Distribution patterns of tree,understorey, and detritus biomass in coniferous and broad-leaved forests of Western Himalaya,India

Forest biomass pools are the major reservoirs of atmospheric carbon in both coniferous and broad-leaved forest ecosystems and thus play an important role in regulating the regional and global carbon cycle. In this study, we measured the biomass of trees, understorey, and detritus in temperate (coniferous and broad-leaved) forests of Kashmir Himalaya. Total ecosystem dry biomass averaged 234.2 t/ha (ranging from 99.5 to 305.2 t/ha) across all the forest stands, of which 223 t/ha (91.9–283.2 t/ha) were stored in above- and below-ground biomass of trees, 1.3 t/ha (0.18–3.3 t/ha) in understorey vegetation (shrubs and herbaceous), and 9.9 t/ha (4.8–20.9 t/ha) in detritus (including standing and fallen dead trees, and forest floor litter). Among all the forests, the highest tree, understorey, and detritus biomass were observed in mid-altitude Abies pindrow and Pinus wallichiana coniferous forests, whereas the lowest were observed in high-altitude Betula utilis broad-leaved forests. Basal area has showed significant positive relationship with biomass (R² = 0.84–0.97, P < 0.001) and density (R² = 0.49–0.87). The present study will improve our understanding of distribution of biomass (trees, understorey, and detritus) in coniferous and broad-leaved forests and can be used in forest management activities to enhance C sequestration.     

Forest structure and C stocks in natural Fagus sylvatica forest in southern Europe: The effects of past management

Managed forests often differ substantially from undisturbed forests in terms of tree structure and diversity. By altering the forest structure, management may affect the C stored in biomass and soil. A survey of 58 natural stands located in the south-westernmost limit of European beech forests was carried out to assess how the C pools are affected by the changes in tree structural diversity resulting from past management. The mean tree density, basal area and the number of large trees found in unmanaged forests were similar to those corresponding to virgin beech forests in Central Europe, whereas large live trees were totally absent from partially cut stands. Analysis of the Evenness index and the Gini coefficient indicated high structural diversity in the three stand types. The results of the Kolmogorov–Smirnov test used to compare the diameter distributions of each group revealed significant differences between stand types in terms of distributions of total tree species and of Fagus sylvatica.

The mean C stocks in the whole ecosystem – trees, litter layer and mineral soil – ranged from 220 to 770 Mg ha⁻¹ (average 380 Mg ha⁻¹). Tree biomass (above and belowground), which averaged 293 Mg C ha⁻¹, constituted the main C pool of the system (50–97%). The statistical test (Kolmogorov–Smirnov) revealed differences in the distribution of C pools in tree biomass between unmanaged and partially cut stands. As a consequence of the presence of large trees, in some unmanaged stands the C stock in tree biomass was as high as 500–600 Mg C ha⁻¹. In the partially cut stands, most of the C was mainly accumulated in trees smaller than 20 cm dbh, whereas in unmanaged stands the 30% of tree C pool was found in trees larger than 50 cm dbh. Furthermore, many unmanaged stands showed a larger C pool in the litter layer. The C content of mineral soils ranged from 40 to 260 Mg C ha⁻¹ and it was especially high in umbrisols. In conclusion, the implementation of protective measures in these fragile ecosystems may help to maintain the highly heterogeneous tree structure and enhance the role of both soils and trees as long-term C sinks.     

