Neighbor Tree Research Articles

Longleaf pine proximity effects on air temperatures and hardwood top-kill from prescribed fire

BackgroundRegulation of the dominance of resprouting understory hardwoods is a common objective for prescribed fire in open-canopy longleaf pine (Pinus palustris Mill.) woodland of the southeastern USA. Nevertheless, little is known about the influence of individual pines on fire and hardwood mortality. We studied growing-season fires in stem-mapped stands in southwest Georgia, USA; the stands displayed large variation in structure due to cutting treatments applied seven years earlier. We measured air temperature and heating duration, and measured post-fire sprouting behavior of four guilds of understory hardwoods: mesic oaks (Quercus spp. L.), upland oaks, xeric oaks, and fleshy-fruited hardwoods. Mean air temperature (i.e., of flames, buoyant plume, and smoldering combustion) and heating duration (time over 60 °C) were analyzed with respect to fuel-bed conditions and neighboring tree density. Hardwood top-kill was analyzed with respect to neighboring tree density and hardwood height.ResultsThe basal area of nearby pines strongly affected heating duration (time over 60 °C), which increased linearly from a mean of 87 s to a mean of 234 s across a gradient of pine basal area from 0 to 30 m2 ha−1. Mean air temperature during prescribed fire was unaffected by pine density but increased linearly from a mean of 114 °C to a mean of 148 °C across a gradient of wiregrass (Aristida stricta Michx.) cover from 0 to 100%, respectively. Neighborhood models showed that time over 60 °C during the burns was longest at the base of pines and decreased by two thirds at 3.3 m distance. Pines affected hardwood top-kill probability at a similar scale, the effect at 4.4 m decreasing by two thirds compared to at the base of the pine. The four hardwood guilds were readily top-killed when ≤1 m tall, but at 2 m height, upland and xeric oaks had become more resistant to top-kill than mesic oaks or fleshy-fruited hardwoods.ConclusionsThe influence of individual pine trees on heating duration and top-kill power of prescribed fire drops by two thirds of maximum within 3 to 4 m of a tree, compared to a maximum at the base of the tree. Neighborhood models provide a method to estimate tree effects on prescribed fire heating duration and top-kill probability, and thus a way of predicting stand structures that provide ecological benefits of openings while remaining below thresholds that trigger vigorous hardwood response.

Impact of long and short-term conservation periods on structure of English yew (Taxus baccata L.) in Arasbaran forests, Iran

Yew (Taxus baccata L.) is one of the most important and threatened tree species in the Arasbaran region of northwestern Iran. To understand the natural stand structure of yew forests to inform forest management, we assessed the structural characteristics and composition of yew communities using the nearest neighbour and full callipering method at three sites with different conservation histories. Within a one-hectare sampling area, tree species identity, diameter, height, and crown diameter were measured. In each of these sampling areas, 56 sample points were surveyed in a 25 m × 25 m grid for tree species identity, diameter, height, and distance from reference to neighbour trees. To quantify the structural characteristics in areas of different conservation status, some indices were calculated including mingling, distance between reference tree and its nearest neighbouring trees, diameter and height differentiation, uniform angle, and Clark-Evans index. Results revealed that four species – hornbeam (68%), maple (8%), yew (7%), and oak (5.2%) – composed 88% of the tree species. The majority of trees had a short distance (2–3 m) between neighbours. The mean diameter differentiation index for long-term and short-term conservation areas was 0.59 and 0.06, respectively. The uniform angle index showed that there was no class value = “1” at all three sites. In the long-term enclosed area, Clark-Evans index was 1.18. In short-term enclosed areas, it was less than 1 (0.82). At all sites, yew trees were in the least vital class. We conclude that enclosing affects the yew stand structure, specifically in long-term periods of enclosure.

