Stocks and dynamics of soil organic carbon and coarse woody debris in three managed and unmanaged temperate forests

The effect of forest conservation on the organic carbon (C) stock of temperate forest soils is hardly investigated. Coarse woody debris (CWD) represents an important C reservoir in unmanaged forests and potential source of C input to soils. Here, we compared aboveground CWD and soil C stocks at the stand level of three unmanaged and three adjacent managed forests in different geological and climatic regions of Bavaria, Germany. CWD accumulated over 40–100 years and yielded C stocks of 11 Mg C ha^?1 in the unmanaged spruce forest and 23 and 30 Mg C ha^?1 in the two unmanaged beech–oak forests. C stocks of the organic layer were smaller in the beech–oak forests (8 and 19 Mg C ha^?1) and greater in the spruce forest (36 Mg C ha^?1) than the C stock of CWD. Elevated aboveground CWD stocks did not coincide with greater C stocks in the organic layers and the mineral soils of the unmanaged forests. However, radiocarbon signatures of the O _e and O _a horizons differed among unmanaged and managed beech–oak forests. We attributed these differences to partly faster turnover of organic C, stimulated by greater CWD input in the unmanaged forest. Alternatively, the slower turnover of organic C in the managed forests resulted from lower litter quality following thinning or different tree species composition. Radiocarbon signatures of water-extractable dissolved organic carbon (DOC) from the top mineral soils point to CWD as potent DOC source. Our results suggest that 40–100 years of forest protection is too short to generate significant changes in C stocks and radiocarbon signatures of forest soils at the stand level.     

Carbon storage in biomass,litter, and soil of different native and introduced fast-growing tree plantations in the South Caspian Sea

Replantation of degraded forest using rapidgrowth trees can play a significant role in global carbon budget by storing large quantities of carbon in live biomass,forest floor,and soil organic matter.We assessed the potential of 20-year old stands of three rapid-growth tree species,including Alnus subcordata,Populus deltoides and Taxodium distichum,for carbon(C) storage at ecosystem level.In September 2013,48 replicate plots(16 m × 16 m) in 8 stands of three plantations were established.36 trees were felled down and fresh biomass of different components was weighed in the field.Biomass equations were fitted using data based on the 36 felled trees.The biomass of understory vegetation and litter were measured by harvesting all the components.The C fraction of understory,litter,and soil were measured.The ecosystem C storage was as follows: A.subcordata(626.5 Mg ha~(-1)) [ P.deltoides(542.9Mg ha~(-1)) [ T.distichum(486.8 Mg ha~(-1))(P \ 0.001),of which78.1–87.4% was in the soil.P.deltoides plantation reached the highest tree biomass(206.6 Mg ha~(-1)),followed by A.subcordata(134.5 Mg ha~(-1)) and T.distichum(123.3 Mg ha~(-1)).The highest soil C was stored in theplantation of A.subcordata(555.5 Mg ha~(-1)).The C storage and sequestration of the plantations after 20 years were considerable(25–30 Mg ha~(-1) year~(-1)) and broadleaves species had higher potential.Native species had a higher soil C storage while the potential of introduced species for live biomass production was higher.     

Short-term changes in the soil carbon stocks of young oil palm-based agroforestry systems in the eastern Amazon

