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1. Interspecific and intraspecific trait variability differentially affect community‐weighted trait responses to and recovery from long‐term drought

   https://doi.org/10.1111/1365-2435.14239  

   Luo, Wentao ; Griffin‐Nolan, Robert J. ; Song, Lin ; Te, Niwu ; Chen, Jiaqi ; Shi, Yuan ; Muraina, Taofeek O. ; Wang, Zhengwen ; Smith, Melinda D. ; Yu, Qiang ; et al ( March 2023 , Functional Ecology)

   Plant traits are useful proxies of plant strategies and can influence community and ecosystem responses to climate extremes, such as severe drought. Few studies, however, have investigated both the immediate and lagged effects of drought on community‐weighted mean (CWM) plant traits, with even less research on the relative roles of interspecific vs. intraspecific trait variability in such responses.

   We experimentally reduced growing season precipitation by 66% in two cold‐semi‐arid grassland sites in northern China for four consecutive years to explore the drought resistance of CWM traits as well as their recovery 2 years following the drought. In addition, we isolated the effects of both interspecific and intraspecific trait variability on shifts in CWM traits.

   At both sites, we observed significant effects of drought on interspecific and intraspecific trait variability which, in some cases, led to significant changes in CWM traits. For example, drought led to reduced CWM plant height and leaf phosphorous content, but increased leaf carbon content at both sites, with responses primarily due to intraspecific trait shifts. Surprisingly, these CWM traits recovered completely 2 years after the extreme drought. Intraspecific trait variability influenced CWM traits via both positive and negative covariation with interspecific trait variability during drought and recovery phases.

   These findings highlight the important role of interspecific and intraspecific trait variability in driving the response and recovery of CWM traits following extreme, prolonged drought.

   Read the freePlain Language Summaryfor this article on the Journal blog.

    

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2. Planktic diatom responses to spatiotemporal environmental variation in high‐mountain tropical lakes

   https://doi.org/10.1111/fwb.14218  

   Luethje, Melina ; Mosquera, Pablo V. ; Hampel, Henrietta ; Fritz, Sherilyn C. ; Benito, Xavier ( January 2024 , Freshwater Biology)

   Tropical lakes harbour high levels of biodiversity, but the temporal and spatial variability of biological communities are still inadequately characterised, making it difficult to predict the impact of accelerated rates of environmental change in these regions. Our goal was to identify the spatiotemporal dynamics of the planktic diatom community in the Cajas Massif in the tropical Andes.

   We analysed seasonal diatom and environmental data over a period of 1 year from 10 lakes located in geologically distinct basins and modelled community–environment relationships using multivariate ordination and variation partitioning techniques. Generalised additive models with a full‐subset information theoretic approach also were used to determine which environmental variables explain single‐species abundance.

   Although the lakes are monomictic and thus have variable thermal structure across the year, seasonal variability of water chemistry conditions was negligible, and seasonal differences in diatom community composition were small. Across space, diatom community composition was correlated primarily with ionic content (divalent cations and alkalinity), related to bedrock composition, and secondly with lake thermal structure and productivity. The ionic gradient overrode the effect of the thermal structure–productivity gradient at the diatom community level, whereas individual diatom species responded more sensitively to variables related to in‐lake and catchment productivity, including chlorophyll‐aand iron, and the proportion of wetlands in the catchment.

   Our results indicate that the spatiotemporal variability of Cajas lakes and their diatom communities is the result of multiple intertwined environmental factors. The emergence of the ionic and thermal structure–productivity gradients in a rather small tropical lake district suggests segregation of ecological niches for diatoms that also may be important in other high‐elevation lake regions. Future studies that track tropical Andean lakes under natural and anthropogenically mediated change, both in contemporary times and in palaeoenvironmental reconstructions, would benefit from the modelling approach (community and species levels) developed here.

