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Silver birch (Betula pendula Roth) is one of the fast-growing tree species that often colonize abandoned agricultural lands in Europe and the European part of Russia. The purpose of this article is to analyze the spatiotemporal dynamics of Betula pendula crown cover on abandoned arable lands in a zone of broad-leaved forests of the Bashkir Cis-Ural (Russia, Republic of Bashkortostan). The assessment of current and retrospective values of crown cover was carried out using a regression model of the dependence of crown cover on the values of red channel brightness in early-spring images from Landsat 5–8 and Sentinel-2 satellites from 2012–2022. To estimate the number and height of trees, a survey was carried out using a LiDAR camera mounted on a UAV. After calculating the crown cover in grid squares and their distance from the seed source in QGIS, variance analysis was carried out to assess the influence of the factor of distance from the seed source on the crown cover. The influence of the factor of distance from the seed source on the crown cover was higher at earlier stages of overgrowth of abandoned agricultural lands. An exception to this dependence was only one sample plot where the prevailing wind direction was opposite to the direction of seed dispersal. The leading factors affecting the distribution of birch on abandoned agricultural lands were wind direction, height of seed trees, and grazing. In the parts of the sample plots that were furthest away from seed sources, the trees were 1–3 years younger or the same age, and stand density was lower than in sites located closer to the seed trees. In general, the results of the present study indicate two opposite relationships between seedling survival and distance to seed trees: (1) seed fall and seedling density decrease with increasing distance from the seed tree, and (2) the probability of seed/seedling survival increases due to decreased competition. [ABSTRACT FROM AUTHOR]

This study was carried out to estimate the effect of crown closure classes (degraded forest, low crown coverage, medium crown coverage, and full crown coverage) and growth characteristics (three heights, diameter at base, diameter at breast height, and crown diameter) on cone production and to estimate fertility variation and its allied parameters in 130-year-old natural populations of Taurus cedar, also called cedar of Lebanon (Cedrus libani A. Rich.). The effect of biotic (e.g., growth characteristics, crown closure) and abiotic (e.g., light penetration, temperature, humidity, and soil characteristics) factors on cone production, fertility variation, and gene diversity was evaluated in two consecutive years of Taurus cedar. The factors, viz., altitude, temperature, aspect, and rainfall, varied, while some of them could be managed by cultural operations such as management of the crown and stand density. The impact of crown closure on cone production, fertility variation, and related parameters were observed in Taurus cedar's natural populations sampled from southern Turkey. Maximum cone productions of 29 and 40/tree were recorded with full crown closure in two consecutive years, due to significant differences among individuals within crown closure class. For instance, cone productions were between 10 and 67 in the full crown closure of the first year. The sibling coefficient, which is a measure of the fertility variation in a stand, was the highest (1.16) for the full crown closure in the first (meaning 86% fertile trees) and the second years (1.55, 65%), while it was the lowest for the medium crown closure (1.09, 92%) in both years. Gene diversity decreased from a degraded patch (0.987) to that with full crown closure (0.984). Results of variance analysis showed a significant (p ≤ 0.05) difference between crown closure classes for cone production within the second year and between years. Significant positive (p ≤ 0.05) correlations were noted between years for cone production (r = 0.22) and between cone production and crown closure in the first and second years (r = 0.29). However, growth characteristics had no effect on cone productions in individual crown closure classes, while there were significant (p ≤ 0.05) correlations between the diameter at breast height and cone production for both years (r = 0.15 and 0.17) in pooled populations. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) plays a crucial role in global carbon cycling. The amount of SOC is influenced by many factors (climate, topography, forest type, forest disturbance, etc.). To investigate this potential effect, we performed a multiple regression model using six different predictor variables in the third national-level forest resource assessment data of Nepal. We found a significant correlation between the SOC and altitude (r = 0.76) followed by crown cover and slope. The altitude alone explains r2 = 58 percent of the variability of the SOC and shows an increasing rate of change of SOC with the increase of altitude. Altitude was identified as a suitable predictor of SOC for large areas with high altitudinal variation followed by crown cover and slope. Increasing amounts of SOC with increasing altitude shows the significance of high-altitude forests in the perspective of climate change mitigation. Altitude, a proxy of temperature, provides insights into the influence of changing temperature patterns on SOC due to future climate change. Further study on forest types and SOC along the altitudinal gradient in Nepal is recommended to deal with the climate change problem in the future. [ABSTRACT FROM AUTHOR]

Oak trees are hosts of diverse gall-inducing parasites, but the information about the leaf gall is poorly understood. This study aims to examine the weight of leaf galls on oak trees (Quercus brantii Lindl.) in different crown directions with different growth forms (high-forest and coppice) on different geographical slopes in healthy and dry stands of Kohgiluyeh and Boyer-Ahmad province, Iran. For this purpose, two sample plots with a one-ha area involving decline traces of trees (dry) and two sample plots without dieback (control) on the northern and southern slopes in forest sites of Boyer-Ahmad and Dena counties of Iran were selected by field survey. After recording the quantitative variables (DBH, mean diameter of sprout-clump, height and canopy cover), we collected 20 leaves from each direction of the crown of each tree sampled. In the laboratory, the galls were removed from the leaves and weighed. The results showed that there was no statistical significance between the different crown directions of the sample trees in both growth forms, although, in most sites, the northern direction of the trees had more galls. Leaf samples from the south decline site were found to have significantly more gall weight than samples from the other sites in both growth forms. Also, high-forest trees had significantly more leaf galls on their leaves than the coppice trees did. Monthly average temperature and altitude seem to be two determining factors in leaf gall development of the oak trees. [ABSTRACT FROM AUTHOR]

