Growth, biomass and stem volume models for downy birch in Iceland

In this study we present results of above-ground biomass (AGB) estimation for Sweden based on ALOS PALSAR backscatter data. The retrieval was performed within the framework of the BIOMASAR algorithm, and the validation was based on the Swedish National Forest Inventory (NFI) plots. The main focus, however, is about the modelling framework on the retrieval of AGB by integrating PALSAR backscatter, ICESAT GLAS metrics and allometric functions to improve the estimation of AGB. To evaluate the AGB retrieval, the average stem volume for each Swedish county from the NFI plots and the corresponding pixels covered by the inventory plots was computed. The result show an high agreement in terms of an RMSE of 8.2%, a bias of -1.9 m3/ha and a R2 value of 0.82. The results indicate that stem volume derived from ALOS PALSAR data can be used to support statistics for Sweden and spatially explicit give information on stem volume distribution across the country, albeit local fluctuations due to the still simplified modelling framework here implemented.

Effects of national forest inventory plot location error on forest carbon stock estimation using k-nearest neighbor algorithm

Summary In Europe, two commercially important treelike birch species occur naturally: silver birch ( Betula pendula Roth) and downy birch ( Betula pubescens Ehrh.). Both species have a wide natural distribution area on the Eurasian continent, ranging from the Atlantic to eastern Siberia. Although birches occur throughout almost the whole of Europe, the most abundant birch resources are in the temperate and boreal forests of Northern Europe. In the Baltic and Nordic countries, the proportion of birch out of the total volume of the growing stock varies between 11 and 28 per cent. In Northern Europe, birch is commercially the most important broadleaved tree species. Birches are light-demanding early successional pioneer species, which grow both in mixed stands and in pure stands. This article provides an overview of the most important ecological characteristics and typical growth and yield patterns of birch, based on European scientifi c literature. Growth and yield research on birch has been relatively active in Northern Europe, where numerous growth and yield models have been developed during the last decades. In this paper, a list of published scientifi c articles on growth modelling is provided and is grouped according to the different types of model. When growing in forest stands, birches have a relatively straight slender stem form. The current practices and silvicultural recommendations, based on research directed at high-quality timber production in silver birch stands, are reviewed. Although the emphasis is on even-aged pure silver birch stands, the management of mixed stands as well as the silviculture of downy birch and curly birch are also briefl y discussed.

The objective of the study was to ascertain the relationship of thinning intensity of downy birch (Betula pubescens Ehrh.) stands with height, crown, and diameter development as well as pulp- wood,�stemvolume, �andbioma ssincrementusinglong-term �(20−30 �years) �fieldexperiments. � Diametergrowt hofbi rchesi ncreasedwi tht hinningi ntensityduri ngt hefirst �15 �ye arsfromt hinning� in all development phases, though after that it did so only for the youngest stands. The thinning responsewaslow . �Thinningintensityhadnoinfluenceonincreaseinheight. �Intermsofstem � volume with bark, the mortality in unthinned stands during the study period was 30-45 m 3 ha -1 . The mean stem number in unthinned birch thickets fell from 25 000 ha -1 at a dominant height of 7 m to 3000 ha -1 �at �18 �m. �Thestemvolumeincre mentoverthefirst �15 �yearswashighest �(5-6 � m 3 ha -1 a -1 )�ontheverylightlythinnedorunthinnedplots, �butlatertherewasnosignificantdif- ferencebetweeninitialthinningintensities. �Themaximumabove-groundleaflessbiomass �(over � 100 Mg ha -1 ) was achieved on very lightly thinned plots. Also, the total production (including thinning removal) of biomass or stem volume or even the production of pulpwood increased with stand density, with these values being greatest for very lightly thinned or unthinned plots. During 50-yearrotation , �thehighestleaflessabove-groundbiomassproductionwas �2.5 �Mgha -1 a -1 as a meanvaluefromtheexperiments. �Thehighestmeanannualproductionofpulpwood �(d�> �6.5 �cm) � was 3.2 m 3 ha -1 a -1 , and, in practice, no saw timber or veneer timber was produced, because of the small size and low quality of the stems. A thinning in downy birch stands increased slightly thesizeofstemstoberemovedinfuturecuttings, �butwithexceptionforverylightthinningit � decreased the production of biomass and merchantable wood.

Monitoring deer food and browsing in forests: Coherence and discrepancies between national and local inventories

Sprouting ability and biomass production of downy and silver birch stumps of different diameters

03/02384 Influence of particle size and moisture content on tendency to bridge in biofuels made from willow shoots: Mattsson, J. E. and Kofman, P. D. Biomass and Bioenergy, 2003, 24, (6), 429–435

