmicos do solo por meio de métodos químicos e espectroscópicos, em duas profundidades do solo (0-0,10 e 0,10-0,20 m). Os solos da Reserva Biológica apresentaram fertilidade natural muito baixa, condição esta limitante para o processo de humificação. As SHs representaram, portanto, menos de 50 % do carbono prontamente oxidável, indicando que as substâncias não-húmicas compõem a maior parte da MO; portanto, a serrapilheira tem o papel central na nutrição das plantas e microrganismos. A distribuição relativa das frações que compõem a MO humificada não foi alterada pela cobertura vegetal nem pela classe de solo. Os ácidos húmicos apresentaram natureza química semelhante à normalmente encontrada para os ácidos fúlvicos, e tais características foram expressas no baixo conteúdo de C e nos elevados valores das razões H/C e O/C e da acidez, o que levou à formação de material humificado pouco condensado.A espectroscopia de infravermelho indicou o efeito do tipo de solo e da cobertura vegetal sobre a qualidade química dos ácidos húmicos. O material humificado isolado da Mata Atlântica apresentou maior intensidade de fluorescência, sugerindo maior labilidade e capacidade de ceder elétrons para reações químicas do solo.

C and N stocks under three plantation forest ecosystems of Chinese fir, Michelia macclurei and their mixture

Chinese fir (Cunninghamia lanceolata), a type of subtropical fast-growing conifer tree, is widely distributed in South China. Its plantation area covers more than 7 × 106 hm2, accounting for 24% of the total area of plantation forests in the country. In recent decades, the system of successive plantation of Chinese fir has been widely used in southern China due to anticipated high economic return. However, recent studies have documented that the practice of this system has led to dramatic decreases in soil fertility and forest environment as well as in productivity. Some forest ecologists and managers recognize the ecological role performed by broadleaf trees growing in mixtures with conifers, and a great deal of studies on mixture effects have been conducted, particularly on mixture species of temperate and boreal forests, but these research results were not completely consistent. Possibilities include dependence of the mixture effects in large part to specific site conditions, the interactions among species in mixtures and biological characteristics of species. Although some researchers also studied the effects of mixtures of Chinese fir and broadleaf tree species on soil fertility, forest environment and tree growth status, little information is available about the effects of Chinese fir and its mixtures with broadleaves on carbon and nitrogen stocks. The experimental site is situated at the Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, Hunan Province (26°40′–27°09′ N, 109°26′–110°08′ E). It is located at the transition zone from the Yunnan-Guizhou Plateau to the low mountains and hills of the southern bank of the Yangtze River at an altitude of 300–1,100 m above mean sea level. At the same time, the site is also a member of the Chinese Ecosystem Research Network (CERN), sponsored by the Chinese Academy of Sciences (CAS). This region has a humid mid-subtropical monsoon climate with a mean annual precipitation of 1,200–1,400 mm, most of the rain falling between April and August, and a mean temperature of 16.5°C with a mean minimum of 4.9°C in January and a mean maximum of 26.6°C in July. The experimental field has red-yellow soil. After a clear-cutting of the first generation Chinese fir (Cunninghamia lanceolata) plantation forest in 1982, three different plantation forest ecosystems, viz. mixture of Michelia macclurei and Chinese fir (MCM), pure Michelia macclurei stand (PMS) and pure Chinese fir stand (PCS), were established in the spring of 1983. A comparative study on C and N stocks under these three plantation forest ecosystems was conducted in 2004. Results showed that carbon stocks were greater under the mixtures than under the pure Chinese fir forest and the pure broad-leaved forest, and the broadleaves and the mixtures showed higher values in nitrogen stocks compared with the pure Chinese fir forest. The spatial distribution of carbon and nitrogen stocks was basically consistent, the value being greater in soil layer, followed by tree layer, roots, understory and litter layer. The carbon and nitrogen stocks in soil layer were both highly correlated with the biomass in understory and litter layer, indicating that understory and forest litterfall exerted a profound effect on soil carbon and nitrogen stocks under plantation ecosystems. However, correlations among soil carbon, nitrogen stocks and below ground biomass of stand have not been observed in this study.