Tree distribution pattern in the permanent sample plots of selection forests

Supraglacial debris cover allows vegetation to colonize glacier surface, and whenever it is enough stable and thick, also shrubs and trees can germinate and grow. Supraglacial tree growth and distribution patterns on the glacier are closely connected with the debris-covered glacier dynamics and evolution. The aim of the research reported here was to evaluate the tree age and tree distribution patterns on the glacier tongue and the influence of ice-cliff backwasting, close to glacier terminus, on tree loss. We analysed the fragile and fast-changing environment that is present on the lower ablation sector of the Miage Glacier (Mont Blanc Massif, Italian Alps) where some ice cliffs are present and backwasting and downwasting phenomena occur. Tree features and short-term evolution were analysed with respect to glacier variations (mainly surface displacements and ice ablation) and geometry changes of the two most representative ice cliffs. The supraglacial trees’ life time resulted to be mainly controlled by glacier surface displacements and by the occurrence of backwasting and downwasting processes, whereas tree germination was associated with fine debris presence. These factors, controlling plants’ life and growth on the glacier, are an actual limit when supraglacial trees are analysed to reconstruct past environmental changes occurred on the glacier tongue. Moreover, we found that a large number of trees die under conditions of dominating backwasting inducing the loss of debris substrate (condition met especially on the northern glacier lobe). Instead, in the case of prevalence of downwasting (condition mainly observed on the southern glacier lobe), trees more easily survive and flow downvalley transported by the glacier flux.

A universal canopy gap fraction model for forests with various tree distributions based on Nilson's models considering directional overlaps among crowns

The point cloud-based 3D model of forest helps to understand the growth and distribution pattern of trees, to improve the fine management of forestry resources. This paper describes the process of constructing a fine rubber forest growth model map based on 3D point clouds. Firstly, a multi-scale feature extraction module within the point cloud column is used to enhance the PointPillars learning capability. The Swin Transformer module is employed in the backbone to enrich the contextual semantics and acquire global features with the self-attention mechanism. All of the rubber trees are accurately identified and segmented to facilitate single-trunk localisation and feature extraction. Then, the structural parameters of the trunks calculated by RANSAC and IRTLS cylindrical fitting methods are compared separately. A growth model map of rubber trees is constructed. The experimental results show that the precision and recall of the target detection reach 0.9613 and 0.8754, respectively, better than the original network. The constructed rubber forest information map contains detailed and accurate trunk locations and key structural parameters, which are useful to optimise forestry resource management and guide the enhancement of mechanisation of rubber tapping.

Compared with traditional remote sensing, multiangular observation provides 3-D structural information of a forest through different directional observations. The MGeoSAIL model, suitable for multiangular observations, was developed based on the single-angle model GeoSAIL. The MGeoSAIL model combines the geometric-optic model with the radiation transfer model and has the advantages of both models. Thus, it is more accurate and feasible. The geometric-optic model calculates the amount of shadowed and illuminated components within a forest scene, while the radiation transfer model [Scattering by Arbitrarily Inclined Leaves (SAIL)] calculates the reflectance and transmittance of tree crowns. The uniform index is introduced to characterize the relationship quantitatively between tree distribution pattern and the bidirectional reflectance distribution function (BRDF). The simulation results show that the MGeoSAIL model could simulate the "hot" spot in red and near-infrared bands, as well as the "bowl" shape in the near-infrared band. The relationship between the uniform index and BRDF is negatively exponential. Finally, the look-up table was calculated using the MGeoSAIL model, and leaf area index (LAI) was inversed from compact high-resolution imaging spectrometry data. The results compared well with the measured LAI in Changbai Mountain area, China.

Large footprint lidar has demonstrated its great potential for accurate estimation of many forest parameters, e.g., forest height, forest biomass and vertical structure of forest canopy. In addition to the canopy vegetation, many factors such as atmosphere, underlying surface, the shape of crown, et al., influence the lidar waveform. The illuminating intensity of the laser beam across the lidar footprint is a Guassian distribution and reduces from 1.0 to e-2 from the center to the edge of the footprint. Hence the forest stand structure plays an important role in the lidar waveform. The contribution of each tree to the lidar waveform varies with its location in a forest stand. This paper simulated the random, uniform and clumped tree distribution patterns in a stand. Then waveforms were simulated using a three dimensional lidar waveform model developed by Sun and Ranson. The results show that the tree distribution patterns affect the lidar waveform profiles. The area (or energy) under the waveform from vegetation (AWAV) and the height of median energy (HOME) were used to estimate the effects. Following trends have been revealed from the simulation: for AWAV and HOME, uniform > random > cluster. There is no obvious difference between regular and random. The waveform area (AWAV) varies much more than HOME. For the clumped case, the number of clusters does not have much effect on the lidar waveform

