Negative density dependence and environmental heterogeneity effects on tree ferns across succession in a tropical montane forest.

Although tree ferns are an important component of temperate and tropical forests, very little is known about their ecology. Their peculiar biology (e.g., dispersal by spores and two-phase life cycle) makes it difficult to extrapolate current knowledge on the ecology of other tree species to tree ferns. In this paper, we studied the effects of negative density dependence (NDD) and environmental heterogeneity on populations of two abundant tree fern species, Cyathea caracasana and Alsophila engelii, and how these effects change across a successional gradient. Species patterns harbor information on processes such as competition that can be easily revealed using point pattern analysis techniques. However, its detection may be difficult due to the confounded effects of habitat heterogeneity. Here, we mapped three forest plots along a successional gradient in the montane forests of Southern Ecuador. We employed homogeneous and inhomogeneous K and pair correlation functions to quantify the change in the spatial pattern of different size classes and a case-control design to study associations between juvenile and adult tree ferns. Using spatial estimates of the biomass of four functional tree types (short- and long-lived pioneer, shade- and partial shade-tolerant) as covariates, we fitted heterogeneous Poisson models to the point pattern of juvenile and adult tree ferns and explored the existence of habitat dependencies on these patterns. Our study revealed NDD effects for C. caracasana and strong environmental filtering underlying the pattern of A. engelii. We found that adult and juvenile populations of both species responded differently to habitat heterogeneity and in most cases this heterogeneity was associated with the spatial distribution of biomass of the four functional tree types. These findings show the effectiveness of factoring out environmental heterogeneity to avoid confounding factors when studying NDD and demonstrate the usefulness of covariate maps derived from mapped communities

Maintaining distances with the engineer: patterns of coexistence in plant communities beyond the patch-bare dichotomy

Two-phase plant communities with an engineer conforming conspicuous patches and affecting the performance and patterns of coexisting species are the norm under stressful conditions. To unveil the mechanisms governing coexistence in these communities at multiple spatial scales, we have developed a new point-raster approach of spatial pattern analysis, which was applied to a Mediterranean high mountain grassland to show how Festuca curvifolia patches affect the local distribution of coexisting species. We recorded 22 111 individuals of 17 plant perennial species. Most coexisting species were negatively associated with F. curvifolia clumps. Nevertheless, bivariate nearest-neighbor analyses revealed that the majority of coexisting species were confined at relatively short distances from F. curvifolia borders (between 0-2 cm and up to 8 cm in some cases). Our study suggests the existence of a fine-scale effect of F. curvifolia for most species promoting coexistence through a mechanism we call 'facilitation in the halo'. Most coexisting species are displaced to an interphase area between patches, where two opposite forces reach equilibrium: attenuated severe conditions by proximity to the F. curvifolia canopy (nutrient-rich islands) and competitive exclusion mitigated by avoiding direct contact with F. curvifolia

Plant trait and vegetation data along a 1314 m elevation gradient with fire history in Puna grasslands, Perú

Alpine grassland vegetation supports globally important biodiversity and ecosystems that are increasingly threatened by climate warming and other environmental changes. Trait-based approaches can support understanding of vegetation responses to global change drivers and consequences for ecosystem functioning. In six sites along a 1314 m elevational gradient in Puna grasslands in the Peruvian Andes, we collected datasets on vascular plant composition, plant functional traits, biomass, ecosystem fluxes, and climate data over three years. The data were collected in the wet and dry season and from plots with different fire histories. We selected traits associated with plant resource use, growth, and life history strategies (leaf area, leaf dry/wet mass, leaf thickness, specific leaf area, leaf dry matter content, leaf C, N, P content, C and N isotopes). The trait dataset contains 3,665 plant records from 145 taxa, 54,036 trait measurements (increasing the trait data coverage of the regional flora by 420%) covering 14 traits and 121 plant taxa (ca. 40% of which have no previous publicly available trait data) across 33 families

Data from: Evidence for a stochastic geometry of biodiversity: the effects of species abundance, richness and intraspecific clustering