The current expansion of the oil palm (Elaeis guineensis Jacq.) in the Brazilian Amazon has mainly occurred within smallholder agricultural and degraded areas. Under the social and environmental scenarios associated with these areas, oil palm-based agroforestry systems represent a potentially sustainable method of expanding the crop. The capacity of such systems to store carbon (C) in the soil is an important ecosystem service that is currently not well understood. Here, we quantified the spatial variation of soil C stocks in young (2.5-year-old) oil palm-based agroforestry systems with contrasting species diversity (high vs. low); both systems were compared with a ~10-year-old forest regrowth site and a 9-year-old traditional agroforestry system. The oil palm-based agroforestry system consisted of series of double rows of oil palm and strips of various herbaceous, shrub, and tree species. The mean (±standard error) soil C stocks at 0–50 cm depth were significantly higher in the low (91.8 ± 3.1 Mg C ha^?1) and high (87.6 ± 3.3 Mg C ha^?1) species diversity oil palm-based agroforestry systems than in the forest regrowth (71.0 ± 2.4 Mg C ha^?1) and traditional agroforestry (68.4 ± 4.9 Mg C ha^?1) sites. In general, no clear spatial pattern of soil C stocks could be identified in the oil palm-based agroforestry systems. The significant difference in soil carbon between the oil palm area (under oil palm: 12.7 ± 2.3 Mg C ha^?1 and between oil palm: 10.6 ± 0.5 Mg C ha^?1) and the strip area (17.0 ± 1.4 Mg C ha^?1) at 0–5 cm depth very likely reflects the high input of organic fertilizer in the strip area of the high species diversity oil palm-based agroforestry system treatment. Overall, our results indicate a high level of early net accumulation of soil C in the oil palm-based agroforestry systems (6.6–8.3 Mg C ha^?1 year^?1) that likely reflects the combination of fire-free land preparation, organic fertilization, and the input of plant residues from pruning and weeding.     

Floristic diversity,carbon storage and ecological services of eucalyptus agrosystems in Cameroon

Although agrosystems are recognized for their socio-economic value, few works have been conducted to assign its sequestration potential and ecological services. Accordingly, this study aimed to evaluate the ecological services of the eucalyptus stands in order to permit to small producers the access in carbon credit market. Three stands were selected according to age. Data were compared to that of a savannah (control). In total, 12,817 individuals belonging to 30 families, 53 genera and 70 species were identified in the plantations against 7107 individuals belonging to 24 families, 36 genera and 42 species in the savannah. Gmelina, Annona, Hymenocardia, Allophyllus, Daniellia, Terminalia and Piliostigma were the most represented genera. There was no significant difference between Savannah and plantations in terms of diversity (p > 0.05). The largest stock of carbon was found in oldest stands (108.51 ± 26.46 t C/ha) against 13.62 ± 3.03 t C/ha in Savannah. Eucalyptus saligna stored 39.66 t C/ha (4 t C ha^?1year^?1) in young stands; 57.28 t C/ha (6 t C ha^?1year^?1) in medium stands and 85.46 t C/ha (9 t C ha^?1year^?1) in old stands. The sequestration potential was higher in eucalyptus stands (398.25 t CO_2eq/ha) than savannah (50.05 t CO_2eq/ha). In total 956.82 t CO_2eq/ha were sequestered for an economic value of $9568.45/ha against 50.05 t CO_2eq/ha corresponding to $500.56/ha in Savannah. Eucalyptus stands are carbon sinks and could be an opportunity for financial benefits in the event of payment for environmental services in the context of the CDM process.     

Quantification of organic carbon and primary nutrients in litter and soil in a foothill forest plantation of eastern Himalaya

The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four forest tree species(Lagerstroemia parviflora, Tectona grandis, Shorea robusta and Michelia champaca) in the Chilapatta Reserve Forest of the Cooch Behar Wildlife Division in the Terai zone of West Bengal, India. The most litter(5.61 Mg ha~(-1))was produced by T. grandis plantation and the least(4.72 Mg ha~(-1)) by L. parviflora. The material turnover rate to the soil through decomposition from total litter was fastest during the first quarter of the year and subsequently decreased during the next two quarters. The material turnover rate was only 1 year, which indicates that more than90% of the total litter produced decomposed within a year.The available primary nutrient content in litter varied across the four plantations over the year. The plantations generally did not significantly influence the soil physical characteristics but did significantly influence the availability of primary nutrients and organic carbon at two depths(1–15 and16–30 cm) over the year. The availability of soil primary nutrients in the four plantations also increased gradually from the first quarter of the year to the third quarter and then decreased during the last quarter to the same level as in the first quarter of the year at both depths. The availability for soil organic carbon in the plantations followed a similar trend. The amount of litter produced and the material turnover in the soil in the different plantations differed, influencing the nutrient availability and organic carbon at the plantations. The amount of soil organic carbon was highest for T. grandis(2.52 Mg ha~(-1)) and lowest for L. parviflora(2.12 Mg ha~(-1)). Litter is the source of soil organic matter,and more the litter that is produced by the plantations, the higher will be the content and amount of soil organic carbon in the plantation.     