Relationships between diameter and height of trees in natural tropical forest in Tanzania

The relationship between tree height (h) and tree diameter at breast height (dbh) is an important element describing forest stands. In addition, h often is a required variable in volume and biomass models. Measurements of h are, however, more time consuming compared to those of dbh, and visual obstructions, rounded crown forms, leaning trees and terrain slopes represent additional error sources for h measurements. The aim of this study was therefore to develop h–dbh relationship models for natural tropical forest in Tanzania. Both general forest type specific models and models for tree species groups were developed. A comprehensive data set with 2 623 trees from 410 different tree species collected from a total of 1 191 plots and 38 sites covering the four main forest types of miombo woodland, acacia savanna, montane forest and lowland forests was applied. Tree species groups were constructed by using a k-means clustering procedure based on the h–dbh allometry, and a number of different non-linear model forms were tested. When considering the complexity of natural tropical forests in general and in particular variations of h–dbh relationships due to high species diversity in such forests, the model fit and performance were considered to be appropriate. Results also indicate that tree species group models perform better than forest type models. Despite the fact that the residual errors level associated with the models were relatively high, the models are still considered to be applicable for large parts of Tanzanian forests with an appropriate level of reliability.     

Emerging forests on abandoned land: Puerto Rico’s new forests

The species composition of forests change continuously as the earth’s biota evolves and adjusts to environmental change. Humans are accelerating the rate of species turnover by moving species around the planet and dramatically changing environmental conditions. Our focus is on new forests in Puerto Rico that emerge naturally on abandoned lands previously converted to agriculture and degraded. These forest stands have combinations of species that are new to the island’s landscapes. New forests exhibit high species dominance during forest establishment, which includes dominance by alien tree species. These alien tree species establish and maintain forest cover, which may facilitate regeneration of native tree species. Landscape analysis and literature review revealed that these emerging stands are highly fragmented (60% were <1 ha in 1991), function as refugia for native organisms, and at 60–80 years old have similar species richness and structural features as native stands of similar age. However, the island’s new forests exhibit important differences from mature native forests on unconverted forestlands. New forests have fewer endemic species and fewer large trees (≥55 cm dbh) than mature native forests; they have higher soil bulk density and lower soil carbon and litter stocks; and they accumulate aboveground biomass, basal area, and soil carbon more slowly than native forests of similar age. We suggest that new forests will become increasingly prevalent in the biosphere in response to novel environmental conditions introduced to the planet by humans.     

Variation of stem density and vegetation carbon pool in subtropical forests of Northwestern Himalaya

The present study was conducted in five forest types of subtropical zone in the Northwestern Himalaya, India. Three forest stands of 0.1 ha were laid down in each forest type to study the variation in vegetation carbon pool, stem density, and ecosystem carbon density. The stem density in the present study ranged from (483 to 417 trees ha^?1) and stem biomass from (262.40 to 39.97 tha^?1). Highest carbon storage (209.95 t ha^?1) was recorded in dry Shiwalik sal forest followed by Himalayan chir forest > chir pine plantation > lower Shiwalik pine forest > northern mixed dry deciduous forest. Maximum tree above ground biomass is observed in dry Shiwalik sal forests (301.78 t ha^?1), followed by upper Himalayan chir pine forests (194 t ha^?1) and lower in Shiwalik pine forests (138.73 t ha^?1). The relationship with stem volume showed the maximum adjusted r² (0.873), followed by total density (0.55) and average DBH (0.528). The regression equation of different parameters with shrub biomass showed highest r² (0.812) and relationship between ecosystem carbon with other parameters of different forest types, where cubic function with stem volume showed highest r² value of 0.873 through cubic functions. Our results suggest that biomass and carbon stocks in these subtropical forests vary greatly with forest type and species density. This variation among forests can be used as a tool for carbon credit claims under ongoing international conventions and protocols.     