Forest tree ingrowth is a highly variable and largely stochastic process. Consequently, predicting occurrence, frequency, and composition of ingrowth is a challenging task but of great importance in long-term forest growth and yield model projections. However, ingrowth data often require different statistical techniques other than traditional Gaussian regression, because these data are often bounded, skewed, and non-normal and commonly contain a large fraction of zeros. This study presents a set of regression models based on discrete Poisson and negative binomial probability distributions for ingrowth data collected from permanent sample plots in the Acadian Forest Region of North America. Models considered here include regular Poisson, zero-inflated Poisson (ZIP), zero-altered Poisson (ZAP; hurdle Poisson), regular negative binomial (NB), zero-inflated negative binomial (ZINB), and zero-altered negative binomial (ZANB; hurdle NB). Plot-level random effects were incorporated into each of these models. The ZINB model with random effects was found to provide the best fit statistics for modeling annualized occurrence and frequency of ingrowth. The key explanatory variables were stand basal area per hectare, percentage of hardwood basal area, number of trees per hectare, a measure of site quality, and the minimum measured diameter at breast height of each plot. A similar model was developed to predict species composition. All models showed logical behavior despite the high variability observed in the original data.

Rola zaburzeń w kształtowaniu struktury i dynamiki naturalnych lasów bukowo-jodłowo-świerkowych w Karpatach Zachodnich

It is generally agreed that preservation of forest areas can contribute strongly to the mitigation of global climate change. However, studies have demonstrated that there are still uncertainties for an accurate estimation of carbon stock particularly in the tropical forest. This study aims therefore to develop some allometric equations that can be used to estimate above-ground tree biomass and carbon partitioning between major carbon pools such as tree and litter for IITA secondary forest ecosystem. Ten permanent sample plots of 20 m × 20 m were randomly laid in the forest reserve. Diameter at breast height, total height, crown diameter and wood density were measured. Forty quadrants of 1 m × 1 m for litter fall collection were also randomly laid in four locations in each permanent sample plots. Twenty four tree species present in all the permanent sample plots were selected for destructive sampling. Mean biomass of each sampled plots were pooled together to develop allometric equations to obtain biomass and carbons were also estimated using standard method. A total of nine hundred and forty seven tree species were measured in the study area. These tree species belong to sixteen different families. Allometric equations of family level and whole stand level for estimating above-ground tree biomass were therefore developed. The best fitted allometric equations were used to predict above-ground tree biomass. Model 3 indicated the highest modelling efficiency of 0.954, 0.960 and 0.984. Therefore taking this into consideration, that model 3 was selected as the best model for predicting the above-ground tree biomass with an estimation of 17698.76 g at family level. Allometric equations of whole stand level for above-ground tree biomass indicated good correlation with H, DBH, CD and WD (0.534, 0.597, 0.751, and 0.648). Model 5, 7 and 8 were designated the highest modelling efficiency of 0.898, 0.922 and 0.948. Model 8 is selected as the best models for predicting the above-ground tree biomass with an estimate of 838036.15 g. Therefore, carbon capture per hectare of above-ground tree biomass was 368280.40 g/ha. Carbon capture per hectare of litter had 2663.259 g/ha using standard method. The distributions of the standard residual values and standard error estimate with the fitted values are adequate.

