The Bitterlich method was studied with multiple basal area factors (BAF) in 3 Pinus taeda L. plantations located in the Midwest of Santa Catarina, Brazil using different management regimes: without ...thinning (1344 trees.ha-1), with one thinning (789 trees.ha-1), and with two thinnings (475 trees.ha-1),. Using the parameters obtained from censuses, we sought to verify the data from different sample treatments for the variables V.ha-1, G.ha-1, N.ha-1 and “d” through a completely randomized design for each management regime and observing the precision obtained by the sampling error and the accuracy detected by the real error. It was observed that the variable “d” was less impacted by the change in the basal area factor (BAF), but the estimates of V.ha-1, G.ha-1 and N.ha-1 were more consistent (precision and accuracy) using factors equal to or less than 5, mainly in thinned areas. Even with no significant differences in any BAF in the 3 experiments, the sampling performed with BAF greater than 5 showed contrasting results in the managed areas depending on the BAF used. Sampling precision is influenced by BAFs, decreasing with the reduction in the number of trees counted within the Bitterlich sampling unit, a direct consequence of the BAF increase. Sampling errors were always overestimated, regardless of the dendrometric variable or area management. Even the largest differences between estimates and parameters being identified in BAF greater than or equal to 5, the experiment indicated the use of any BAF, with the largest requiring greater sampling intensity.
•Generalized additive basal area increment models were fit for 22 Austrian species.•Climatic effects were included using the long-term mean and deviations thereof.•This formulation separates climatic ...site effects from yearly weather conditions.•Positive and adverse mixture effects were included but no interactions could be fit.•The omission of National Inventory specific variables facilitates model application.
Forest trees exhibit a large variation in basal area increment, which depends on tree specific factors, inter-tree relations and the environment. Studying the effect of the above factors on tree growth is essential for forest ecology and forest management. In this study, a basal area increment model for 22 tree species of the Austrian National Forest Inventory was parameterized. The model included effects of tree size, competition, harvesting and disturbances, climate, soil, and species mixtures. The models were fitted using generalized additive models. Basal area increment increased with tree size for all species, and competition and density reduced tree growth. Shade-tolerant tree species showed a more pronounced decrease with competition, than light-demanding tree species. Tree growth increased with disturbance intensity, but confidence intervals for high disturbance intensities became larger. Many variants of the model that included climatic effects were tested, but the best variants used long-term-mean temperature and precipitation during the growing season and the positive and negative deviations thereof, which separated climatic site effects from temperature deviations due to yearly weather conditions. Several of the tested dryness indices were not able to explain tree growth from inventory data. Soil type and soil moisture were significant for many tree species, each of them accounting for a maximum of 10% of difference in tree growth. Little growth was observed on calcareous Leptosols, whereas trees grew best on Planosols, on flysch or calcareous Cambisols. Growth was decreased on dry sites, but very moist and wet sites could result in either a decrease or an increase in growth, depending on the tree species. Mixture effects were significant for almost all mixtures with a sufficient number of observations in the data set. Notable exceptions were the mixtures of Pinus sylvestris L. with Picea abies (L.) Karst. and Abies alba Mill. and the mixtures of Quercus spp. with Pinus sylvestris L. and Fagus sylvatica L.. Mixture effects were both favorable and adverse at individual tree level. Picea abies and Fagus sylvatica were two tree species, which were mainly favored by mixture effects. Interactions of mixture with age or site could not be modelled from the data because they were confounded with other effects of the inventory data. The new basal area increment model provided a comprehensive formulation, which can be use part of individual tree growth simulators and is easily transferable to other regions and environments and can be extended in the future.
Changes in forest growth have been found in European forests and worldwide. However most observations have been derived from samples of restricted size, whose representativeness at a regional forest ...scale is questionable. National forest inventories provide an interesting perspective for both regional scale assessment of these trends and the investigation of their variations over environmental gradients, but have been little used.
The aim of our work was to carry out an exploratory modelling analysis of productivity changes, based on the French national forest inventory data. The objectives were: (i) to assess recent trends in forest productivity and to investigate a possible recent decline as found in previous studies; and (ii) to investigate trend variations relative to site fertility factors. We focused on pure and even-aged stands of common beech (
Fagus sylvatica L.) in north-eastern France, already documented from previous studies based on retrospective data.
