Trees In Diameter Classes Research Articles

Comparison of Single and Ensemble Regression Model Workflows for Estimating Basal Area by Tree Size Class in Pine Forests of Southeastern U.S

Quantifying basal area in terms of diameter classes is important for informing forest management decisions. It is commonly derived from stand diameter distributions using field measurements, LiDAR, and a distribution function. This study compares alternative methods for directly estimating basal area in three tree diameter classes that are relevant to timber operations and wildlife habitat planning in southern United States pine forests. Specifically, linear modeling, ensemble linear modeling (ELM) and ensemble general additive modeling (EGAM) were compared. The results showed that the EGAM method provided the highest r-squared values and the lowest RMSE, and the ELM method provided good interpretability and 30 times faster processing than the EGAM method. Both ensemble methods produced a spatially explicit standard error estimate output without additional steps, unlike the single linear model. In general, the estimation results of this study were comparable or improved over prior studies’ estimates of basal area by tree diameter class.

Exploring the Vegetation Characteristics of Karst Landscapes: A Study of Community Forest in Tubokarto Village, Wonogiri, Indonesia

Karst landscapes are characterized by unique relief and drainage patterns, which influence the types of vegetation that can inhabit these environments. Vegetation in karst ecosystems plays a crucial role in groundwater filtration. Plant species diversity within these communities contributes to structural variations across different habitats. This study evaluates the potential of vegetation in community forests in Tubokarto Village, Wonogiri Regency, by analyzing species composition and vegetation. Using a purposive sampling method, we selected areas with polyculture planting patterns and agroforestry, applying a sampling intensity of 2.2% with 20 × 100 m strip plots. The results showed that the species composition at the location consisted of 18 species in 7 families. The stand density for trees is 221 ind ha–1, poles 436 ind ha–1, saplings 1,144 ind ha–1, and seedlings 2,650 ind ha–1. Tectona grandis emerged as the dominant species, with the highest Importance Value Index (IVI) values: 142.79 at the tree level, 212.48 for poles, 197.84 for saplings, and 122.29 for seedlings. Species diversity indices were 1.53 for trees, 0.97 for poles, 1.36 for saplings, and 1.21 for seedlings. The species richness index showed values of 2.79 for trees, 1.49 for poles, 1.21 for saplings, and 1.80 for seedlings, while the species evenness index ranged from 0.43 to 0.76. The vegetation structure of Tubokarto Village spans strata B and C, with tree diameter class distribution resembling that of natural forests. Environmental factors, including climate and soil composition, are likely influencing species growth patterns.

Phylogenetic Effect on Tree Radial Growth Depends on Drought and Tree Sizes

AbstractTree radial growth is one of the most direct measures of tree performance and is also sensitive to climate. Growth performance is the consequence of the interplay between ecological and evolutionary processes. However, the effect of the evolutionary relatedness among species (i.e., phylogeny) on tree radial growth, especially under stressful conditions, remains largely unknown. Furthermore, there is still no ecological evidence for the influence of phylogeny on tree growth across different tree attributes (i.e., tree diameter variation and tree canopy height) and topographic habitat types. We used Blomberg's K to quantify the tree growth phylogenetic signal (TGPS) using two long‐term dendrometer data sets: one a continuous census of 225 tree species at 3‐month intervals in a tropical forest in southwest China from 2009 to 2017; the other, 12 tree species measured at 6‐month intervals in a temperate forest in Washington State, USA from 2013 to 2019. We found that TGPS values were higher in the temperate forest than in the tropical forest. Precipitation, tree diameter, canopy strata, and habitat types all influenced TGPS values. TGPS values were significantly (p < 0.05) and negatively related to precipitation in Xishuangbanna, and the three of four tree diameter classes in the temperate forest, respectively. Stressful growing conditions arose from either based on low precipitation or among large‐diameter trees competing with each other in the upper canopy led to phylogenetic conservatism in trees' radial growth performance. We conclude that phylogeny is pivotal to understanding the growth response differences among species and their responses to climate variability.