Accurate wall-to-wall estimation of forest crown cover is critical for a wide range of ecological studies. Notwithstanding the increasing use of UAVs in forest canopy mapping, the ultrahigh-resolution UAV imagery requires an appropriate procedure to separate the contribution of understorey from overstorey vegetation, which is complicated by the spectral similarity between the two forest components and the illumination environment. In this study, we investigated the integration of deep learning and the combined data of imagery and photogrammetric point clouds for boreal forest canopy mapping. The procedure enables the automatic creation of training sets of tree crown (overstorey) and background (understorey) data via the combination of UAV images and their associated photogrammetric point clouds and expands the applicability of deep learning models with self-supervision.Based on the UAV images with different overlap levels of 12 conifer forest plots that are categorized into “I”, “II” and “III” complexity levels according to illumination environment, we compared the self-supervised deep learning-predicted canopy maps from original images with manual delineation data and found an average intersection of union (IoU) larger than 0.9 for “complexity I” and “complexity II” plots and larger than 0.75 for “complexity III” plots. The proposed method was then compared with three classical image segmentation methods (i.e., maximum likelihood, Kmeans, and Otsu) in the plot-level crown cover estimation, showing outperformance in overstorey canopy extraction against other methods. The proposed method was also validated against wall-to-wall and pointwise crown cover estimates using UAV LiDAR and in situ digital cover photography (DCP) benchmarking methods. The results showed that the model-predicted crown cover was in line with the UAV LiDAR method (RMSE of 0.06) and deviate from the DCP method (RMSE of 0.18). We subsequently compared the new method and the commonly used UAV structure-from-motion (SfM) method at varying forward and lateral overlaps over all plots and a rugged terrain region, yielding results showing that the method-predicted crown cover was relatively insensitive to varying overlap (largest bias of less than 0.15), whereas the UAV SfM-estimated crown cover was seriously affected by overlap and decreased with decreasing overlap. In addition, canopy mapping over rugged terrain verified the merits of the new method, with no need for a detailed digital terrain model (DTM). The new method is recommended to be used in various image overlaps, illuminations, and terrains due to its robustness and high accuracy. This study offers opportunities to promote forest ecological applications (e.g., leaf area index estimation) and sustainable management (e.g., deforestation).

Accurate estimates of canopy cover (CC) are central for a wide range of forestry studies. As direct measurements are impractical, indirect optical methods have often been used to estimate CC from the complement of gap fraction measurements obtained with restricted-view sensors. In this short note we evaluated the influence of the image pixel resolution (ground sampling distance; GSD) on CC estimation in poplar plantations obtained from field (cover photography; GSD < 1 cm), unmanned aerial (UAV; GSD

Juniper forests grow in mountain areas and many difficulties are encountered in their sampling. Sector sampling as an unbiased and cost-effective method was tested for the sampling of a 12.5-ha juniper forest. To begin with, a point-map of trees was created and 50 quadrats were determined systematically. Fixed area plots were measured within these 50 × 50 m quadrats. In each quadrat, eight sectors with 45° angle were determined. One-sector and two-sector scenarios randomly besides four-sector scenario systematically were conducted. Accuracy and precision of sampling methods were compared. Also, statistical analysis was conducted to compare sector sampling scenarios with fixed area plot (FAP) and real data. Results showed that four-sector scenario estimates were close to FAP method in precision and accuracy. Statistical analysis showed that there was no significant difference between sector sampling scenarios and FAP and in real data. But in correlation analysis only the four-sector scenario could compete with FAP method. Regarding consumed time and sampling error simultaneously, the efficiency of sector sampling was higher than that of FAP method for estimating density and close to FAP method for estimating crown cover. It can be concluded that in laborious situations such as in juniper forests, sector sampling can be competitive with FAP method with noticeable parsimony. But more study is still needed to decrease sampling error and optimize sector angle with the purpose of cost saving.

In this study a pre-stratification was applied to estimate quantitative attributes of oak forests by cluster sampling method in Bayangan district, Kermanshah province. Firstly stratification was conducted according to NDVI on landsat-8 images and four strata were determined. Sample size was computed according to allowable error and samples were allocated to three strata with regard to their heterogeneity. Totally 34 five-plot clusters include 170 samples with 90×90 meter dimensions were measured in 30000 ha area of study area. Crown diameter and diameter at breast height (DBH) were measured and finally density, crown cover and basal area per unit area were computed. Results of stratified sampling showed 149.5 tree, 1367.6 m2.ha-1 (13.67 percent) and 3.21 m2.ha-1 for density, crown cover and basal area respectively. While this measures for cluster sampling without stratification were 221.8, 2013.5 and 4.77 respectively. This was due to high acreage (weight) but low density and crown cover in the first strata with huge effect on forest mean. Error percent was 1.74, 2.65 and 3.14 for pre-stratification status and 9.11, 9.14 and 9.33 for cluster sampling without stratification. It can be said that pre-stratification can decrease sample size from 66 to 80 percent. We conclude that with regards to heterogeneity of Zagros forests in type, density and crown cover, pre-stratification can improve precision of cluster sampling and is recommended for general inventories.