Methods of Forest Structure Research: a Review

The forest structure generally refers to the configuration and distribution of different plant species and sizes. Investigation and analysis of forest structures help us to understand the history, current status, and future development of forest ecological systems. This paper aims at a systematic summary of the quantitative analysis methods of forest structure. The marked second-order characteristic method has obvious advantages in explaining the relationships among tree species and the dynamic relationship between tree size differentiation and scale. The quantitative analysis method of spatial structure based on the relationships of nearest neighbor trees, compared with traditional non-spatial indices or functions, does not only analyze four important aspects of the forest structure (spatial distribution pattern diversity, species diversity, size diversity, crowding degree diversity), but also demonstrates its strength in elaborating fine-scale spatial stand structure. This nearest-neighbor analytical method also bridges the gap between stand structure parameters and tree competition indices, especially through the multivariate distribution of structural parameters. This nearest-neighbor analytical method provides an in-depth, multi-faceted interpretation of forest structure at different levels. Structure-based forest management has been proposed based on this analytical method of spatial structure, and is a proven way to effectively improve forest quality.

A decade of the India Biodiversity Portal: Planning ahead with technology to enhance citizen science participation in India

The India Biodiversity Portal (IBP) was initiated a decade ago, aiming to aggregate data on all species within India. The portal has been running a citizen science module for the past 8 years, aggregating observation data from the general public. The portal runs many flagship citizen science campaigns, such as the Neighborhood Trees Campaign, National Moth Week, Spotting Alien Invasive species, Mapping Indian Snails and Slugs and Frogwatch. We have learnt valuable lessons in harnessing participation in citizen science, implementing functionality and in integrating technological advancements into the platform codebase. Following up on these, we are implementing new features that will streamline development, entice users and further spur participation. We discuss some of the proposed changes and our justification, including the impacts we expect in generating better citizen science data. A key lesson arising out of our campaigns in remote regions of India, where internet penetration is relatively new, is that most users are connected to the web exclusively through a mobile device. Most do not have access to a personal computer or an email account. Yet they are internet savvy and use mobile applications to accomplish complex tasks such as banking activities, often logging in and being authenticated exclusively through a mobile number. We are implementing short-messaging-service (SMS) or one-time password-based login mechanisms, for login even without an email account for authentication. Although many initiatives have been investing in platform-specific mobile apps to cater to a growing mobile user community, maintaining and updating multiple mobile apps alongside enhancements to the web version is a resource-intensive task that most platforms cannot afford. Inconsistency in functions and usability across different versions of the same platform may lead to gaps in data collection. To address this challenge and streamline development, we have begun updating the portal codebase to enable Progressive Web Apps, which will replace conventional mobile applications while also serving as Single Page Applications that provide a unified experience across device platforms and alleviating the need for updating mobile apps separately. For existing contributors on the portal, comparisons of their contributions against other users are a motivating factor to contribute further. Leaderboards and reputation systems are proven methods to promote activity and provide recognition to participants. Such leaderboards also incentivise newer participants to emulate leaders and climb the boards. We are building a reputation system that not only recognizes quantity but also the quality of the user’s contribution. In addition, we are working on integrating intelligent push notification technology that will constantly engage users by keeping them abreast of activity related to content reflecting their interest on the portal. These features are expected to engage contributors and keep them motivated towards further data contributions. Finally, the most rewarding outcome from contributing citizen science data is in visualizing its impact. The most obvious are improvements in species distribution maps that are generated for each species page on the portal. Users are greatly motivated by contributing data that may enhance known distributions and may constitute range extensions for a species. Distribution maps on the portal are being revamped so that information is presented to the user in real-time through visualisations that are are both attractive and easy to interpret. These will provide users with gratification and help spur participation further. IBP is also instituting the ability to automate the classification of its data to identify publication-grade data. Through a combination of user’s reputation and other data quality criteria, the data on IBP will be automatically graded, allowing such data to be pushed to Global Biodiversity Information Facility on a periodic basis as a Darwin Core Archive, contributing to global biodiversity data.

Advanced Aboveground Spatial Analysis as Proxy for the Competitive Environment Affecting Sapling Development.

