The choice of definition has a large effect on reported quantities of dead wood in boreal forest

A survey was conducted to assess the impact of the choice of definition on reported quantities of dead wood in Swedish forests, which to more than 90% are located in the boreal zone. The data collection was made on a subsample of the permanent plots of the Swedish national forest inventory. The objects included were standing dead trees and snags down to 5-cm diameter at breast height, dead lying stems and branches down to a threshold diameter of 1 cm and stumps down to a threshold diameter of 5-cm at normal stump height. Standing trees, snags and stumps were inventoried on 10-m radius circular plots while the downed objects were inventoried using both circular plots and line intersect sampling; thin objects (diameter 1–5 cm) were assessed only through line intersect sampling. The results showed that the estimated volume of dead wood was as high as 25 m³ ha^?1 when all components were included. With the standard Swedish definition, the corresponding estimate was only 10.9 m³ ha^?1, or 43% of the total value. Since definitions of dead wood vary greatly between countries we conclude that great caution must be exercised when figures are compared in connection with international reporting. For example, adding stumps to the Swedish definition would increase the amounts of dead wood from 10.9 to 15.7 m³ ha^?1, i.e. with 44%.     

Impacts of salvage-logging on the status of deadwood after windthrow in Swiss forests

Downed and standing deadwood (DW) is a key resource for maintaining forest biodiversity. Although extreme events such as windthrow and fires produce large quantities of DW, this substrate is often drastically reduced by logging activities. To elucidate the respecting consequences of salvage-logging, we assessed both quantity and quality of storm-derived DW (storms Vivian 1990 and Lothar 1999) in Swiss forests using a sample of 90 windthrow sites with ≥3 ha complete windthrow and at elevations ranging from 350 to 1,800 m a.s.l. The majority had been salvage-logged (SL) a few years after the windthrow. On each site, we recorded DW amount and quality on six circular sample plots 20 or 50 m² in size. DW volume on SL sites was surprisingly high, with 76.4 m³ ha^?1 on average 20 years after Vivian and 73.8 m³ ha^?1 10 years after Lothar. In comparison, DW volumes on unsalvaged sites, that is, with no post-windthrow intervention (NI), amounted to 270 m³ ha^?1. A wide variety of wood decay stages and diameter classes (10 to ≥70 cm) was found on both NI and SL sites, suggesting considerable habitat diversity for DW-associated species irrespective of the treatment. The considerable amounts of DW left after salvage-logging distinctly exceed the minimum DW volumes in forest stands proposed by Müller and Bütler (Eur J For Res 129: 981–992, 2010) in a conservation context, which demonstrates the importance of wind disturbance for biodiversity. Further studies should quantify DW of individual tree species, since habitat requirements are species-specific.     

Nutrition management of cedar and hemlock plantations in coastal British Columbia

Recent re-measurements of silvicultural trials in conifer plantations on nutrient-poor cedar-hemlock (CH) cutovers on northern Vancouver Island have confirmed co-limitation by nitrogen and phosphorus. Repeated fertilization increased volumes of both cedar and hemlock on CH sites (at 2,500 stems ha^?1) by about 100 m³ ha^?1 relative to unfertilized plots 22 years following initial fertilization, and increased the productivity of regenerating conifers to a level approximating that of neighbouring hemlock-amabilis fir (HA) sites. More surprising was the response to fertilization on the more-productive HA sites. After 22 years, cedar in fertilized HA plots had produced an extra 180 m³ ha^?1 compared to unfertilized HA plots, while hemlock had produced an extra 250 m³ ha^?1 in fertilized plots (at 2,500 stems ha^?1). Thus, contrary to expectations, the greatest volume responses of both hemlock and cedar to fertilization occurred on the good (HA) sites rather than on the poor (CH) sites. Ecological studies of CH and HA sites supported the hypothesis that the poor nutrient supply and productivity of CH sites is a long-term consequence of excessive moisture, and that the two site types bracket a critical ecological threshold of moisture, aeration and redox.     