Highlights • Fever tree woodlands are important in the ecology and economics of tropical systems. • Fever trees stem size, crown cover and ground cover were evaluated. • Fever trees are resilient, but fever tree woodland crown and ground covers are vulnerable to disturbance. • Crown health of small fever trees respond negatively to wildlife disturbance. • Ground cover is less but more diverse in conservation areas while ground cover is more but less diverse in human disturbed areas. Abstract Losses of acacia woodlands have been reported throughout eastern and southern Africa. Of particular concern is the loss of fever tree (Vachellia xanthophloea) woodlands along the riparian areas of lakes which may result in the loss of important terrestrial and aquatic ecosystem services. For example, the Lake Naivasha basin in Kenya has endured considerable population growth and associated changes in land management with potential consequences for fever tree woodlands. This study assessed how fever tree woodland integrity differed with varying degrees of human and wildlife disturbances among surrounding land use management types. A field survey of fever tree woodlands suggest that land management types influenced degrees of human and wildlife disturbances, with settlement areas having significantly more human disturbance and conservation areas having significantly more wildlife disturbance. Furthermore, while land management type did not significantly influence the stem sizes of fever trees, it did influence the condition of woodland crown and ground covers. Settlement areas with high human disturbance were correlated with healthier crown covers (a possible artifact of the removal of dead or dying crown for fuelwood) while conservation areas with high wildlife disturbance were correlated with less healthy crown covers in smaller trees (<45 cm diameter at breast height) that were not killed but stunted by wildlife browsing. Settlement areas were dominated by more but less diverse ground cover while conservation areas were correlated with less but more diverse ground cover. While fever trees show resilience to multiple disturbances, the early warning of changes to the woodlands imply that the future of the fever tree woodlands is at risk and that limits to the encroachment of land management activities into the fever tree woodlands should be established. [ABSTRACT FROM AUTHOR]

Since N-tree sampling methods produce biased estimate, bias evaluation should be applied to N-tree estimator. The purpose of this study is to assess the N tree distance sampling method bias with modified estimator Kleinn and Vilcko in estimating number per hectare and canopy cover in Zagros forests. For this purpose, 6-10 trees from real forest map were tested with full inventories. For comparing the results of characteristics in different trees in N-tree method with full inventories, ANOVA was used. Evaluation of N tree distance sampling method was done by using accuracy criterion and standard error of mean. Bias was also evaluated via one-sample t-test and relative bias. Results showed that in estimating number per hectare and canopy cover, there is no significant difference between tree numbers with full inventory. Bias test for six and seven trees per hectare was significant, but it was not significant for eight, nine and 10 trees. Canopy cover for all tree numbers showed no significant difference. So, in order to achieve a maximum accuracy (minimum bias), at least eight trees within sample plot should be measured. Finally, this study implies that in forests with lower density and cluster pattern, bias change in N tree distance method does not follow a predictable decreasing pattern.

Aim of the study: To analyse the effectiveness of thinning on tree growth, forest structure and microclimatic variables along seven years after cuttings in a secondary Nothofagus antarctica forest in Southern Patagonia. Area of study: Five hectares of homogeneous stand of secondary forests (54º15’46” SL, 66º59’41” WL) in Tierra del Fuego, Argentina. Material and methods: One control and two thinning levels were established, and forest structure, growth, crown dynamic and microclimate variables in long-term permanent plots were evaluated. Main comparisons were made using multiple ANOVAs. Main results: Intensive thinning in secondary forests allowed to increase tree individual growth rates by doubling the radiation levels at the understory level that enhances the silvopastoral management. These forests showed a desirable resilience to the forest interventions and natural disturbances (e.g. heavy defoliator attack), with a rapid reaction in the canopy cover growth. Research highlights: Monitoring of thinning for silvopastoral management must include easy and cheap measuring variables, e.g. diameter growth as a proxy for timber production objectives and hemispherical photos (crown cover and radiation) as a proxy for pasture production. Long-term monitoring allowed to identify reliable indicators that assist new sustainable management alternatives.

Soil macrofauna biodiversity has an important role in ecosystem services. In order to find how soil macrofauna biodiversity is related to trees and shrubs in riparian forest of Maroon River in Khuzestan province, soil macrofauna were collected using hand-sorting procedure from 0-10 and 10-25 cm soil depths in 50 cm × 50 cm plots, 50 meters from each other on transects 100 meters apart and perpendicular to the river. Totally, 175 sampling plots were taken. In each plot, quantitative characteristics of trees and shrubs were measured. Soil macrofauna abundance and biomass were highest at 0-10 cm soil depth. Macrofauna biodiversity had a stronger correlation with Tamarisk properties than Euphrates poplar. In contrast, macrofauna biodiversity was not different under Tamarisk and Euphrates poplar. But earthworm was higher under Euphrates poplar cover. The most important parameter of soil macrofauna biodiversity in this area was crown cover. Therefore we could state that regardless of tree species, crown cover of these forests should be conserved because it maintains soil macrofauna biodiversity.

