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

Chacón‐Labella, Julia; Cruz, Marcelino de la; Vicuña, Rafael; Tapia, Karla; Escudero, Adrián

doi:10.1016/j.ppees.2014.02.003

Cited by 25 publications

(28 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Another possible explanation for the scarcity of accumulators among the adult class could be that the recruitment of adults and young trees had occurred under different environmental conditions. For example, adults could have recruited after some perturbation whereas juveniles would have recruited in more stable conditions (Chacón‐Labella et al ). We have no information about recent disturbances in the REA, but the incidence of extreme climatic events such as ENSO fluctuations could not be ruled out.…”

Section: Discussionmentioning

confidence: 99%

The effects of individual tree species on species diversity in a tropical dry forest change throughout ontogeny

Espinosa

Cruz²,

Jara‐Guerrero

et al. 2015

Ecography

View full text Add to dashboard Cite

Understanding how diversity is maintained in species‐rich communities, such as tropical forests, remains a challenge in ecology. Recent work suggests that the controversy between competing theories could be better resolved by considering the spatial scale at which different processes rule community assembly. Here we use individual species–area relationships (ISAR) to evaluate the spatial organization of tree diversity around individuals of different species in a completely‐mapped tropical dry forest in south Ecuador. We test two hypotheses. First, stressful environmental conditions promote facilitative interactions that will generate spatial signals of accumulation of diversity around individual trees – contrary to what has been reported in humid tropical forests. Second, spatial signals will shift through ontogeny. As, as larger, older trees generate new microsite conditions that affect the recruitment of younger, smaller trees. We compute ISAR functions for adult trees, for young trees and a new crossed‐ISAR function measuring the accumulation of diversity of young trees around the old trees. We compare observed ISARs to the expectations of inhomogeneous Poisson (i.e. null) models controlling for the effects of environmental variation and habitat association on tree distribution. Although the prevalent response among adult trees was not different from null expectations, which means that the organization of diversity in this size class could be explained by environmental heterogeneity alone, most species accumulated more diversity than expected over short spatial scales in the small stem size class. Only two species accumulated significant diversity in the crossed‐ISARs. Our study indicates the role of facilitation in the organization of plant diversity in this dry forest, but that facilitation is limited to some key species acting on early life stages and accumulating diversity around them. Our results demonstrate the benefit of considering different life‐stages and crossed analyses to disentangle the processes affecting community assembly in tropical dry forests.

show abstract

Section: Discussionmentioning

confidence: 99%

The effects of individual tree species on species diversity in a tropical dry forest change throughout ontogeny

Espinosa

Cruz²,

Jara‐Guerrero

et al. 2015

Ecography

View full text Add to dashboard Cite

show abstract

“…Hence, if g aa ( r ) – g ar ( r ) = 0, adults would be surrounded by the same density of adults and recruits, indicating that adult and seedlings exploit the available habitat in the same way. Negative deviations at short scales would indicate increased recruitment in the proximity of adults, and thus, the existence of some facilitative effects of adults on seed germination or seedling establishment, while positive deviations would indicate segregation between adults and seedlings (Getzin et al , Chacón‐Labella et al ). A value of g rr ( r ) – g ra ( r ) >> 0, on the other hand, would indicate the existence of an additional clustering mechanism within recruits, independent of the control pattern of adults (Getzin et al ).…”

Section: Methodsmentioning

confidence: 99%

What causes conspecific plant aggregation? Disentangling the role of dispersal, habitat heterogeneity and plant–plant interactions