Effects of afforestation on soil carbon and its fractions: a case study from the Loess Plateau,China

Afforestation has been implemented to reduce soil erosion and improve the environment of the Loess Plateau,China.Although it increased soil organic carbon(SOC),the stability of the increase is unknown.Additionally,the variations of soil inorganic carbon(SIC) following afforestation needs to be reconfirmed.After planting Robinia pseudoacacia,Pinus tabuliformis,and Hippophae rhamnoides on bare land on the Loess Plateau,total soil carbon(TSC) was measured and its two components,SIC and SOC,as well as the light and heavy fractions within SOC under bare lands and woodlands at the soil surface(0–20 cm).The results show that TSC on bare land was 24.5 Mg ha~(-1) and significantly increased to 51.6 Mg ha~(-1) for R.pseudoacacia,47.0 Mg ha~(-1) for P.tabuliformis and 39.9 Mg ha~(-1) for H.rhamnoides.The accumulated total soil carbon under R.pseudoacacia,P.tabuliformis,and H.rhamnoides,the heavy fraction(HFSOC) accounted for 65.2,31.7 and 76.2%,respectively; the light fraction(LF-SOC) accounted for 18.0,52.0 and 4.0%,respectively; SIC occupied 15.6,15.3 and 19.7%,respectively.The accumulation rates of TSC under R.pseudoacacia,P.tabuliformis,and H.rhamnoides reached159.5,112.4 and 102.5 g m~(-2) a~(-1),respectively.The results demonstrate that afforestation on bare land has high potential for soil carbon accumulation on the Loess Plateau.Among the newly sequestrated total soil carbon,the heavy fraction(HF-SOC) with a slow turnover rate accounted for a considerably high percentage,suggesting that significant sequestrated carbon can be stored in soils following afforestation.Furthermore,afforestation induces SIC sequestration.Although its contribution to TSC accumulation was less than SOC,overlooking it may substantially underestimate the capacity of carbon sequestration after afforestation on the Loess Plateau.     

Do thinnings influence biomass and soil carbon stocks in Mediterranean maritime pinewoods?

The effects of silvicultural treatments on carbon sequestration are poorly understood, particularly in areas like the Mediterranean where soil fertility is low and climatic conditions can be harsh. In order to improve our understanding of these effects, a long-term thinning experiment in a stand of Mediterranean maritime pine (Pinus pinaster Ait.) was studied to identify the effects of thinning on soil carbon (forest floor and mineral soil), above and belowground biomass and fine and coarse woody debris. The study site was a 59-year-old pinewood, where three thinnings of differing intensities were applied: unthinned (control), moderate thinning and heavy thinning. The three thinning interventions (for the managed plots) involved whole-tree harvesting. The results revealed no differences between the different thinning treatments as regards the total soil carbon pool (forest floor + mineral soil). However, differences were detected in the case of living aboveground biomass and total dead wood debris between unthinned and thinned plots; the former containing larger amounts of carbon. The total carbon present in the unthinned plots was 317 Mg ha^?1; in the moderately thinned plots, it was 256 Mg ha^?1 and in the case of heavily thinned plots, 234 Mg ha^?1. Quantification of these carbon compartments can be used as an indicator of total carbon stocks under different forest management regimes and thus identify the most appropriate to mitigate the effects of global change. Our results indicated that thinning do not alter the total soil carbon content at medium term, suggesting the sustainability of these silvicultural treatments.     