Deadwood in New Zealand's indigenous forests

We present the results of a systematic, unbiased national survey of deadwood volume and biomass in New Zealand's remaining indigenous forests based on an 8-km grid of 894 permanent plots. New Zealand's old growth evergreen temperate forests are largely comprised of long-lived, slow-growing tree species typically growing in cool, humid conditions; collectively these conditions are thought to promote accumulation of high deadwood stocks. We estimated deadwood biomass and volume in New Zealand's forests and compared these stocks with published values from other broadleaved evergreen temperate forests. Mean deadwood biomass in New Zealand was 54 Mg ha⁻¹ but ranged across plots from 0 to 550 Mg ha⁻¹. Mean deadwood volume was 158 m³ ha⁻¹ and ranged across plots from 0 to 1890 m³ ha⁻¹. Fallen logs accounted for 63% of total deadwood volume and 65% of total deadwood biomass, with standing dead trees being the remainder. Each piece of deadwood was classified into one of three broad decay classes and >40% of deadwood was fallen logs of the intermediate decay class. Deadwood biomass and volume varied 1.8- and 1.9-fold, respectively, among forest types and was greatest in broadleaved forests, dominated by Weinmannia racemosa (Cunoniaceae), Metrosideros umbellata (Myrtaceae) and Metrosideros robusta, and broadleaf-Nothofagus (Nothofagaceae) forests supporting the large tree species Nothofagus fusca. Deadwood biomass and volume were least in broadleaf-conifer admixtures. We used structural equation models to determine whether deadwood biomass could be predicted from climate and environment (vapor pressure deficit, elevation and slope), live tree biomass, forest composition (captured by two ordination axes), wood density of live trees, and tree size (a proxy for stand age). The model that best fit the data retained only vapor pressure deficit, live tree biomass and the first ordination axis as predictors of deadwood biomass. However, this model predicted just 2.4% of the variation in deadwood biomass, suggesting that additional factors not captured by this dataset, such as disturbance dynamics, may control deadwood abundance. Comparisons with other temperate and tropical forests did not support the hypothesis that New Zealand's cool temperate rainforests support higher than expected biomass or volume of deadwood.     

Stand characteristics of mixed oriental beech (<Emphasis Type="Italic">Fagus orientalis</Emphasis> Lipsky) stands in the stem exclusion phase,northern Iran

The structure of forest stands changes through developmental phases. This study is carried out in the unmanaged, oriental beech (Fagus orientalis Lipsky) stands in the north of Iran. The aim of this research was to quantify structural characteristics of stands in the stem exclusion phase using common structural indices, which include mingling, tree–tree distance, stem diameter, and tree height differentiation. According to our measurements from three stands, naturally regenerated stands tend to be mixed in species composition have slightly heterogeneous diameter distributions and uniform tree height. The average distance between trees was 3.3 m. Stocking volume of the stands had an average of 540 m³ ha^?1 and 412 stem ha^?1. Dead wood volume was 24 m³ ha^?1, and as a standing volume, the most frequent species in dead wood pool was oriental beech (F. orientalis) (48 %). The common form of dead trees was snag (41 %). The mean value of mingling and tree-to-tree interval indices revealed that beech was mixed intensively with hornbeam and appears to be a more successful competitor for space and light compared with hornbeam; moreover, we found relatively high evidence of inter-species competition in this phase. A better understanding of stand characteristics in the stem exclusion phase as a critical part of the natural dynamics of forest ecosystems could facilitate predictions about the future changes within the stand.     

How much carbon can the Siberian boreal taiga store: a case study of partitioning among the above-ground and soil pools

In the context of global carbon cycle management, accurate knowledge of carbon content in forests is a relevant issue in contemporary forest ecology. We measured the above-ground and soil carbon pools in the darkconiferous boreal taiga. We compared measured carbon pools to those calculated from the forest inventory records containing volume stock and species composition data. The inventory data heavily underestimated the pools in the study area(Stolby State Nature Reserve, central Krasnoyarsk Territory, Russian Federation). The carbon pool estimated from the forest inventory data varied from 25(t ha-1)(low-density stands) to 73(t ha-1)(highly stocked stands). Our estimates ranged from 59(t ha-1)(lowdensity stands) to 147(t ha-1)(highly stocked stands). Our values included living trees, standing deadwood, living cover, brushwood and litter. We found that the proportion of biomass carbon(living trees): soil carbon varied from99:1 to 8:2 for fully stocked and low-density forest stands,respectively. This contradicts the common understanding that the biomass in the boreal forests represents only16–20 % of the total carbon pool, with the balance being the soil carbon pool.     