The dataset consisted of 925 temporary plots inventoried between 1979 and 2007. We developed two regression models of stand basal area increment (
BAI) against stand developmental stage (dominant height), site fertility (site index in the
SI model, environmental indicators in the
EI model) and stand density (relative density index). The effect of calendar date was tested in order to investigate possible historical trends. Site fertility–date interactions were also tested to investigate the site-dependence of trends.
The fitted models showed a high goodness of fit (adj.
R
2 over 0.69). We showed an increase in stand
BAI of 27.8% between 1977 and 1987, (10.4% between 1979 and 1987). Stand
BAI then decreased by approximately 5% between 1987 and 2004. We thus confirmed the hypothesis of a recent decline in common beech vitality in its temperate range. The chronologies clearly depicted the effect of severe drought events (1976 and 2003), pointing out the predominant role of water availability in the changes observed. No significant site-dependence of the trend was identified.
Statistical confidence in estimates of timber volume, carbon storage, and other forest attributes depends, in part, on the uncertainty in field measurements. Surprisingly, measurement uncertainty is ...rarely reported, even though national forest inventories routinely repeat field measurements for quality assurance. We compared measurements made by field crews and quality assurance crews in the Forest Inventory and Analysis program of the U.S. Forest Service, using data from 2790 plots and 51740 trees and saplings across the 24 states of the Northern Region. We characterized uncertainty in 12 national core tree-level variables; seven tree crown variables used in forest health monitoring; three variables describing seedlings; and 11 variables describing the site, such as elevation, slope, and distance from a road. Discrepancies in measurement were generally small but were higher for some variables requiring judgment, such as tree class, decay class, and cause of mortality. When scaled up to states, forest types, or the region, uncertainties in basal area, timber volume, and aboveground biomass were negligible. Understanding all sources of uncertainty is important to designing forest monitoring systems, managing the conduct of the inventory, and assessing the uncertainty of forest attributes required for making regional and national forest policy decisions.
•The study aims at constructing wall-to-wall estimates of forest growing stock (GSV).•We combine NFI plot data, remotely sensed and auxiliary variables.•We applied the methodology in Mediterranean ...Forest.•We create a wall-to-wall GSV forest map in a large test area.•The GSV map was used to produce model-based estimates of GSV at small scale.
Spatial predictions of forest variables are required for supporting modern national and sub-national forest planning strategies, especially in the framework of a climate change scenario. Nowadays methods for constructing wall-to-wall maps and calculating small-area estimates of forest parameters are becoming essential components of most advanced National Forest Inventory (NFI) programs. Such methods are based on the assumption of a relationship between the forest variables and predictor variables that are available for the entire forest area. Many commonly used predictors are based on data obtained from active or passive remote sensing technologies. Italy has almost 40% of its land area covered by forests. Because of the great diversity of Italian forests with respect to composition, structure and management and underlying climatic, morphological and soil conditions, a relevant question is whether methods successfully used in less complex temperate and boreal forests may be applied successfully at country level in Italy.
For a study area of more than 48,657 km2 in central Italy of which 43% is covered by forest, the study presents the results of a test regarding wall-to-wall, spatially explicit estimation of forest growing stock volume (GSV) based on field measurement of 1350 plots during the last Italian NFI. For the same area, we used potential predictor variables that are available across the whole of Italy: cloud-free mosaics of multispectral optical satellite imagery (Landsat 5 TM), microwave sensor data (JAXA PALSAR), a canopy height model (CHM) from satellite LiDAR, and auxiliary variables from climate, temperature and precipitation maps, soil maps, and a digital terrain model.
Two non-parametric (random forests and k-NN) and two parametric (multiple linear regression and geographically weighted regression) prediction methods were tested to produce wall-to-wall map of growing stock volume at 23-m resolution. Pixel level predictions were used to produce small-area, province-level model-assisted estimates. The performances of all the methods were compared in terms of percent root mean-square error using a leave-one-out procedure and an independent dataset was used for validation. Results were comparable to those available for other ecological regions using similar predictors, but random forests produced the most accurate results with a pixel level R2 = 0.69 and RMSE% = 37.2% against the independent validation dataset. Model-assisted estimates were more precise than the original design-based estimates provided by the NFI.