Tree saplings are exposed to a competitive growth environment in which resources are limited and the ability to adapt determines general vitality and specific growth performance. In this study we analyzed the aboveground spatial neighborhood of oak [Quercus petraea (Matt.) Liebl.] and beech (Fagus sylvatica L.) saplings growing in Germany, by using hemispherical photography and terrestrial laser scanning as proxy for the competitive pressure saplings were exposed to. The hemispherical images were used to analyze the light availability and the three-dimensional (3D) point clouds from the laser scanning were used to assess the space and forest structure around the saplings. The aim was to increase the precision with which the biomass allocation, growth, and morphology of the saplings could be predicted by including more detailed information of their environment. The predictive strength of the models was especially increased through direct neighborhood variables (e.g., relative space filling), next to the light availability being the most important predictor variable. The biomass allocation patterns within the more light demanding oak were strongly driven by the space availability around the saplings. Diameter and height growth variables of both species reacted significantly to changes in light availability, and partly also to the neighborhood variables. The leaf morphology [as leaf-area ratio (LAR)] was also driven by light availability and decreased with increasing light availability. However, the branch morphology (as mean branch weight) could not be explained for oak and the model outcome for beech was hard to interpret. The results could show that individuals of the same species perform differently under constant light conditions but differing neighborhoods. Assessing the neighborhood of trees with highly precise measurement devices, like terrestrial laser scanners, proved to be useful. However, the primary response to a dense neighborhood seemed to be coping with a reduction of the lateral light availability aboveground, rather than responding to an increase of competition belowground. The results suggest continuing efforts to increase the precision with which plant environments can be described through innovative and efficient methods, like terrestrial laser scanning.

Analysing tree–neighbourhood interactions in ecotones of montane evergreen and deciduous forests in China

AbstractQuestionsDo neighbourhood interactions in trees result in discernible spatial and phylogenetic signals among their nearest neighbours in a montane evergreen and deciduous forest? Are neighbourhood patterns of different species associated with their abundances and traits?LocationBadagongshan National Nature Reserve, Hunan, China.MethodsWe used four nearest‐neighbour indices: average spatial distance to the nearest conspecific cohort‐mate (SNCC), average spatial distance to the nearest conspecific adult (SNCA), average phylogenetic distance to the nearest heterospecific cohort‐mate (PNHC), and average phylogenetic distance to the nearest heterospecific adult (PNHA). We focused on 77 abundant species in a 25‐ha plot. We evaluated whether the changes in SNCC, PNHC, SNCA and PNHA deviated significantly from expected values of spatially random mortality during two life stage transitions.ResultsFor more than one‐fourth of the tested species, the changes in SNCC and PNHC deviated significantly from the expectations of random mortality. Nearly one‐third of the tested species showed greater SNCC at the juvenile stage than expected of random mortality, which may be mainly explained by conspecific tree competition for space and resources. Approximately 60% and 40% of the tested species showed significantly smaller SNCA and PNHA than expected by random mortality, respectively, which suggests the effects of facilitation and habitat filtering. In addition, abundant and taller species were suppressed by conspecific cohorts to a greater degree than locally rarer and shorter species. Deciduous species were more negatively influenced by conspecifics and closely related heterospecifics than evergreen species.ConclusionsOur study focused on long‐term responses of individual species to their conspecific and phylogenetic neighbourhoods and revealed the associations between species traits and neighbourhood patterns. Such trait–neighbourhood interactions provide support for stabilizing mechanisms driving species coexistence in this species‐rich subtropical forest.

Connectivity explains local ant community structure in a Neotropical forest canopy: a large-scale experimental approach.

Understanding how habitat structure and resource availability affect local species distributions is a key goal of community ecology. Where habitats occur as a mosaic, variation in connectivity among patches influences both local species richness and composition, and connectivity is a key conservation concern in fragmented landscapes. Similarly, availability of limiting resources frequently determines species coexistence or exclusion. For primarily cursorial arthropods like ants, gaps between neighboring trees are a significant barrier to movement through the forest canopy. Competition for limited resources such as nest sites also promotes antagonistic interactions. Lianas (woody vines) connect normally isolated neighboring tree crowns and often have hollow stems inhabited by ants. We used two large-scale liana-removal experiments to determine how connectivity and nest site availability provided by lianas affect arboreal ant species richness, species composition, and β-diversity in a lowland tropical forest in Panama. Removing lianas from a tree crown reduced ant species richness up to 35%, and disproportionately affected species that require large foraging areas. Adding artificial connectivity to trees mitigated the effects of liana removal. Ant colonization of artificial nests was higher (73% occupied) in trees without lianas vs. trees with lianas (28% occupied). However, artificial nests typically were colonized by existing polydomous, resident ant species. As a result, nest addition did not affect ant community structure. Collectively, these results indicate that lianas are important to the maintenance of arboreal ant diversity specifically by providing connectivity among neighboring tree crowns. Anticipated increases in liana abundance in this forest could increase the local (tree-level) species richness of arboreal ants, with a compositional bias toward elevating the density of broad-ranging specialist predators.