Biomass and biomass change in lodgepole pine stands in Alberta

We describe methods and results for broad-scale estimation and mapping of forest biomass for the Canadian province of Alberta. Differences over successive decades provided an estimate of biomass change. Over 1500 permanent sample plots (PSP) were analyzed from across the range of lodgepole pine (Pinus contorta var. latifolia Engelm.), the major forest tree species of Alberta. The PSP network is densest in stands aged between 70 and 100 years and is well-represented by stands of all ages to 150 years of age. Stand biomass (Mg ha(-1)) was estimated for each PSP plot as the sum of the respective biomass components for each tree (live and standing dead). The biomass components for live trees were stem, bark, branches, foliage and roots. The components for standing dead trees excluded foliage. Equations from previous biomass studies were used for biomass component estimation. Biomass estimates of additional non-tree components were attempted, but without much success. Biomass of the soil organic layer was estimated once on 452 PSPs and a mean estimate of total dead fuels on the ground (28.4 Mg ha(-1)) was available only for the entire distribution of lodgepole pine. However, values of these two components were essentially constant over time and therefore did not alter the analysis or conclusions obtained by analyzing total tree biomass alone. We then used this spatial network of 1549 plots as the basis for mapping biomass across Alberta. Mapping methods were based on Australian National University SPLINe (ANUSPLIN) software, Hutchinson's thin-plate smoothing spline in four dimensions (latitude, longitude, elevation and biomass). Total tree biomass (mean = 172 Mg ha(-1)) was dominated by stem biomass (mean = 106 Mg ha(-1)), which was an order of magnitude greater than the mean estimates for the bark (11 Mg ha(-1)), branch (12 Mg ha(-1)) and foliage (12 Mg ha(-1)) components. A close relationship was found between total tree biomass and stand stem volume (R(2) = 0.992 with n = 3585; note that volume and biomass were calculated independently). We compared total tree biomass for two decades, the 1980s and the 1990s. After correcting for changes in harvest removals over time, the mean change in total biomass was positive (0.99 Mg ha(-1) year(-1)) and differed significantly from zero (n = 421; P < 0.001). Estimates ranged from -13.9 to 8.0 Mg ha(-1) year(-1). The heart of the lodgepole pine distribution (primarily the Foothills subregions) showed an increase in biomass, whereas isolated pockets of lodgepole pine in the boreal northern subregion indicated a decline in biomass.     

Forest Type,Diversity and Biomass Estimation in Tropical Forests of Western Ghat of Maharashtra Using Geospatial Techniques

Tropical forests are the world’s largest terrestrial storehouses of carbon and are recognized as rich, diverse and highly productive ecosystems. The present study was conducted to characterize the land use, diversity and biomass of tropical forest in Western Ghat of Maharashtra State in India through satellite remote sensing and GIS. The study has been designed and implemented to promote analysis on Western Ghat biodiversity resources including trees, shrubs and herbs based on inventorying, monitoring and mapping. Field measured biomass is integrated with spectral responses of various bands and indices of the Landsat TM satellite image for estimation of above-ground biomass in a 36,046 km² area of relic forest in the Central Western Ghat. The above-ground biomass from field-based inventory varied from 30.2 to 151.1 ton/ha in moist deciduous forest, 9.2–99.1 ton/ha in dry deciduous forest, 42.1–158.6 ton/ha in semi-evergreen forest, and 160.9–271 ton/ha in evergreen forest. The total above-ground biomass of the study area was estimated to be 95.2 M tons. A regression equation between field above-ground biomass and a Normalized Difference Vegetation Index was used for spectral modeling to estimate and prepare the above-ground biomass map in the region. A total 120 plant species in 81 genera and 31 families were identified in the study area. This study emphasizes the importance of relic forests for their biodiversity, carbon sequestration and total biomass.     

Regeneration dynamics and sylvigenesis in the moist deciduous forests of southwest India