Himalayan musk deer (Moschus leucogaster; hereafter musk deer) are endangered as a result of poaching and habitat loss. The species is nocturnal, crepuscular, and elusive, making direct observation of habitat use and behavior difficult. However, musk deer establish and repeatedly use the same latrines for defecation. To quantify musk deer habitat correlates, we used observational spatial data based on presence–absence of musk deer latrines, as well as a range of fine spatial‐scale ecological covariates. To determine presence–absence of musk deer, we exhaustively searched randomly selected forest trails using a 20‐m belt transect in different study sites within the Neshyang Valley in the Annapurna Conservation Area. In a subsequent way, study sites were classified as habitat or nonhabitat for musk deer. A total of 252 plots, 20 × 20 m, were systematically established every 100 m along 51 transects (each ~0.5 km long) laid out at different elevations to record a range of ecological habitat variables. We used mixed‐effect models and principal component analysis to characterize relationships between deer presence–absence data and habitat variables. We confirmed musk deer use latrines in forests located at higher elevations (3,200–4,200 m) throughout multiple seasons and years. Himalayan birch (Betula utilis) dominated forest, mixed Himalayan fir (Abies spectabilis), and birch forest were preferred over pure Himalayan fir and blue pine (Pinus wallichiana) forest. Greater crown cover and shrub diversity were associated with the presence of musk deer whereas tree height, diameter, and diversity were weakly correlated. Topographical attributes including aspect, elevation, distance to water source, and slope were also discriminated by musk deer. Over‐ and understory forest management can be used to protect forests likely to have musk deer as predicted by the models to ensure long‐term conservation of this rare deer. Greater crown cover and shrub diversity were associated with the presence of HMD, whereas tree height, diameter, and diversity were not strongly correlated. Topographical attributes including aspect, elevation, distance to water source, and slope were also discriminated by HMD. Over‐ and understory forest management can be used to protect forests likely to have the HMD (predicted by the models) and ensure long‐term conservation of this rare deer. [ABSTRACT FROM AUTHOR]

Tree cover is quantified using a variety of structural metrics that relate to canopy density, which are often modelled from remotely sensed data. Comparing different metrics, and maps of such metrics, is difficult due to a poor understanding as to how they relate to each other. Two commonly used metrics in Australia are crown projective cover (CPC) and foliage projective cover (FPC). CPC and FPC are the proportion of ground area covered by the vertical projection of tree crowns, and the foliage of tree crowns, respectively. They are dimensionless proportions that vary between zero and one. The relationship between CPC and FPC is a function of the plant area index (PAI), the foliage clumping factor at a zenith angle of zero, the foliage projection function at a zenith angle of zero, tree stand density, mean crown radii, and the proportion of wood to all canopy elements ( α ). The non-linear relationship was investigated using a dataset of 745 field sites across Australia, for which 1003 coincident CPC and FPC measurements had been made. As measurements of LAI and the other variables were not available, the parameter k was introduced to simplify the equations, which then had only two unknowns: α and k . Best-fit values of α and k were determined using non-linear weighted least-squares regression across all the field sites. Using these values to predict FPC from CPC, and vice versa, achieved low root mean square errors (0.05-0.07) across the field data. The models allow different mapping products to be compared, and also have the potential to facilitate the derivation of FPC from airborne lidar data when field measurements of FPC are not available for calibration. This was demonstrated using a lidar dataset and 12 coincident field sites, across which FPC was derived from a lidar fractional cover metric with an RMSE of 0.08. Further research is required to investigate the stability of this method across different areas and lidar systems. [ABSTRACT FROM AUTHOR]

Drought events have a major impact on vegetation structure and function. Recently, solar-induced chlorophyll fluorescence (SIF) has been widely used to understand the photosynthesis rates of vegetation under drought stress conditions. However, it is still unclear whether the reduction in SIF shown under drought stress conditions is regulated by physiological or structural factors. To understand the underlying reduction mechanism of SIF under drought stress, we conducted an experiment under a drought condition using one-year-old Prunus yedoensis seedlings. We compared the experiment trees with control trees that were not exposed to drought stress. We collected spectral and gas exchange data to monitor physiological changes and scanned the trees with a terrestrial laser scanner to monitor the structural changes. The discrete anisotropic radiative transfer (DART) and Fluspect models were used to simulate canopy-level SIF. We found that drought stress caused leaf-level steady-state fluorescence yield to increase, while maximum photosynthetic rate, stomatal conductance, and the quantum yield of Photosystem II decreased significantly. Regarding the canopy structural changes, the leaf inclination angle distribution of the experiment trees gradually turned toward erectophile over time (55.2 ± 9.3° to 74.7 ± 6.0°; mean ± standard deviation), whereas that of the control trees remained relatively constant (52.9 ± 8.8°). Furthermore, reduction of crown cover of the experiment trees was 3-fold (77.4 ± 9.8%) compared with the control trees (26.0 ± 16.2%). The simulated nadir-view canopy-level SIF of the experiment trees was reduced 2.8-fold compared to the control trees. These findings, obtained specifically from Prunus yedoensis seedlings, indicate that canopy-level SIF reduced due to the canopy structural changes, although leaf-level fluorescence yield increased. Therefore, canopy structural changes should be considered when attempting to understand SIF reduction in drought conditions. [Display omitted] • Tested SIF reduction under a drought condition using Prunus yedoensis seedlings. • Leaf inclination angles increased in trees subjected to drought stress. • Crown cover reduced 3-fold in experiment trees compared to the control trees. • Drought stress caused leaf-level Fs to increase, while canopy-level SIF decreased. • Canopy structural changes controlled canopy-level SIF reduction under drought. [ABSTRACT FROM AUTHOR]