Quantitative comparisons of tree height observations from different sources are scarce due to the difficulties in effective sampling. In this study, the reliability and robustness of tree height ...observations obtained via a conventional field inventory, airborne laser scanning (ALS) and terrestrial laser scanning (TLS) were investigated. A carefully designed non-destructive experiment was conducted that included 1174 individual trees in 18 sample plots (32 m × 32 m) in a Scandinavian boreal forest. The point density of the ALS data was approximately 450 points/m2. The TLS data were acquired with multi-scans from the center and the four quadrant directions of the sample plots. Both the ALS and TLS data represented the cutting edge point cloud products. Tree heights were manually measured from the ALS and TLS point clouds with the aid of existing tree maps. Therefore, the evaluation results revealed the capacities of the applied laser scanning (LS) data while excluding the influence of data processing approach such as the individual tree detection. The reliability and robustness of different tree height sources were evaluated through a cross-comparison of the ALS-, TLS-, and field- based tree heights. Compared to ALS and TLS, field measurements were more sensitive to stand complexity, crown classes, and species. Overall, field measurements tend to overestimate height of tall trees, especially tall trees in codominant crown class. In dense stands, high uncertainties also exist in the field measured heights for small trees in intermediate and suppressed crown class. The ALS-based tree height estimates were robust across all stand conditions. The taller the tree, the more reliable was the ALS-based tree height. The highest uncertainty in ALS-based tree heights came from trees in intermediate crown class, due to the difficulty of identifying treetops. When using TLS, reliable tree heights can be expected for trees lower than 15–20 m in height, depending on the complexity of forest stands. The advantage of LS systems was the robustness of the geometric accuracy of the data. The greatest challenges of the LS techniques in measuring individual tree heights lie in the occlusion effects, which lead to omissions of trees in intermediate and suppressed crown classes in ALS data and incomplete crowns of tall trees in TLS data.
Aim
To evaluate current and future dynamics of 25 tree species spanning United States and Canada.
Location
United States and Canada.
Methods
We combine, for the first time, the species compositions ...from relative importance derived from the USA’s Forest Inventory Analysis (FIA) with gridded estimates based on Canada's National Forest Inventory (NFI‐kNN))‐based photo plot data to evaluate future habitats and colonization potentials for 25 tree species. Using 21 climatic variables under RCP 4.5 and RCP 8.5, we model climatic habitat suitability (HQ) within a consensus‐based multimodel ensemble regression approach. A migration model is used to assess colonization likelihoods (CL) for ~100 years and combined with HQ to evaluate the various combinations of HQ + CL outcomes for the 25 species.
Results
At a continental scale, many species in the conterminous United States lose suitable climatic habitat (especially under RCP 8.5) while Canada and USA’s Alaska gain climate habitat. For most species, even under optimistic migration rates, only a small portion of overall future suitable habitat is projected to be naturally colonized in ~100 years, although considerable variation exists among species.
Main conclusions
For the species examined here, habitat losses were primarily experienced along southern range limits, while habitat gains were associated with northern range limits (especially under RCP 8.5). However, for many species, southern range limits are projected to remain relatively intact, albeit with reduced habitat quality. Our models predict that only a small portion of the climatic habitat generated by climate change will be colonized naturally by the end of the current century—even with optimistic tree migration rates. However, considerable variation among species points to the need for significant management efforts, including assisted migration, for economic or ecological reasons. Our work highlights the need to employ range‐wide data, evaluate colonization potentials and enhance cross‐border collaborations.
•We explored recent changes of ecosystem services (ES) in Mediterranean forests.•Timber volume increment, water provision, and carbon sequestration showed a decline since 1990.•Recent changes in ES ...were largely driven by the structure of the forest stands.•Temporal analyses revealed more potential trade-offs between ES than purely static assessments.
