Spatial Point Pattern Analysis Research Articles

Observations of root hair patterning in soils: Insights from synchrotron-based X-ray computed microtomography

Abstract Background And Aims Root hair emergence is affected by heterogeneities in water availability in the growth medium. Root hairs preferentially emerge into air, whereas their emergence into water is inhibited. Yet, these results were based either on destructive methods or on roots grown on an agar-air interface. Additionally, there is a lack of knowledge about the spatial distribution of root hairs as hairs elongate radially across the rhizosphere. Therefore, root hair growth in soils remains largely unexplored. Methods Maize (Zea Mays L.) plants were grown in microcosms which were scanned with a synchrotron-based X-ray $$\mu $$ μ CT. The distribution of root hairs along the root epidermis and radially across the rhizosphere (i.e. as function of distance from the root epidermis) was analysed using spatial point pattern analysis. Results While hairs emerged randomly in air-filled pores, their emergence was inhibited where the root was in contact with the soil matrix. As hairs elongated radially into the soil, they were preferentially located in the close proximity of soil particles. In maize, we rarely observed root hairs penetrating into soil aggregates. Conclusion We conclude that in maize, root hairs grow in air-filled pores at the root-soil interface, where the flow of nutrients and water is impeded. Across the rhizosphere, hairs establish contact to the soil by growing in the proximity to soil particles. The effect of hairs on uptake processes, plant anchorage and rhizosheath formation might be limited (in maize) as they hardly penetrate into soil aggregates.

Environmental Exposure to Pesticides and the Risk of Child Neurodevelopmental Disorders.

Background and Objectives: Neurodevelopment is a fragile brain process necessary for learning from the beginning of childhood to adulthood. During the procedure, several risks could affect it, including environmental factors such as neurotoxic chemicals or environmental pollutants and, within them, exposure to pesticides. Materials and Methods: This ecological descriptive study attempted to assess the association between environmental exposure to pesticides and neurodevelopmental disorders. This study was conducted on 4830 children diagnosed for 11 years in a total population of 119,897 children in three areas: high, medium, and low greenhouse concentrations. Results: Chromosomal abnormalities were the most common prenatal disorder (28.6%), while intrauterine physical factors were the least common (0.5%). Among perinatal diagnoses, gestational age less than 32 weeks was the most common (25%), while hyperbilirubinemia requiring exchange transfusion and birth complications was the least common (0.4%). Brain damage was the most common problem detected in postnatal diagnosis (36.7%), while unspecified postnatal abnormalities were the least common (3.1%). Conclusions: The areas with the highest greenhouse concentration had higher incidences of neurodevelopmental disorders, particularly in boys, and lower age of referral. Chromosomal abnormalities were prevalent for prenatal diagnoses, gestational age below thirty-two weeks for perinatal diagnoses, and brain damage for postnatal diagnoses. Future studies should analyze the connection between pesticide exposure and neurodevelopmental disorders using spatial point pattern analysis.

Lonesome plants: How isolation affects seed set of a threatened dioecious shrub.

Plant reproductive failure is a critical concern for conserving rare and endangered species that typically have low-density and sparse populations. One important factor contributing to reproductive failure is the spatial arrangement of plants within a population, which can lead to isolation and negatively affect seed production, particularly in obligate outcrossers. Additionally, plant size can compound this effect, influencing seed production via multiple processes. Here, we investigate how spatial distribution and size influence the reproductive success of Vasconcellea chilensis, an endemic-threatened papaya species in Chile. We first examined whether V. chilensis can produce seeds via apomixis using pollinator exclusion experiments. We then used Spatial Point Pattern Analysis (SPPA) in three populations to explore the spatial arrangement of plants. Finally, we assessed whether plant size and neighbor distance influence the reproductive success V. chilensis is a dioecious shrub unable to produce fruits through apomixis. The SPPA revealed significant clustering of female and male plants at different spatial scales, indicating a non-random distribution. Moreover, a significant spatial association between the sexes was observed. In two populations, closer proximity to male plants was linked to higher seed production. Our study revealed that the reproductive system of V. chilensis is susceptible to distance-dependent reproductive failure due to pollen limitation. While the species' spatial structure may partially mitigate this risk, female plants isolated from male counterparts will likely experience reduced seed set.