Most ecological theories that aim to explain coexistence in megadiverse communities employ a set of three rules to describe the stochastic geometry of biodiversity: (i) individuals exhibit intraspecific clustering; (ii) species abundances vary according to a log-normal distribution and (iii) the spatial arrangement between species is independent. The first two rules have received strong empirical support, but the third remains largely unexplored. To address this deficiency, we evaluated the independent species arrangement rule in a species-rich shrubland and its potential drivers, that is, the levels of species richness and intraspecific clustering exhibited by a given species at different scales, and the relative abundance of such species in the community. We found that interspecific associations were rare and that independence was positively related to species richness and intraspecific clustering, but negatively related to relative species abundances. Synthesis. Our results agree with the independent species arrangement rule and they provide empirical support for the stochastic geometry of biodiversity. In the context of species-rich plant communities, the likelihood of two species encountering is very small. However, our study demonstrated a novel feature of this context, where both intraspecific clustering (due limitations on dispersal) and relative species abundances play fundamental roles in determining the probability of two species encountering and interacting, especially at very fine spatial scales

Data from: A new non-parametric method for analyzing replicated point patterns in ecology

Most ecological studies that involve point pattern analyses are based on a single plot, which prevent the separation of the effects of various processes that could act simultaneously, as well as limiting the conclusions that can be extracted from these studies. However, considering the spatial distribution of individuals in several plots as replicates of the same process could help to differentiate its specific effects from those of other confounding processes. Thus, we introduce a new method for analyzing spatial point patterns that are replicated according to a two–factorial design. By summarizing the spatial patterns as K–functions, the proposed method computes the average K–functions for each level of the two factors (i.e., predictors) and for each combination of levels, before estimating the sum of squared deviations from the overall mean K–function. Inferences of the strength of the relationship between the predictors, their interaction, and the spatial structure are made based on a non–parametric bootstrap procedure, which considers the dependency among spatial scales. We illustrate the proposed approach based on an analysis of the effects of altitude (with two levels: low and high) and slope (with two levels: flat and steep slopes) on the spatial pattern of Croton wagneri, a dominant shrub in an Andean dry scrubland. Our method detected a significant effect of the interaction between slope and altitude, which could not have been detected using current point pattern analysis methodology. The prevalence of single–plot analysis in ecological studies may be due to a lack of familiarity with appropriate methods for replicated point patterns, as well as the greater complexity of these methods and the absence of appropriate software. Our approach can be applied to a significant number of ecological questions while maintaining a simple, understandable, and easily reportable methodological framework

Individual species affect plant traits structure in their surroundings: evidence of functional mechanisms of assembly

This study was partially supported by projects CGL2009-13190-C03-02 (ISLAS ESPACIO), CGL2012-38427 (MOUNTAINS) and REMEDINAL2 (P2009/AMB-1783). J.C.L. was supported by a FPI Grant linked to project CGL-2009-13190 (ISLAS), which was awarded by the Spanish Ministry of Economy and Competitiveness. We thank Carlos Díaz for his valuable assistance in field and laboratory work, and Marcos Méndez for his valuable comments and suggestions regarding Fig. 1. We also thank Alex Fajardo, Eric Marcon and an anonymous reviewer for their valuable comments on a previous version.Evaluating community assembly through the use of functional traits is a promising tool for testing predictions arising from Niche and Coexistence theories. Although interactions among neighboring species and their inter-specific differences are known drivers of coexistence with a strong spatial signal, assessing the role of individual species on the functional structure of the community at different spatial scales remains a challenge. Here, we ask whether individual species exert a measurable effect on the spatial organization of different functional traits in local assemblages. We first propose and compute two functions that describe different aspects of functional trait organization around individual species at multiple scales: individual weighted mean area relationship and individual functional diversity area relationship. Secondly, we develop a conceptual model on the relationship and simultaneous variation of these two metrics, providing five alternative scenarios in response to the ability of some target species to modify its neighbor environment and the possible assembly mechanisms involved. Our results show that some species influence the spatial structure of specific functional traits, but their effects were always restricted to the finest spatial scales. In the basis of our conceptual model, the observed patterns point to two main mechanisms driving the functional structure of the community at the fine scale, “biotic” filtering meditated by individual species and resource partitioning driven by indirect facilitation rather than by competitive mechanisms.Depto. de Farmacología, Farmacognosia y BotánicaFac. de FarmaciaTRUEpu