Spatial association of fruit yield of Bertholletia excelsa Bonpl. trees in eastern Amazon

Brazil nut (Bertholletia excelsa) is one of the most important non-timber forest product (NTFP) species in the world. Better management and conservation practices will only be possible with an in-depth knowledge of tree species ecology. This study aimed to assess the spatial association of fruit yield of Bertholletia excelsa (B. excelsa) trees in two forest types (old growth terra firme forest and Amazon-cerrado transitional forest) in the Brazilian Amazon. Fruit yield was measured in both forest types during 2010. At each forest type, fruit yield was divided into different yield classes (number of fruits) for subsequent spatial modeling. The bivariate Ripley’s K-function was applied to quantify the spatial association of fruit yield of B. excelsa trees over different fruit yield classes. The results revealed that the forest type influences the spatial association of B. excelsa fruit yield. The old growth terra firme forest presented random spatial association for fruit yield, which implies that fruit yield of B. excelsa trees in this forest type is not limited by tree location and site resources. On the other hand, the Amazon-cerrado transitional forest presented significant negative spatial association for fruit yield across different yield classes, which means that under some conditions fruit yield of a given tree influences the fruit yield of the neighboring tree in this forest type. Site resources in the Amazon-cerrado transitional forest is limited and naturally favors inter- and intra-specific competition. Finally, the results imply the need for adoption of different management and conservation strategies for B. excelsa in different forest types in the Brazilian Amazon.

Tree spatial patterns modulate peak snow accumulation and snow disappearance

Forests and snow covered regions frequently co-occur across the northern hemisphere. In these environments, forests are structurally and spatially complex mosaics of tree neighborhoods that are intrinsically linked to ecosystem functions. Tree and canopy structures influence snow accumulation and disappearance processes through interception and radiation attenuation. However, it is unclear if spatial heterogeneity within the forest canopy induces heterogeneity in snow accumulation and persistence. We quantitatively identified different tree neighborhoods and tested the differential effects of these within-stand neighborhoods on snow processes. Neighborhood types included individual ponderosa pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii) and western larch (Larix occidentalis) trees, dense overstory tree clumps, openings, and regeneration patches. Intensive measurements of snow accumulation (density and depth) and persistence (disappearance date) were made within replicate neighborhoods for three years. Overall, neighborhood type and year had a significant effect on accumulation and snow disappearance. Openings were significantly different from clumps and individuals, always accumulating more snow. Openings retained snow significantly later than clumps but were not significantly different from individuals. Within the individual tree neighborhood type, a nested species effect indicated no differences in accumulation but significant differences in disappearance between deciduous and evergreen conifers, with snow persisting longer beneath deciduous western larch. Our results suggest that canopy interception is the primary mechanism driving the accumulation phase, while snow disappearance patterns are largely a consequence of spatial variation of longwave radiation. Reducing canopy interception and longwave radiation by increasing the abundance of widely spaced single trees and small openings with silvicultural treatments should increase snow depth and duration, and thus snow water storage. Maintaining a heterogeneous canopy structure that includes tree clumps can be used to meet multiple objectives such as provision of ungulate winter range habitat, and heterogenous understory plant phenology.