Litterfall in relation to stand parameters and climatic factors in Pinus brutia forests in Turkey

With this study we investigated the effective factors on annual amount of total litterfall and needle litterfall in Pinus brutia forests and estimated them with a regression model based on certain stand parameters. We studied 27 permanent plots representing different stand structure and environmental conditions in South-Western Turkey. Litterfall was collected in three month intervals corresponding to each of four seasons for a three-year period. We found a significant relationship between litterfall and stand properties such as crown closure (%), basal area (m²?ha^?1), stand stem volume (m³?ha^?1), above-ground biomass (t?ha^?1), mean annual volume increment (m³?ha^?1?yr^?1) and site index (T?=?75). Similar relationships also hold true between litterfall and each of such climatic factors as seasonal mean temperature (°C), relative humidity (%) and temperature/precipitation ratio (dimensionless). The mean annual litterfall considerably varied depending on stand characteristics and certain environmental factors. Both needle litterfall and total litterfall may be predicted for long term by regression models using certain stand parameters. Models developed for litterfall of P. brutia forests in this study may be used for national C inventory in Turkey.     

Deadwood volume in strictly protected,natural, and primeval forests in Poland

Standing and downed deadwood at different stages of decay provides a crucial habitat for a wide range of organisms. It is particularly abundant in unmanaged forests, such as strictly protected areas of national parks and nature reserves. The present work used the available data for such sites in Poland, analyzing a total of 113 studies concerning 79 sites to determine the causes contributing to variation in deadwood volume based on the duration of conservation, changes in deadwood volume over time (for those sites which were examined multiple times), elevation above sea level, forest type, stage of forest development, input of dead trees from the years preceding deadwood measurements, live tree volume, and the proportion of downed to standing deadwood). Depending on species composition and site altitude, most tree stands fell into one of four categories: subalpine spruce forests, montane beech-fir forests, low altitude beech-fir forests, or oak-hornbeam and riparian forests. The mean deadwood volume for all forest types amounted to 172.0 m³/ha. The mean volume of deadwood in montane beech-fir forests (223.9 m³/ha) was statistically significantly greater than in the other three forest types, for which it ranged from 103.5 to 142.5 m³/ha. A direct effect of the duration of conservation on deadwood volume was not identified. Nevertheless, analysis of repeated measurements on the same sample plots at 10-year intervals showed a consistent rise in mean deadwood volume. A linear regression model for all the analyzed factors reported from montane beech-fir forests and subalpine spruce forests showed that in addition to site altitude, another statistically significant variable was the input of dead trees (R²?=?63.54%).     

Method for estimation of stem carbon fixation of Japanese black pine by combining stem analysis and soft X-ray densitometry

We derived a formula for estimating the relationship between stem carbon weight and stem volume, which was calculated from DBH and tree height using a combination of stem analysis and soft X-ray densitometry. The results indicate carbon weight in a 33-year-old coastal Japanese black pine (Pinus thunbergii) forest is approximately 68,186 kg ha^?1 in Yamagata Prefecture and 38,253 kg ha^?1in a 42-year-old black pine forest in Hokkaido Prefecture, Japan. Also, age-related changes in the stem density following oven-drying of samples of black pine trees are small: the oven-dried density (hereafter “density”) of black pine trees in the two locations mentioned above were 425.6 (kg m^?3) and 523.2 (kg m^?3) respectively, which is comparable to the density (converted from basic density) of black pine of Land Use, Land-Use Change and Forestry (LULUCF) (533 kg m^?3). When compared with the carbon weight by the oven-dried density of LULUCF, the carbon weights calculated from each density were 27 % lower in Yamagata and 6 % lower in Hokkaido. This difference directly affects carbon weight for large-scale estimation and thus can create an error at a regional scale. This methodology can contribute to the management of forests acting as carbon sinks.     