    

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3. Community context and dispersal stochasticity drive variation in spatial spread

   https://doi.org/10.1111/1365-2656.13331  

   Dallas, Tad ; Melbourne, Brett ; Hastings, Alan ; Rodriguez‐Cabal, ed., Mariano ( September 2020 , Journal of Animal Ecology)

   Dispersal is a key process in shaping species spatial distributions. Species interactions and variation in dispersal probabilities may jointly influence species spatial dynamics.

   However, many studies examine dispersal as a neutral process, independent of community context or intraspecific variation in dispersal behaviour.

   Here, we use controlled, replicated communities of twoTriboliumspecies (T. castaneumandT. confusum) to examine how intraspecific variation in dispersal behaviour and community context influence dispersal dynamics in simple experimental landscapes composed of homogeneous habitat patches.

   We found considerable individual‐level variation in dispersal probability that was unrelated to body size variation. Further, the context of dispersal mattered, asT. castaneumdispersal was reduced in two‐species communities, whileT. confusumdispersal was unaffected by community composition. Incorporating individual‐level variation into a two‐species stochastic spatial Ricker model, we provide evidence that individual‐level variability in dispersal behaviour results in more variable spatial spread than assuming individuals have the same dispersal probability. Further, interspecific competition resulted in more variable spatial spread.

   The variability in spatial spread observed in our tightly controlled and replicated experimental system and in our stochastic model simulations points to potential fundamental limitations in forecasting species shifting ranges without considering potential interspecific interactions and demographic variability in dispersal behaviour.

    

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4. Functional response of subordinate species to intraspecific trait variability within dominant species

   https://doi.org/10.1111/1365-2745.13249  

   Khalil, Mohammed I. ; Gibson, David J. ; Baer, Sara G. ; Jones, ed., Holly ( August 2019 , Journal of Ecology)

   Dominant species can act as a biotic filter in structuring plant communities by constraining the establishment and survival of subordinate species. The effect of intraspecific trait variability of dominant species on the functional response of subordinate species, however, is not well understood.

   We quantified intraspecific variation in four functional traits of 26 subordinate species in an experimental grassland established with two population sources (i.e. cultivars and local ecotypes) of three dominant grasses (Sorghastrum nutans, Andropogon gerardiiandSchizachyrium scoparium) and three pools of subordinate species (each from one origin) within each of the dominant grass source treatments.

   Twenty of the 26 subordinate species exhibited intraspecific trait variability for one trait or more in response to dominant species population source, and variation among population sources of the dominant species was non‐random. Dominant grass population source affected intraspecific variability in functional traits of multiple subordinate species. Cultivar sources of the dominant grasses and some of the subordinate species that established with them had higher and generally more variable functional leaf area and leaf nitrogen content compared to local ecotypes of the dominant grasses and the subordinate species that established with them. Local ecotype sources of the dominant grasses increased leaf area based functional diversity of subordinate species.

   Synthesis.This study provides evidence that intraspecific trait variability in dominant species acts as a biotic filter to constrain niche availability and dimensionality affecting trait variation of subordinate species during community assembly.

    

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5. Understanding and predicting harmful algal blooms in a changing climate: A trait‐based framework

   https://doi.org/10.1002/lol2.10294  

   Litchman, Elena ( December 2022 , Limnology and Oceanography Letters)

   The worldwide proliferation of harmful algal blooms (HABs) both in freshwater and marine ecosystems make understanding and predicting their occurrence urgent. Trait‐based approaches, where the focus is on functional traits, have been successful in explaining community structure and dynamics in diverse ecosystems but have not been applied extensively to HABs. The existing trait compilations suggest that HAB taxa differ from non HAB taxa in key traits that determine their responses to major environmental drivers. Multi‐trait comparisons between HAB‐forming and other phytoplankton taxa, as well as within the HAB groups to characterize interspecific and intraspecific differences will help better define ecological niches of different HAB taxa, develop trait‐based mechanistic models, and better identify environmental conditions that would likely lead to HABs. Building databases of HAB traits and using them in diverse statistical and mechanistic models will increase our ability to predict the HAB occurrence, composition, and severity under changing conditions, including the anthropogenic global change.

    

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