Application of the Global Uncertainty and Sensitivity Analysis to assess the importance of deadwood characteristics for forest biodiversity

AbstractData acquisition for sustainable forest management has focused on obtaining high quality information to estimate biomass. Improving the quality of non-timber sustainability indicators, like deadwood volume, has been a minor interest. To explore how inventory approaches could be improved, we applied a Global Uncertainty and Sensitivity Analysis (GUSA) to evaluate which factors propagate more errors in deadwood modelling and how better data collection can minimize them. The impact of uncertainty on deadwood characteristics (diameter, collapse ratio, decay class, tree species, and position) was explored under stakeholders´ preferences, management actions, and climate change scenarios. GUSA showed that removing the prediction error in deadwood tree species and diameter would alter the most the total uncertainty in deadwood volume. We found that assessment of high deadwood volume was less uncertain for the scenarios where small deadwood items were left decaying on the forest floor (BAU) and for high-end climate change scenario (RCP8.5) which resulted in lower deadwood accumulation in forest stands and therefore also in lower likelihood of erroneous estimates. Reduced uncertainty in tree species and diameter class will elevate the certainty of deadwood volume to a similar level achieved in living biomass estimation. Our uncertainty and sensitivity analysis was successful in ranking factors propagating errors in estimate of deadwood and identified a strategy to minimize uncertainty in predicting deadwood characteristics. The estimation of uncertainty in deadwood levels under the scenarios developed in our study can help decision makers to evaluate risk of decreasing deadwood value for biodiversity conservation and climate change mitigation.

Individual Diameter Growth Modeling of Terminalia alata (B. Heyne. ex Roth) in Terai Arc Landscape of Nepal.

The development of a model is highly crucial in cases where there are intricate geographical features, and conducting a forest inventory is both time-consuming and expensive, requiring significant manual effort for measurement. Acquiring reliable data regarding the forest's condition and future progression is essential for making informed decisions about its management. Therefore, this research aimed to create an individual tree diameter growth model specifically for Terminalia alata (B. Heyne. ex Roth). This study was conducted in Terai Arc Landscape of Nepal, encompassing 14 districts in the Terai and Chure regions of Nepal. Individual tree data (diameter at breast height, tree height, crown height, crown cover, longitude, and latitude) from three different time periods (2011, 2017, and 2022) were obtained with 673 sample plots maintained for forest research assessment by Government of Nepal, and annual diameter growth was estimated. Multiple linear, linear mixed, and generalized additive models were employed to fit the growth modeling for individual tree diameter growth of T. alata. We observed higher mean diameter growth rates in 0-25 cm and 101-125 cm tree diameter classes (0.318 cm·yr-1). There were significant differences in diameter growth across tree quality classes, but no significant differences due to crown classes were observed. Although the generalized additive model (Adj. R 2 = 0.32) performed better than the linear mixed model (adj. R 2 = 0.23) and the multiple linear model (adj. R 2 = 0.03), it still explained only a small proportion of the variance in diameter growth. This suggests that other factors, such as unmeasured environmental variables, biotic interactions, or complex nonlinear relationships, may play a significant role in explaining the variation. In addition, the low R 2 values indicate that the models may need further refinement, possibly by incorporating interaction terms, random effects, or other possible nonlinear approaches. Future research should also consider the potential influence of spatial or temporal heterogeneity on the growth dynamics.

Species Composition and Diversity of Plants along Human-Induced Disturbances in Tropical Moist Sal Forests of Eastern Ghats, India