Sex-driven neighborhood effects on herbivory in the dioecious Mediterranean palm Chamaerops humilis L.

Although it is well recognized that the strength of plant-herbivore interactions can vary with the plant sex, the distance, and the density of conspecific neighbors, no study has yet assessed their combined influence. Here, we filled this knowledge gap by focusing on the dioecious palm Chamaerops humilis L., and its two main herbivores, the invasive moth Paysandisia archon Burmeister and the feral goat Capra hircus L. We evaluated levels and spatial patterns of herbivory, as well as those of plant size and number of inflorescences in two palm populations in Mallorca (Balearic Islands, Spain). Our spatial point pattern analyses revealed that palms not affected by moth herbivory or goat florivory were spatially aggregated, goats fed more strongly upon inflorescences in palms with more neighbors, but they consumed more leaves in isolated palms. Interestingly, we could reveal for the first time that plant sex is a key plant trait modulating neighborhood effects. For instance, whereas aggregated female palms experienced lower intensity of goat florivory than isolated ones, male palms showed the opposite pattern. Palm size and number of inflorescences also showed sex-related differences, suggesting that sexual dimorphism is a key driver of the observed neighborhood effects on herbivory. Our study highlights the importance of considering relevant plant traits such as sex when investigating plant neighborhood effects, calling for further research to fully understand the dynamics governing plant-herbivore interactions in dioecious systems.

Mortality by road transport injury in Brazilian municipalities between 2000 and 2018

ObjectivesThis study aimed to investigate patterns of mortality by road transport injury (RTI) in Brazilian municipalities, focused on deaths of motorcyclists, between 2000 and 2018, and their relation with population size and economic status. Study designThis was an ecological epidemiological study with a descriptive and analytical nature. MethodsThe age-standardized RTI mortality rates were calculated for the Brazilian municipalities, referring to the 3-year periods of 2000/2002 (T1), 2009/2011 (T2), and 2016/2018 (T3). The rates were stratified according to macroregion and population size and were compared in terms of percentage variation from one 3-year period to another. The Moran Global and Local indices were used in the spatial point-pattern analysis of the rates. To verify the association with the gross domestic product (GDP) per capita, the Spearman correlation coefficient was applied. ResultsA decline in RTI mortality rates was found between 2000 and 2018, with the most significant declines observed in municipalities from the South and Southeast regions of Brazil. However, increases were observed among motorcyclists. Clusters of municipalities were detected, which presented high mortality rates among the motorcyclists in the Northeast region and in some states of the North and Midwest regions. The mortality rates showed a negative correlation with the GDP per capita of the Brazilian municipalities. ConclusionsAlthough there were decreases in RTI mortality rates between 1990 and 2018, there was a significant increase in deaths among motorcyclists, especially in the Northeast, North, and Midwest regions of the country. Such differences can be explained by unequal growth in the size of the motorcycle fleet in those regions, by less law enforcement capability, and by the implementation of educational actions.

Quantitative Single-Molecule Localization Microscopy.

Super-resolution fluorescence microscopy allows the investigation of cellular structures at nanoscale resolution using light. Current developments in super-resolution microscopy have focused on reliable quantification of the underlying biological data. In this review, we first describe the basic principles of super-resolution microscopy techniques such as stimulated emission depletion (STED) microscopy and single-molecule localization microscopy (SMLM), and then give a broad overview of methodological developments to quantify super-resolution data, particularly those geared toward SMLM data. We cover commonly used techniques such as spatial point pattern analysis, colocalization, and protein copy number quantification but also describe more advanced techniques such as structural modeling, single-particle tracking, and biosensing. Finally, we provide an outlook on exciting new research directions to which quantitative super-resolution microscopy might be applied.

