Linking temperature sensitivity of mangrove communities, populations and individuals across a tropical-temperate transitional zone

Yiyang Kang; David A. Kaplan; Michael Osland

doi:10.1111/1365-2745.14296

Home/Archive/USGS

USGS · 70252739

Linking temperature sensitivity of mangrove communities, populations and individuals across a tropical-temperate transitional zone

Yiyang Kang·David A. Kaplan·Michael Osland

View original source ↗Export metadata ↓

Abstract

Climate change is reshaping coastal wetlands worldwide, driving ecosystem shifts like mangrove poleward expansion into saltmarshes in tropical-temperate transitional zones. Though warming is recognized as the primary driver, a lack of detailed field studies limits our ability to predict mangrove responses to rapid climate warming. Here, we characterized how mangroves vary across a temperature gradient at 18 sites along Florida's Gulf of Mexico coast (USA). We used minimum air temperature ( T min ) derived from daily data from 1989 to 2021 as the independent variable and applied plot-based and synoptic approaches to quantify species-specific mangrove variation at community, population, and individual levels. We then used these results to spatially project future mangrove ecosystem properties under multiple warming scenarios. Across the T min gradient from −10.8 to −1.4°C, mangrove canopy height and coverage ranged from 0.4 to 11.5 m and 15% to 98%, respectively, with both exhibiting sigmoidal increases with T min . Estimated mangrove aboveground biomass ranged from 0 to 496.7 Mg/ha and showed a positive linear relationship with T min due both to the tall tree stratum's increased biomass per tree and higher abundance. While the population abundance and coverage of Rhizophora mangle and Laguncularia racemosa had positive linear relationships with T min , Avicennia germinans exhibited a significant quadratic relationship, reflecting the higher freeze tolerance of this species. Such tolerance may stem from A. germinans ' higher morphological plasticity observed at the individual level, adapting to cold stress by exhibiting a more shrub-like architecture at colder sites. Based on these field-derived quantitative relationships, we projected substantial increases in mangrove coverage and canopy height near current range limits, with tall A. germinans dominating in the north and R. mangle dominating the centre and south of the study region. Synthesis. To better predict the ecological consequences in coastal wetlands under future climate change, it is essential to understand how mangroves respond to winter temperature regimes across a temperature gradient. Collectively, these cross-level and species-specific results advance our understanding of mangrove temperature sensitivity and provide information about the future of coastal wetland structure and function in response to a changing climate.

Explore related subjects

Journal of Ecology Article

Source-reported bounding extent: 26.312382041257592° to 30.22117396127888° latitude; -85.3840901076647° to -81.80641192812863° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Yiyang Kang, David A. Kaplan, Michael Osland. 2024-03-25. Linking temperature sensitivity of mangrove communities, populations and individuals across a tropical-temperate transitional zone. https://doi.org/10.1111/1365-2745.14296

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Long-term aridity shapes grassland drought resistance and modulates the roles of plant diversity and functional composition

Understanding the drivers of plant community stability is crucial for predicting ecosystem responses to extreme drought events. In grasslands, drought resistance supports the maintenance of key functions such as above-ground primary productivity, making the identification of resistance drivers essential to guide management under climate change. Proposed factors contributing to grassland stability include multiple diversity facets, functional traits and long-term climate, but most assessments focus on temporal invariability under historical disturbance regimes, leaving mechanisms of extreme drought resistance and their variation across climatic contexts relatively underexplored. Here, we analysed data from 54 grassland sites of the International Drought Experiment to examine the resistance of above-ground net primary productivity to a short-term (i.e. 1 year) extreme drought. We investigated the relative importance and joint influence of functional composition (i.e. community-weighted means of leaf and root traits), plant diversity facets (taxonomic, functional and phylogenetic) and climate (aridity and rainfall variability) on drought resistance. We used structural equation models to disentangle direct, indirect, and moderating pathways linking these drivers to drought resistance. Long-term aridity appeared as one of the most important drivers of grassland resistance to drought, with more arid sites showing lower resistance. Moreover, aridity impacted resistance through indirect effects by shaping functional composition and plant diversity, and by moderating the influence of plant diversity and functional composition. Functional composition related to dehydration avoidance and dehydration tolerance was also positively associated with resistance, while diversity had a weaker relationship with resistance, mostly through functional and phylogenetic facets. Interannual rainfall variability also influenced resistance, with different effects in more arid versus humid and less arid sites. Synthesis . Widely studied stability drivers such as plant diversity and functional composition have only partial explanatory power for short-term drought resistance of above-ground productivity in grasslands at a global scale. The abiotic context, particularly long-term aridity, is crucial for understanding ecosystem responses to rainfall variation and can improve predictive models for advancing the study of ecosystem resistance to drought. Along with management practices that target high species diversity or specific traits, restoration and conservation practices should support vulnerable sites experiencing high aridity

