Climate warming may weaken stabilizing mechanisms in old forests

Abstract

Plant competition may intensify with climate warming, but whether this will occur equally for conspecific and heterospecific competition remains unknown. Competitive shifts have the potential to instigate community change because the relative strengths of conspecific and heterospecific negative density dependence mediate the stabilizing mechanisms underpinning species coexistence.We examined a mature temperate forest to assess both direct and indirect climate effects at multiple scales: individual species, interspecies relationships, and community stability mechanisms. Our coupled approach (1) quantified tree mortality risk dependence on the interactive effects of competition, climatic water deficit, snowpack, and soil moisture for 28,913 trees over 8 years (3149 mortalities), then (2) used a climate-projection ensemble to forecast changes in conspecific and heterospecific competition from 2020 to 2100. We predict that projected climate warming will destabilize the foundational forest community by increasing the strength of heterospecific competition at a greater rate and to a greater degree than conspecific competition for four of five abundant tree species, particularly on dry microsites. Modeling showed that these findings were most pronounced after the year 2038, at which point snowpacks were projected to be too small to ameliorate the effects of drought on competitive interactions.Our finding that heterospecific competition is more sensitive than conspecific competition to climate warming may indicate the impending loss of ecosystem functioning. We join the growing body of work showing a predominance of indirect drought effects, yet coupled climate models still fail to consider how changing community dynamics may impact forest cover and, in turn, disrupt forest-climate carbon feedbacks. Ecosystems sharing characteristics with our example forest-those with low species richness and therefore a limited biodiversity insurance effect-may be similarly vulnerable to climate-mediated destabilization. In such communities, increased heterospecific competition among even a small number of species can more easily destabilize communities without recourse from redundant species. This study of an overlooked but vital mechanism of community change can be adapted by research in a range of ecosystems to improve the understanding of climate change consequences.

Leaf gene expression trajectories during the growing season are consistent between sites and years in American beech

“…The arrival of spring is a continually moving target and increasingly becoming so with climate change [1,2,[11][12][13]46]. Therefore, understanding spring-summer growth dynamics is important since global warming is expected to induce phenological shifts in flowering and leaf-out timings of most trees and affect mortality [3,4,7]. In parallel, we particularly paid attention to a set of 324 co-regulated transcripts in both study sites that could possibly be involved in controlling the phenology of delayed leaf expansion as a consequence of late spring (figure 2, table 1).…”

“…Trees over their long lifespan experience a multitude of severe conditions, but climate change is shifting essential phenological events and intensifying many of the environmental deviations. These deviations can exceed the reaction norms of trees [3][4][5][6][7][8]. For temperate trees, shifts in the spring arrival, and changing precipitation regimes can affect the phenological scheduling of vital biological events such as vessel activation [9], the acquisition of soil nutrients [10], flowering [3,[11][12][13], leaf flushing [14][15][16][17][18], xylogenesis [19], seeding and fruiting [20][21][22], and senescence-induced nutrient re-uptake from leaves [16,[23][24][25][26].…”

Leaf gene expression trajectories during the growing season are consistent between sites and years in American beech

“…The arrival of spring is a continually moving target and increasingly becoming so with climate change [1,2,[11][12][13]46]. Therefore, understanding spring-summer growth dynamics is important since global warming is expected to induce phenological shifts in flowering and leaf-out timings of most trees and affect mortality [3,4,7]. In parallel, we particularly paid attention to a set of 324 co-regulated transcripts in both study sites that could possibly be involved in controlling the phenology of delayed leaf expansion as a consequence of late spring (Fig.…”

“…Trees over their long lifespan experience a multitude of severe conditions, but climate change is shifting essential phenological events and intensifying many of the environmental deviations. These 1/26 deviations can exceed the boundaries of reaction norms trees have evolved [3][4][5][6][7][8]. For temperate trees, changes in the arrival of spring, and shifting precipitation regimes can affect the phenological scheduling of vital biological events such as vessel activation [9], the acquisition of soil nutrients [10], flowering [3,[11][12][13], leaf flushing [14][15][16][17][18], xylogenesis [19], seeding and fruiting [20][21][22], and senescence induced nutrient re-uptake from leaves [16,[23][24][25][26].…”

Spatiotemporal Analysis of Landscape Ecological Risk and Driving Factors: A Case Study in the Three Gorges Reservoir Area, China

“…Areas with frequent landscape-type transitions at the junction generally exhibited negative correlations, while the study area generally exhibited positive correlations; landscape ecological risk increased with an increase in temperature. This may be due to higher temperatures causing increased forest instability and tree mortality rates [62,63]. This further increases the degree of forest loss and the ecological risk to the landscape, demonstrating the negative impact that global warming can have on ecosystems.…”