Drilling predation on Early Jurassic bivalves and behavioral patterns of the presumed gastropod predator—evidence from Pliensbachian soft-bottom deposits of northern Germany

AbstractDrilling predation is a common reason for mortality of benthic mollusks but did not become common until the late Mesozoic. The scarcity of drill holes in the early Mesozoic fossil record limits our understanding of the evolution of drilling behavior and its role on shaping early Mesozoic marine communities. Here, we use drilling traces on several bivalve taxa from the Lower Jurassic (Pliensbachian) marine soft-bottom deposits in northern Germany to explore behavioral patterns of the predator (e.g., site selectivity, change in site-selective behavior with age). Although none of the known drilling gastropod groups existed in the Pliensbachian, including the studied localities, the drill-hole morphology suggests that the predator was probably a gastropod. The ecology and identity of the target prey changes from a diverse array of epifaunal to infaunal taxa in older deposits to focus on a single, large, deep infaunal taxon, Gresslya intermedia, in younger deposits, suggesting a potential trend in prey selectivity over time. Spatial point pattern analysis of traces (SPPAT) reveals an aggregated pattern of drill holes on Gresslya, suggesting strong selectivity in drill-hole location. Drilling on a single large infaunal taxon and site selectivity are common patterns also inferred previously from the drilled deep infaunal Eothyasira from the Pliensbachian of southern Germany. In addition to the scarcity of predators, the highly specialized behavior of the early drilling predators, including strong prey selectivity in terms of prey identity and life habit, can partly explain the rarity of the early Mesozoic drill holes.

Quantifying the Morphology and Mechanisms of Cancer Progression in 3D In-Vitro Environments: Integrating Experiments and Multiscale Models.

Mathematical models of cancer growth have become increasingly more accurate both in the space and time domains. However, the limited amount of data typically available has resulted in a larger number of qualitative rather than quantitative studies. In the present study, we provide an integrated experimental-computational framework for the quantification of the morphological characteristics and the mechanistic modelling of cancer progression in 3D environments. The proposed framework allows for the calibration of multiscale, spatiotemporal models of cancer growth using state-of-the-art 3D cell culture data, and their validation based on the resulting experimental morphological patterns using spatial point-pattern analysis techniques. We applied this framework to the study of the development of Triple Negative Breast Cancer cells cultured in Matrigel scaffolds, and validated the hypothesis of chemotactic migration using a multiscale, hybrid Keller-Segel model. The results revealed transient, non-random spatial distributions of cancer cells that consist of clustered, and dispersion patterns. The proposed model was able to describe the general characteristics of the experimental observations and suggests that chemotactic migration together with random motion was found to be a plausible mechanism leading to accumulation, during the examined time period of development. The developed framework enabled us to pursue two goals; first, the quantitative description of the morphology of cancer growth in 3D cultures using point-pattern analysis, and second, the relation of tumour morphology with underlying biophysical mechanisms that govern cancer growth and migration.

Spatial facilitation and competition regulate tree species assembly in a tropical dry forest

Analyzing the spatial association pattern among species can help to better understanding the mechanisms that drive forest dynamics and assembly. We applied techniques of spatial point pattern analysis to data from a fully mapped plot of tropical dry forest (TDF) in Colombia to assess the spatial association network among the eight most abundant species and we tested the hypothesis that species traits related to the ability to cope with drought stress could explain the observed spatial association patterns. We conducted three analyses, first we classified the types of spatial association patterns of species pairs against a null model of spatial independence, second, we used a heterogeneous Poisson (HP) null-model to assess competitive and facilitative interactions, and finally, we integrated the spatial association network with a traits space spanned by hydraulic functional traits. Overall, the proportion of significant negative and positive associations were low and we found at smaller spatial scales (5 m) prevalence of positive association patterns (11%) and at intermediate scales (16 m) negative interactions (13%). The dominant, evergreen and bird-dispersed species Trichilia oligofoliata, which followed a hydraulically save strategy, was involved in most positive associations at small scales, whereas the evergreen large statured species Aspidosperma polyneuron, which also follows a conservative resource-use strategy, was involved in most negative interactions. In TDFs where water stress is prevalent, tree community assembly and spatial patterns formation are regulated by environmental heterogeneity (e.g., topography), and both facilitative and competitive processes act simultaneously, but at different spatial scales and involving different species. Our findings highlight the potential importance of the examined association patterns, not only for our understanding of community assembly, but also to provide restoration directions.