Sustained management of natural forest depends on their ability to regenerate. The pace at which older trees are replaced by younger ones is important in this respect. This study was conducted to assess the demographic details of natural regeneration dynamics of south Indian moist deciduous forests. The status of natural regeneration has been assessed in eight localities of varying levels of disturbance in Thrissur Forest Division of Kerala State of southwest India. Enumeration of trees and their regeneration were analyzed at three levels of organization; whole-stand, stratum, and species.The trees of the forest were grouped into upper, middle and lower vertical strata. Species richness was highest in the middle stratum. Upper stratum species were commercially important. The mean basal area for the Forest Division was 12.83 m²/ha. and average number of trees per hectare (>=20 cm dbh) was 150. Regeneration of the upper stratum species was higher at about 10% gap in the canopy.The growing stock of established seedlings and saplings (height > 100 cm and dbh <=10cm) was very low compared to unestablished seedlings (height <=100 cm). Owing to very low survival probability in the sapling stage (dbh >=1 cm to <=10 cm), a low numbers of poles (dbh >=10 cm to <=20 cm) in the upper stratum was observed. Presence of fire, grazing, browsing and over expoitation by humans are the major constraints of natural regeneration recognized in these forests.     

Spatial and Temporal Patterns in Stand Structure,Biomass, Growth,and Mortality in a Monospecific Nothofagus solandrivar. cliffortioides (Hook,f.) Poole Forest in New Zealand

Abstract

In 250 20 m X 20 m permanent plots in the Craigie-burn Range, Canterbury, New Zealand, 1970 stem density was 2,191/ha, basal area was 52.4 m²/ha, and stem biomass was 178.1 Mg/ha. Net production of stemwood (1974-1987) was 2.0 Mg/ha/yr; mortality was 3.5 Mg/ha/yr. By 1987 density had decreased by 30%, basal area by 12%, and stem biomass by 13%.

Stands with many short trees of small mean dbh were common at high elevation, whereas stands with fewer, taller trees with large mean dbh were common at low elevation. Stemwood production and mortality rate were higher in tall stands. Mortality was well distributed among plots, indicating small, frequent canopy openings; stand turnover calculations were 66 year (based on 2.2% annual biomass loss) to 83 year (based on 1.2% annual stemwood production). Larger canopy openings were also evident, but were more infrequent, so stand turnover times due to 'catastrophic' disturbances were in the range of 350-4000 yr. Consequently, the small, high-frequency disturbances blurred effects of larger disturbances on stand structure and also constrained the fluctuation in forest biomass.     

Tree diversity and carbon stocks of some major forest types of Garhwal Himalaya,India

Four forest stands each of twenty major forest types in sub-tropical to temperate zones (350 m asl–3100 m asl) of Garhwal Himalaya were studied. The aim of the study was to assess the stem density, tree diversity, biomass and carbon stocks in these forests and make recommendations for forest management based on priorities for biodiversity protection and carbon sequestration. Stem density ranged between 295 and 850 N ha⁻¹, while total biomass ranged from 129 to 533 Mg ha⁻¹. Total carbon storage ranged between 59 and 245 Mg ha⁻¹. The range of Shannon–Wiener diversity index was between 0.28 and 1.75. Most of the conifer-dominated forest types had higher carbon storage than broadleaf-dominated forest types. Protecting conifer-dominated stands, especially those dominated by Abies pindrow and Cedrus deodara, would have the largest impact, per unit area, on reducing carbon emissions from deforestation.     

Forest structure and live aboveground biomass variation along an elevational gradient of tropical Atlantic moist forest (Brazil)