Long-term response to area of competition control in <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> plantations

Numerous studies have quantified the responses to vegetation management in Eucalyptus plantations but most publications have reported early responses in tree growth and a gap in knowledge exist about the magnitude and duration of growth responses throughout the whole rotation. We evaluated the long-term response (9 years-old) of E. globulus across a gradient of sites to different intensity levels of free area of competing vegetation around individual tree seedlings. Competing vegetation intensity levels considered free areas ranging between 0 (control) to 2.54 m² plus a treatment with total weed control. Competing vegetation biomass production during the first growing season was 2.9, 6.5, 2.2 and 12.9 Mg ha^?1, for sites ranging from low to high annual rainfall. Across sites, maximum response in stand volume ranged between 58 and 262 m³ ha^?1 at age 9 years and was proportional to the amount of competing biomass controlled during the first growing season. Total competing vegetation control showed the largest response in stand volume at sites with 2.9 and 12.9 Mg ha^?1 of competing vegetation. However, the 2.54 m² vegetation control treatment showed the maximum response for sites with 2.2 and 6.5 Mg ha^?1 of competing vegetation. The duration of response for vegetation control treatments ranged between 5 and 9 years. However, at the site with the largest accumulation of competing vegetation biomass the response to vegetation control showed a sustained and divergent response. Our results suggest that vegetation control improved site resources acquisition increasing long-term stand productivity by reducing environmental limitations to tree growth differentially at each site.     

Sapling biomass allometry and carbon content in five afforestation species on marginal farmland in semi-arid Benin

Allometric equations are routinely used in the estimation of biomass stocks for carbon accounting within forest ecosystems. However, generic equations may not reflect the growth trajectories of afforestation species that are introduced to degraded farmland characterized by water and nutrient limitations. Using sequential measurements of the height, basal diameter, and above- and belowground biomass of juvenile trees, we developed allometric equations for five woody species (Moringa oleifera Lam., Leucaena leucocephala Lam., Jatropha curcas L., Anacardium occidentale L. and Parkia biglobosa Jacq.) subjected to a gradient of water and nutrient availability in an afforestation trial on degraded cropland in the semi-arid zone of Benin, West Africa. For three of the species studied, the allometric relationships between basal diameter and biomass components (i.e. leaves, stems and roots) were described best by a simple power-law model (R² > 0.93). The incorporation of species-specific height–diameter relationships and total height as additional predictors in the power-law function also produced reasonable estimates of biomass. Fifteen months after planting, roots accounted for 10–58% of the total biomass while the root-to-shoot ratio ranged between 0.16 and 0.73. The total biomass of the saplings ranged between 1.4 and 10.3 Mg ha^?1, yielding 0.6–4.3 Mg C ha^?1, far exceeding the biomass in the traditional fallow system. The rate of stem carbon sequestration measured ca. 0.62 Mg C ha^?1 year^?1. Overall, the allometric equations developed in this study are generally useful for assessing the standing shoot and root biomass of the five afforestation species during the juvenile growth stage and can help in reporting and verifying carbon stocks in young forests.     

Biomass production,carbon sequestration and nutrient characteristics of 22-year-old support trees in black pepper (<Emphasis Type="Italic">Piper nigrum</Emphasis>. L) production systems in Kerala,India