Stomatal distribution pattern for 90 species in Loess Plateau – Based on replicated spatial analysis

Stomata are the valves controlling carbon and water exchange between plant leaves and the atmosphere. Stomatal position changes throughout the whole growth of leaves, and the position is gradually fixed until the leaves mature, whether stomatal spatial distributions exhibit clear patterning remains unclear. In this study, we measured stomatal density and stomatal position of 90 widespread plants from the Loess Plateau, quantifying the spatial patterns of stomatal distribution using replicated spatial point pattern analysis. The results showed that the stomatal distribution pattern was similar in all plants except five species (Ginkgo biloba, Festuca glauca, Hemerocallis fulva, Hylotelephium spectabile and Kochia scoparia). Stomatal density, aggregation and uniform distribution were slightly affected by phylogeny and depended on spatial scale of analysis. At small spatial scales (0–60 μm), were regularly distributed but at large spatial scales (60–400 µm) they were randomly distributed. Stomatal density was negatively correlated (p < 0.001) with the proportion of randomly distributed and positively correlated (p < 0.001) with the proportion of stomatal aggregated distributed, and no significant effect on the proportion of stomatal uniform distribution. These results highlight the linkages between stomatal distribution and phylogeny, which may provide reference for future optimization of transpiration models.

Spatial distributions of Tribrachidium, Rugoconites, and Obamus from the Ediacara Member (Rawnsley Quartzite), South Australia

AbstractThe spatial distribution of in situ sessile organisms, including those from the fossil record, provides information about life histories, such as possible dispersal and/or settlement mechanisms, and how taxa interact with one another and their local environments. At Nilpena Ediacara National Park (NENP), South Australia, the exquisite preservation and excavation of 33 fossiliferous bedding planes from the Ediacara Member of the Rawnsley Quartzite reveals in situ communities of the Ediacara Biota. Here, the spatial distributions of three relatively common taxa, Tribrachidium, Rugoconites, and Obamus, occurring on excavated surfaces were analyzed using spatial point pattern analysis. Tribrachidium have a variable spatial distribution, implying that settlement or post-settlement conditions/preferences had an effect on populations. Rugoconites display aggregation, possibly related to their reproductive methods in combination with settlement location availability at the time of dispersal and/or settlement. Additionally, post-settlement environmental controls could have affected Rugoconites on other surfaces, resulting in lower populations and densities. Both Tribrachidium and Rugoconites also commonly occur as individuals or in low numbers on a number of beds, thus constraining possible reproductive strategies and environmental/substrate preferences. The distribution of Obamus is consistent with selective settlement, aggregating near conspecifics and on substrates of mature microbial mat. This dispersal process is the first example of substrate-selective dispersal among the Ediacara Biota, thus making Obamus similar to numerous modern sessile invertebrates with similar dispersal and settlement strategies.

Multi-GPU-Parallel and Tile-Based Kernel Density Estimation for Large-Scale Spatial Point Pattern Analysis

Kernel density estimation (KDE) is a commonly used method for spatial point pattern analysis, but it is computationally demanding when analyzing large datasets. GPU-based parallel computing has been adopted to address such computational challenges. The existing GPU-parallel KDE method, however, utilizes only one GPU for parallel computing. Additionally, it assumes that the input data can be held in GPU memory all at once for computation, which is unrealistic when conducting KDE analysis over large geographic areas at high resolution. This study develops a multi-GPU-parallel and tile-based KDE algorithm to overcome these limitations. It exploits multiple GPUs to speedup complex KDE computation by distributing computation across GPUs, and approaches density estimation with a tile-based strategy to bypass the memory bottleneck. Experiment results show that the parallel KDE algorithm running on multiple GPUs achieves significant speedups over running on a single GPU, and higher speedups are achieved on KDE tasks of a larger problem size. The tile-based strategy renders it feasible to estimate high-resolution density surfaces over large areas even on GPUs with only limited memory. Multi-GPU parallel computing and tile-based density estimation, while incurring very little computational overhead, effectively enable conducting KDE for large-scale spatial point pattern analysis on geospatial big data.