Spatial-Temporal Patterns of Spruce Budworm Defoliation within Plots in Québec

We investigated the spatial-temporal patterns of spruce budworm (Choristoneura fumiferana (Clem.); SBW) defoliation within 57 plots over 5 years during the current SBW outbreak in Québec. Although spatial-temporal variability of SBW defoliation has been studied at several scales, the spatial dependence between individual defoliated trees within a plot has not been quantified, and effects of defoliation level of neighboring trees have not been addressed. We used spatial autocorrelation analyses to determine patterns of defoliation of trees (clustered, dispersed, or random) for plots and for individual trees. From 28% to 47% of plots had significantly clustered defoliation during the 5 years. Plots with clustered defoliation generally had higher mean defoliation per plot and higher deviation of defoliation. At the individual-tree-level, we determined ‘hot spot trees’ (highly defoliated trees surrounded by other highly defoliated trees) and ‘cold spot trees’ (lightly defoliated trees surrounded by other lightly defoliated trees) within each plot using local Getis-Ord Gi* analysis. Results revealed that 11 to 27 plots had hot spot trees and 27% to 64% of them had mean defoliation <25%, while plots with 75% to 100% defoliation had either cold spot trees or non-significant spots, which suggested that whether defoliation was high or low enough to be a hot or cold spot depended on the defoliation level of the entire plot. We fitted individual-tree balsam fir defoliation regression models as a function of plot and surrounding tree characteristics (using search radii of 3–5 m). The best model contained plot average balsam fir defoliation and subject tree basal area, and these two variables explained 80% of the variance, which was 2% to 5% higher than the variability explained by the neighboring tree defoliation, over the 3–5 m search radii tested. We concluded that plot-level defoliation and basal area were adequate for modeling individual tree defoliation, and although clustering of defoliation was evident, larger plots were needed to determine the optimum neighborhood radius for predicting defoliation on an individual. Spatial autocorrelation analysis can serve as an objective way to quantify such ecological patterns.

Scots pine Pinus sylvestris mortality after surface fire in oligotrophic pine forest Peucedano-Pinetum in Kampinos National Park

Abstract Pines are generally fire-resistant trees. There is a shortage of research on the behaviour of Scots pine after surface fire in older stands. The aim of the work was to describe the effect of the surface fire intensity on the mortality of pines of various diameter at breast height (DBH), including older trees. The research was conducted in Peucedano-Pinetum oligotrophic Scots-pine forest in Kampinos National Park (KPN, central Poland) on the area of two adjacent surface fire sites originated in spring 2015 in 60- to 200-year-old stands (site area: 10,92 ha). There were 45 (28 burned and 17 control) permanent plots established after the fire. The share of not burned, superficially burned and completely burnout organic horizon of the soil was determined within all of them. DBH and location of pine trees were measured within all of the plots on the area of 200 m2. For all of the trees for which full information about soil organic horizon damage was mapped, the prevailing type of disturbance in their close neighbourhoods with radii of 1 and 2 m was assessed. The mortality of trees was assessed after each vegetation period up to 2017, basing on the presence of green needles on the trees. The influence of fire intensity on the survival of trees was examined on whole permanent plot level as well as on individual tree level. Strong linear correlation was observed between Scots pine mortality and the share of plots area with damaged organic layer, especially at the end of the third vegetation period after fire. Logistic regression models constructed for individual trees suggest that bigger tree diameter (hence, thicker bark) diminished the odds of mortality only after two vegetation periods from the fire. After the third vegetation period, only the intensity of surface fire in the close neighbourhood of trees influenced (negatively) the chance on survival. The size of trees did no matter in this case. Nearly all of the trees that were located within burnout organic matter areas died. The results did not support the commonly known mechanism of enhancement of bigger Scots pine tree survival after surface fire because of thicker bark responsible for heat protection. Probably, the main cause of observed mortality was not overheating of cambium but it was rather connected to massive fine root loses. Scots pines growing on oligotrophic arid sites modify their root system to explore topsoil layers with higher proportion of shallow roots, growing even in organic litter layer. This corresponds with massive (regardless of size) pine mortality within sites characterised by complete burnout of organic matter layer and very high survival in those ones with only surfacely burned litter layer. The results can improve the assessment of surface fires consequences in managed Scots pine stands growing in oligotrophic conditions.