Today, the overgrowth of woody and shrubby vegetation on former agricultural lands is a serious problem. The aim of this research has been to investigate age-related changes in the forest inventory indicators of forest stands on abandoned farmlands. Taking into account the temporal factor when monitoring the carbon budget allows identifying a number of processes in the dynamics of carbon sequestration that cannot be estimated in a single study. To address this issue, data from permanent sample plots have been analyzed in 2011 with repeated measurements in 2023. The sample plots are located on the abandoned farmlands on the border of the Krasnoyarsk forest-steppe area. The dynamics of the process of Today, the overgrowth of woody and shrubby vegetation on former agricultural lands is a serious problem. The aim of this research has been to investigate age-related changes in the forest inventory indicators of forest stands on abandoned farmlands. Taking into account the temporal factor when monitoring the carbon budget allows identifying a number of processes in the dynamics of carbon sequestration that cannot be estimated in a single study. To address this issue, data from permanent sample plots have been analyzed in 2011 with repeated measurements in 2023. The sample plots are located on the abandoned farmlands on the border of the Krasnoyarsk forest-steppe area. The dynamics of the process of overgrowth and development of plantations has shown that as the abandoned farmlands form, in addition to the dominant Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth) and aspen (Populus tremula L.), Siberian larch (Larix sibirica Ledeb.), Siberian spruce (Picea obovata Ledeb.) and goat willow (Salix caprea L.) are also found. The dynamic process of pine abandoned farmlands has been established over a period of 15 to 27 years after land abandonment. The mixed plantations of various successional origins have ranged in age from 10 to 30 years old. Various processes have been observed in the research plots in terms of changes in the density of abandoned farmlands (overgrowth, thinning). The reforestation of abandoned farmlands occurs from the forest border and at a distance of up to 50 m continues after 30 years. The abandoned farmlands are characterized by various forms of overgrowth: clumps, biogroups, complete and by single trees. The average quantitative assessment has shown that that the most intense changes in height, diameter, height to the crown base, height to the largest crown width, and crown diameters have occurred in the test area where the minimum density has been observed, which has been decreasing dynamically. In the plot with the maximum density, morphological indicators have been characterized by an average increase. Minimal changes have been recorded in the sample plot where the density has increased significantly over 12 years. The growth rate of trees of the same diameter in height has been greater in 2023 compared to 2011. It is possible that this has been influenced by a combination of external and internal factors, including climate change. To assess the carbon productivity of forest stands growing on the abandoned farmlands, it is advisable to use regression equations developed for a specific area. The results of the study of the dynamics of carbon sequestration by young forests growing on the abandoned farmlands indicate the feasibility of using postagrarian lands for the implementation of forest climate projects.

Guidelines to Avoid Remeasurement Problems in Permanent Sample Plots in Tropical Rain Forests

Dynamic processes in indigenous spruce phytocenoses have been studied in the challenging climatic conditions of the subtundra zone, moderated by the heat brought from the south by the waters of the large Pechora River. Field material has been collected on permanent sample plots during 3 periods (2005–2006, 2013, 2022) in spruce forests of different types. The dynamics of the size structure and vitality status of woody plants in indigenous spruce forests have been analyzed based on the variability of tree stem diameters at a height of 1.3 m and the height of undergrowth. The data obtained show that with an increase in the average diameter of spruce trees in stands of subtundra spruce forests of different types, the coefficient of variation increases. The distribution of trees by absolute diameter classes is characterized by a slight stretch, usually with 1 maximum shifted to the left. In spruce forests developing on swampy-podzolic soils, most of the trees belong to small diameter classes (≤10 cm). In spruce forests of the green-moss type group, the interval of diameter classes is extended due to the presence of large trees in the stands. This dimensional structure is typical for the indigenous spruce forests of the middle taiga. The distribution of the total stand of timber by diameter classes is described as a pulsating curve with a single maximum, which, in some cases, may be interrupted at larger diameter classes. The size of the undergrowth has turned out to be more variable over time. Under the canopy of stands of subtundra spruce forests, a continuous renewal process is being observed. Stationary monitoring of the viability and damage of trees and undergrowth, based on a visual assessment of the plant by the crown, has shown an improvement in both the upper layers of the tree canopy and the lower layers of the undergrowth. The stand and undergrowth, which have been characterized as weakened at the beginning of the observation, moved into the healthy category during the monitoring period. The results of the research are part of the environmental monitoring of self-regulating spruce forests in the Pechora River basin. Long-term scientific work on permanent sample plots allows us to study the variability of plant communities and their response to global change, which contributes to a deeper understanding of the mechanisms underlying these changes, as well as ways of adapting to them. The data obtained will serve as a basis for further environmental monitoring and forecasting of the state of self-regulating Pechora forests.