Trees species’ dispersal mode and habitat heterogeneity shape negative density dependence in a temperate forest

Conspecific negative density dependence (CNDD) is a potentially important mechanism in maintaining species diversity. While previous evidence showed habitat heterogeneity and species’ dispersal modes affect the strength of CNDD at early life stages of trees (e.g., seedlings), it remains unclear how they affect the strength of CNDD at later life stages. We examined the degree of spatial aggregation between saplings and trees for species dispersed by wind and gravity in four topographic habitats within a 25-ha temperate forest dynamic plot in the Qinling Mountains of central China. We used the replicated spatial point pattern (RSPP) analysis and bivariate pair-correlation function (PCF) to detect the spatial distribution of saplings around trees at two scales, 15 and 50 ​m, respectively. Although the signal was not apparent across the whole study region (or 25-ha), it is distinct on isolated areas with specific characteristics, suggesting that these characteristics could be important factors in CNDD. Further, we found that the gravity-dispersed tree species experienced CNDD across habitats, while for wind-dispersed species CNDD was found in gully, terrace and low-ridge habitats. Our study suggests that neglecting the habitat heterogeneity and dispersal mode can distort the signal of CNDD and community assembly in temperate forests.

Covariate construction of nonconvex windows for spatial point patterns

In some standard applications of spatial point pattern analysis, window selection for spatial point pattern data is complex. Often, the point pattern window is given a priori. Otherwise, the region is chosen using some objective means reflecting a view that the window may be representative of a larger region. The typical approaches used are the smallest rectangular bounding window and convex windows. The chosen window should however cover the true domain of the point process since it defines the domain for point pattern analysis and supports estimation and inference. Choosing too large a window results in spurious estimation and inference in regions of the window where points cannot occur. We propose a new algorithm for selecting the point pattern domain based on spatial covariate information and without the restriction of convexity, allowing for better estimation of the true domain. Amodified kernel smoothed intensity estimate that uses the Euclidean shortest path distance is proposed as validation of the algorithm. The proposed algorithm is applied in the setting of rural villages in Tanzania. As a spatial covariate, remotely sensed elevation data is used. The algorithm is able to detect and filter out high relief areas and steep slopes; observed characteristics that make the occurrence of a household in these regions improbable. Keywords: Covariate, Euclidean shortest path, Nonconvex, Spatial point pattern, Window selection

Abstract PR001: Spatial proximity between CD8+ T cells and tumor cells correlates with invasive recurrence in DCIS

Abstract Purpose: The immune microenvironment in ductal carcinoma in situ (DCIS) and its significance are not well established. In this study, we characterized the immune microenvironment of DCIS to determine if immune cell densities, or their spatial relationships with tumor cells, are predictive of recurrence with invasive breast cancer. Methods: One hundred thirty-two cases of DCIS were included in this study. Seventy (53%) cases were high grade, 72 (54%) were HER2+, and 91 (69%) were HR+. Twenty cases recurred with invasive breast cancer. Immune infiltrates were characterized by multiplex immunofluorescence staining of FFPE sections using two 6-plex panels. Panel IP1.2 included markers for CD3, CD20, Foxp3, pan-cytokeratins, Ki67, and HLADR. Panel IP2.2 included markers for CD3, CD8, CD68, pan-cytokeratins, PD-1, and PD-L1. Staining was performed on a Leica Bond autostainer and images were acquired on a Vectra Polaris imaging system. Image analysis was performed utilizing inForm and QuPath software packages, as well as R scripts. Counts for each cell population were determined and spatial point pattern analyses were performed to quantitate the spatial relationships between tumor cells and various immune cell types. Results: High infiltrates of T cells, CD8+ T cells (Tc), Foxp3+ T cells, and B cells were associated with high grade, hormone receptor (HR) negativity, HER2 positivity, and the presence of comedonecrosis. PD-1+ T cells and PD-1+ Tc were associated with high grade, HR negativity, and HER2 positivity. PD-L1+ immune cells, but not PD-L1+ tumor cells, were also associated with high grade, HR negativity, and HER2 positivity. None of the cell populations were associated with invasive recurrence. However, the spatial proximity of tumor cells with T cells, in particular Tc, was significantly associated with a subsequent invasive event. Patients whose DCIS had a high tumor-to-Tc proximity score (indicating close proximity of tumor and Tc) were less likely to have an invasive recurrence. Conclusion: These findings suggest that the tumor immune microenvironment is an important factor in identifying DCIS cases at risk for invasive recurrence and that manipulating the immune microenvironment may be an efficacious strategy to alter or prevent disease progression. Citation Format: Michael J. Campbell, Nicole Schindler, Alexa Glencer, Jennifer Bolen, Hidetoshi Mori, Tristan Loveday, Harriet Rothschild, Gillian Hirst, Scott Vandenberg, Alexander Borowsky, Laura Esserman. Spatial proximity between CD8+ T cells and tumor cells correlates with invasive recurrence in DCIS [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr PR001.