Taking the pulse of forest plantations success in peri-urban environments through continuous inventory

Urban expansion increases the need for, and pressure on, green areas. Reforestation projects in the rural–urban fringe represent an opportunity for enhancing the environmental quality of peri-urban spaces and a means to contribute to cities carbon neutrality policies. Yet, relatively little information exists regarding the long term (10–25 years) survival and growth rate in urban and peri-urban plantations. This paper reports and discusses the results achieved by a reforestation in the peri-urban space of Rome (Italy), 25 years after its establishment. The plantation has been periodically surveyed between 6 and 24 years of age by means of continuous inventories, with the aim of monitoring growth dynamics. Permanent sample plots have been investigated and stratified by tree species composition (broadleaves vs. conifers, single vs. multispecies) for data analysis. On the whole, plantations show suitable results in terms of rate of growth, carbon storage and uptake, especially in coniferous and mixed stands. The average stand volume of the forest plantation, currently ranges from one-and-a third to one-and-a-half times the average values estimated for natural high forest stands of the same age and species groups at country level. The species groups exhibit differential growth patterns over the observed period, that are mainly due to differences in the ecological traits of the planted trees. Ten years after the establishment, the average annual value of carbon uptake in conifer and mixed species group exceeds 10 Mg CO₂ equivalent ha^?1 year^?1, a figure corresponding to 4 times the value of deciduous broadleaves (oaks and other species) and 1.5 times the value of evergreen oaks. Twenty years after the establishment, the average annual carbon uptake peaks to 25 Mg CO₂ equivalent ha^?1 year^?1 in the mixed species group, exceeds 15 Mg CO₂ equivalent ha^?1 year^?1 in the conifers, and ranks between 6 and 12.5 Mg CO₂ equivalent ha^?1 year^?1 in the groups dominated by broadleaved species. Overall with a surface area just under 300 ha, the carbon uptake level of the Castel di Guido reforestation allows to offset the 0.04% of CO₂ emissions of the city of Rome. Although the spatial coexistence of even-aged plantation blocks characterized by a range of ecological traits, is expected to ensure a more continuous carbon sequestration, being less susceptible to damage of any kind, the current lack of silvicultural management may also lead to degradation processes, by triggering e.g. fuel accumulation and, by consequence, forest fires. In this line, recommendations are provided in order to improve the ecological and functional efficiency of the investigated reforestation. The field experiment demonstrates, ultimately, the capability of the continuous forest inventory to take the pulse over several decades of tree species performance and carbon uptake levels in urban and peri-urban reforestations.     

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.     

Effects of management on coarse woody debris volume and composition in boreal forests in northern Sweden

Forest management practices have led to a reduction in the volume and a change in the composition of coarse woody debris (CWD) in many forest types. This study compared CWD volume and composition in reserves and two types of managed forest in the central boreal zone of Sweden. Ten areas were surveyed, each containing clear-cut, mature managed and old-growth stands, to determine the volume of standing and lying CWD in terms of species composition, decay class and size class. Volumes of CWD on clear-cuts and in mature managed forests were high compared with previous studies. Old-growth forests (72.6 m³ ha^?1) contained a greater volume of CWD than mature managed forests (23.3 m³ ha^?1) and clear-cuts (13.6 m³ ha^?1). Differences were greatest for the larger size classes and intermediate decay stages. Despite stand ages being up to 144 years, CWD volume and composition in managed forests was more similar to clear-cuts than to old-growth forests.     

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.     