This study presents a k-nearest neighbor bagging approach for predicting forest attributes, specifically growing stock volume (GSV), by integrating optical Sentinel-2, radar Sentinel-1, and spaceborne lidar GEDI datasets following a two-step procedure. Over a large region ( ∼ 4600 km 2 ), some selected GEDI variables were imputed to national forest inventory (NFI) plots, then models were developed to predict GSV based on the combined imputed GEDI and Sentinel variables. For GEDI imputation, three strategies were followed, each one using different auxiliary datasets: (A) solely relying on Sentinel data, (B) using Sentinel data complemented by maximum height values from both GEDI and NFI data sources, (C) using Sentinel and height values from an independent canopy height map derived from GEDI and Sentinel through Deep Learning. For each strategy, the models were built using a k-nearest neighbor approach and evaluated on an independent test dataset. The results indicated that the ability of Strategy A to predict forest volume as the percentage of explained variance ( R 2 ) was considerably limited (0.08) and the relative root mean squared error (RMSE%) was high (66%). Upon adding heights, Strategy B outperformed the previous strategy, with a R 2 of 0.58 and a relatively low RMSE% (43%). Compared to Strategy A, the use of estimated heights from a canopy height map improved predictions, but did not outperform Strategy B; R 2 was 0.34 and RMSE% 53%. Imputations yielded better models when using original GEDI footprint heights as inputs, rather than relying on height estimates extracted from the canopy height map. Therefore, small area model-assisted estimation may be preferred over wall-to-wall maps to reduce area-based local estimation errors. • NFI, GEDI & Sentinel-1/2 data can be efficiently combined in multi-phase inventory. • We used K-NN bagging in the auxiliary variable space to pair GEDI with NFI plots. • Predicting GSV using GEDI benefits from relying on whole vegetation profile data. • Matching whole GEDI structure info with NFI plots is essential to upscale forest attributes. • We recommend upscaling of NFI data to GEDI footprints prior to model-based mapping.

The objective of this paper is to propose a method for simulating and predicting the evolution of wood resources in the 'Lan- des de Gascogne' region. Lemoine's growth and yield model has been successfully utilized to predict future timber resources from exis- ting data collected in two successive surveys (1977 and 1988) conducted by the National Forest Inventory (NFI). Lemoine's model was calibrated by analysing the error in estimation of stand features between the NFI plots and experimental plots originally used to built Le- moine's model. The proposed corrected term is based on the best linear unbiased predictor of the error. The calibrated model exhibited a better accuracy than the original model version. We suggest that coupling the calibrated Lemoine's model with NFI data is a useful me- thod for predicting timber resources at a regional level. wood resource / national forest inventory / growth model / model calibration / maritime pine

Aim of study: In this study we compared the accuracy of the Weibull and the Johnson’s SB functions for describing diameter distributions in pedunculate oak (Quercus robur L.) and birch (Betula pubescens Ehrh.) stands.Area of study: Galicia (Northwest Spain).Material and Methods: A total of 172 diameter distributions in pedunculate oak and 202 in birch stands were finally evaluated. We compared the accuracy of three commonly used estimation methods of the Weibull and four estimation methods of the Johnson’s SB functions for describing these diameter distributions.Main results. For Quercus robur L. stands, the most suitable methods were the Percentiles followed by Maximum Likelihood for the Weibull PDF and the method of Moments for the Johnson’s SB PDF. For Betula pubescens Ehrh. stands, the best fits obtained with the Percentiles and Maximum Likelihood methods were also superior to the method of Moments, whereas the Conditional Maximum Likelihood and method of Moments provided the best results for the Johnson’s SB PDF, depending on the statistic and the value of the location parameter considered.Research highlights: Both distributions were suitable. The results were better for pedunculate oak than for birch stands.Keywords: Knoebel and Burkhart; location parameter; percentiles; maximum likelihood; moments; mode.

Early reduction of Otiorhynchus spp. larval root herbivory on Betula pubescens by beneficial soil fungi

To improve our understanding of factors influencing the success of natural regeneration with downy birch (Betula pubescens Ehrh.) and silver birch (Betula pendula Roth) on abandoned farmlands, a survey was conducted to analyse the effects of site conditions and site preparation characteristics. The study was based on a sample plot inventory conducted in one northern and one southern district of Sweden, in which 29 successfully established, naturally regenerated stands, about to be cleaned or thinned, were assessed. Radical site preparation increased stand density and uniformity of established regeneration, and gave faster initial development, than establishment without site preparation on former leys or meadows. Large proportions of the total sample area were classified as moist, and soils consisting of sand–fine sand or peat were frequent. The frequency of birch stems was highest in mesic sites, and on soils consisting of sand, sand–fine sand or peat. Distances to seed-trees were generally shorter than 80 m, and downy birch was the dominant species in most stands.

Whole-tree harvesting (WTH), where logging residues are removed in addition to stems, is widely practised in Fennoscandian boreal forests. WTH increases the export of nutrients from forest ecosystems. The extent of nutrient removals may depend on tree species, harvesting method, and the intensity of harvesting. We developed generalized nutrient equations for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies Karsten), and birch (Betula pendula Roth and Betula pubescens Ehrh.) stands to be able to calculate the amounts of nitrogen, phosphorus, potassium, and calcium in stems and above-ground biomass (stem and crown) as a function of stand volume. The equations were based on Fennoscandian literature data from 34 pine, 26 spruce, and 5 birch stands, and they explained, depending on the tree species and nutrient, 61–99% and 56–87% of the variation in the nutrient amounts of stems and above-ground biomass, respectively. The calculations based on the equations showed that nutrient removals caused by stem-only harvesting (SOH) and WTH per harvested stem m3 were smaller in pine than in spruce and birch stands. If the same volume of stem is harvested, nutrient removals are, in general, nearly equal at thinnings and final cuttings in SOH, but larger in thinnings than final cuttings in WTH. If the principal aim is to minimize the nutrient removals per harvested stem m3, the harvesting should be done at mature pine stands. The effect of biomass removal on overall site nutrient status depends on site-specific factors such as atmospheric deposition, weathering of minerals, and the size of the nutrient pools in the soil.

Comparison of precision of biomass estimates in regional field sample surveys and airborne LiDAR-assisted surveys in Hedmark County, Norway

Estimating biomass in Hedmark County, Norway using national forest inventory field plots and airborne laser scanning