scholarly journals The importance of forest structure to biodiversity–productivity relationships

2017 ◽  
Vol 4 (1) ◽  
pp. 160521 ◽  
Author(s):  
Friedrich J. Bohn ◽  
Andreas Huth
Keyword(s):  
Species Distribution ◽  
Forest Structure ◽  
Basal Area ◽  
Tree Height ◽  
National Forest Inventory ◽  
National Forest ◽  
Forest Stands ◽  
Annual Productivity ◽  
Structure Indices ◽  
Modelling Approach

While various relationships between productivity and biodiversity are found in forests, the processes underlying these relationships remain unclear and theory struggles to coherently explain them. In this work, we analyse diversity–productivity relationships through an examination of forest structure (described by basal area and tree height heterogeneity). We use a new modelling approach, called ‘forest factory’, which generates various forest stands and calculates their annual productivity (above-ground wood increment). Analysing approximately 300 000 forest stands, we find that mean forest productivity does not increase with species diversity. Instead forest structure emerges as the key variable. Similar patterns can be observed by analysing 5054 forest plots of the German National Forest Inventory. Furthermore, we group the forest stands into nine forest structure classes, in which we find increasing, decreasing, invariant and even bell-shaped relationships between productivity and diversity. In addition, we introduce a new index, called optimal species distribution, which describes the ratio of realized to the maximal possible productivity (by shuffling species identities). The optimal species distribution and forest structure indices explain the obtained productivity values quite well ( R 2 between 0.7 and 0.95), whereby the influence of these attributes varies within the nine forest structure classes.

scholarly journals Zur Auswirkung der Hangneigungskorrektur auf Schätzwerte im Schweizerischen Landesforstinventar (LFI) | Investigation of the effect of the slope correction method as applied in the Swiss National Forest Inventory of estimates

2001 ◽  
Vol 152 (6) ◽  
pp. 215-225 ◽  
Author(s):  
Michael Köhl ◽  
Peter Brassel
Keyword(s):  
Forest Inventory ◽  
Basal Area ◽  
Correction Method ◽  
National Forest Inventory ◽  
National Forest ◽  
Average Deviation ◽  
Forest Inventories ◽  
Slope Correction ◽  
Number Of Stems ◽  
Elliptical Area

For forest inventories on slopes, it is necessary to correct the test areas, because the circular areas, when projected, become elliptical. Based on 93 samples from the Swiss National Forest Inventory (FNI), it was determined whether the simplified method, which increases the radius to match that of the elliptical area, leads to a distortion of the results. An average deviation of 2% was found between the FNI estimated values and the actual values for the basal area and the number of stems. For estimations of smaller units, greater distortions of the results are expected.

scholarly journals Regional Variability of the Romanian Main Tree Species Growth Using National Forest Inventory Increment Cores

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 409
Author(s):  
Gheorghe Marin ◽  
Vlad C. Strimbu ◽  
Ioan V. Abrudan ◽  
Bogdan M. Strimbu
Keyword(s):  
Mixed Models ◽  
Forest Inventory ◽  
Basal Area ◽  
National Forest Inventory ◽  
Forest Growth ◽  
National Forest ◽  
Sessile Oak ◽  
Basal Area Growth ◽  
Temporal Grouping ◽  
Area Growth

In many countries, National Forest Inventory (NFI) data is used to assess the variability of forest growth across the country. The identification of areas with similar growths provides the foundation for development of regional models. The objective of the present study is to identify areas with similar diameter and basal area growth using increment cores acquired by the NFI for the three main Romanian species: Norway spruce (Picea abies L. Karst), European beech (Fagus sylvatica L.), and Sessile oak (Quercus petraea (Matt.) Liebl.). We used 6536 increment cores with ages less than 100 years, a total of 427,635 rings. The country was divided in 21 non-overlapping ecoregions based on geomorphology, soil, geology and spatial contiguousness. Mixed models and multivariate analyses were used to assess the differences in annual dimeter at breast height and basal area growth among ecoregions. Irrespective of the species, the mixed models analysis revealed significant differences in growth between the ecoregions. However, some ecoregions were similar in terms of growth and could be aggregated. Multivariate analysis reinforced the difference between ecoregions and showed no temporal grouping for spruce and beech. Sessile oak growth was separated not only by ecoregions, but also by time, with some ecoregions being more prone to draught. Our study showed that countries of median size, such as Romania, could exhibit significant spatial differences in forest growth. Therefore, countrywide growth models incorporate too much variability to be considered operationally feasible. Furthermore, it is difficult to justify the current growth and yield models as a legal binding planning tool.