Intermediate-severity disturbance impacts in a mixedwood forest: A multi-scale analysis

Mixed Quercus-Pinus stands are increasingly desired by forest managers to achieve a range of objectives, including biodiversity enhancement and resilience to global change. To create and perpetuate desired mixed Quercus-Pinus stand composition and structure, quantitative information on natural disturbance impacts on stand development and succession is necessary. Wind is the most common natural canopy disturbance in eastern North America, and impacts vary in severity and spatiotemporal scales. Intermediate-severity disturbance (ISD; events that occur along a classification gradient between frequent gap-scale and infrequent, stand-replacing events) is hypothesized to be an important driver of mixed Quercus-Pinus creation and maintenance. Our overarching goal was to quantify patterns of intermediate-severity wind disturbance in a mixed Quercus-Pinus echinata Mill. forest on the Cumberland Plateau in Tennessee, USA. Specifically, our objectives were to: 1) quantify post-disturbance species composition, stand structure, and residual tree spatial patterns, 2) infer individual-tree, neighborhood, and site-specific impacts on tree mortality, and 3) describe frequency, size, shape, and spatial distribution of ISD-created canopy openings. We inventoried plots in Pinus echinata-dominated, disturbance-impacted portions of the forest. To infer individual-tree and spatially-explicit neighborhood characteristics that influenced survival probability, we applied a random forest classification algorithm. To document changes in tree spatial distribution before and after disturbance, we used spatial point pattern analysis. To characterize forest-scale disturbance patterns, we classified canopy gaps from high-resolution orthoimagery. The most important predictors of survival were basal area, taxonomic group, and distance to nearest neighbor. Pre-disturbance trees and residuals were spatially randomly distributed. Most detected openings were 50–150 m2, and the opening size-frequency distribution exhibited a reverse J-shape. Openings were spatially clustered within the forest at distances < 200 m and complex in shape. We provide quantitative recommendations on the frequency, size, shape, and spatial distribution of silvicultural entries patterned after natural disturbance. To emulate natural disturbance patterns, we recommend patch seedtree harvests with reserves or patch clearcuts with reserves, and these harvest-created openings should be concentrated (i.e., clustered) in portions of the stand in which P. echinata is most dominant and/or most competitive. Site preparation with prescribed fire, herbicide, and/or mechanical thinning may also be necessary to prepare the seedbed and reduce hardwood competition to favor Pinus establishment in openings.

Effects of tree mortality on the spatial patterns and interspecific associations of individuals in karst evergreen deciduous broad-leaved mixed forests

Tree mortality is an important ecological process in forests. It is crucial to understand how tree mortality affects spatial patterns and interspecific associations for revealing the mechanisms of tree mortality and community dynamics. We employed the correlation method of spatial point pattern analysis to analyse the variations in spatial patterns and interspecific relations before and after mortality using data obtained from two surveys of a 25 hm2 plot in the Mulun National Natural Reserve, China. The results showed that most species had an aggregated distribution both pre- and post-mortality. The proportion of species with aggregated distribution reduced slightly post-mortality compared with that for pre-mortality. Increases in the number of species with random distribution at small scale indicated that tree death was not random. At the species level, there were significant positive associations between dead and live trees of the 13 common species at different levels of 0-30 m range, suggesting weak intraspecific and interspecific competition among dominant species. Pre- and post-mortality interspecific associations were mostly positive, which remained stable during the period of two surveys for most species, indicating that the community had reached a rather stable stage. Following tree mortality, the number of species with positive associations increased at 1-30 m scales, whereas the number of species with negative and no associations decreased at most scales. These results indicated that the pressure of interspecific competition was relieved to some extent after individual death.