Consequences of biodiversity shift across phylogenetic scales for aspen and willow growth, survival, and herbivory

AbstractQuestionIt has been established that community biodiversity has consequences for ecosystem function. Yet research assessing these biodiversity–ecosystem function (BEF) relationships usually occurs at only one phylogenetic scale; as such, the dependence of BEF relationships on phylogenetic scale has not been characterized. We present a novel framework for considering the consequences of biodiversity across phylogenetic scales, allowing us to ask: Do the consequences of intraspecific and interspecific diversity affect the growth, survival, and leaf herbivory of three temperate tree species?Study siteSalicaceous tree plantation, Minnesota, northern USA.MethodsWe established an experimental plantation consisting of trees of three species within the willow (Salicaceae) family. Two aspen (Populus tremuloides, P. alba) and one willow (Salix nigra) species were represented by three unique genotypes such that tree neighborhoods varied both in genotype richness (intraspecific diversity) and species richness (interspecific diversity). We assessed the consequences of tree identity and diversity across these two phylogenetic scales for all trees’ aboveground productivity and survival, and for herbivore damage (on P. tremuloides) at the end of the second full growing season of the experiment.ResultsDiversity at any phylogenetic scale had no effect on the growth and survival of P. alba or S. nigra. However, intraspecific diversity increased the likelihood of P. tremuloides survival while interspecific diversity reduced P. tremuloides survival. Intraspecific diversity also reduced leaf removal and galling herbivory on P. tremuloides, while interspecific diversity had no effect on leaf removal and increased galling herbivory. Neither scale of diversity affected leaf mining.ConclusionsTree diversity within and among populations and species affected plant performance and ecosystem properties differentially, demonstrating that BEF relationships shift across phylogenetic scales in a taxon‐specific manner. We call for further experiments that explicitly span these scales by measuring ecosystem and physiological responses to the manipulation of diversity within and among species.

Effects of different disturbance patterns on stand structure of infected pure Pinus massoniana plantation

To explore the effects of different disturbance patterns on restoring the health of an infected stand, concentrated disturbance of not cutting trees before 10 years after infection, mode-rate disturbance of cutting infected pine trees, and strong distrubance of cutting infected pine trees, the neighboring trees and poorly growing pine trees were compared in a pure Pinus massomiana plantation infected by Bursaphelenchus xylophlius in Anji, Zhejiang, China. After 16 years, the importance values of P. massoniana in the three treatments were: concentrated disturbance > mode-rate disturbance > strong disturbance. However, the importance values of broad-leaved trees showed the opposite trend. Compared with the concentrated disturbance, the average DBH of P. massoniana in the moderate and strong disturbance treatments were 1.2 and 1.7 times higher, respectively, and those of broad-leaved species were 1.3 and 1.9 times higher, respectively. The average height of pine trees in the moderate and strong disturbance treatments increased 1.5 and 2.0 times, respectively, and those of broad-leaved species 1.2 and 1.8 times, respectively. The tree volume per hectare in moderate and strong disturbance treatments were 5.2 and 3.8 times that of concentrated disturbance treatment, respectively. In the moderate and strong disturbance treatments, the number of trees in each diameter class was greater than in the concentrated disturbance treatment. The stand diameter distribution in the multi-storied moderate and strong disturbance treatments followed an inverse J-shaped curve. The species richness and biodiversity were significantly higher in the mode-rate and strong disturbance treatments than in the concentrated disturbance treatment. The individual size inequality and structural complexity indices followed the order of moderate disturbance > strong disturbance > concentrated disturbance. Under moderate and strong disturbance treatments, the single-storied and evenly aged pure P. massoniana plantation became multi-storied and unevenly aged mixed stands. All the three disturbance patterns promoted the succession of broad-leaved trees, with the pace of succession in the order of strong disturbance > moderate disturbance > concentrated disturbance. In conclusion, moderate disturbance achieved better restoration. Thinning pure P. massoniana plantation could accelerate the succession of a mixed stand to enhance resistance against Bursaphelenchus xylophlius invasion.

