Woody Debris Stocks Research Articles

Estimation of coarse woody debris stocks in forest ecosystems of «Tsyrkunivskyi forest» and «Dergachivskyi forest» Emerald network objects (Kharkiv region)

The estimation of coarse woody debris stocks in forest ecosystems of «Tsyrkunivskyi forest» and «Dergachivskyi forest» Emerald network objects was performed. Estimation was conducted based on State Forest Inventory data of State enterprise «Kharkiv Forest Research Station» forest fund. Data of dead wood in forest stands of eighteen tree species were analyzed. The stock of the following components of coarse woody debris was studied: standing dead wood, fallen dead wood. Data analysis was performed using MS Excel 2016 software. It was found that the total area of forest stands in which standing dead wood was found during forest inventory was 9984.6 ha, or 49.6%, of the total forest area; for fallen dead wood corresponding indicators were 2662.5 ha (13.2%). The total stock of coarse woody debris was 20761 m3, which is concentrated in the stands of pedunculate oak (Quercus robur L.) (75.6%) and Scots pine (Pinus sylvestris L.) (11.1%). Standing dead wood prevailed (80.1%) fallen dead wood (19.9%) in the structure of dead wood volume. Mean volume of standing dead wood by forest type was from 1.3 m3 ·ha–1 (dry maplelinden dibrova) to 33.3 m3 ·ha–1 (wet maple-linden sudibrova), fallen dead wood — from 1.0 m3 ·ha–1 (dry maple-linden dibrova) to 11.5 m3 ·ha–1 (wet maple-linden dibrova). In oak stands mean volume of standing dead wood was 1.4 m3 ·ha–1, fallen dead wood — 1.3 m3 ·ha–1. Obtained results indicate that in general, the dead wood volumes in forest ecosystems in studied Emerald network objects estimated based on State Forest Inventory data, are quite low compared to the forest ecosystems of other protected areas, where one of the priorities are the natural complexes protection and biodiversity conservation. It may be associated with the influence of forestry activities in studied protected areas.

Changes in plant debris and carbon stocks across a subalpine forest successional series

BackgroundAs a structurally and functionally important component in forest ecosystems, plant debris plays a crucial role in the global carbon cycle. Although it is well known that plant debris stocks vary greatly with tree species composition, forest type, forest origin, and stand age, simultaneous investigation on the changes in woody and non-woody debris biomass and their carbon stock with forest succession has not been reported. Therefore, woody and non-woody debris and carbon stocks were investigated across a subalpine forest successional gradient in Wanglang National Nature Reserve on the eastern Qinghai-Tibet Plateau.ResultsPlant debris ranged from 25.19 to 82.89 Mg∙ha− 1 and showed a global increasing tendency across the subalpine forest successional series except for decreasing at the S4 successional stage. Accordingly, the ratios of woody to non-woody debris stocks ranged from 26.58 to 208.89, and the highest and lowest ratios of woody to non-woody debris stocks were respectively observed in mid-successional coniferous forest and shrub forest, implying that woody debris dominates the plant debris. In particular, the ratios of coarse to fine woody debris stocks varied greatly with the successional stage, and the highest and lowest ratios were found in later and earlier successional subalpine forests, respectively. Furthermore, the woody debris stock varied greatly with diameter size, and larger diameter woody debris dominated the plant debris. Correspondingly, the carbon stock of plant debris ranged from 10.30 to 38.87 Mg∙ha− 1 across the successional series, and the highest and lowest values were observed in the mid-coniferous stage and shrub forest stage, respectively. Most importantly, the carbon stored in coarse woody debris in later successional forests was four times higher than in earlier successional forests.ConclusionsThe stock and role of woody debris, particularly coarse woody debris, varied greatly with the forest successional stage and dominated the carbon cycle in the subalpine forest ecosystem. Thus, preserving coarse woody debris is a critical strategy for sustainable forest management.