Lara‐Romero

Cruz

Escribano-Ávila

et al. 2016

Oikos

Self Cite

View full text Add to dashboard Cite

Spatial patterns of plant species are determined by an array of ecologica factors including biotic and abiotic environmental constraints and intrinsic species traits. Thus, an observed aggregated pattern may be the result of short‐distance dispersal, the presence of habitat heterogeneity, plant–plant interactions or a combination of the above. Here, we studied the spatial pattern of Mediterranean alpine plant Silene ciliata (Caryophyllaceae) in five populations and assessed the contribution of dispersal, habitat heterogeneity and conspecific plant interactions to observed patterns. For this purpose, we used spatial point pattern analysis combined with specific a priori hypotheses linked to spatial pattern creation. The spatial pattern of S. ciliata recruits was not homogeneous and showed small‐scale aggregation. This is consistent with the species’ short‐distance seed dispersal and the heterogeneous distribution of suitable sites for germination and establishment. Furthermore, the spatial pattern of recruits was independent of the spatial pattern of adults. This suggests a low relevance of adult‐recruits interactions in the spatial pattern creation. The difference in aggregation between recruits and adults suggests that once established, recruits are subjected to self‐thinning. However, seedling mortality did not erase the spatial pattern generated by seed dispersal, as S. ciliata adults were still aggregated. Thus, the spatial aggregation of adults is probably due to seed dispersal limitation and the heterogeneous distribution of suitable sites at seedling establishment rather than the presence of positive plant–plant interactions at the adult stage. In fact, a negative density‐dependent effect of the conspecific neighbourhood was found on adult reproductive performance. Overall, results provide empirical evidence of the lack of a simple and direct relationship between the spatial structure of plant populations and the sign of plant–plant interactions and outline the importance of considering dispersal and habitat heterogeneity when performing spatial analysis assessments.

show abstract

“…Significant deviations from a homogeneous Poisson process at scales r > 10 m are usually accepted as a confirmation of the existence of and environmental heterogeneity ruling the spatial pattern of forests trees (Wiegand and Moloney ; Chacón‐Labella et al. ). For each plot, we compared the L ‐function computed on the pattern of pine recruits with the 3rd lowest and 3rd highest value of 99 simulations of patterns generated by a homogeneous Poisson process.…”

Section: Methodsmentioning

confidence: 99%

Pine invasions in treeless environments: dispersal overruns microsite heterogeneity

Pauchard

Escudero

Garcı́a

et al. 2016

Ecology and Evolution

Self Cite

View full text Add to dashboard Cite

Understanding biological invasions patterns and mechanisms is highly needed for forecasting and managing these processes and their negative impacts. At small scales, ecological processes driving plant invasions are expected to produce a spatially explicit pattern driven by propagule pressure and local ground heterogeneity. Our aim was to determine the interplay between the intensity of seed rain, using distance to a mature plantation as a proxy, and microsite heterogeneity in the spreading of Pinus contorta in the treeless Patagonian steppe. Three one‐hectare plots were located under different degrees of P. contorta invasion (Coyhaique Alto, 45° 30′S and 71° 42′W). We fitted three types of inhomogeneous Poisson models to each pine plot in an attempt for describing the observed pattern as accurately as possible: the “dispersal” models, “local ground heterogeneity” models, and “combined” models, using both types of covariates. To include the temporal axis in the invasion process, we analyzed both the pattern of young and old recruits and also of all recruits together. As hypothesized, the spatial patterns of recruited pines showed coarse scale heterogeneity. Early pine invasion spatial patterns in our Patagonian steppe site is not different from expectations of inhomogeneous Poisson processes taking into consideration a linear and negative dependency of pine recruit intensity on the distance to afforestations. Models including ground‐cover predictors were able to describe the point pattern process only in a couple of cases but never better than dispersal models. This finding concurs with the idea that early invasions depend more on seed pressure than on the biotic and abiotic relationships seed and seedlings establish at the microsite scale. Our results show that without a timely and active management, P. contorta will invade the Patagonian steppe independently of the local ground‐cover conditions.

show abstract

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

Cited by 25 publications

References 53 publications

The effects of individual tree species on species diversity in a tropical dry forest change throughout ontogeny

The effects of individual tree species on species diversity in a tropical dry forest change throughout ontogeny

What causes conspecific plant aggregation? Disentangling the role of dispersal, habitat heterogeneity and plant–plant interactions

Pine invasions in treeless environments: dispersal overruns microsite heterogeneity

Contact Info

Product

Resources

About