Productivity of successive rotations of Acacia mangium plantations in Sumatra,Indonesia: impacts of harvest and inter-rotation site management

The impacts of wood harvest, biomass removal and inter-rotation site management practices on productivity of Acacia mangium in South Sumatra were studied over 12 years across successive rotations. The productivity measured as MAI increased from 29.4 m³ ha^?1 year^?1 in the first to 48.0 m³ ha^?1 year^?1 in the second rotation. Whole tree harvesting (total stem, branches and leaves) caused a 21 % reduction in volume compared to harvesting merchantable wood alone in the next rotation. The rates of nutrients accumulation in trees were highest during the first year of growth, and declined from age 2 years. Significant amounts of nutrients were recycled through litter fall from 1 year after planting. Results highlight the importance of management which promotes nutrient supply on stand growth. Removal of slash and litter lowered soil pH, by about 0.1 unit. A small reduction was also found in soil organic carbon and nitrogen in the top soil during the first 3–4 years but values returned to pre-harvest levels by the end of the rotation. Extractable soil phosphorus and exchangeable cations decreased by the end of second rotation but these measures underestimate the nutrient pools available for A. mangium. These findings along with results from other studies have helped to implement operations which promote conservation of site resources for sustainable production in the region.     

Bioenergy production and soil conservation from Norway spruce (Picea abies L. Karst) plantations in Denmark

This study analyses the trade-off between bioenergy production and soil conservation through thinning operations in Norway spruce (Picea abies L. Karst) plantations in Denmark. Thinning operations were evaluated under different regimes and intensities for a complete rotation period of sixty years and for different site qualities (site-classes I–VI). Applying a dynamic forest growth modeling tool, evolution of forest structure was predicted to observe the potentials for biomass production and inevitable soil degradation. Results showed thinning from below, with a higher utilization (maintenance of a minimum basal area of 25 m² ha^?1) could produce more bioenergy. However, these operations require simultaneous severe forest soil degradation. Therefore, the optimum thinning for bioenergy production under preservation constraints was thinning from above with a lower intensity (maintenance of a minimum basal area of 45 m² ha^?1). The ratio of bioenergy win (kWh) to soil-loss (m³ ha^?1) was calculated for this regime varying between 74,894 kWh m^?3 in a high quality site (site-class I) and 6,516 kWh m^?3 in a low quality site (site-class VI) with an average of 44,282 kWh m^?3. However, this could not always preserve the highest amount of growing stock essential for natural dynamics of forest ecosystem with an exception of the low quality sites (site-class VI). Thus, when aiming at bioenergy production through thinning operations, trade-offs with soil conservation and growing stock preservation should be regarded to prevent environmental degradation.     

Aboveground biomass and carbon stock in the largest sacred grove of Manipur,Northeast India

Aboveground biomass and carbon stock in the largest sacred grove of Manipur was estimated for trees with diameter [10 cm at 1.37 m height.The aboveground biomass,carbon stock,tree density and basal area of the sacred grove ranged from 962.94 to 1130.79 Mg ha~(-1),481.47 to 565.40 Mg ha~(-1) C,1240 to 1320 stem ha~(-1) and79.43 to 90.64 m~2 ha~(-1),respectively.Trees in diameter class of 30–40 cm contributed the highest proportion of aboveground biomass(22.50–33.73%).The aboveground biomass and carbon stock in research area were higher than reported for many tropical and temperate forests,suggesting a role of spiritual forest conservation for carbon sink management.     

Hybrid poplar (Populus spp.) adaptation to a semi-arid region: results from Northwest New Mexico (2002–2011)

A provenance test was initiated in spring 2002 at the New Mexico State University Agricultural Science Center at Farmington to examine the adaptability of various hybrid poplar (Populus spp.) crosses to the high elevation, semi-arid conditions of this region of the Southwestern United States. Ten crosses of P. deltoides, P. maximowiczii, P. nigra and P. trichocarpa obtained from nurseries in the Pacific Northwest were grown in replicates (3 plots × 16 trees) under drip irrigation programmed to match tree evapotranspiration (ET) rates. By the end of year 10, six crosses had maintained a 90 % or higher survival rate and had an average wood volume of 246 m³ ha^?1. The P. deltoides × P. nigra (P. × canadensis) clone OP-367 surpassed a ten-year commercial target of 25-cm diameter at breast height (DBH) after eight seasons, and by the end of 2011 attained a DBH of 28.0 cm, height of 19.9 m and wood volume of 473 m³ ha^?1. Results suggest that hybrid poplar production is possible in this type of semi-arid environment using appropriate germplasm and drip irrigation regimes scheduled according to tree ET demand.     