Diverse kinds of fast growing multipurpose trees are traditionally grown as support trees (standards) for trailing black pepper vines in the humid tropics of India. Apart from differential black pepper yields, such trees exhibit considerable variability to accumulate biomass, carbon and nutrients. An attempt was made to assess the biomass production, carbon sequestration potential (tree + soil) and nutrient stocks of six multipurpose tree species (age: 22 years) used for trailing black pepper vines (Acacia auriculiformis, Artocarpus heterophyllus, Grevillea robusta, Macaranga peltata, Ailanthus triphysa and Casuarina equisetifolia). Results indicate that G. robusta showed the highest total biomass production (365.72 Mg ha^?1), with A. triphysa having the least value (155.13 Mg ha^?1). Biomass allocation among tissue types followed the order stemwood > roots > branchwood > twigs > leaves. Total C stocks were also highest for G. robusta (169 Mg C ha^?1), followed by A. auriculiformis (155 Mg C ha^?1). Mean annual carbon increment also followed a similar trend. Among the various tissue fractions, stemwood accounted for the highest N, P and K stocks, implying the potential for nutrient export from the site through wood harvest. All the support trees showed significantly higher soil carbon content compared to the treeless control. Soil N, P and K contents were higher under A. auriculiformis than other species. Nitrogen fixation potential, successional stage of the species, stand age and tree management practices such as lopping may modify the biomass allocation patterns and system productivity.     

Litterfall,decomposition and nutrient release of <Emphasis Type="Italic">Shorea robusta</Emphasis> and <Emphasis Type="Italic">Tectona grandis</Emphasis> in a sub-tropical forest of West Bengal,Eastern India

We studied leaf litter fall, decomposition and nutrient release patterns of Shorea robusta and Tectona grandis by using a litter bag technique to better understand the release pattern of nutrients to soil from leaf litter. Annual litterfall varied from 13.40 ± 2.56 t ha^?1 a^?1 for S. robusta to 11.03 ± 3.72 t ha^?1 a^?1 for T. grandis and the decay constant (k) of decomposed leaf litter was distinctly higher for T. grandis (2.70 ± 0.50 a^?1) compared to S. robusta (2.41 ± 0.30 a^?1). Biomass loss was positively correlated with the initial litter C, WSC, C/N and ash content in S. robusta and N, P and K concentration for T. grandis. Biomass was negatively correlated with lignin and L/N ratio for S. robusta and L, WSC, L/N and C/N ratio for T. grandis (P < 0.01). Nutrient use efficiency (NUE) and nutrient accumulation index (NAI) of S. robusta was higher than for T. grandis. The retranslocation of bioelements from senescent leaves ranked as P > N > K. Annual N, P and K input to soil through litterfall differed significantly between the two species in the following order: N>K>P. S. robusta was superior in terms of K and P return and T. grandis was superior in terms of N return. The two tree species showed a similar patterns of nutrient release (K > P > N) during decomposition of their leaf litter. Nutrients of N, K and P were the primary limiting nutrients returned to soil through litterfall with important roles in soil fertility and forest productivity.     

Variation in vegetation composition,biomass production,and carbon storage in ridge top forests of high mountains of Garhwal Himalaya

Abstract

The present study was aimed to anticipate how forest composition, regeneration, biomass production, and carbon storage vary in the ridge top forests of the high mountains of Garhwal Himalaya. For this purpose five major forest types—(a) Pinus wallichiana, (b) Quercus semecarpifolia, (c) Cedrus deodara, (d) Abies spectabilis, and (e) Betula utilis mixed forests—were selected on different ridge tops in the Bhagirathi Catchment Area of the Uttarkashi District of Garhwal Himalaya. The highest species richness (10 species) and stand density (804 ± 184.5 stems ha^?1) were recorded in Abies spectabilis forests, whereas lowest species richness (4 species) and species density (428 ± 144.7 stems ha^?1) were found in Quercus semecarpifolia forests. The total basal cover (TBC) values were maximum (91.1 ± 24.4 m² ha^?1) in Cedrus deodara forests and minimum (26.5 ± 11.7 m² ha^?1) in Pinus wallichiana forests. The highest total biomass density (TBD) (464.2 ± 152.5 Mg ha^?1) and total carbon density (TCD; 208.9 ± 68.6 Mg C ha^?1) values were recorded for Cedrus deodara forests; however, lowest TBD (283.4 ± 74.8 Mg ha^?1) and TCD (127.5 ± 33.7 Mg C ha^?1) values for Quercus semecarpifolia forests. Our study suggests that Abies spectabilis-dominated forests should be encouraged for biodiversity enrichment and reducing carbon emissions on ridge top forests of high mountains.     