Plant biodiversity data are prerequisites for the sustainable management of a forest. We used quantitative ecological tools to determine the species composition, diversity (richness and evenness), population structure, distribution patterns, and regeneration status of trees in a Tropical Moist Sal Forest of Eastern Ghats, India. For this purpose, a field inventory was conducted during 2020–2022 in sixteen 1.0 ha forest stands along a human-induced disturbance gradient. A total of 161 species (61 trees, 40 shrubs, 60 herbs) belonging to 77 families and 143 genera were recorded in the 16.0 ha of forest area. The results revealed a significant (p < 0.01) decrease in the tree and shrub species density, basal area, species richness, and diversity along the gradient of disturbance. However, in the case of herbs, the Shannon–Weiner diversity index increased significantly (p < 0.01) with increasing disturbance levels. Irrespective of forest types and disturbance levels, the tree diameter class (10–30 cm) accounted for the highest stem density in the forest. A mixed trend was found in the case of the basal area; the >41 cm diameter class constituted the highest basal area in the Pure Sal Forest while the 10–30 cm class was in the Moist Deciduous Forest without Sal. Tree species richness was found higher in lower diameter classes. Disturbances impacted the distribution pattern of trees; in the Pure Sal Forest, the contagious distribution of trees were 61.54%, 40%, and 12.5% in undisturbed, low-disturbed, and moderately disturbed sites, respectively. The percent of trees showing random and regular distribution increased with the increased level of disturbance in all forest types. The number of tree species having good regeneration decreased with the increased disturbance intensity in all forest types. Frequent grazing, repeated forest fires, and poor soil seed banks at the Moderately Disturbed site were the main reasons for the poor/no regeneration of Pterocarpus marsupium, Adina cordifolia, Terminalia bellerica, and some other economical species. Significant changes in structural attributes of the tree community revealed the impact of human-induced disturbances in the Moist Sal Forests of Eastern Ghats. The disturbance mosaics promoted the growth of many invasive weed species and lianas, depleting the number of valuable species in the forest. This study suggests the adaption of sustainable biodiversity conservation approaches through the active participation of the tribal so that the remnants the Moist Sal Forests of Eastern Ghats can be controlled to prevent further degradation.

Effect of Tapping on Gum and Incense Yield of Selected Trees Species in Elwaye and Dhas Districts, Borana Zone, Southern Oromia

Ethiopia is one of the Gum and Resin producing countries with a large potential. Borana pastoralists particularly utilised these resources as a source of revenue. The majority of Ethiopia’s gum-resin products are collected from natural oozing. In southern Ethiopia, improved tapping mechanisms are uncommon. This study was conducted to determine the effect of different tapping machines and tapping at different tree diameter classes on the gum and incense yields of selected tree species. Commiphora corrugata, Boswellia microphylla, and Boswellia neglecta tree species were selected for their potential existence and economic importance. A factorial experiment was arranged in a randomised complete block design (RCBD) in which three types of tapping materials including natural oozing and three levels of tree size (diameter classes) were used. Accordingly, materials (Panga, Axe, Sonki, and control) were applied at diameters of (5-8 cm, 8.1-11 cm and >11 cm) for a tree height below DBH (at < 130 cm) and above DBH (at >130 cm) on selected tree species while natural oozing was remained untapped and used as controls. Accordingly, the highest mean yield was recorded for trees tapped by axe (5.99 g/tree), followed by Sonki (5.01 g/tree) and bigger diameter class >11 cm (7.10 g/tree) for Commiphora corrugata. The highest mean yield was also obtained for trees tapped by axe (10.76 g/tree) in the first year and (43.71 g/tree) in the second year and bigger diameter class >11 cm (15.16 g/tree) in the first year and (47.81 g/tree) in the second year for Boswellia microphylla. Moreover, the highest mean yield was recorded for naturally oozing trees (6.16 g/tree) and bigger diameter class >11 cm (6.33 g/tree) for Boswellia neglecta. Tapped trees generally provided significantly higher yields than untapped or control trees, and frankincense yield increased with increasing tree size

Structure, composition and diversity of tree species in Martelu Purba Nature Reserve, North Sumatra, Indonesia