A New Intelligent System for Glaucoma Disease Detection

Glaucoma is a redundant disease and a major cause of blindness resulting from damage in the optic nerve. This disease generally spreads very slowly and does not show any symptom at the beginning. The research presented in this paper is both a clinical and a technological aid for diagnosis of early glaucoma based on four different artificial intelligence classification techniques, which are: multi-layer perceptron, support vector machine, K-nearest neighbour and decision tree. A majority vote system was applied to these techniques in order to optimize the performances of the proposed system. As far as the ratio cup to disc, which is one of the descriptors of the collected database, in this paper we detect automatically the cup by the k-means algorithm and the disc using mathematical morphology method. Moreover, we proposed a contour adjustment technique (Ellipse Fitting). The obtained results are satisfying, promising, and prove the efficiency and the coherence of our new database.

Variance components and parent–offspring cor- relations of growth traits vary among the initial planting spacings in Zelkova serrata

Abstract Variance components of tree height (HT) and stem diameter at 1.3 m above the ground (DBH) were investigated for the eight open-pollinated families of Zelkova serrata (Thumb.) Makino planted with three different initial planting spacings in a progeny test site, Chiba, Japan. Parent–offspring correlations were also evaluated by using these families and their mother trees. The smallest values of HT and DBH were observed in the narrowest initial planting spacing (1.10 x 1.10 m) compared to those in medium (1.30 x 1.36 m) and wide (2.00 x 1.80 m) spacings, suggesting that adverse effects of competition with neighboring trees occurred on both height and radial growth. Similar to HT and DBH, the initial planting spacings also affected the genetic parameter estimates: the ratio of family variance component to total phenotypic variance showed the highest value in narrow initial planting spacing for both HT and DBH. Thus, family variance component might include competition effects, leading to biased genetic parameter estimates. In contrast, parent–offspring correlation coefficients showed the highest value in wide initial planting spacing where competition effect might be smaller. Therefore, the growth traits of Z. serrata might be inherited from the parent to the offspring when competition effect was small.

Typology of native species as the shade tree for merbau (Intsia bijuga) plantations in Papua, Indonesia based on ecological species group

Sirami EV, Marsono Dj, Sadono R, Imron MA. 2019. Typology of native species as the shade tree for merbau (Intsia bijuga) plantations in Papua, Indonesia based on ecological species group. Biodiversitas 20: 43-53. Ecological species group is an ecological principle that can be used as a reference in determining the potential native tree species of Papua as the shade trees for merbau in the mixed forest plantations. This research was conducted to identify the potential native trees as the shade for merbau plantation in Papua. The data collection used systematic line technique with hypothetical plot and sampling tree as the plot center. The Dice Index was used to analyze the level of association between merbau and the neighboring trees as well as to serve as a basis for determining ESG and Important Value Index was used to analyze the level of tree dominance. The main potential shade trees consisting of Pometia coriacea Radlk., Lepiniopsis ternatensi Valeton, Spathiostemon javensis Blume, Palaquium amboinense Burck., and Pimelodendron amboinicum Hassk. Whereas complementary and alternative potential shade consisting of Haplolobus lanceolatus H.J.Lam ex Leenh, Haplolobus celebicus H.J.Lam, Horsfieldia laevigata Warb., Horsfieldia irya (Gaertn.)Warb. Prunus costata Kalkman, Sterculia macrophylla Vent., Dysoxylum mollissimum Blume, Pertusadina multifolia (Havil.) Ridsdale, Streblus elongatus (Miq.) Corner and Geijera salicifolia Schott. The main shade trees possessed a main function for rendering shade toward younger merbau in the plantation area. Meanwhile, complementary and alternative shade trees were intended for increasing soil nutrient availability and optimizing microclimate surround merbau seedlings.