Plant domestication disrupts biodiversity effects across major crop types

ISSN:1461-023XISSN:1461-024

Shrubs locations

Spatial coordinates corresponding to 7865 individuals belonging to 48 species of perennial shrubs and grasses

Tales from the underground: Soil heterogeneity and not only above-ground plant interactions explain fine-scale species patterns in a Mediterranean dwarf-shrubland

8 Pág.Questions: The current paradigm of plant community assembly relies on a set of processes operating at particular spatial scales. It is assumed that as the spatial scale becomes finer, environmental filtering loses its importance in favor of biotic interactions and neutral processes. Thus, at the very fine spatial scale represented by a rectangular plot of 72.25 m2 in a Mediterranean semiarid dwarf-shrubland, we ask: (a) are the spatial distributions of individuals of the different species explained by neutral models; (b) are these distributions dependent on above-ground plant interactions with the dominant species in the community; and/or (c) are they responding to the spatial variation of different soil variables, in a kind of fine-scale environmental filtering?. Location: Central Spain. Methods: To assess the correlates of fine-scale (i.e., from 0.05–2.00 m) spatial patterns of the species in the community, we fully mapped all perennial individuals inside the rectangular plot. For each species, we fitted one complete spatial randomness (CSR) model that does not assume spatial heterogeneity and three weighted-average inhomogeneous Poisson process (IPP) models using six soil covariates, distribution patterns of the four above-ground dominant plants in the community or both types of covariates. All models were evaluated and compared to select the best-fitting weighted-average model. Results: We recorded 7,988 individuals of 22 species. Patterns of all species were appropriately explained by IPP models. For most species the best-fitting weighted-average model included both soil and dominant plants (i.e., 15) or only soil covariates (i.e., 6). The improvement provided by the best-fitting weighted-averaging model in comparison with the CSR model was consistently high (81%). Conclusions: Our approach suggests that species in this dwarf-shrubland are mainly structured by soil heterogeneity and modulated in some cases by the interactions established with the dominant species.This study was supported by the projects Islas-Espacio (CGL2009-13190-C03-02), REMEDINAL TE-CM (S2018/EMT-4338) and ROOTS (CGL2015-66809-P)Peer reviewe

Tales from the underground: Soil heterogeneity and not only above‐ground plant interactions explain fine‐scale species patterns in a Mediterranean dwarf‐shrubland

We thank Carlos Díaz, Nacho de la Paz and Sara Aguilar for their help with fieldwork and in the laboratory. The co-ordinating Editor (Sándor Bartha) and three anonymous reviewers provided useful and detailed suggestions to improve the manuscript.Questions The current paradigm of plant community assembly relies on a set of processes operating at particular spatial scales. It is assumed that as the spatial scale becomes finer, environmental filtering loses its importance in favor of biotic interactions and neutral processes. Thus, at the very fine spatial scale represented by a rectangular plot of 72.25 m2 in a Mediterranean semiarid dwarf-shrubland, we ask: (a) are the spatial distributions of individuals of the different species explained by neutral models; (b) are these distributions dependent on above-ground plant interactions with the dominant species in the community; and/or (c) are they responding to the spatial variation of different soil variables, in a kind of fine-scale environmental filtering? Location Central Spain. Methods To assess the correlates of fine-scale (i.e., from 0.05–2.00 m) spatial patterns of the species in the community, we fully mapped all perennial individuals inside the rectangular plot. For each species, we fitted one complete spatial randomness (CSR) model that does not assume spatial heterogeneity and three weighted-average inhomogeneous Poisson process (IPP) models using six soil covariates, distribution patterns of the four above-ground dominant plants in the community or both types of covariates. All models were evaluated and compared to select the best-fitting weighted-average model. Results We recorded 7,988 individuals of 22 species. Patterns of all species were appropriately explained by IPP models. For most species the best-fitting weighted-average model included both soil and dominant plants (i.e., 15) or only soil covariates (i.e., 6). The improvement provided by the best-fitting weighted-averaging model in comparison with the CSR model was consistently high (81%). Conclusions Our approach suggests that species in this dwarf-shrubland are mainly structured by soil heterogeneity and modulated in some cases by the interactions established with the dominant species.Islas-Espacio projectREMEDINAL TE-CMROOTSDepto. de Farmacología, Farmacognosia y BotánicaFac. de FarmaciaTRUEpu