scholarly journals Forest stands volume estimation by using Finnish Multi-Source National Forest Inventory in Stołowe Mountains National Park

2016 ◽  
Vol 58 (1) ◽  
pp. 3-12
Author(s):  
Przemko Pachana
Keyword(s):  
Forest Inventory ◽  
National Park ◽  
Pearson Correlation ◽  
Satellite Image ◽  
National Forest Inventory ◽  
Volume Estimation ◽  
National Forest ◽  
Forest Stands ◽  
Timber Volume ◽  
Growing Stock

Abstract The purpose of the present study was to convey to the reader the method and application of the Finnish Multi-Source National Forest Inventory (MS-NFI) that was devised in the Finnish Forest Research Institute. The study area concerned is Stołowe Mountains National Park, which is located in the south-western Poland, near the border with the Czech Republic. To accomplish the above mentioned aim, the following data have been applied: timber volume derived from field sample plots, satellite image, digital map data and digital elevation model. The Pearson correlation coefficient between independent and dependent variables has been verified. Furthermore, the non-parametric k-nearest neighbours (k-NN) technique and genetic algorithm have been used in order to estimate forest stands biomass at the pixel level. The error estimates have been obtained by leave-one-out cross-validation method. The main computed forest stands features were total and mean timber volume as well as maximum and minimum biomass occurring in the examined area. In the final step, timber volume map of the growing stock has been created.

scholarly journals Horizontal Visibility in Forests

2021 ◽  
Vol 13 (21) ◽  
pp. 4455
Author(s):  
Mait Lang ◽  
Andres Kuusk ◽  
Kersti Vennik ◽  
Aive Liibusk ◽  
Kristina Türk ◽  
...  
Keyword(s):  
Forest Structure ◽  
Laser Scanning ◽  
Prediction Models ◽  
Important Variable ◽  
Pattern Generation ◽  
Forest Understory ◽  
Arc Length ◽  
Forest Stands ◽  
Horizontal Visibility ◽  
Structure Indices

The important variable of horizontal visibility within forest stands is gaining increasing attention in studies and applications involving terrestrial laser scanning (TLS), photographic measurements of forest structure, and autonomous mobility. We investigated distributions of visibility distance, open arc length, and shaded arc length in three mature forest stands. Our analysis was based (1) on tree position maps and TLS data collected in 2013 and 2019 with three different scanners, and (2) on simulated digital twins of the forest stands, constructed with two pattern-generation models incorporating commonly used indices of tree position clumping. The model simulations were found to yield values for visibility almost identical to those calculated from the corresponding tree location maps. The TLS measurements, however, were found to diverge notably from the simulations. Overall, the probability of free line of sight was found to decrease exponentially with distance to target, and the probabilities of open arc length and shaded arc length were found to decrease and increase, respectively, with distance from the observer. The TLS measurements, which are sensitive to forest understory vegetation, were found to indicate increased visibility after vegetation removal. Our chosen visibility prediction models support practical forest management, being based on common forest inventory parameters and on widely used forest structure indices.

scholarly journals Estimation of diameter and height of individual trees for Pinus sylvestris L. based on the individualising of crowns using airborne LiDAR and the National Forestry Inventory data.

2016 ◽  
Vol 25 (1) ◽  
pp. 046 ◽  
Author(s):  
Manuel-Ángel Valbuena-Rabadán ◽  
Jacinto Santamaría-Peña ◽  
Félix Sanz-Adán
Keyword(s):  
Pinus Sylvestris ◽  
Tree Height ◽  
Point Clouds ◽  
National Forest Inventory ◽  
Airborne Lidar ◽  
National Forest ◽  
Autonomous Community ◽  
Total Height ◽  
Crown Delineation ◽  
Geometrical Relationships