A basal area increment model for individual trees in mixed continuous cover forests in Iranian Caspian forests

The aim of this study was to develop and test a new basal area growth model in mixed species continuous cover forests in northern Iran. We analyzed 421 core samples from 6 main species in the forest area to develop our growth model. In each plot, we measured variables such as total tree height (m), diameter at breast height (DBH) (cm) and basal area of larger trees as cumulative basal areas of trees (GCUM) of DBH > 5 cm. The empirical data were analyzed using regression analysis. There was a statistically significant nonlinear function between the annual basal area increment, as the dependent variable, and the basal area of the individual trees and competition as explanatory variables. Reference area from the largest trees, was circular plot with area of 0.1 ha. GCUM was estimated for trees of DBH > 5 cm. Furthermore, we investigated the dependencies of diameter growth of different species on stand density at different levels of competition, and diameter development of individual trees through time. The results indicate that competition caused by larger neighborhood trees has a negative effect on growth. In addition, the maximum diameter increment is affected by competition level. Therefore, the maximum diameter increment of species occurs when the trees are about 35–40 cm in dense-forest (40 to 0 m2 per ha) and when the trees are about 60 to 70 cm in very dense forest (60 to 0 m2 per ha) which is more likely to Caspian natural forests with high level density due to uneven-aged composition of stands.

Identifying the linear region based on machine learning to calculate the largest Lyapunov exponent from chaotic time series.

To reduce the error caused by the human factor, this paper proposes a modification of a well-known small data method to obtain the largest Lyapunov exponent more accurately, which is based on machine learning for better identification of linear region. Firstly, we use the k-d tree neighborhood search algorithm to improve the computational efficiency of the average divergence index data. Secondly, the unsaturated data are obtained by the density peak based clustering algorithm from the average divergence index data. Thirdly, we use the density peak based clustering algorithm to identify the linear region from the first-order difference curve of the retained data. Finally, the largest Lyapunov exponent is obtained by using the least squares method to fit the linear region. Our method is applied to simulate five famous theoretical chaotic systems, the results show that the proposed method can automatically identify the linear region, which is more accurate than the small data method for the largest Lyapunov exponent calculation and the effectiveness of our method is verified through the simulation of two real-world time series.

Ship Detection in SAR Images Based on Maxtree Representation and Graph Signal Processing

This paper discusses an image processing architecture and tools to address the problem of ship detection in synthetic-aperture radar images. The detection strategy relies on a tree-based representation of images, here a Maxtree, and graph signal processing tools. Radiometric as well as geometric attributes are evaluated and associated with the Maxtree nodes. They form graph attribute signals which are processed with graph filters. The goal of this filtering step is to exploit the correlation existing between attribute values on neighboring tree nodes. Considering that trees are specific graphs where the connectivity toward ancestors and descendants may have a different meaning, we analyze several linear, nonlinear, and morphological filtering strategies. Beside graph filters , two new filtering notions emerge from this analysis: tree and branch filters . Finally, we discuss a ship detection architecture that involves graph signal filters and machine learning tools. This architecture demonstrates the interest of applying graph signal processing tools on the tree-based representation of images and of going beyond classical graph filters. The resulting approach significantly outperforms state-of-the-art algorithms. Finally, a MATLAB toolbox allowing users to experiment with the tools discussed in this paper on Maxtree or Mintree has been created and made public.

Behavioral switching in Magellanic woodpeckers reveals perception of habitat quality at different spatial scales

The switching pattern between behavioral modes provides a mechanistic basis for understanding how animals perceive and memorize the habitat quality in their home ranges. We assessed if Magellanic woodpeckers (Campephilus magellanicus) move based on habitat quality at local (neighboring trees) and home range scales. We used state-space models to examine the relationship between remotely-sensed estimates of habitat quality (tree decay) and movement of adult woodpeckers tracked with GPS telemetry in southern Chile. Woodpeckers spent most time (> 80%) in the area-restricted search (ARS) mode in contrast to the exploratory transient mode, characterized by frequent directional displacements (> 50 m). The extent to which individuals switched between behavioral modes was related to habitat quality at different scales. Woodpeckers switched to and remained in the ARS mode when encountering moderate levels of heterogeneity in habitat quality. At very low or high heterogeneity levels, however, individuals switched to and remained in the transient mode, respectively. Likewise, as habitat quality declined locally and across home range, woodpeckers were more likely to adopt a transient mode. Although woodpeckers seemed to easily perceive and memorize habitat quality at different spatial scales, our results suggest that spatial memory will less effective under extreme levels of habitat heterogeneity.