Litter biomass and leaf area index (LAI) are two important attributes which play crucial roles on the biological processes which impact forest productivity, including photosynthesis, water and nutrient cycles. Litter biomass of a Beech-Hornbeam stand located at the mid-elevation of the Hyrcanian region (Forest management plan of Neka-Zalemroud, district five) was measured using 27 litter traps in a one-year period. In addition, LAI was determined by means of gravimetric method, applying a leaf area meter as well as a metal pipe cutter. A regression model was parameterized to predict the values of litter biomass and LAI using a set of allometric parameters including density, basal surface area, trunk volume, and crown area / volume. Total litter biomass and leaf biomass were determined to be 5.472 and 3.707 ton per hectare per year, respectively. Mean LAI was measured to be 7.5, and 7.7 using leaf area meter, and metal pipe cutter, respectively. The analysis shows that area and volume of crown presents a greater coefficient of determination and smaller root mean squared error than other allometric parameters, indicating the best predictors regarding litter biomass and LAI. Stand-specific models of Beech-Hornbeam were detected more robust than species-specific models of Beech and Hornbeam. Furthermore, species-specific models of Hornbeam were significantly less robust than those specified for Beech.

In order to determine the most suitable water storage method and irrigation interval level on growth and primary establishment of Prosopis cineraria and Ziziphus spina-christi, a trial was conducted under split plots experimental design based on randomized complete blocks, with four replications at Dashtyari territory of Chabahar township (south of Sistan and Baluchestan province of I.R. Iran) for five year period to support reforestation projects. The main factor was water storage method at two levels (turkey nest and terrestrial dam) and the sub factor was irrigation interval with three levels (10, 20 and 30 days). The terrestrial dam and irrigation interval treatments were chosen as control due to local conventional conditions. Results showed that the 10 day irrigation interval was the most suitable treatment for the species establishment and it increased the seedlings survival, growth and establishment significantly. Survival and establishment of P. cineraria was significantly greater than Z. spina christii. Effects of turkey nest and terrestrial dam on survival and species characteristics were often not significant, whereas effects of terrestrial dam on the species vegetative characteristics and establishment were greater than the other treatment.

The aim of the study was to develop forest plantation at appropriate sites of Bushehr province for environmental purposes and to extend olive plantation on marginal lands for economical purposes and to improve local people livelihood. For this reason 12 varieties of Olea europaea including Arbakin, Zard zeitoon, Roghani Roodbari, Mari, Mishen, Lichio, Lemski, Shengeh, Sabz Zeitoon, Sevilana, Beledi and Manzalina were planted on a site located in Chahvak Agricultural Experimental Station in 1997 under statistical design of Randomized Complete Blocks with three replicates and 7 x 8 m. spacing and 10 seedlings per plot. The variance analysis and Duncan test were applied to analyze the data. The data analysis showed that there was significant difference (p

Juniper forests grow in mountain areas and many difficulties are encountered in their sampling. Sector sampling as an unbiased and cost-effective method was tested for the sampling of a 12.5-ha juniper forest. To begin with, a pointmap of trees was created and 50 quadrats were determined systematically. Fixed area plots were measured within these 50 × 50 m quadrats. In each quadrat, eight sectors with 45° angle were determined. One-sector and two-sector scenarios randomly besides four-sector scenario systematically were conducted. Accuracy and precision of sampling methods were compared. Also, statistical analysis was conducted to compare sector sampling scenarios with fixed area plot (FAP) and real data. Results showed that four-sector scenario estimates were close to FAP method in precision and accuracy. Statistical analysis showed that there was no significant difference between sector sampling scenarios and FAP and in real data. But in correlation analysis only the four-sector scenario could compete with FAP method. Regarding consumed time and sampling error simultaneously, the efficiency of sector sampling was higher than that of FAP method for estimating density and close to FAP method for estimating crown cover. It can be concluded that in laborious situations such as in juniper forests, sector sampling can be competitive with FAP method with noticeable parsimony. But more study is still needed to decrease sampling error and optimize sector angle with the purpose of cost saving. [ABSTRACT FROM AUTHOR]

This research was conducted to investigate the spatial structure to estimate the crown cover and density of a coppice oak forest in west of Iran (Loristan province) using Kriging and IDW (Inverse Distance Weighting) interpolation methods. Field sampling was performed based on a 100m×100m systematic grid using 1500 m2 circular samples of. Totally, 54 sample plots were measured at 54 ha. Experimental variograms for forest stem density and crown cover were calculated and plotted using the geo-referenced inventory plots. The calculated variograms of stem density and crown cover showed medium spatial autocorrelation fitted by spherical models. Estimations were made by ordinary block (38m×38m) kriging and IDW (power=2). Cross-validation results showed that all estimations are unbiased. Therefore, Kriging and IDW are able to accurately estimate and map the crown cover and density of this kind of coppice forests.