Abstract. Rangkuti AB, Hartini KS, Susilowati A, Rambey R, Harahap MM, Arinah H, Irmayanti L, Pamoengkas P, Indriani F, Peniwidiyanti, Ruhidi A. 2023. Structure, composition and diversity of tree species in Martelu Purba Nature Reserve, North Sumatra, Indonesia. Biodiversitas 24: 78-85. Martelu Purba Nature Reserve is one of the conservation areas in North Sumatra that functions to protect biodiversity. However, there is limited information related to the vegetation community contained in the nature reserve. This study aimed to assess the diversity, structure and composition of tree species in the Martelu Purba Nature Reserve as well as to reveal the conservation status of the species in reserve. The research used the line transect method with a total of 112 observation plots representing various vegetation and environmental conditions. The results showed that there were 39 tree species belonging to 25 families, with 31, 25, 24, and 26 species at the tree, pole, sapling, and seedling stages, respectively. Shorea platyclados and Syzygium cerasiforme were species with the highest Important Value Index (IVI) at the tree and pole stages with 173.04% and 31.01%, respectively, while Gamblea malayana was the most important at the sapling and seedling stages with IVI of 66.43%, and 30.00%, respectively. The Shannon-Wiener diversity index (H') was categorized as low (1.58), the Margalef species richness index (DMg) was high at all growth stages, and the Evenness index (E) was high, indicating that all species were evenly distributed across the research plots. The distribution of tree diameter classes ranged from 20 - 40 cm for trees with the smallest diameter to 81-110 cm for trees with the largest diameter. Based on their conservation status, there were two species with conservation concerns, namely Coffea arabica (Endangered) and Lithocarpus maingayi (Vulnerable). The application of good silvicultural methods needs to be carried out in the context of conservation efforts. One example is through vegetative propagation of species with long flowering periods.

Tree-cavity survival for biodiversity in temperate forests of South America: A multi-scale approach

Tree cavities are critical habitat attributes for a diversity of species that use them for reproduction and shelter. Worldwide, their availability has shown an intense decline in forests because of the loss of old-growth stands and the reduction in cavity recruitment. These disturbance processes are influenced by factors occurring across different scales: from cavities to landscapes. We analyzed the survival of 613 cavities in 455 trees in old-growth and second-growth forests over 10 years in Andean temperate forests in southern South America, Chile. Kaplan–Meier and Cox proportional hazards models were used to determine median cavity survival and its influencing factors at the cavity, tree, stand and landscape scales. The median survival was six years. Non-excavated cavities (6 years) survived longer than excavated cavities (4 years), with a significantly longer lifespan in large decaying trees. Cavities’ survival was strongly influenced by cavity- and tree-scale factors, including their origin, the vertical cavity depth, tree decay class, tree branch order and tree diameter class. In old-growth forests, most cavities were found in live decaying trees, while in second-growth forests they were mostly in long-dead trees (snags). We suggest that management should maintain forest structural complexity, retaining dead wood and trees in different stages of decay to permit a continuous supply of substrates over time for the formation of cavities.

Assessment of the Effects of Artificial Fungi Inoculations on Agarwood Formation and Sap Flow Rate of Aquilaria malaccensis Lam. Using Sonic Tomography (SoT) and Sap Flow Meter (SFM)

Agarwood is a valuable aromatic resinous wood that is biosynthesised when a fungal attack injures the healthy wood tissue of the Aquilaria tree. The magnitude of infection related to sap flow (SF) is one of the most critical functional traits to evaluate the tree’s response to various adverse conditions. Therefore, the objective of this study was to investigate the reliability of sonic tomography (SoT) and sap flow meter (SFM) in studying the influence of inoculation fungi Pichia kudriavzevii Boidin, Pignal and Besson, and Paecilomyces niveus Stolk and Samson, on deteriorated wood (Dt) and SF rate in Aquilaria malaccensis Lam. A. malaccensis trees with small, medium, and large diameters were inoculated with each fungus separately at the bottom, middle, and top positions of the tree and the area of sapwood was measured after 6, 12, and 24 months to stimulate the agarwood formation. Furthermore, the SF rate was assessed using SFM in the position of the selected trees. There was a significant difference (p ≤ 0.05) in Dt% and SF rate between inoculated and uninoculated trees. The Dt percentage in trees inoculated with P. kudriavzevii, P. niveus, and control trees was 25.6%, 25.7%, and 15.0%, respectively. The SF rate was lower in P. kudriavzevii, with 207.7 cm3/h, than in the control trees, with 312.9 cm3/h in the small-diameter class. In summary, the results of this study emphasise the importance of inoculation duration (24 months) and the effects of water conductivity, especially tree diameter class (small), on the biosynthetic response of resinous substance.