Soil organic carbon stocks and fractions in different orchards of eastern plateau and hill region of India

Soil organic carbon (SOC) plays an important role in soil fertility and productivity. It occurs in soil in labile and non-labile forms that help in maintaining the soil health. An investigation was undertaken to evaluate the dynamics of total soil organic carbon (C _tot), oxidisable organic carbon (C _oc), very labile carbon (C frac ₁), labile carbon (C frac ₂), less labile carbon (C frac ₃), non-labile carbon (C frac ₄), microbial biomass carbon (C _mic) and SOC sequestration in a 6-year-old fruit orchards. The mango, guava and litchi orchards caused an enrichment of C _tot by 17.2, 12.6 and 11 %, respectively, over the control. The mango orchard registered highest significant increase of 20.7, 13.5 and 17.4 % in C frac ₁, C frac ₂ and C frac ₄, respectively, over control. There is greater accumulation of all the C fractions in the surface soil (0–0.30 m). The maximum total active carbon pool was 36.2 Mg C ha^?1 in mango orchard and resulted in 1.2 times higher than control. The passive pool of carbon constituted about 42.4 % of C _tot and registered maximum in the mango orchard. The maximum C _mic was 370 mg C kg^?1 in guava orchard and constituted 4.2 % of C _tot. The carbon management index registered 1.2 (mango orchard)- and 1.13 (guava and litchi orchard)-fold increase over control. The mango orchard registered highest carbon build rate of 1.53 Mg C ha^?1 year^?1 and resulted in 17.3 % carbon build-up over control. Among the carbon fractions, C frac ₁ was highly correlated (r = 0.567**) with C _mic.     

Predictive models for biomass and carbon stocks estimation in Grewia optiva on degraded lands in western Himalaya

Grewia optiva Drummond is one of important agroforestry tree species grown by the farmers in the lower and mid-hills of western Himalaya. Different models viz., monomolicular, logistic, gompetz, allometric, rechards, chapman and linear were fitted to the relationship between total biomass and diameter at breast height (DBH) as independent variable. The adjusted R² values were more than 0.924 for all the seven models implying that all models are apparently equally efficient. Out of the six non-linear models, allometric model (Y = a × DBH ^b ) fulfils the validation criterion to the best possible extent and is thus considered as best performing. Biomass in different tree components was fitted to allometric models using DBH as explanatory variable, the adjusted R² for fitted functions varied from 0.872 to 0.965 for different biomass components. The t values for all the components were found non-significant (p > 0.05), thereby indicating that model is valid. Using the developed model, the estimated total biomass varied from 6.62 Mg ha^?1 in 4 year to 46.64 Mg ha^?1 in 23 year old plantation. MAI in biomass varied from 1.66–2.05 Mg ha^?1 yr^?1. The total biomass carbon stocks varied from 1.99 Mg ha^?1 in 4 year to 15.27 Mg ha^?1 in 23 year old plantation. Rate of carbon sequestration varied from 0.63–0.81 Mg ha^?1 yr^?1. Carbon storage in the soil up to 30 cm soil depth varied from 25.4 to 33.6 Mg ha^?1.     

Carbon dioxide sequestration capability of an unmanaged old-growth broadleaf deciduous forest in a Strict Nature Reserve

The seasonal trend of plant carbon dioxide (CO₂) sequestration is related to the photosynthetic activity, which in turn changes in response to environmental conditions. Great interest has turned to the CO₂ sequestration (CS) potential of temperate forests which play an important role in global carbon (C) cycle contributing to the lowering of atmospheric CO₂ concentration. In such context, the CS of an unmanaged old broad-leaf deciduous forest developing inside a Strict Nature Reserve, and its variations during the year were analyzed considering the monthly variations of leaf area index (LAI) and net photosynthetic rates (N_P). Overall, the total yearly CS of the forest was 141 Mg CO₂ ha^?1 year^?1 with the highest CS value monitored in June (405 Mg CO₂ month^?1) due to the highest LAI (5.0 ± 0.8 m² m^?2) and a high N_P in all the broadleaf species. The first CS decline was observed in August due to the more stressful climatic conditions that constrained N_P rates. Overall, the total CS of the forest reflects the good ecological health of the ecosystem due to its conservative management.     