Spatial phylogenetic and phenotypic patterns reveal ontogenetic shifts in ecological processes of plant community assembly

The analysis of the spatial phylogenetic and phenotypic structure of plant communities can provide insight into the underlying processes and interactions governing their assembly, and how these may change during plant ontogeny. We used point pattern analysis to find out if saplings and adult plants are surrounded by phylogenetically and phenotypically more similar or more dissimilar neighbours than expected by chance, and whether these associations change from the sapling to the adult stage. To this end, we combined information on the phylogenetic structure and eight phenotypic traits of 15 woody plant species in two Mediterranean mixed forests of southeastern Spain. At the community level, we found that the sapling bank at both sites did not show phylogenetic or phenotypic spatial patterns, but adults showed phylogenetic clustering (i.e. heterospecific neighbours were more similar than expected). At the species level, we found frequently repulsive patterns in the sapling bank of less abundant species (i.e. heterospecific sapling or adult neighbours were more dissimilar than expected) in both, phylogenetic and phenotypic analyses. For the adult stage, we found phylogenetic attraction (i.e. more similar neighbours) in just one species and phenotypic clustering in four species. The processes driving the assembly of the communities of saplings and adults leave detectable signals in the spatial phylogenetic and phenotypic structure of our two forest communities. Our findings reinforce the existence of ontogenetic shifts in the mechanisms involved in plant community assembly. Facilitation between phylogenetically distant and phenotypically divergent species favours the recruitment of less abundant species. However, processes acting later in the ontogeny ameliorate the competition between close relatives and determine the spatial structure of adult plants. Nevertheless, the role of phenotype in shaping the interactions between adult plants was context‐ and trait‐dependent. The use of spatial point pattern analysis allowed a nuanced interpretation of the phylogenetic and phenotypic structures of plant communities.

Size and location of host‐plant shape the spatial pattern of forest insect

Abstract Insect–host relationships can generate spatial patterns. The effect of plant species has been widely investigated, whereas the effect of plant size was ignored. The authors characterized the spatial pattern of the swift moth Endoclita excrescens Butler by combining spatial analysis by distance indices (SADIE) and spatial point pattern analysis (SPPA). Two contiguous plots of monospecific plantations of Manchurian ash Fraxinus mandshurica with different diameters at breast height (DBH) were sampled, and the position, DBH, and count of attack holes of each ash tree were recorded. The aggregation at the landscape scale is far stronger than those at the stand scale. At the landscape scale, trees with small number of bored holes were close to each other at distances of r &lt; 4 m. None of the significant patterns were found at the stand scale. SADIE results showed a strong association between count of attack holes and DBH at the landscape scale, whereas weak association at the stand scale. SPPA results showed that, either at the landscape or stand scale, the locations of ash trees were randomly distributed at small distance, but aggregated at large distance. The counts of holes are only dependent on the point (tree) at small distances (r &lt; 2.5 m) at the landscape scale. These results provide basic information for sampling and precision‐targeted controlling programs.

Environment and density-dependency explain the fine-scale aggregation of tree recruits before and after thinning in a mixed forest of Southern Europe.

Thinning in forest management primarily reduces the density of trees and alters the patchiness and spatial complexity of environmental factors and individual interactions between plant recruits. At fine spatial scales, little is known about the relative weight of ecological processes affecting tree regeneration before and after thinning events. Here we studied the density and aggregation of tree recruits in fully-mapped plots located in mixed forests in Northern Iberian Peninsula (Southern Europe) for over four years, which comprises one year before and three years after a thinning event. We applied spatial point-pattern analyses to examine (a) the aggregation of recruits, and their association with trees and (b) the relative effect of both environmental (i.e., the patchiness of the local environment) and density-dependent factors (i.e., the aggregation of trees and/or recruits) to predict the density, aggregation, and survival of recruits. We found, in thinning plots, that recruits were less dense, their aggregation pattern was more heterogeneous, were distributed randomly in respect of trees and their survival was almost unaffected by the tree proximity. By contrast, recruits in control plots were denser, were only aggregated at distances lower than 1.0 m, were closer to trees, and such closer distance to trees affected negatively in their survival. Independently of the treatment, the aggregation of recruits was chiefly determined by the density-dependent factors at less than 1.0 m and environmental factors at distances beyond that proximity. Overall, our results suggest that thinning affected the aggregation of recruits at two spatial scales: (a) by favoring the tree-recruit and recruit-recruit facilitation at less than 1.0 m and (b) by modifying spatial heterogeneity of the environment at distances beyond that proximity.