Tree species composition, stand structure and distribution patterns across three Kashmir Himalayan forests, India

ABSTRACT Himalayan ecosystems provide a unique opportunity to analyze the determinants of species richness across large elevation gradients. Understanding forest diversity and structure is fundamental to set conservation priorities. A quantitative assessment of tree species was conducted in Kashmir Himalayan forests to ascertain their composition, stand structure and distribution in 143 plots of 50 × 50 m2. Altogether, 13 species were recorded, ranging from five in subalpine (SA) forests to 10 in mixed conifer (MC) forests. There was a compositional dissimilarity among forest types. Pinus wallichiana was the most important species in low-level blue pine (BP) forests, whereas Abies pindrow prevailed in mid-elevation MC and high-elevation SA forests. Pinaceae contributed around 98% of stems and was the most speciose family, followed by Sapindaceae and Betulaceae. Stand density and basal area differed among forest types and were significantly correlated with elevation and slope. The tree diameter class distribution displayed an approximate reverse J-shaped pattern indicating the influence of disturbance. As the first two axes of the canonical correspondence analysis explained more than 93% of the inertia in the species-environment relation, elevation and slope are the main drivers of species distribution. Information about these forest attributes could provide better ecological insights for sustainable forest management.

Land use impacts on Boswellia dalzielii Hutch. an African frankincense tree in Burkina Faso

Boswellia dalzielii Hutch., an African frankincense tree, is a socio-economically important aromatic and medicinal tree. It is currently threatened by uncontrolled exploitation, and therefore requires action to ensure its sustainable management. This study assessed the population structure and regeneration of its natural stands across three land use types in Burkina Faso: woodlands, fallows and farmlands. Sixty, fifty and fifty 50 m × 20 m plots were established respectively in woodlands, fallows and farmlands. All the plots were surveyed for adult tree (dbh ≥ 5 cm) density, dbh, total height and health conditions. Data on regeneration density (dbh < 5 cm), source (generative, stem shoots, suckers), total height and collar diameter were also collected. The results show similar total tree heights (7.0 m-9.0 m) but significantly (p < 0.05) smaller tree dbh in woodlands (mean ± SD: 20.5 ± 0.49 cm) and fallows (29.3 ± 0.64 cm) than in farmlands (32.8 ± 0.15 cm). Adult tree density (trees/ha) was 1.3 and 2.7 times higher in woodlands (82.37 ± 6.57) than in fallows (62.00 ± 3.98) and farmlands (30.02 ± 1.63), respectively. The density of regeneration in woodlands was 28 and 6 times higher than in fallows and farmlands, respectively. The majority (> 50%) of regenerating plants were suckers and no seedling regeneration was found in farmlands. The distribution of trees in diameter classes was J-shaped in woodlands, bell-shaped in farmlands and positive asymmetric in fallows, indicating recruitment bottlenecks. We found that 80.18% of individuals encountered were unhealthy. Intensive debarking and cutting were the main threats to the species and no conservation strategy was in place in the study region. We suggest measures to reduce intensive debarking and cutting, which should contribute to better management of the species.