Biomass storage in low timber productivity Mediterranean forests managed after natural post-fire regeneration in south-eastern Spain

Despite the low timber productivity of Mediterranean Pinus halepensis Mill. forests in south-eastern Spain, they are a valuable carbon sequestration source which could be extended if young stands and understories were considered. We monitored changes in biomass storage of young Aleppo pine stands naturally regenerated after wildfires, with a diachronic approach from 5 to 16 years old, including pine and understory strata, at two different quality sites (dry and semiarid climates). At each site, we set 21 permanent plots and carried out different thinning intensities at two ages, 5 and 10 years after fires. We found similar post-fire regeneration capacity at both sites in terms of total above-ground biomass storage ~6 Mg ha^?1 (3 Mg ha^?1 of the above-ground pine biomass plus 3 Mg ha^?1 of the above-ground understory biomass), but with a contrasting pine layer structure. Generally, across the diachronic study, the earlier thinning reduced biomass stocks at both sites, except for the best quality site (the dry site), where the earliest thinning (applied at post-fire year 5) enlarged carbon storage by 11 % as compared to non-thinned plots. We found root:shoot ratios of an average 0.37 for the pine layer and 0.45 for the understory layer. These results provided new information which not only furthers our understanding of carbon sequestration in low timber productivity Mediterranean forests, but will also help to develop new guidelines for sustainable management adapted to the high-risk terrestrial carbon losses of fire-prone areas.     

Carbon stock estimation for tree species of Sem Mukhem sacred forest in Garhwal Himalaya, India

Carbon stock estimation was conducted in tree species of Sem Mukhem sacred forest in district Tehri of Garhwal Himalaya, Uttarakhand, India. This forest is dedicated to Nagraj Devta and is dominated by tree species, including Quercus floribunda, Quercus semecarpifolia and Rhododendron arboreum. The highest values of below ground biomass density, total biomass density and total carbon density were (34.81±1.68) Mg·ha^?1, (168.26±9.04) Mg·ha^?1 and (84.13±4.18) Mg·ha^?1 for Pinus wallichiana. Overall values of total biomass density and total carbon density calculated were 1549.704 Mg·ha^?1 and 774.77 Mg·ha^?1 respectively. Total value of growing stock volume density for all species was 732.56 m³·ha^?1 and ranged from (144.97±11.98) m³·ha^?1 for Pinus wallichiana to (7.78±1.78) m³·ha^?1 for Benthamidia capitata.     

A generalized algebraic difference approach allows an improved estimation of aboveground biomass dynamics of <Emphasis Type="Italic">Cunninghamia lanceolata</Emphasis> and <Emphasis Type="Italic">Castanopsis sclerophylla</Emphasis> forests

Key message

A generalized algebraic difference approach (GADA) developed in this study improved the estimation of aboveground biomass dynamics of Cunninghamia lanceolata (Lamb.) Hook and Castanopsis sclerophylla (Lindl.) Schott forests. This could significantly improve the fieldwork efficiency for dynamic biomass estimation without repeated measurements.

Context

The estimation of biomass growth dynamics and stocks is a fundamental requirement for evaluating both the capability and potential of forest carbon sequestration. However, the biomass dynamics of Cunninghamia lanceolata and Castanopsis sclerophylla using the generalized algebraic difference approach (GADA) model has not been made to date.