Оцінювання запасів грубого деревного детриту у лісових екосистемах національного природного парку «Слобожанський»

Dead wood is an important component of forest ecosystems. It performs a number of environmental functions. Coarse woody debris includes standing dead trees, fallen dead trees, fragments of fallen trees (trunks), branches (fragments of branches), and rough tree roots. It is a substrate and habitat for living organisms, including a number of species of mosses, lichens, fungi, invertebrates, as well as birds and mammals. Woody detritus plays an important role in the biological cycle of substances and energy, and carbon deposition, is a source of nutrients. Therefore, the study of quantitative and qualitative features of dead wood, in particular on protected areas, is a considerable nowadays problem. The aim of the work is to estimate identified by forest inventory stocks of dead wood in forest ecosystems of Slobozhansky NNP by categories, as well as to analyze the distribution of its volumes in stands of dominant tree species and forest types. The estimation of coarse woody debris stocks was performed based on forest inventory data of Slobozhansky National Nature Park conducted by Ukrainian State Project Forestry Production association “Ukrderzhlisproekt”. Data from 493 forest stands of nine tree species were analyzed. The stock of the following fractions of coarse woody debris was studied: standing dead wood, fallen (downed) dead wood. Data analysis was performed using MS Excel 2016 software. It was found that the total area of forest stands in which standing or downed dead wood was found during forest inventory was 2149.8 ha, or 47.5% of the total forest area of NNP. The total stock of coarse woody debris was 19478 m3, more than 95% of which is concentrated in the stands of Scots pine (Pinus sylvestris L.) (78.8%) and pedunculate oak (Quercus robur L.) (16.6%). Standing dead wood prevailed (62.1%) fallen dead wood (37.9%) in the structure of dead wood volume. The volume of dead wood was in the range of 5–50 m3∙ha–1, and on average in studied forest ecosystems in which it was found was 9.1 m3∙ha–1. In Scots pine forest stands coarse woody debris was found on an area of 1703.5 hectares with total stock of 15355 m3, consists of standing dead trees (9952 m3, 64.8%) and fallen dead wood (5403 m3, 35.2%). The volume of dead wood in forest stands was 5–50 m3∙ha–1, on average – 9.0 m3∙ha–1. In pedunculate oak stands coarse wood debris was found on an area of 384.7 hectares with a total stock of 3224 m3, consists of standing dead wood (1469 m3, 45.6%) and fallen dead wood (1755 m3, 54.4%). The volume of dead wood in forest stands was 5–20 m3∙ha–1, on average – 8.4 m3∙ha–1.

Carbon Losses from Decomposing Windrowed Sitka Spruce Woody Debris Over a 16-Year Chronosequence

Meeting the reporting requirements of the Kyoto Protocol has focused attention on the potential of forests in sustainably sequestering carbon (C) to mitigate the effects of rising levels of atmospheric CO2. Much uncertainty remains concerning the ultimate effect of management on such sequestration effects. The management of woody debris (WD) and other deadwood stocks is an example of a management intervention with the scope of affecting the source-sink dynamics of forest C. Windrowing is the most commonly employed approach to the management of post-harvest WD. This study investigated the quantities of windrowed deadwood C across a chronosequence of reforested commercial Sitka spruce stands in Ireland and how its decomposition rate affected its contribution to forest C sequestration. The C stocks in windrowed WD ranged from 25 to 8 t C ha−1 at the 4- and 16-year-old stands, respectively. Losses due to the decomposition of these stocks ranged from 5.15 t C ha−1 yr−1 at the youngest site (4 years old) to 0.68 t C ha−1 yr−1 at the oldest site (16 years old). Using a visual decay-class categorization of WD components and an assessment of wood density, decay rate constants were estimated for logs, branches, and stumps (the main WD constituents of windrows) as 0.037, 0.038, and 0.044, respectively. These results, derived from stand stock evaluations, were placed into context with data previously published from the same chronosequence that characterized the day-to-day fluxes to or from this pool. This comparison indicated that though only a very small quantity of C was lost in dissolved leachate form, the most significant pathway for loss was respiratory and ranged from 16 to 8 t C ha−1 yr−1 at the 9- and 16-year-old sites. These estimates were many times greater in extent than estimates made using a density-loss approach, the difference indicating that fragmentation and weathering play a large role in woody decomposition in intensively managed forests.