Journal of Ecology↗

USGS2026

Overstorey mortality promotes juvenile piñon pine growth during favourable weather at cooler, wetter sites

Hotter droughts have resulted in widespread tree die-off events globally, frequently leading to regeneration failure. Dry forest recovery often depends on the growth and survival of extant juvenile trees. However, it is unclear how microenvironmental changes following overstorey tree die-off affect juvenile trees, particularly in dryland systems where tree recruitment is typically limited by water availability and heat stress. We simulated an overstorey tree die-off event by girdling trees in piñon-juniper woodlands across the south-western United States. We sampled juvenile piñon pine growth from live and dead overstorey treatments across six study sites spanning a regional latitudinal gradient and local elevational gradients. We examined how juvenile branch and needle growth differed between live and dead overstorey treatments, and whether responses varied with weather conditions and juvenile tree size following overstorey mortality. We found greater juvenile branch and needle growth under dead compared with live overstorey trees for 2 years following overstorey mortality at mid- and high-elevation sites which are typically cooler and wetter than the other sites. These observed growth releases were contingent on favourable post-mortality weather conditions. Higher growth under dead overstorey occurred at sites experiencing near-average climatic water deficits compared with sites experiencing above-average climatic water deficits. Growth at all sites increased from the first to second year after overstorey mortality. Across sites, growth was unrelated to juvenile tree size. Synthesis . Our results underscore differentiation in juvenile responses to overstorey tree die-off driven by local site conditions and weather across the range of Pinus edulis . Overstorey mortality resulted in consistently higher juvenile growth only at climatically favourable sites and during favourable weather, while unmeasured microsite differences could help account for variation observed at the hottest and driest site. Results from less climatically favourable sites suggest that overstorey trees neither directly limit nor facilitate juvenile growth, though further study over longer timeframes is needed to resolve the pace and magnitude of potential recovery or decline. Overall, juvenile vigour may be promoted following overstorey mortality only in a narrow spatial (site) and temporal (weather) environmental context, suggesting additional vulnerabilities for piñon populations under more arid conditions.

Arizona, Colorado↗

USGS2025

Causal interpretations can be based on mechanistic knowledge

There exists a long-standing disconnect between statistical and mechanistic approaches to the development of causal understanding. Statistical approaches, which have dominated the literature, have focused on the need to obtain perfectly unbiased estimates of causal effects often using either experimental, quasi-experimental or other methods. Mechanistic approaches have instead focused on investigating how systems work by elucidating the structures and processes whereby variations in one system property can propagate to other system properties. Explicit references to ‘causal effects’ have tended to require adherence to statistical methods and standards, inadvertently downplaying the suitability of mechanistic knowledge for that purpose. It has been recently demonstrated that both mechanistic and statistical approaches can contribute to the long-term goal of developing causal knowledge and understanding. Proponents of statistical causal inference have seldom recommended that mechanistic evidence be relied upon to support causal interpretations. This paper provides a clear and thorough example where a causal interpretation can be supported based on mechanistic knowledge. Arguing for a causal interpretation based on knowledge of mechanisms has typically been an informal process and one that has thus far infrequently led to explicit declarations of causal knowledge by scientists. To overcome this problem, we illustrate a recently described procedure referred to as ‘causal knowledge analysis’ to summarize explicit support for causal interpretations. In this paper, we first clarify the basis of the long-standing disagreement by describing the crux of the problem as viewed from a statistical perspective and by describing how it can be overcome when there is sufficient mechanistic knowledge. We then offer a proof-of-concept example based on robust documentation and description of the mechanisms whereby plants causally regulate the responses of coastal marsh elevation to changes in sea level. Synthesis —The evidential requirements for declaring a relationship to be causal have been obscured until very recently, leading to a long neglect of this issue by scientists. Meanwhile, subject matter experts have accumulated a vast body of undeclared causal knowledge that we now need to recognize in order to position scientists as essential players in defending causal interpretations.

Journal of Ecology↗