Live aboveground biomass (AGB) is an important source of uncertainty in the carbon balance from the tropical regions in part due scarcity of reliable estimates of live AGB and its variation across landscapes and forest types. Studies of forest structure and biomass stocks of Neotropical forests are biased toward Amazonian and Central American sites. In particular, standardized estimates of aboveground biomass stocks for the Brazilian Atlantic forest are rarely available. Notwithstanding the role of environmental variables that control the distribution and abundance of biomass in tropical lowland forests has been the subject of considerable research, the effect of short, steep elevational gradients on tropical forest structure and carbon dynamics is not well known. In order to evaluate forest structure and live AGB variation along an elevational gradient (0–1100 m a.s.l.) of coastal Atlantic Forest in SE Brazil, we carried out a standard census of woody stems ≥4.8 cm dbh in 13 1-ha permanent plots established on four different sites in 2006–2007. Live AGB ranged from 166.3 Mg ha⁻¹ (bootstrapped 95% CI: 144.4,187.0) to 283.2 Mg ha⁻¹ (bootstrapped 95% CI: 253.0,325.2) and increased with elevation. We found that local-scale topographic variation associated with elevation influences the distribution of trees >50 cm dbh and total live AGB. Across all elevations, we found more stems (64–75%) with limited crown illumination but the largest proportion of the live AGB (68–85%) was stored in stems with highly illuminated or fully exposed crowns. Topography, disturbance and associated changes in light and nutrient supply probably control biomass distribution along this short but representative elevational gradient. Our findings also showed that intact Atlantic forest sites stored substantial amounts of carbon aboveground. The live tree AGB of the stands was found to be lower than Central Amazonian forests, but within the range of Neotropical forests, in particular when compared to Central American forests. Our comparative data suggests that differences in live tree AGB among Neotropical forests are probably related to the heterogeneous distribution of large and medium-sized diameter trees within forests and how the live biomass is partitioned among those size classes, in accordance with general trends found by previous studies. In addition, the elevational variation in live AGB stocks suggests a large spatial variability over coastal Atlantic forests in Brazil, clearly indicating that it is important to consider regional differences in biomass stocks for evaluating the role of this threatened tropical biome in the global carbon cycle.     

Estimates of forest biomass in the Brazilian Amazon: New allometric equations and adjustments to biomass from wood-volume inventories

Uncertainties in biomass estimates in Amazonian forests result in a broad range of possible magnitude for the emissions of carbon from deforestation and other land-use changes. This paper presents biomass equations developed from trees directly weighed in open forest on fertile soils in the southern Amazon (SA) and allometric equations for bole-volume estimates of trees in both dense and open forests. The equations were used to improve the commonly used biomass models based on large-scale wood-volume inventories carried out in Amazonian forest. The biomass estimates from the SA allometric equation indicate that equations developed in forests on infertile soils in central Amazonia (CA) result in overestimates if applied to trees in the open forests of SA. All aboveground components of 267 trees in open forests of SA were cut and weighed, and the proportion of the biomass stored in the crowns of trees in open forest was found to be higher than in dense forest. In the case of inventoried wood volume, corrections were applied for indentations and hollow trunks and it was determined that no adjustment is needed for the form factor used in the RadamBrasil volume formula. New values are suggested for use in models to convert wood volume to biomass estimates. A biomass map for Brazilian Amazonia was produced from 2702 plots inventoried by the RadamBrasil Project incorporating all corrections for wood density and wood volume and in factors used to add the bole volume of small trees and the crown biomass. Considering all adjustments, the biomass map indicates total biomass of 123.1 Gt (1 Gt = 1 billion tons) dry weight (aboveground + belowground) for originally forested areas in 1976 in the Brazilian Legal Amazon as a whole (102.3 Gt for aboveground only) at the time of the RadamBrasil inventories, which were carried out before intensive deforestation had occurred in the region. Excluded from this estimate are 529,000 km² of forest lacking sufficient RadamBrasil inventory data. After forest losses of 676,000 km² by 2006 – not counting 175,000 km² of this deforested area lacking RadamBrasil data – the estimated dry biomass stock was reduced to 105.4 and 87.6 Gt (aboveground + belowground and only above-ground). Thus, in 2006 the carbon storage in forested areas in Brazilian Amazonia as a whole will be around 51.1 Gt (assuming 1 Mg dry biomass = 0.485 Mg C). Biomass estimates by forest type (aggregated into 12 vegetation classes) are provided for each state in the Brazilian Legal Amazon.     