Time since fire and prior fire interval shape woody debris dynamics in obligate‐seeder woodlands

AbstractWoody debris plays an important role in many ecosystem functions, including nutrient and carbon cycling, providing substrates for plant recruitment and habitat for fauna. Fires can affect woody debris stocks, through generating new pieces by killing or severing plant parts and consuming pre‐existing woody debris. We develop a model of woody debris dynamics with variation in time since fire and prior fire interval applicable to obligate‐seeder forests and woodlands, considering down woody debris and standing dead trees as discrete components. We then test predictions of change in woody debris derived from this model in Eucalyptus salubris woodlands in South‐Western Australia, using a multi‐century chronosequence with recent fires varying between having short (<50 yr since the previous fire) or long (>50 yr, but often much longer) prior intervals. As per our woody debris dynamics model, most attributes measured were affected by time since fire, prior fire interval, or their interaction. Woody debris biomass was greatest shortly after fire, reflecting high quantities of standing dead trees resulting from stand‐replacement disturbance. Standing dead tree density and biomass then declined with increasing time since fire, but individual dead tree size was high beyond 200 yr since fire. Down woody debris biomass remained relatively stable with time since fire, but piece size increased. Dimensions of woody debris were strongly influenced by prior fire interval, with long prior intervals resulting in pieces at least twice the size than those occurring after short prior intervals. Fire management to maximize the availability of large woody debris pieces for fauna should aim to minimize short fire intervals, while from a carbon management perspective, all fires in obligate‐seeder forests and woodlands set in train large and prolonged emissions of carbon.

Dead Wood Necromass in a Moist Tropical Forest: Stocks, Fluxes, and Spatiotemporal Variability

Woody debris (WD) stocks and fluxes are important components of forest carbon budgets and yet remain understudied, particularly in tropical forests. Here we present the most comprehensive assessment of WD stocks and fluxes yet conducted in a tropical forest, including one of the first tropical estimates of suspended WD. We rely on data collected over 8 years in an old-growth moist tropical forest in Panama to quantify spatiotemporal variability and estimate minimum sample sizes for different components. Downed WD constituted the majority of total WD mass (78%), standing WD contributed a substantial minority (21%), and suspended WD was the smallest component (1%). However, when considering sections of downed WD that are elevated above the soil, the majority of WD inputs and approximately 50% of WD stocks were disconnected from the forest floor. Branchfall and liana wood accounted for 17 and 2% of downed WD, respectively. Residence times averaged 1.9 years for standing coarse WD (CWD; > 20 cm diameter) and 3.6 years for downed CWD. WD stocks and inputs were highly spatially variable, such that the sampling efforts necessary to estimate true values within 10% with 95% confidence were > 130 km of transects for downed CWD and > 550 ha area for standing CWD. The vast majority of studies involve much lower sampling efforts, suggesting that considerably more data are required to precisely quantify tropical forest WD pools and fluxes. The demonstrated importance of elevated WD in our study indicates a need to understand how elevation above the ground alters decomposition rates and incorporate this understanding into models of forest carbon cycling.

The hidden role of woody debris stocks as a woodfuel source: why cutting down trees if woodfuel can be gathered from forest floor?

SUMMARY: Recently, the key role played by woody debris within the ecological dynamics of forest ecosystems has been acknowledged; however, its contribution as a source of woodfuel has barely been studied, despite being the most important energy resource for one-third of world population. Over decades, the widely held belief that woodfuel exclusively comes from woody living biomass has labelled woodfuel collection as a driver of tropical deforestation. The poor understanding about gathering ways of this resource in the rural developing world has hidden the fact that it is mainly sourced from woody necromass, of which their stocks and productivity may be estimated at 35 Pg and 6.5 Pg year-1 in tropical forests, respectively. Whether necromass productivity of both geographically accessible tropical forest for rural communities and other types of woody vegetation is taken into account together, a potential supply of 2.19 Pg year-1 could be estimated, which would meet by far, the projected global rural woodfuel demand. It concludes that household-oriented woodfuel collection is far from being a driver of deforestation; instead, this latter might jeopardize access to this energy source. This paper tries to provide a new insight about the relationship between rural energy security and forest-based ecosystem services and their repercussions on climate change.

Carbon Stocks of Fine Woody Debris in Coppice Oak Forests at Different Development Stages