Assessment of Wood Production and Structural Composition of Domboma Community Based Forest in Dasse Chiedom, Moyamba District, Sierra Leone

This research was carried out in August and September 2020 in the Domboma community-Based forest of Domboma community in Dasse chiefdom, Moyamba district, southern Sierra Leone. The objective of the study was to assess wood production and structural composition of Domboma community Based-forest in Dasse Chiefdom, Moyamba District. The systematic sampling design was adopted and data were collected in 12 circular sample plots with a radius of 10 m and an area of 0.031 ha. The stand was divided into four transects that were 50 m apart and the interval between sample plots in any transect was 10 m. In total, 12 plots covering a sampling area of 0.38 ha were laid out. In each plot all trees ? 10 cm diameter at breast height (DBH, 1.3 m above ground level) were measured for both DBH and total height, using diameter tape and suunto hypsometer, respectively. The species was identified for every measured tree either directly by botanical name or by local names. The total individual trees enumerated were 147. These individual trees were distributed into four diameter classes as follows; 76 trees in diameter class 1, 33 trees in diameter class 2, 4 trees in diameter class 3 and 34 trees in diameter class 4. The Shannon-wiener index of diversity calculated was 3.38 using natural logarithm for the four diameter classes. The index of dominance was 0.76 and the index of dispersion estimated was 16.0 for all diameter classes respectively. The average (DBH) and height of trees were 51.17cm and 27.06m respectively. The basal area and wood volume were 241.35m2/ha and 31227.62m3/ha respectively and the stocking was 390 stems ha-1. The 26-tree species found in all the 12 plots were listed in IUCN redlist categories as follows; 19.2% as data deficient (DD), 57.7% as least concerned (LC), 3.8% as nearly threatened (NT), 11.5% as vulnerable (VU), 7.7% as endangered (EN) and none of the species was classified as critically endangered.

Effects of site and tree size on wood density and bark properties of Lebombo ironwood (Androstachys johnsonii Prain)

Background: Wood and bark are important renewable natural resources. Density is an important property that is used to describe wood and bark quality for a number of end uses. However, wood and bark density, bark proportion and dimensions vary with age and site, as well as among and within trees. The aim of this study was to investigate the effect of site, diameter class, and vertical position within the stem on the density of wood and bark, bark volume, bark dry-mass and thickness of Lebombo ironwood (Androstachys johnsonii Prain). Methods: The study was conducted on 93 Lemombo ironwood trees growing in Mozambique. Eight discs were sampled from each selected tree and diameter over and under bark was measured. Bark thickness, bark mass and bark density were determined along with the basic wood density of each disc. Results: The overall average whole-stem properties were estimated at: 786 kg m–3 wood density, 586 kg m–3 bark density, 19% bark volume, 19% bark dry-mass, and 9 mm bark thickness. Height level uniquely explained most of the variation in bark mass (97%), bark volume (95%) and wood density (86%). Diameter class explained most of the variation in bark density (51%) and bark thickness (51%). Site only explained a small proportion of the variation in all dependent variables. Conclusions: Overall, the patterns of variation of all wood and bark properties were highly dependent on tree diameter class and vertical position within the stem. Site differences were not a significant source of variation in the properties studied. Improved knowledge of the wood and bark properties of this species will aid its sustainable management and utilisation.

Variation of Heartwood Proportion and Wood Colour from Fast Grown 5-Year-Old Teak

The heartwood percentage and wood colour of fast plantation grown teak destined for harvest at 5 years of age were characterized using automatic image processing ’ImageJ’ routines and CieLab’s colour system with the following coefficients: L for lightness, a* for redness and b* for yellowness. Analyses were conducted on material from different dry and wet sites. Comparison with 6-year old plantation from a dry site was conducted to study differences arising in older trees. Analyses of variation of those properties between and within different tree diameter classes were also conducted. The results showed that brightness, redness and yellowness values of 5-year old teak trees were 60.7, 10.7 and 23.1, respectively. Tree clone had a more dominant effect on wood colour and heartwood proportion than site, thus if specific colour preferences are needed of plantation trees, clone selection is important. The drier site produced larger proportions of heartwood in trees, as well as a more attractive figure. The trees produced heartwood proportions of 20% and 14% from the dry and wet sites respectively. On average, these 5 year old teak trees already produced 18% heartwood. Faster tree growth (larger diameter) appeared to have produced significantly larger heartwood proportions. Radially, the palest colour (the highest L but the lowest a*b* parameters) occurred in an area between heartwood and sapwood indicating the presence of a transition zone in all the tree samples.