Biomass and carbon pools of disturbed riparian forests

Quantification of carbon pools as affected by forest age/development can facilitate riparian restoration and increase awareness of the potential for forests to sequester global carbon. Riparian forest biomass and carbon pools were quantified for four riparian forests representing different seral stages in the South Carolina Upper Coastal Plain. Three of the riparian forests were recovering from disturbance (thermal pollution), whereas the fourth represents a mature, relatively undisturbed riparian forest. Above and belowground carbon pools were determined from linear transects established perpendicular to the main stream channels and spanning the width of the riparian area. The objective of this study was to quantify the biomass and carbon pools in severely disturbed, early successional bottomland hardwood riparian forests and to compare these values to those of a less disturbed, mature riparian forest.

Aboveground biomass in all four riparian forests increased during the 2.5-year investigation period. The total carbon pool in these South Carolina Coastal Plain riparian forests increased with forest age/development due to greater tree and soil carbon pools. The mature riparian forest stored approximately four times more carbon than the younger stands. The importance of the herbaceous biomass layer and carbon pool declined relative to total aboveground biomass with increasing forest age. As stands grew older fine root biomass increased, but an inverse relationship existed between percentages of fine root biomass to total biomass. The root carbon pool increased with forest age/development due to a combination of greater fine root biomass and higher root percent carbon.

Aboveground net primary production (NPP) in young riparian forests rapidly approached and exceeded NPP of the more mature riparian forest. As a woody overstory became established (after 8–10 years) annual litterfall rate as a function of NPP was independent of forest age and litterfall amount in the young riparian forests was comparable to mature riparian forests. Biomass in the riparian forest floor and carbon pool declined with increasing riparian forest development. Woody debris in these riparian forests comprised a relatively small carbon pool. An understanding of bottomland hardwood riparian forest carbon pools at different stages of succession allows us to assess how time since disturbance influences these pools, leading to a better understanding of the recovery processes.     

Improving the estimate of forest biomass carbon storage by combining two forest inventory systems

Quantifying forest carbon storage and its spatial distribution at regional scales is critical for the creation of greenhouse gases inventories, the evaluation of forest services and carbon-oriented forest management. The plot-based forest inventory (PBFI) and stand-based forest inventory (SBFI) collect extensive information on trees and stands respectively, and together, provide an opportunity to improve the regional estimates of forest carbon. In this study, we applied the SBFI to overcome the spatial extent limits of the PBFI in neighboring plots and improve the regional carbon estimation. We found that the forests in Sichuan Province reserved a total of 624.2?Tg?C in biomass and featured a large spatial heterogeneity, with high values in natural forests and low values in plantations. We found that the solo use of PBFI derived a slightly higher (46.63?Mg?C/ha) estimation on average compared with the integrated method (43.6?Mg?C/ha). However, when considering the spatial distribution, the PBFI generated an overestimation of young forests located between 3000and 4000?m in elevation, and an underestimation in mature forests. The spatially explicit biomass carbon estimation could be helpful in guiding regional forest management and biodiversity conservation.     