Dead woody debris is a significant component of the carbon cycle in forest ecosystems. This study was conducted in coppice-originated oak forests to determine carbon stocks of dead woody debris in addition to carbon stocks of different ecosystem compartments from the same area and forests which were formerly elucidated. Weight and carbon stocks of woody debris were determined with recent samplings and compared among development stages (diameter at breast height (DBH, D1.3m)), namely small-diameter forests (SDF) = 0–8 cm, medium diameter forests (MDF) = 8–20 cm, and large-diameter forests (LDF) = 20–36 cm). Total woody debris was collected in samplings; as bilateral diameters of all woody debris parts were less than 10 cm, all woody parts were in the “fine woody debris (FWD)” class. The carbon concentrations of FWD were about 48% for all stages. Mass (0.78–4.92 Mg·ha−1) and carbon stocks (0.38–2.39 Mg·ha−1) of FWD were significantly (p > 0.05) different among development stages. FWD carbon stocks were observed to have significant correlation with D1.3m, age, basal area, and carbon stocks of aboveground biomass (Spearman rank correlation coefficients; 0.757, 0.735, 0.709, and 0.694, respectively). The most important effects on carbon budgets of fine woody debris were determined to be coppice management and intensive utilization. Also, national forestry management, treatments of traditional former coppice, and conversion to high forest were emphasized as having substantial effects.

Natural and anthropogenic influences on coarse woody debris stocks in Nothofagus–Araucaria forests of northern Patagonia, Argentina

AbstractCoarse woody debris (CWD) is an important element driving ecological processes, strengthening ecosystem resilience and for biodiversity within forest ecosystems. However, the abundance and distribution of CWD and their relation to natural and human factors are poorly known in southern South America. In this work we studied the density and volume of CWD types in Nothofagus–Araucaria stands in northern Patagonia (Neuquén – Argentina) and relationships with forest composition and structure. We also studied their relationships with fire history, topography and human‐related variables. Twenty‐three stands with Nothofagus pumilio, Nothofagus antarctica and/or Araucaria araucana were sampled to estimate quantities of logs, snags and dead branches using the planar‐intersect method. CWD density and volume in these forests were moderate and varied across the landscape with a spatial pattern determined by biotic, abiotic and human use–related variables. Mean CWD volume was 52.9 m3 ha−1 (range: 1.6–143.7) and significantly varied among forest types and watersheds. CWD was positively related to dbh, tree height and slope, but negatively related to tree density. CWD was clearly influenced by composition and structural characteristics of stands, where the tree species traits had an important role. As well, the observed amount and type of CWD, whereby most of the stands showed low levels of old (pre‐disturbance) logs/snags and poor new inputs of deadwood, may be explained by fire frequency. Firewood gathering and livestock grazing negatively affected deadwood stocks and topography counteracts this effect by limiting human access. Fire disturbance history, windthrow and dieback pulses produced by insect outbreaks and human access seemed to be the main causes that best explained CWD spatial distribution and abundance patterns in north‐western Patagonian forests.

High stocks of coarse woody debris in a tropical rainforest, East Kalimantan: Coupled impact of forest fires and selective logging

Forest fires coupled with logging have now become one of the most extensive causes of forest degradation, affecting the balance between carbon emissions and sequestration in lowland tropical forests in Southeast Asia. Being transient pools of disturbance-killed trees, coarse woody debris (CWD) stocks play a key role in the carbon budget of such disturbed forests. Here, we investigated for the first time how logging affects the CWD input during and following a fire and, consequently, post-fire CWD stocks. Measurements were made at a permanent site in Bukit Soeharto Education Forest (BSEF) in East Kalimantan, Indonesia. This site consisted of plots that had been subjected to three different logging intensities (HF: heavily felled, trees with diameter at breast height (DBH) ⩾30cm were felled; LF: lightly felled, trees with DBH ⩾50cm were felled; UF: unfelled), all of which were burned by a fire that occurred during a drought associated with the El Niño Southern Oscillation in 1998, shortly after logging. CWD mass were measured in 2012, following 14years of monitoring the CWD inputs. The average CWD mass across the three logging treatments was 89Mgha−1, which is higher than the reported values for undisturbed forests but within the recorded range for recently disturbed forests. The amount of CWD inputs due to tree death during the fire was similar among the three treatments. However, there was a large difference in the CWD input in the post-fire period. In UF plots, large CWD inputs lasted for 2years following the fire due to delayed tree death, whereas in HF and LF plots, where the above-ground biomass had greatly reduced by selective logging, no further large CWD inputs occurred after the fire. Consequently, the CWD stocks in the HF and LF plots were 50–60% lower than those in the UF plots. A simulation predicted that these CWD inputs during and shortly after the fire still constitute a large proportion of the CWD stocks in 2012, suggesting that the CWD pool is a rather durable carbon store in BSEF. In the HF and LF plots, there was few large diameter CWD pieces, reflecting the selective logging of large diameter trees, whereas, in the UF plots, there were large standing dead and uprooted trees. Since the larger diameter CWD pieces are persist in the forest for a longer time continuing to store carbon and to provide habitats for diverse wild life, selective logging could have large impacts on forest ecology and function not only by decreasing the total CWD inputs and stocks but also by decreasing the large diameter CWD pieces.