Variation of Heartwood Proportion and Wood Colour from Fast Grown 5-Year-Old Teak

The heartwood percentage and wood colour of fast plantation grown teak destined for harvest at 5 years of age were characterized using automatic image processing ’ImageJ’ routines and CieLab’s colour system with the following coefficients: L for lightness, a* for redness and b* for yellowness. Analyses were conducted on material from different dry and wet sites. Comparison with 6-year old plantation from a dry site was conducted to study differences arising in older trees. Analyses of variation of those properties between and within different tree diameter classes were also conducted. The results showed that brightness, redness and yellowness values of 5-year old teak trees were 60.7, 10.7 and 23.1, respectively. Tree clone had a more dominant effect on wood colour and heartwood proportion than site, thus if specific colour preferences are needed of plantation trees, clone selection is important. The drier site produced larger proportions of heartwood in trees, as well as a more attractive figure. The trees produced heartwood proportions of 20% and 14% from the dry and wet sites respectively. On average, these 5 year old teak trees already produced 18% heartwood. Faster tree growth (larger diameter) appeared to have produced significantly larger heartwood proportions. Radially, the palest colour (the highest L but the lowest a*b* parameters) occurred in an area between heartwood and sapwood indicating the presence of a transition zone in all the tree samples.

DOES THE SIZE OF THE TREES DETERMINE THE RICHNESS AND DISTRIBUTION OF VASCULAR EPIPHYTES IN AMAZONIAN FLOODPLAIN FORESTS?

Vascular epiphytes (VE) are among the most threatened group of plants due to the extraction of trees (phorophytes). Yet, surveys and ecological information on vascular epiphytes are rather scarce particularly in wetlands. To understand the effect of tree assemblage on the occurrence of VE and in order to elucidate ecological patterns of distribution and composition, 16 (25 x 25 m) permanent plots were sampled in an oligotrophic floodplain forest ( igapo - PELD MAUA) and compared to the same amount and size of plots in a nutrient-rich floodplain ( varzea - RDS Mamiraua), both in Central Amazon. All trees and associated VE were counted and identified. The diversity in varzea is driven by the turnover of epiphytes in trees with different diameters, while in igapo there is a pronounced concentration of VE in trees with smaller diameters. Conservation actions in varzea forests should prioritize the maintenance of forest structure, sustaining taxonomic diversity in all diameter classes of trees. In igapo forests efforts to conserve epiphytes must first consider the taxonomic identity and, after, size of trees in the community. The comparison of our results with those of other PELDs in wetlands and other ecosystems will enhance our knowledge on the biogeographic patters and constrains on the distribution of this important botanical component.

Time lag of stem sap flow and its relationships with transpiration characteristics in Quercus liaotungensis and Robina pseudoacacia in the loess hilly region, China

Using Granier-type thermal dissipation probes (TDP), we measured stem xylem sap flow of the natural dominant species Quercus liaotungensis and a reforestation species Robinia pseudoacacia from July to September in 2016 in the semiarid loess hilly region. Meteorological factors and soil water content were simultaneously monitored during the study period. Using cross-correlation analysis, time lag between diurnal patterns of sap flux density and vapor pressure deficit (VPD) was quantitatively estimated. Differences in the time lag between the two species and possible influence by different diameter classes and soil water contents were analyzed. The results showed that the diurnal courses of sap flux density were similar to those of meteorological factors, with daily peaks ear-lier than VPD. The peak of VPD lagged behind the sap flux densities of Q. liaotungensis and R. pseudoacacia 118.2 min and 39.5 min, respectively. The peak of PAR lagged behind the sap flux density of Q. liaotungensis 12.4 min, but was 68.5 min ahead of that for R. pseudoacacia. Time lag between sap flux density and VPD significantly varied between tree species and was affected by soil water content. Those during higher soil water content period were about 32.2 min and 68.2 min longer than those during the period with lower soil water content for the two species, respectively. There was no correlation between time lag and tree diameter classes. The time lag between VPD and sap flux density for R. pseudoacacia was about 21.4 min longer in smaller diameter trees than in larger trees, which was significantly different under the lower soil water content. Our results suggested that the time lag effect between VPD and sap flux densities in the two species reflected their sensitivities to driving factors of transpiration, and that higher soil water content was favorable to sap flux density reaching its peak early. The lower soil water content might lead to lower sensitivity of the trees to meteorological factors. R. pseudoacacia was more sensitive to changes of soil water content.