The role of brash in augmenting forest site carbon capital and maintaining site nutrition in a Sitka spruce forest in Ireland

The decomposition of harvest residues (brash) in managed forests has an important influence on the carbon (C) and nitrogen (N) stocks of these ecosystems. The brash input from thinning events in a 25-year-old Sitka spruce plantation was determined. A litter-bag method was used to determine the mass loss and decomposition rate of brash left on the forest floor. The changes in C and N concentrations and the C:N ratio of the needles and branches were also monitored as decomposition progressed for 2.5 years. Using the decomposition rate (k _b) and estimated brash inputs, we then determined the total cumulative stock of C that the brash could supply to the deadwood pool over a 41-year rotation period. The three thinning events resulted in the addition of 37.99 t C ha^?1 and 0.61 t N ha^?1 to the forest floor. A significant mass loss of 44 % was recorded from brash decomposition bags after 2.5 years, with a rapid loss of 35 % in the first year, after which the rate of decomposition slowed. The k _b-value and residence time (95 % decomposition) were 0.311 year^?1 and 9.6 years, respectively. There was a 69 % increase in the N concentration of needles after 1.5 years, while an increase of 185 % in the N concentration of branches was recorded after 2.5 years. The C concentration (48.55 ± 0.20 %) did not differ significantly between the needles and branches over time. The accumulated C stock from decomposing brash at clearfell was estimated at 18.51 t C ha^?1.     

Quantifying biological nitrogen fixation of agroforestry shrub species using 15N dilution techniques under greenhouse conditions

Some land-use systems in Saskatchewan, Canada include the nitrogen-fixing trees buffaloberry (Shepherdia argentea Nutt.), caragana (Caragana arborescens Lam.) and sea buckthorn (Hippophae rhamnoides L.). These species provide various ecological functions such as ameliorating soil moisture, light and temperature but little work has been done quantifying biological nitrogen fixation by these species. Greenhouse experiments were conducted to quantify N₂-fixation using the ¹⁵N natural abundance and the ¹⁵N dilution methods. Buffaloberry failed to form nodules in all but one of the four replicates in the natural abundance experiment. Using the ¹⁵N dilution method, the percentage of N derived from atmosphere (%Ndfa) in the shoot of buffaloberry averaged 64 %. For caragana, the mean  %Ndfa was 59 and 65 % and seabuckthorn was 70 and 73 % measured using the natural abundance and dilution methods, respectively. Because of large variability in biomass production between plants grown in the natural abundance experiment and the dilution experiment, the amounts of N₂ fixed also were very variable. Buffaloberry fixed an average of 0.89 g N m^?2; the average for caragana ranged from 1.14 to 4.12 g N m^?2 and seabuckthorn ranged from 0.85 to 3.77 g N m^?2 in the natural abundance and dilution experiments, respectively. This corresponds to 16 kg N ha^?1 year^?1 for buffaloberry; an average of 15–73 kg N ha^?1 year^?1 in caragana and 11–67 kg N ha^?1 year^?1 in seabuckthorn. The substantial amounts of N₂ fixed by these species indicate that they have the potential to contribute to the overall N balance in land-use systems in which they are included.     

Preliminary study on the assessment of deadwood volume by the French national forest inventory

? As the French national forest inventory does not currently monitor the lying compartment of the forest deadwood, the figures obtained on this topic are therefore partial. This study provides cost estimates and guidelines for assessing stumps, and standing and lying deadwood.

? Comparisons were made between a fixed-area sampling method and a line-intersect one. LIS was judged more time-efficient, especially in dense understorey. Computer simulations were performed in order to estimate the gain in precision with increasing transect lengths. The results showed a continuous improvement in precision associated with increases in transect length. The longest transect tested (50 m) still had a large coefficient of variation, suggesting that improvement in precision at the plot level could still be gained with longer transects.

? Therefore, from a practical standpoint in terms of fieldwork, we suggest that on a national scale lying deadwood should be measured by line-intersect sampling, whereas stumps, standing dead trees and snags can be monitored using standard fixed-area plots. To meet needs at the national level, we consider that local imprecision could be compensated for by the large number of plots measured each year.