Woody Debris Stocks of Evergreen Broad-Leaf Forest in Mid-Subtropical Region of China

Woody Debris Stocks of Evergreen Broad-Leaf Forest in Mid-Subtropical Region of China

Stock and Flow of Carbon in Plant Woody Debris in Two Different Types of Natural Forests in Bateke Plateau, Central Africa

In order to know the role of plant woody debris in the carbon cycle, a study of carbon stocks and carbon flow of plant woody debris was conducted in the natural forests of the centre of the republic of Congo in the Bateke Plateau. Allometric equations were used to measure the carbon stock of in dead wood debris of Lesio-louna tropical rainforest. Three plots of 40 m × 40 m were delimited in each forest types. All plots were within 300 m of each other. The average stocks of carbon in coarse woody debris obtained are 10993 g·m-2 and 14172 g&#183m-2, respectively, in the Gallery forest (GF) and the hill-slope forest clump (HF), the difference of carbon stock between the two forests is not significant (p = 0.78). The interannual mean flow in both forests is respectively 1776 and 545 g·m-2&#183an-1 in the FG and the MSDS; this medium is not significant (p = 0.10). Carbon stocks of fine woody debris are respectively 965 and 83 g·m-2 in the GF and HF, difference is significant (p = 0.0013). The interannual mean flow of carbon in fine woody debris in the GF and the HF were respectively 310 g·m-2·an-1 and 51 g·m-2·an-1.

Domestic timber harvesting affects wood quantities in Tasmanian dry eucalypt forests

SummaryDomestic fuelwood harvesters illegally reduced coarse (≥10-cm diameter) downed woody debris stocks in Tasmanian mature dry eucalypt forests, 27–34 m tall, by 96.9 m3 ha−1 or 22.7 t ha−1. There was no effect of domestic harvesting on quantities of dead trees or live trees. Few dead trees were encountered in natural (unharvested) sites. Domestic harvesters preferentially removed debris <70 cm in diameter, leaving domestically harvested sites with 40% less volume and biomass of downed woody debris than natural sites. Assuming domestic harvesting, at the measured intensity, extends 25 m into forests either side of the state forest road system that passes through the studied forest type, dead wood stocks in that forest type and tenure throughout the state have been reduced by 688 000 m3 or 161 000 t. Domestic harvesting potentially damages biodiversity values, diminishes habitat available for species dependent on fallen logs and reduces forest carbon stocks. Domestic harvesters are advised to obtain licences to collect fuelwood from areas with an appropriate forest practices plan.

Soil-induced impacts on forest structure drive coarse woody debris stocks across central Amazonia

Background: Coarse woody debris (CWD) is an essential component in tropical forest ecosystems and its quantity varies widely with forest types.Aims: Relationships among CWD, soil, forest structure and other environmental factors were analysed to understand the drivers of variation in CWD in forests on different soil types across central Amazonia.Methods: To estimate CWD stocks and density of dead wood debris, 75 permanent forest plots of 0.5 ha in size were assessed along a transect that spanned ca. 700 km in undisturbed forests from north of the Rio Negro to south of the Rio Amazonas. Soil physical properties were evaluated by digging 2-m-deep pits and by taking auger samples.Results: Soil physical properties were the best predictors of CWD stocks; 37% of its variation was explained by effective soil depth. CWD stocks had a two-fold variation across a gradient of physical soil constraints (i.e. effective soil depth, anoxia and soil structure). Average biomass per tree was related to physical soil constraints, which, in turn, had a strong relationship with local CWD stocks.Conclusions: Soil physical properties appear to control average biomass per tree (and through this affect forest structure and dynamics), which, in turn, is correlated with CWD production and stocks.