Gap-Disturbance Regimes in Different Forest Types of Japan

Abstract

In this study, I defined a gap as a small opening formed in a forest canopy (area < 0.1 ha) and tried to synthesize gap-disturbance regimes of primary mature stands in different forest types of Japan, such as warm temperate evergreen broad-leaved (4 stands in 3 localities), cool temperate deciduous broad-leaved (10 in 5) and subalpine evergreen coniferous (3 in 1) forests. Mean percentage of the total gap area within the total forested area (percentage gap area) in each forest type was 17.0% in warm temperate (number of surveyed gaps was 161), 13.8% in cool temperate (278 gaps), and 8.0% in subalpine (100 gaps) forests. Mean gap density (ha^-1) and mean gap size (m²) were 19.5 and 77.1 in warm temperate, 16.4 and 92.0 in cool temperate, and 19.1 and 41.9 in subalpine forests, respectively. These figures indicate that gap density is not substantially different among the forest types, but the mean gap size of subalpine forests is smaller than the other two, resulting in lower percentage gap area of this forest type. The gap size distributions were similar among the forest types; smaller gaps were much more frequent than larger ones, and gaps > 400 rrr were rare in warm temperate and cool temperate forests. In subalpine forests gaps > 200 m² were rare. Gaps formed by multiple gapmakers comprised 19.9% of all gaps in warm temperate, 9.9% in cool temperate, and 44.9% in subalpine forests, which implies that gap formation by simultaneous tree fall or gap enlargement is more frequent in subalpine forests. Canopy trees died less often by uprooting in every forest type; dominant mode for the death of canopy trees was by leaving standing-dead or with broken trunks in every forest type. Since typhoons are obviously a chief agent of forest disturbance in Japan, frequency or magnitude of typhoon disturbance may influence these differences in the gap-disturbance regimes. In addition to the disturbance, tree architectures seem to affect some of these differences; narrower crown size of conifers compared with broad-leaved trees is considered one major cause for smaller gap size of the conifer forest.     

Liana abundance in a Puerto Rican forest

Liana (woody vine) abundance varies among tropical forests and is often high in disturbed forests. In two areas of subtropical wet forest in Puerto Rico, El Verde and Bisley, we recorded the density of liana stems ≥1 cm dbh, and the percent of tree crowns (trees ≥10 cm dbh) that lianas infested. Both study areas have been disturbed by hurricanes several times in the past century; however, sample plots in each area were divided between plots that were less disturbed and those that were more disturbed, by both hurricanes and humans. The mean density and basal area of liana stems at El Verde were significantly higher in the less disturbed plots than in the more disturbed plots. The percent tree crown infested by lianas was higher on certain tree species and on larger trees, both of which characterized the less disturbed forest. Results at Bisley were similar to those at El Verde. Liana density and tree crown infestation in these Puerto Rican forests were low compared with most other tropical forests, contrasting especially with high values in other disturbed forests. Liana abundance varies among forests for complex reasons, including differences in disturbance, biogeography, seasonality, and tree host features.     

Structural and environmental characterization of old-growth temperate rainforests of northern Chiloé Island,Chile: Regional and global relevance

Old-growth forests are ecologically relevant reservoirs of biodiversity and provide valuable and unique ecosystem functions in the landscape. However, what constitutes an old-growth stand is confusing because the definition depends largely on the forest type under study. Despite the ecological importance of old-growth temperate rainforests in southern Chile in comparison to other global forests, no attempts have been made to characterize them as a way to assess their structural variability. Here, we characterized old-growth stands of Valdivian and North Patagonian rain forest types located in Chiloé Island (Chile, 42°30′S) using inventory data from 23 permanent plots (0.1 ha each) located in rural landscapes and protected areas of northern Chiloé Island. For each stand, its age (average age of the oldest trees present in each stand) and disturbance regimes (evidence of recent human impact, e.g. cuttings or fires, and tree growth rates) were used as defining old-growth criteria. We characterized the structure (tree species richness, size-density distributions, vertical stratification and presence of snags) and floristic composition of each stand. Environmental variables (i.e. temperature, distance to coastline and elevation) were related to stand structure using multivariate constrained correspondence analysis. Old-growth forests were commonly characterized by (a) tree basal areas >80 m²/ha; (b) density of shade-tolerant tree species in the emergent and dominant canopy layer >36%; (c) higher tree species richness (>7 tree species) than successional stands; (d) presence of large canopy emergents (>80 cm dbh, >25 m tall); (e) high vertical heterogeneity; and (f) minimum stand ages older than 200 years. Old-growth forests showed a distinctive structural variability and floristic diversity influenced both by stand age and disturbance history of the stands. Structural variability was also related to environmental differences among sites (e.g. air temperature, distance to coastline, soil types). Old-growth forest features described here can offer a baseline for managers interested in maintaining and restoring old-growth forest structure in southern temperate rain forests.     