Digital cover photography (DCP) is a high resolution, vertical field-of-view method for ground-based estimation of forest metrics, and has advantages over fisheye sensors owing to its ease of application and high accuracy. We conducted the first thorough technical appraisal of DCP using both single-lens-reflex (DSLR) and point-and-shoot cameras and concluded that differences result primarily from the better quality optics available for the DSLR camera. File compression, image size and ISO equivalence had little or no effect on estimates of forest metrics. We discuss the application of DCP for ground truthing of remotely sensed canopy metrics, and highlight its strengths over fisheye photography for testing and calibration of vertical field-of-view remote sensing.

Collection of appropriate qualitative and quantitative data is necessary for proper management and planning. In this research, a region with 457 ha area was selected in northwest of Khoram Abad. An inventory grid with 200 × 400 m size was designed and established in the study area. Then, 40 control plots with 1 hectare area were laid out. Samplings carried out by diagonal transects with 50, 75, 100, 125 and 140m length on square control plots. Finally, the results of sampling by different lengths of transects were compared with control plots using analysis of variance and (E %) ^2×T criterion. The results of ANOVA showed that different lengths of transects had no significant differences (at confidence level of 95%) with control plots for estimation of species number per hectare and crown cover parameters. Transects with 140m length had the most precision for estimating the above-mentioned parameters. Also, comparison of results for different lengths of transects with (E %) ^2×T criterion showed that transects with 75 and 140m lengths are more appropriate for estimating the crown cover and species number per hectare.

Aim of study: Harvesting proposals (e.g. variable retention) for Nothofagus pumilio forests are based on canopy opening, to increase recruitment and enhance seedling growth, by modifying light and soil moisture. Seed production and seedling recruitment will define the success of harvesting, where remnant forest structure are the main influence factors, as well as biotic and abiotic factors. The objective was to analyse seed production, seedling recruitment and recruitment efficiency in primary and harvested forests through variable retention along the first 10 years after harvesting, as well as the influence of regional climate. Area of study: The study were conducted in a pure Nothofagus pumilio forest located in central Tierra del Fuego (54°18’ S, 67°49’ W), where harvested stands with variable retention and unmanaged forests were sampled in long-term permanent plots. Material and methods: Data of forest regeneration plots were used (n = 72) (2007 a 2014), and forest structure and seed production (2006 a 2013) were also measured. Regional climate was characterised for these years from satellite images (Sea Surface Temperature) and climate re-analysis models (rainfall and temperature of land surface). Main results: Harvesting modified forest structure; however, aggregated retention maintained some characteristics of the primary unmanaged forests. These changes influenced seed production and recruitment. Seed production and recruitment were related to crown cover and the amount of seed production; however, recruitment efficiency was not affected by harvesting. The studied variables significantly changed along the years after harvesting. Seed production and recruitment were also related to regional climate factors, where it was possible to explain their variations through temperature (e.g. summer temperature) and rainfall (e.g. winter rainfall) for the different retention types in harvested forests and the primary forests. Research highlights: Variable retention harvesting generated different micro-conditions that influence seed production and recruitment. These variables were related to canopy cover. However, recruitment efficiency was not affected by harvesting. Seed production and recruitment (primary forests and harvested stands) were related to regional climate factors and their variations can be explained from variables related to temperature and rainfall.

This study was done to evaluate the effect of afforestation in sand dunes at the vicinity of Shush, because of the importance of soil protection and wind erosion in sand dunes, also sand dunes afforestation as an effective and long lasting fixation mechanism. The study site was covered by petroleum mulch about 20 years ago and afforested by Prosopis juliflora. To study the effects of afforestation on sand dunes, two 10 ha afforested sites (25-50 and 75-100 percent canopy coverage) and control were selected. In each of studied site 15 plots were established and soil physiochemical properties were determined. Our result indicated that afforestation caused soil texture to change from sandy to sandy-loam. Also, soil phosphorus, potassium, organic carbon and nitrogen increased in 0-5 cm soil depth by afforestation that could be because of nutrient absorption from soil depth and returning to the surface by litter fall compared to the control. This study revealed that 25-50 percent canopy coverage resulted in better soil physiochemical properties compared to control site. In conclusion, sand dunes afforestation not only resulted in sand dunes fixation but also soil fertility and long lasting fixation. [ABSTRACT FROM AUTHOR]