Carbon stocks in primary and secondary tropical forests in Singapore

Tropical forests contain large reserves of carbon that are vulnerable to perturbation linked to human activities, including deforestation and climate change. Accurate estimates of forest carbon are therefore required urgently to support efforts to conserve tropical forests. We quantified carbon stocks in primary and 60-year-old secondary forest plots located on infertile Ultisols in Bukit Timah Nature Reserve, one of the few remaining areas of forest in Singapore. We used tree census data for 24.2ha of primary forest and 23ha of secondary forest, together with allometric equations, to estimate aboveground and coarse root biomass. Coarse woody debris stocks were censused along 2.44km and 2.12km of transects in primary and secondary forest, respectively. Soil carbon and fine root carbon stocks were assessed from soil samples taken to 3m depth in a 2-ha secondary forest plot and a 2-ha primary forest plot, combined with bulk density measured in a nearby soil profile pit. Total estimated carbon stock in the primary forest, which was located on the hilltop and upper slopes (80–115m elevation), was 337MgCha−1, of which 50% was aboveground biomass, 33% in soil, 12% in coarse roots, 4.6% in coarse woody debris, and 0.8% in fine roots. In the secondary forest, located on lower slopes and valley (50–85m elevation), the total carbon stock was 274MgCha−1 and the relative importance of aboveground biomass and soil were reversed, with 38% in aboveground biomass, 52% in soil, 6.9% in coarse roots, 1.5% in coarse woody debris, and 1.3% in fine roots. Including carbon in deep subsoil (i.e. to 3m) increased soil carbon stocks by ∼40% compared to 1m depth. Overall, the 60-year-old secondary forest contained 60% as much biomass as the primary forest, while the primary forest had lower carbon stocks than other primary forests in the region.

Cross-section mass: an improved basis for woody debris necromass inventory

Quantification of woody debris stocks is important for carbon budgets (Brown 2002) (Keith et al. 2009), fire ecology (Hely et al. 2000), and biodiversity conservation (Martikainen et al. 2000). Thus, woody debris are now often the subject of national inventories (Siitonen 2001, CFIC 2004) and have been the focus of significant methodological development and a wide variety of used methods have been described (Valentine et al. 2001, Bebber and Thomas 2003, Jordan et al. 2004, Affleck 2008). The necromass of woody debris is typically estimated from the product of estimated volume and estimated density (dry mass per volume) (Harmon et al. 1986). We refer to this as the volume-density approach. Density is usually measured in terms of mass per volume of solid wood – that is, volume excluding void space, except for the tiny pores considered to be a natural part of the wood. However, the volume of logs is usually estimated assuming circular cross-sections of solid wood. The combination of density measurements per volume solid wood and volume measurements that include void space and assume circular crosssections leads to biased estimates of necromass whenever there is void space and/or deviations from circular cross-sections – i.e., in most forests most of the time. These biases can be avoided through detailed measurements of void space and of noncircular logs (Keller et al. 2004, Grove et al. 2009) but such methods are time-consuming and infrequently employed. We advocate an unbiased alternative approach to quantifying necromass of woody debris – an approach based on computing cross-section mass, the dry mass per unit length, of logs. Here, we first review the sources of bias in the volumedensity approach as typically employed, and various methods for overcoming these biases within the context of that approach. We then present the cross-section mass approach, and show how it avoids the key challenges of the volume-density approach because it does not require estimation of volume. We close with a brief discussion.

Modelling fallen branch volumes in a temperate eucalypt woodland: implications for large senescent trees and benchmark loads of coarse woody debris

AbstractFallen branches are a substantial component of coarse woody debris and a key ecological resource. The depletion of stocks of coarse woody debris since European settlement has contributed to the degradation of Australian grassy box woodlands, including the loss of biodiversity. Restoration options for remnant woodlands include the augmentation of coarse woody debris stocks. However, the extensive modification of grassy box woodlands has left few reference sites for establishing benchmarks to guide such restoration. In this paper we demonstrate a method for predicting fallen branch debris loads in the absence of reference sites, using data from a yellow box–red gum woodland. Our methodology is in two stages: first, the total volume of branch debris under individual trees was modelled; and second, these models were applied to groups of trees to predict stand‐level loads of fallen branch debris. Although the models were developed for yellow box–red gum woodlands, the methodology would be applicable to other communities that lack reference sites. Predicted benchmark loads of fallen branch debris for yellow box–red gum woodland were between 7.0 m3 ha−1 and 11.9 m3 ha−1. Large senescing trees contributed the bulk of fallen branch debris. Model predictions indicated a 100‐cm diameter at breast height (dbh) tree was 10 times more likely to produce debris than a 50‐cm dbh tree, and if debris was present a 100‐cm dbh tree produced approximately 10 times the volume of branch debris produced by a 50‐cm dbh tree. These results highlight the importance of large senescing trees for the production of fallen branch debris and support the keystone role of large trees within remnant woodlands, and the need to conserve these structures. Our results also support the active management of regrowth woodland stands to facilitate the progression of individual trees to maturity and senescence. In particular, thinning of regrowth stands may promote the growth of retained trees, ensuring they contribute to fallen branch debris stocks with a minimum time lag.