Estimating Pinus palustris tree diameter and stem volume from tree height,crown area and stand-level parameters

Accurate and efficient estimation of forest growth and live biomass is a critical element in assessing potential responses to forest management and environmental change. The objective of this study was to develop models to predict longleaf pine tree diameter at breast height （dbh） and merchantable stem volume （V） using data obtained from field measurements. We used longleaf pine tree data from 3,376 planted trees on 127 permanent plots located in the U.S. Gulf Coastal Plain region to fit equations to predict dbh and V as functions of tree height （H） and crown area （CA）. Prediction of dbh as a function of H improved when CA was added as an additional independent variable. Similarly, predic- tions of V based on H improved when CA was included. Incorporation of additional stand variables such as age, site index, dominant height, and stand density were also evaluated but resulted in only small improvements in model performance. For model testing we used data from planted and naturally-regenerated trees located inside and outside the geographic area used for model fitting. Our results suggest that the models are a robust alternative for dbh and V estimations when H and CA are known on planted stands with potential for naturally-regenerated stands, across a wide range of ages. We discuss the importance of these models for use with metrics derived from remote sensing data.     

Biomass estimations in forests of different disturbance history in the Atlantic Forest of Rio de Janeiro,Brazil

Tropical forests are large reservoirs of biomass and there is a need for information on existing carbon stocks in these ecosystems and especially the effects of logging on these stocks. Reliable estimates of aboveground biomass stocks within the Atlantic Forest are rarely available. Past human disturbance is an important factor affecting forest structure variation and biomass accumulation among tropical forest ecosystems. To support the efforts of improving the quality of estimations of the current and future biomass carbon storage capacity of this disturbed forest region we tested a non-experimental small scale approach to compare the aboveground tree biomass (AGB) of forest sites. Three sites with known disturbance histories have been investigated: complete cut down, selective logging and conservation since 70 years. The woody plant community (dbh ≥ 10 cm) was censused and canopy openness in conjunction with leaf area index has been obtained by hemispherical photographs at each site. Estimates of aboveground tree biomass have been carried out using an allometric equation for moist tropical forests already applied for the study area. Additionally, a FAO standard equation has been employed for crosschecking our results. We identified significant differences in recent AGB of the three compared forest sites. With 313 (±48 Mg ha⁻¹) the highest AGB-values have been found in the preserved forest area within a National Park, followed by 297 (±83) Mg ha⁻¹ at the former clear cut site. Lowest AGB has been calculated for the area with past selective logging: 204 (±38) Mg ha⁻¹. Values calculated with the FAO standard equation showed the same trend but at a lower AGB level. Our results based an a small scale approach suggest that biomass productivity can recover in a forest which was completely cleared 60 years ago to reach AGB values up to a level that almost represents the situation in a preserved forest. Selective logging may slow down AGB accumulation and the effect is measurable after several decades.     

Assessment of Carbon Balance in Community Forests in Dolakha, Nepal

This study assessed the net above-ground carbon stock in six community forests in the Dolakha district, Nepal. A survey was conducted of above-ground timber species, using random sampling. A tree-ring chronology for Pinus roxburghii was created to construct a growth model representative of the various mainly-pine species. The allometric model combined with tree ring analysis was used to estimate carbon stock and annual growth in the above-ground tree biomass. The out-take of forest biomass for construction material and fuelwood was estimated on the basis of interviews and official records of community forest user groups. The average annual carbon increment of the community forests was 2.19 ton/ha, and the average annual carbon out-take of timber and fuelwood was 0.25 ton/ha. The net average carbon balance of 1.94 ton/ha was equivalent to 117.44 tons of carbon per community forest annually. All the community forests were actively managed leading to a sustainable forest institution, which acts as a carbon sink. It is concluded that community forests have the potential to reduce emissions by avoiding deforestation and forest degradation, enhance forest carbon sink and improve livelihoods for local communities.