Aims Accurate field quantification of stem counts is time consuming and laborious, especially in ecosystems containing many small individuals where counts are immense. There are many large, long-term data sets worldwide that include various measures of woody plant abundance, such as crown cover, that are faster and easier to measure than true counts of individuals. Quantifying the number of individuals allows in-depth research into various topics including functional ecology, carbon accounting, conservation and metabolic theory. Here we test the accuracy of predicting the abundance of individual woody plants from cover and forest structure measures, and explore the implications of refined abundance measures for understanding the rarity of woody plant species across southeast Queensland. Location Southeast Queensland ( SEQ), Australia. Methods To supplement an existing data set of 1251 sites with measured crown covers for woody plants in various strata, we sampled stem counts in an additional 30 sites, forming a calibration data set. We ensured that these 30 sites covered the environmental variation in the study area. Generalized additive mixed effects models were used to predict stem counts for all woody plants in the original data set from their crown cover and forest structure values and a site-level variable accounting for water balance. We used these refined abundance data to investigate relationships between local and regional abundance for different size classes. Results Stem densities increased with crown cover in a non-linear fashion; slowing once crown cover reached ca. 5% for shrubs and ca. 50% for trees, depending on their maximum potential height. Using the predicted stem count data, we found that shrubs were more locally abundant than trees, but less regionally abundant. Larger trees (>20 m maximum potential height) showed a negative relationship between local and regional abundance; there was no significant relationship between other size classes. Conclusions Our study demonstrates how crown cover can be converted to stem counts using a calibration data set and flexible mixed-effects models. This enables further ecological analysis at a fraction of the investment required to re-survey. Analyses of abundances revealed that tree species are less locally abundant than smaller woody species, likely due to space filling constraints, but more regionally abundant. [ABSTRACT FROM AUTHOR]

Mexican oak forests (genus Quercus ) are frequently used for traditional charcoal production. Appropriate management programs are needed to ensure their long-term use, while conserving the biodiversity and ecosystem services, and associated benefits. A key variable needed to design these programs is the spatial distribution of standing woody biomass. A state-of-the-art methodology using small format aerial photographs was developed to estimate the total aboveground biomass (AGB) and aboveground woody biomass suitable for charcoal making (WSC) in intensively managed oak forests. We used tree crown area (CA _ap ) measurements from very high-resolution (30 cm) orthorectified small format digital aerial photographs as the predictive variable. The CA _ap accuracy was validated using field measurements of the crown area (CA _f ). Allometric relationships between: (a) CA _ap versus AGB, and (b) CA _ap versus WSC had a high significance level ( R ^2 > 0.91, p

Analyzing spatial patterns of population distribution in forests may assist to infer the underlying ecological processes and the factors responsible for pattern formation. This study aimed at analyzing the effects of management activities on species richness, diversity, distribution pattern, and forest stand structure in Chisapani Community Forest of Tanahun District, Nepal. The forest was stratified on the basis of crown cover and nested quadrat plots of 20 × 25 m were laid randomly. Trees having ≥5 cm diameter at breast height (dbh) were identified, and their diameter and height were recorded. Altogether, 44 species were recorded representing 39 genera and 27 families. The mean species density of the forest was 192 trees ha−1and the average basal area was 16.2 m2 ha−1. Tukey’s post-hoc test showed the significant difference in species richness between open and dense crown class. ExceptWoodfordia fruticosa, all other species were found with patchy distribution. This study showed that unrestricted access does not necessarily maintain species diversity or regulate the forest stand structure, because people preferred species with high economic potential. Hence, a strategy for maintaining species diversity, regulating stand structure, and finding synergy between biodiversity conservation and conservation outcome is needed. [ABSTRACT FROM PUBLISHER]

In order to comparison of afforestation and selection of the best Acacia species as well as determination of their irrigation period, this project has been carried out for 4 years in Sarkhoon research station on 40 km far from north of Bandar-Abbas. Acacia species are important for grazing, animal nutrition, medicinal and industrial consumption, soil conservation, ecosystem balance and supply of fuel-wood. The lay out of this experiment was a split plot designe with 6 irrigation treatments as main factor and 4 Acacia species. Irrigation treatments were as follows: A: rain-fed, B: Irrigation interval every 10 days, C: Irrigation interval every 20 days, D: Irrigation interval every 30 days, E: Irrigation interval every 40 days, F: Irrigation interval every 50 days, Different Acacia species were: Acacia nilotica, Acacia ehrenbergiana, Acacia tortilis, Acacia oerfota. The survival of seedlings were studied at the end of every month. The canopy cover and height growth were measured at the beginning of every year. According to statistical analysis of the fourth year, there was significant differences at level of one and five percent (α=0.01, α=0.05) between different species and irrigation treatments. Therefore F (irrigation interval every fifty days) are recommended for a, b, d (Acacia nilotica, A. ehrenbergiana, A. oerfota). A. tortilis could be planted under rain-fed condition.