Forest carbon stocks in Newfoundland boreal forests of harvest and natural disturbance origin I: field study

Quantification of stand and forest C stocks in response to different disturbances is necessary to develop climate change mitigation strategies and to evaluate forest C accounting tools. Live tree, dead tree, woody debris (WD), stump, buried wood, and organic and mineral soil C stocks are described in chronosequences of black spruce ( Picea mariana (Mill.) BSP) (harvest and fire origin) and balsam fir ( Abies balsamea (L.) Mill.) (insect and harvest origin). The largest C stocks were found in mineral soil (≤179 Mg·ha–1), organic soil (≤123 Mg·ha–1), and live tree (≤93 Mg·ha–1) pools. Live tree C changed predictably with disturbance history and time since disturbance, increasing with forest age. Regeneration growth slowed under snags. Thinning accelerated production of larger trees but reduced site live tree C. Dead tree and WD C were temporally dynamic and strongly influenced by disturbance history and time since disturbance, but abundances in differently disturbed forests converged at low levels 40–60 years after disturbance. Only immediately following natural disturbances were there large amounts of snag C (26–30 Mg·ha–1). WD C was relatively abundant &lt;3 years after harvesting (15–17 Mg·ha–1) and 31–36 years after natural disturbance (9 Mg·ha–1). Buried wood stocks were small, but comparable with WD stocks in some forests.

Coarse woody debris stocks as a function of forest type and stand age in Costa Rican tropical dry forest: long-lasting legacies of previous land use

The ecological importance of trees lasts much longer than their life spans. Standing dead trees (snags) and fallen trunks and branches are an important component of above-ground carbon stocks and nutrient reserves, provide habitat for wildlife, and interact with disturbance regimes (e.g. by serving as fuel for fires) (Clark et al. 2002, Harmon et al. 1986, Pyle et al. 2008). Despite these diverse functions, woody debris stocks remain poorly quantified in tropical forests in general (Brown 1997), and in tropical dry forests in particular (Harmon et al. 1995). More empirical studies of the patterns of woody debris and processes that control its dynamics are needed to understand its role in global biogeochemical cycles and for ecosystem simulation models, many of which do not represent coarse woody debris (CWD) as a separate pool (Cornwell et al. 2009).

Dynamics of carbon, biomass, and structure in two Amazonian forests

Amazon forests are potentially globally significant sources or sinks for atmospheric carbon dioxide. In this study, we characterize the spatial trends in carbon storage and fluxes in both live and dead biomass (necromass) in two Amazonian forests, the Biological Dynamic of Forest Fragments Project (BDFFP), near Manaus, Amazonas, and the Tapajós National Forest (TNF) near Santarém, Pará. We assessed coarse woody debris (CWD) stocks, tree growth, mortality, and recruitment in ground‐based plots distributed across the terra firme forest at both sites. Carbon dynamics were similar within each site, but differed significantly between the sites. The BDFFP and the TNF held comparable live biomass (167 ± 7.6 MgC·ha−1 versus 149 ± 6.0 MgC·ha−1, respectively), but stocks of CWD were 2.5 times larger at TNF (16.2 ± 1.5 MgC·ha−1 at BDFFP, versus 40.1 ± 3.9 MgC·ha−1 at TNF). A model of current forest dynamics suggests that the BDFFP was close to carbon balance, and its size class structure approximated a steady state. The TNF, by contrast, showed rapid carbon accrual to live biomass (3.24 ± 0.22 MgC·ha−1·a−1 in TNF, 2.59 ± 0.16 MgC·ha−1·a−1 in BDFFP), which was more than offset by losses from large stocks of CWD, as well as ongoing shifts of biomass among size classes. This pattern in the TNF suggests recovery from a significant disturbance. The net loss of carbon from the TNF will likely last 10–15 years after the initial disturbance (controlled by the rate of decay of coarse woody debris), followed by uptake of carbon as the forest size class structure and composition continue to shift. The frequency and longevity of forests showing such disequilibruim dynamics within the larger matrix of the Amazon remains an essential question to understanding Amazonian carbon balance.