A set of Permanent Sample Plots (PSP) was established in the lowland mixed dipetrocarp forest within PT Inhutani II concession at Malinau (2o45' - 3o15'N, 116o30'), East Kalimantan (Figure 1). They were designed for comparative studies of conventional logging (CNV) and reduced-impact logging (RIL) techniques under the ITTO Project PD 12/97 Rev.1 (F), Forest, Science and Sustainability. Bulungan Model Forest. The Malinau concession is located about 30 km to the East of CIFOR's Bulungan Research Forest in a forest area with elevation between 100 m to 300 m above sea level. The terrain is undulating with slopes ranging from 10% to 70%. The mean annual rainfall in the area is 3.790 mm, with the number of wet months of more than 9 months per year. This pocket guideline is intended to give visitors to PSPs information on how to access to the location of plots and distribution of trees with dbh = 20cm in each plot. The CIFOR's Seturan station is used as a starting point to travel to the plots.

Fruits are a major food resource for wildlifes and have evolved different traits which attract specific frugivores and facilitate seed dispersal. This study examines the quantity of the frequency of fruit tree species, distribution amongst fruit traits and estimates the potential availability of the fruit resource for frugivores in a 16-ha permanent forest plot at Doi Suthep–Pui, Thailand. The similarity amongst traits for fleshy fruited species was explored using Principal Component Analysis (PCA). Fleshy fruited species comprised 122 of 208 tree species >2 cm diameter at breast height (DBH) recorded in the permanent plot. Amongst fleshy fruited species, small fruits (length <20 mm) were most common (63.16% of species) while large fruits were rare (4.1%). Black was the most common fruit colour (43.4%). Principal Component Analysis of fruit traits explained 57% of total variance on the first three axes, and allowed identification of three species groups. Litsea martabanica and Persea gamblei are the greatest density and represented the major PCA group; black, small-sized and thin husk indehiscent fruits. These fruiting trees scattered throughout the permanent plot and were of good regeneration status. Indicating fleshy fruit can be a food resource for frugivores especially small-sized fruit. Furthermore, large-fruited species such as Madhuca floribunda is low density but important to preserve for food resource of large frugivores. This finding is very important not only for forest protection policy but also for wildlife conservation as food resources.

The province of Ontario holds approximately 70.2 million hectares of forests: about 17% of Canada’s and 2% of the world’s forests. Approximately 21 million hectares are managed as commercial forests, with an annual harvest in the early part of the decade approaching 200 000 ha. Yield tables developed by Walter Plonski in the 1950s provide the basis for most wood supply calculations and growth projections in Ontario. However, due to changes in legislation, policy, and the planning process, they no longer fully meet the needs of resource managers. Furthermore, Plonski`s tables are not appropriate for the range of silvicultural options now practised in Ontario. In October 1999, the Canadian Ecology Centre- Forestry Research Partnership (CEC-FRP) was formed and initiated a series of projects that collectively aimed at characterizing, quantifying and ultimately increasing the economically available wood supply. Comprehensive, defensible, and reliable forecasts of forest growth and yield were identified as key knowledge gaps. The CEC-FRP, with support from the broader science community and forest industry, initiated several new research activities to address these needs, the results of which are outlined briefly in this paper. We describe new stand level models (e.g., benchmark yield curves, FVS Ontario, stand density management diagrams) that were developed using data collected from permanent sample plots and permanent growth plots established and remeasured during the past 5 decades. Similarly, we discuss new height–diameter equations developed for 8 major commercial tree species that specifically account for stand density. As well, we introduce a CEC-FRP-supported project aimed at developing new taper equations for plantation grown jack pine and black spruce trees established at varying densities. Furthermore, we provide an overview of various projects undertaken to explore measures of site productivity. Available growth intercept and site index equations are being evaluated and new equations are being developed for major commercial tree species as needed. We illustrate how these efforts are advancing Ontario’s growth and yield program and supporting the CEC-FRP in achieving its objective of increasing the supply of fibre by 10% in 10 years while maintaining forest sustainability. Key words: permanent sample plots (PSPs), permanent growth plots (PGPs), normal yield tables, sustainable forest management, NEBIE plot network, forest inventory, Forest Vegetation Simulator

Tropical forests harbour the most diverse plant communities on Earth. This high diversity makes it particularly challenging to understand and predict how these communities will be altered by changing climatic conditions. However, doing so is imperative since, like other systems, tropical forests have experienced and are predicted to experience increases in CO2 and temperature, as well as large shifts in precipitation patterns (Bawa & Markham 1995; IPCC 2007; Malhi & Phillips 2004). Nonetheless, studies of how tropical species will respond to climate change are scarce (e.g. Colwell et al. 2008; Miles, Grainger & Phillips 2004).