Aim of study: The objective of this study is to test the validity of the DBH and total height allometric models fitted to the crown polygon data obtained by the application of a crown delineation and individualisation algorithm which uses the geometrical relationships between the points in the original LiDAR point clouds in the Pinus sylvestris L. stands.Area of study: The study area is located in the province of Álava in the Autonomous Community of the Basque Country.Material and Methods: The crowns are delineated using data from airborne LiDAR point clouds obtained in the 2008 overflight of the Basque Autonomous Community. The DBH and total height data for field trees are obtained from the plots in the 4th National forest inventory.Main Results: For the adjusted total height and DBH models coefficients of determination of 0.87 and 0.74 respectively were obtained. The root mean squared errors were 10.67% and 18.97% respectively. The distributions of obtained DBH and total height fitted values and the distributions of the DBH and total height of the field trees are very similar except for the DBH below 15 cm.Research highlights: For stands of Pinus sylvestris L. in Álava, the geometrical relationships between the points that correspond to laser signal echoes obtained with airborne LiDAR sensors can be used directly to delineate approximations of the horizontal projections of the crowns of the trees. Although the procedure set out here was developed for stands of P. sylvestris L. in Álava, it can be applied to other conifers in regular stands by adjusting the working parameters of the function which delineates the crowns on the basis of the point cloud.Abbreviations used: IFN4: 4th National Forest Inventory; Ht: Field Tree Height; Hl: LiDAR Tree Height; DCL: LiDAR Crown Diameter.

scholarly journals Wiederholungsaufnahmen als Instrument zur Qualitätssicherung im Schweizerischen Landesforstinventar

2016 ◽  
Vol 167 (3) ◽  
pp. 118-127 ◽  
Author(s):  
Berthold Traub ◽  
Fabrizio Cioldi ◽  
Christoph Düggelin
Keyword(s):  
Forest Inventory ◽  
Stand Structure ◽  
Tree Height ◽  
National Forest Inventory ◽  
Stand Age ◽  
National Forest ◽  
Stage Of Development ◽  
Statistical Measures ◽  
Expected Values ◽  
Stand Attributes

Repeat surveys as a quality assurance tool in the Swiss National Forest Inventory The Swiss National Forest Inventory (NFI) repeats surveys to guarantee the quality of fieldwork. To this end, approximately 10% of sample plots are completely surveyed a second time over a field season. Based on the results of the repeat survey, the current investigation focuses on the assessment precision, i.e. the reproducibility of various tree and stand attributes in NFI4. It also investigates whether the change from periodic (NFI1–NFI3) to continuous (NFI4) fieldwork has had a positive effect on the reproducibility of the attributes. The current results of the repeat surveys for NFI4 (2009/2017) are compared with those for NFI3 (2004/2006) to this end. We used statistical measures as well as measurement quality objectives (MQO) set by the NFI instructor team as a reference for evaluating reproducibility. The results vary for tree attributes which are vital for estimating stock. The result for the diameter at breast height (dbh) corresponds to the expected values, while that for upper stem diameter at seven meters height and tree height were approximately 5% below the expected values. With regard to the seven stand attributes also analyzed, four of them exceeded the quality goals (stand age, stand stability, the degree of cover of secured regeneration, and stage of development). The results for the mixture proportion, the stand structure and crown closure were between 5 and 18% below MQO. The result for presence of woody species shows that the recording of larger plants (above 130 cm) is clearly more reproducible than for smaller plants (40–130 cm). In NFI4, the reproducibility for almost all studied attributes was improved. The results suggest that the modified structure of fieldwork (with only three field teams and continuous fieldwork in NFI4) has a positive influence on the reproducibility of the included attributes.

scholarly journals Predicting tree heights for biomass estimates in tropical forests – a test from French Guiana

2014 ◽  
Vol 11 (12) ◽  
pp. 3121-3130 ◽  
Author(s):  
Q. Molto ◽  
B. Hérault ◽  
J.-J. Boreux ◽  
M. Daullet ◽  
A. Rousteau ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Forest Structure ◽  
French Guiana ◽  
Tree Height ◽  
Biomass Estimation ◽  
Forest Plot ◽  
Model Parameters ◽  
Forest Stands ◽  
Forest Stand Structure ◽  
Height Model