Aims

This study aimed to quantify aboveground biomass (AGB, including stem, branch and leaf biomass) dynamics and AGB increment in C. lanceolata and C. sclerophylla forests by combining a GADA for diameter prediction with allometric biomass models.

Methods

A total of 12 plots for a C. lanceolata plantation and 11 plots for a C. sclerophylla forest were selected randomly from a 100 m × 100 m systematic grid placed over the study area. GADA model was developed based on tree ring data for each stand.

Results

GADA models performed well for diameter prediction and successfully predicted AGB dynamics for both stands. The mean AGB of the C. lanceolata stand ranged from 69.4 ± 7.7 Mg ha^?1 in 2010 to 102.5 ± 11.4 Mg ha^?1 in 2013, compared to 136.9 ± 7.0 Mg ha^?1 in 2010 to 154.8 ± 8.0 Mg ha^?1 in 2013 for C. sclerophylla. The stem was the main component of AGB stocks and production. Significantly higher production efficiency (stem production/leaf area index) and AGB increment was observed for C. lancolata compared to C. sclerophylla.

Conclusion

Dynamic GADA models could overcome the limitations posed by within-stand competition and limited biometric data, can be applied to study AGB dynamics and AGB increment, and contribute to improving our understanding of net primary production and carbon sequestration dynamics in forest ecosystems.

     

Conversion of tropical moist forest into cacao agroforest: consequences for carbon pools and annual C sequestration

Tropical forests store a large part of the terrestrial carbon and play a key role in the global carbon (C) cycle. In parts of Southeast Asia, conversion of natural forest to cacao agroforestry systems is an important driver of deforestation, resulting in C losses from biomass and soil to the atmosphere. This case study from Sulawesi, Indonesia, compares natural forest with nearby shaded cacao agroforests for all major above and belowground biomass C pools (n = 6 plots) and net primary production (n = 3 plots). Total biomass (above- and belowground to 250 cm soil depth) in the forest (approx. 150 Mg C ha^?1) was more than eight times higher than in the agroforest (19 Mg C ha^?1). Total net primary production (NPP, above- and belowground) was larger in the forest than in the agroforest (approx. 29 vs. 20 Mg dry matter (DM) ha^?1 year^?1), while wood increment was twice as high in the forest (approx. 6 vs. 3 Mg DM ha^?1 year^?1). The SOC pools to 250 cm depth amounted to 134 and 78 Mg C ha^?1 in the forest and agroforest stands, respectively. Replacement of tropical moist forest by cacao agroforest reduces the biomass C pool by approximately 130 Mg C ha^?1; another 50 Mg C ha^?1 may be released from the soil. Further, the replacement of forest by cacao agroforest also results in a 70–80 % decrease of the annual C sequestration potential due to a significantly smaller stem increment.     

Optimal management of Korean pine plantations in multifunctional forestry

Korean pine is one of the most important plantation species in northeast China.Besides timber,it produces edible nuts and plantations sequester carbon dioxide from the atmosphere.This study optimized the management of Korean pine plantations for timber production,seed production,carbon sequestration and for the joint production of multiple benefits.As the first step,models were developed for stand dynamics and seed production.These models were used in a simulation–optimization system to find optimal timing and type of thinning treatments and optimal rotation lengths.It was found that three thinnings during the rotation period were optimal.When the amount or profitability of timber production is maximized,suitable rotation lengths are 65–70 years and wood production is 5.5–6.0 m~3 ha~(-1) a~(-1).The optimal thinning regime is thinning from above.In seed production,optimal rotation lengths are over 100 years.When carbon sequestration in living biomass is maximized,stands should not be clear-cut until trees start to die due to senescence.In the joint production of multiple benefits,the optimal rotation length is 86 years if all benefits(wood,economic profits,seed,carbon sequestration) are equally important.In this management schedule,mean annual wood production is 5.5 m~2 ha~(-1) and mean annual seed yield 141 kg ha~(-1).It was concluded that it is better to produce timber and seeds in the same stands rather than assign stands to either timber production or seed production.