The Mediterranean Region constitutes a biodiversity hotspot and its forests have provided multiple ecosystem services (ES) to human societies for millennia. In the last decades, many Mediterranean forests have undergone a decreasing level of direct human pressure and a growing exposure to environmental stress factors (e.g. wildfires and droughts). However, the degree to which these processes have affected the provision of ES remains largely unexplored. We used an extensive database of 3417 permanent plots (period 1990–2015, 25 years) from the Spanish National Forest Inventory in Catalonia (North-Eastern Spain) and a range of four ecological models to measure and estimate changes in five different ES: wild mushrooms production, timber volume increment, water provision, carbon sequestration and erosion mitigation. We then assessed general trends in ES, their spatial–temporal patterns and searched for potential trade-offs in their delivery. Using mixed-effects models, we explored the differences among three biogeographical regions, as well as the effect of different environmental and site level drivers, including descriptors of stand structure and development, the legacies of management practices and disturbances, as well as the influence of historical climate conditions and their recent anomalies. Our results show a general decline of timber volume increment, water provision and carbon sequestration, along with an increase in erosion mitigation across inland and montane regions. Fitted model parameters suggest a predominant role of stand structure in driving changes in forest ES supply in the study area. In particular, stands with high basal areas were associated with steeper declines in most ES, whereas high mean tree diameter generally contributed to ES increases. Finally, our results showed a series of potential trade-offs among temporal changes in ES that were not reflected in exclusively static analyses, highlighting the relevance of including the temporal dimension in regional assessments of ES. Future forest management and planning could better account for overall ES value as well as expected changes in their future provision, paving the way to landscape planning that balances these two essential components of forest ES.
Hand-Held Personal Laser Scanning Balenović, Ivan; Liang, Xinlian; Jurjević, Luka ...
Croatian Journal of Forest Engineering,
01/2021, Letnik:
42, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The emergence of hand-held Personal Laser Scanning (H-PLS) systems in recent years resulted in initial research on the possibility of its application in forest inventory, primarily for the estimation ...of the main tree attributes (e.g. tree detection, stem position, DBH, tree height, etc.). Research knowledge acquired so far can help to direct further research and eventually include H-PLS into operational forest inventory in the future. The main aims of this review are:
- to present the current state of the art for H-PLS systems
- briefly describe the fundamental concept and methods for H-PLS application in forest inventory
- provide an overview of the results of previous studiesÞ emphasize pros and cons for H-PLS application in forest inventory in relation to conventional field measurements and other similar laser scanning systems
- highlight the main issues that should be covered by further H-PLS-based forest inventory studies.
AIM: Understanding the drivers of forest structure, function and change is a fundamental problem in both theoretical ecology and applied forestry for carbon mapping and monitoring. An important ...component of forest ecology research often utilizes allometric equations to scale up local measurements to predict large‐scale forest and ecosystem‐level properties. However, both applied and theoretical allometries in forest ecology (such as metabolic scaling theory, MST) assume that many scaling relationships are insensitive to broad‐scale climate gradients or species life histories. We aim to test these assumptions by mapping continental‐scale forest allometry across environmental gradients in the United States. LOCATION: United States. METHODS: We fit exponents to two allometric relationships in c. 100,000 Forest Inventory Analysis (FIA) field plots: (1) the relationship between the height of an individual tree and its diameter, and (2) plot‐level tree size distributions. We compare fitted exponents to environmental and life‐history variables, such as climate, topography and forest structure, in an attempt to explain allometric variability and deviations from theoretically predicted allometries. RESULTS: We find that the structural allometry of forests varies strongly as a function of location in the United States. Allometric exponents appear to asymptote at approximately where MST theory predicts with increasing forest height, while deviations from MST are partially explained as a function of environmentally driven recruitment limitations and successional status. MAIN CONCLUSIONS: While we find support for invariant tree and stand allometric scaling relationships in forests that are in steady state with regard to demography and resources, we also find considerable spatial variability in forest allometric relationships when steady‐state conditions are violated. These findings suggest that extensions of metabolic scaling theory should incorporate variation in demographic dynamics in younger successional forests, and factors influencing recruitment limitation.
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