Особливості моделювання твірної поверхні стовбурів дуба звичайного

Узагальнено досвід дослідження форми стовбурів дерев, який дав змогу зробити висновок про переваги математичного моделювання твірної поверхні для аналізу збігу стовбурів. На основі дослідного матеріалу, зібраного в дубових насадженнях Придніпровського правобережного Лісостепу на 17 тимчасових пробних площах, проаналізовано залежність форми стовбурів дуба звичайного (Quercus robur L.) від висоти та діаметра на висоті 1,3 м. За допомогою графічного аналізу та t-тесту середніх значень коефіцієнтів форми Шиффеля на 5 %-му рівні значущості виявлено відмінність у формі стовбурів дуба різних груп діаметрів. За розрядами висот статистично значущої різниці, за характером збігу не встановлено. Виконаний аналіз дав змогу обґрунтувати доцільність моделювання збігу стовбурів дуба звичайного незалежно від висоти, але в межах 3-х груп діаметрів: 20-28 см, 32-40 см та 44-64 см. Як моделі твірної поверхні стовбурів апробовано показниково-степеневі математичні рівняння A. Kozak (1988) і R. Newnham (1992). Підбір параметрів рівнянь виконано для вибірки з 171 модельного дерева в середовищі R за допомогою функції nls − нелінійна мінімізація суми квадратів відхилень. Систематична помилка обох рівнянь виявилася близькою до нуля (0,9-1,7 %), що дало змогу прийняти їх для моделювання твірної поверхні стовбурів різної форми для встановлених груп діаметрів. Розроблені моделі дають змогу прогнозувати діаметри стовбурів дуба на будь-якій висоті зі стандартною помилкою 1,5-3,2 см. Все ж аналіз розподілу залишків математичних моделей засвідчив переваги моделі A. Kozak (1988), яку рекомендовано використовувати надалі для моделювання розмірно-якісної структури стовбурів дуба звичайного.

Can Field Crews Telecommute? Varied Data Quality from Citizen Science Tree Inventories Conducted Using Street-Level Imagery

Street tree inventories are a critical component of urban forest management. However, inventories conducted in the field by trained professionals are expensive and time-consuming. Inventories relying on citizen scientists or virtual surveys conducted remotely using street-level photographs may greatly reduce the costs of street tree inventories, but there are fundamental uncertainties regarding the level of data quality that can be expected from these emerging approaches to data collection. We asked 16 volunteers to inventory street trees in suburban Chicago using Google Street ViewTM imagery, and we assessed data quality by comparing their virtual survey data to field data from the same locations. We also compared virtual survey data quality according to self-rated expertise by measuring agreement within expert, intermediate, and novice analyst groups. Analyst agreement was very good for the number of trees on each street segment, and agreement was markedly lower for tree diameter class and tree identification at the genus and species levels, respectively. Interrater agreement varied by expertise, such that experts agreed with one another more often than novices for all four variables assessed. Compared to the field data, we observed substantial variability in analyst performance for diameter class estimation and tree identification, and some intermediate analysts performed as well as experts. Our findings suggest that virtual surveys may be useful for documenting the locations of street trees within a city more efficiently than field crews and with a high level of accuracy. However, tree diameter and species identification data were less reliable across all expertise groups, and especially novice analysts. Based on this analysis, virtual street tree inventories are best suited to collecting very basic information such as tree locations, or updating existing inventories to determine where trees have been planted or removed. We conclude with evidence-based recommendations for effective implementation of this type of approach.