Abstract. The recent development of REDD+ mechanisms requires reliable estimation of carbon stocks, especially in tropical forests that are particularly threatened by global changes. Even though tree height is a crucial variable for computing aboveground forest biomass (AGB), it is rarely measured in large-scale forest censuses because it requires extra effort. Therefore, tree height has to be predicted with height models. The height and diameter of all trees over 10 cm in diameter were measured in 33 half-hectare plots and 9 one-hectare plots throughout northern French Guiana, an area with substantial climate and environmental gradients. We compared four different model shapes and found that the Michaelis–Menten shape was most appropriate for the tree biomass prediction. Model parameter values were significantly different from one forest plot to another, and this leads to large errors in biomass estimates. Variables from the forest stand structure explained a sufficient part of plot-to-plot variations of the height model parameters to improve the quality of the AGB predictions. In the forest stands dominated by small trees, the trees were found to have rapid height growth for small diameters. In forest stands dominated by larger trees, the trees were found to have the greatest heights for large diameters. The aboveground biomass estimation uncertainty of the forest plots was reduced by the use of the forest structure-based height model. It demonstrated the feasibility and the importance of height modeling in tropical forests for carbon mapping. When the tree heights are not measured in an inventory, they can be predicted with a height–diameter model and incorporating forest structure descriptors may improve the predictions.

scholarly journals Relascope sampling for crown ratio estimation

2013 ◽  
Vol 43 (5) ◽  
pp. 459-468 ◽  
Author(s):  
Sebastian Schnell ◽  
Jonas Wikman ◽  
Göran Ståhl
Keyword(s):  
Measurement Errors ◽  
Basal Area ◽  
Tree Height ◽  
Sampling Errors ◽  
Forest Stands ◽  
Vertical Angle ◽  
Pilot Studies ◽  
Crown Length ◽  
Study Sites ◽  
Angle Count Sampling

In this study, we apply vertical angle count sampling to estimate the crown ratio of trees in unthinned forest stands. The rationale is to be able to quickly assess the relative crown size of forest stands to support thinning decisions by simply counting trees. We provide estimators and discuss their precision based on pilot studies in Scots pine (Pinus sylvestris L.) plantations in northern Sweden. A separate study was conducted to investigate the amount of measurement errors, i.e., how many trees are wrongly selected or overlooked when using the method. Sampling errors for estimating crown ratio were found to be remarkably low, partly due to high correlation between crown length and tree height and partly due to low variability in the study sites. Measurement errors were in the range of what is commonly obtained with horizontal angle count sampling for basal area estimation.

scholarly journals An enhanced forest classification scheme for modeling vegetation–climate interactions based on national forest inventory data

2018 ◽  
Vol 15 (2) ◽  
pp. 399-412 ◽  
Author(s):  
Titta Majasalmi ◽  
Stephanie Eisner ◽  
Rasmus Astrup ◽  
Jonas Fridman ◽  
Ryan M. Bright
Keyword(s):  
Forest Management ◽  
Land Cover ◽  
Forest Structure ◽  
Forest Inventory ◽  
Classification Scheme ◽  
Growing Season ◽  
National Forest Inventory ◽  
Lookup Table ◽  
National Forest ◽  
Forest Classification

Abstract. Forest management affects the distribution of tree species and the age class of a forest, shaping its overall structure and functioning and in turn the surface–atmosphere exchanges of mass, energy, and momentum. In order to attribute climate effects to anthropogenic activities like forest management, good accounts of forest structure are necessary. Here, using Fennoscandia as a case study, we make use of Fennoscandic National Forest Inventory (NFI) data to systematically classify forest cover into groups of similar aboveground forest structure. An enhanced forest classification scheme and related lookup table (LUT) of key forest structural attributes (i.e., maximum growing season leaf area index (LAImax), basal-area-weighted mean tree height, tree crown length, and total stem volume) was developed, and the classification was applied for multisource NFI (MS-NFI) maps from Norway, Sweden, and Finland. To provide a complete surface representation, our product was integrated with the European Space Agency Climate Change Initiative Land Cover (ESA CCI LC) map of present day land cover (v.2.0.7). Comparison of the ESA LC and our enhanced LC products (https://doi.org/10.21350/7zZEy5w3) showed that forest extent notably (κ = 0.55, accuracy 0.64) differed between the two products. To demonstrate the potential of our enhanced LC product to improve the description of the maximum growing season LAI (LAImax) of managed forests in Fennoscandia, we compared our LAImax map with reference LAImax maps created using the ESA LC product (and related cross-walking table) and PFT-dependent LAImax values used in three leading land models. Comparison of the LAImax maps showed that our product provides a spatially more realistic description of LAImax in managed Fennoscandian forests compared to reference maps. This study presents an approach to account for the transient nature of forest structural attributes due to human intervention in different land models.

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