To assess the diversity of woody species (as a major task to understand the changes in forest ecosystem), collection of appropriate qualitative and quantitative data is of particular importance. This study attempts to introduce the most appropriate sampling method for estimating woody species diversity in the northern Zagros forests. An area of 40 ha in Blakeh forest was selected, in which 40 quadrangular samples of one ha each in a 100 m × 100 m grid were established. In each plot a set of characteristics such as species, tree position, the number of trees and smallest/largest crown diameter were measured. All inventory data were processed in GIS to produce a dispersion map of trees. Different sampling methods (rectangular samples with 20 × 50 m, transect methods with 50 and 100 m length, quadrangular method with 10 × 10 m, 15 × 15 m, 20 × 20 m, 40 × 40 m sample sizes) were implemented in a 100×100m sampling grid. The %E2 ×T criterion was used to compare the results. In addition, quadrangular methods were analyzed using the Shannon-Wiener and Simpson diversity and the Margaleff and Minhinick enrichment indices. The quadrangular method with 40 × 40 m and 20 × 20 m sample size was shown to be the most appropriate method for estimating stem number per ha and percentage of canopy cover.

Abstract: Forest monitoring has received increasing attention over the past decades from various international initiatives, among them the REDD+ program which crafts an incentive-based mechanism for reducing deforestation and forest degradation rates. The success of REDD+ depends also on effective monitoring systems that can produce credible and comparable forest cover estimates. If remote sensing technologies are to be involved, methods need to be developed to implement the politically negotiated forest definitions into the technical process of image analysis. We present here a new framework for translating elements of the currently discussed forest definitions into the analysis of satellite images. The framework is based on a hierarchical classification scheme which separates the process of image classification from the application of a specific forest definition. We test this approach for two contrasting tropical regions on RapidEye images which are classified using the Random Forests algorithm. The results show that the developed framework can be operationally applied on a project level and results in standardized forest cover maps with high accuracies. Furthermore, it can serve as a research tool for analyzing consequences of political decisions regarding the forest definitions as it readily enables the user to produce forest maps and estimate forest cover for different underlying forest definitions. [Copyright &y& Elsevier]

Abstract: Several heavy wet snowfalls occurred during 2007–2009 across a broad-scale thinning and fertilization experiment to bring overstocked juvenile lodgepole pine (Pinus contorta var. latifolia) in the foothills of Alberta, Canada into an intensive management regime. We examined the bending and breakage of trees in relation to thinning and fertilization and used a multimodel information-theoretic approach to model stand and tree level predictors of snow damage. Fertilized stands suffered the greatest amount of snow damage, and this was most noteworthy when stands were also thinned; here 22% (17% broken stems) of trees were damaged compared to 8% (4% broken stems) in the thinned and unfertilized stands. At the stand level, needle weight and crown cover were reliable predictors of snow damage. At the tree level, separate models were developed for each combination of thinning and fertilization. All models used total tree volume; usually the smaller trees in the stands were more susceptible to damage but in the thinned and fertilized stands larger but slender trees with large asymmetrical crowns tended to be damaged. Also, trees with lower total stem volume were more susceptible to damage. Only in the thinned and fertilized stands were variables related to crown shape and asymmetry important predictors of snow damage. We conclude that snow damage is an important agent for self-thinning in unthinned stands and fertilization tends to exacerbate damage because of increase in foliage size. In areas with regular occurrence of heavy snow, we do not recommend fertilization at the same time as thinning, as the larger and more economically important trees in the stand are at risk. [Copyright &y& Elsevier]

Plant diversity assessment was carried out on the basis of species richness, tree crown cover and dominance-diversity pattern in different forests of Kedarnath Wildlife Sanctuary (KWLS), Central Himalaya, India during 2006-2009. The maximum tree species richness (10 spp.) was observed in Rhododendron arboreum Sm. dominated mixed forest and minimum in Quercus leucotrichophora A. Camus. forest (8 spp.). Maximum tree density (170 trees/ha) and high importance value index (89.68) was found in Q. semecarpifolia Sm. forest. Mixed Rhododendron arboreum Sm. forest showed high tree diversity (H=0.96), while shrub were found highest in Quercus leucotrichophora A. Camus forest (H=0.62) and herb diversity in Q. semecarpifolia Sm.forest (H=0.73) respectively Maximum tree crown cover (82%) was observed in Rhododendron arboreum Sm. dominated mixed forest while minimum tree crown cover (58%) was observed in Q. semecarpifolia Sm. forest. In general random distribution pattern (A/F ratio) was observed in all three types of forest. Alterations of land use pattern and population pressure are found to be main cause of increase in resources exploitation and that ultimately decreases species richness and diversity. Agro-forestry, alternate use of sites for resources and providing a recovery period to the forests are some of the strategies suggested for forest conservation, management and sustainable utilization of resources by the local people. [ABSTRACT FROM AUTHOR]

Digital cover photography (DCP) is a high resolution, vertical field-of-view method for ground-based estimation of forest metrics, and has advantages over fisheye sensors owing to its ease of application and high accuracy. We conducted the first thorough technical appraisal of DCP using both single-lens-reflex (DSLR) and point-and-shoot cameras and concluded that differences result primarily from the better quality optics available for the DSLR camera. File compression, image size and ISO equivalence had little or no effect on estimates of forest metrics. We discuss the application of DCP for ground truthing of remotely sensed canopy metrics, and highlight its strengths over fisheye photography for testing and calibration of vertical field-of-view remote sensing. [ABSTRACT FROM AUTHOR]