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Abstract Whole‐ecosystem interactions and feedbacks constrain ecosystem responses to environmental change. The effects of these constraints on responses to climate trends and extreme weather events have been well studied. Here we examine how these constraints respond to changes in day‐to‐day weather variability without changing the long‐term mean weather. Although environmental variability is recognized as a critical factor affecting ecological function, the effects of climate change on day‐to‐day weather variability and the resultant impacts on ecosystem function are still poorly understood. Changes in weather variability can alter the mean rates of individual ecological processes because many processes respond non‐linearly to environmental drivers. We assessed how these individual‐process responses to changes in day‐to‐day weather variability interact with one another at an ecosystem level. We examine responses of arctic tundra to changes in weather variability using stochastic simulations of daily temperature, precipitation, and light to drive a biogeochemical model. Changes in weather variability altered ecosystem carbon, nitrogen, and phosphorus stocks and cycling rates in our model. However, responses of some processes (e.g., respiration) were inconsistent with expectations because ecosystem feedbacks can moderate, or even reverse, direct process responses to weather variability. More weather variability led to greater carbon losses from land to atmosphere; less variability led to higher carbon sequestration on land. The magnitude of modeled ecosystem response to weather variability was comparable to that predicted for the effects of climate mean trends by the end of the century.
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Resource limitation determines temperature response of unicellular plankton communities
Abstract A warmer ocean will change plankton physiological rates, alter plankton community composition, and in turn affect ecosystem functions, such as primary production, recycling, and carbon export. To predict how temperature changes affect plankton community dynamics and function, we developed a mechanistic trait‐based model of unicellular plankton (auto‐hetero‐mixotrophic protists and bacteria). Temperature dependencies are specifically implemented on cellular process rather than at the species level. As the uptake of resources and metabolic processes have different temperature dependencies, changes in the thermal environment will favor organisms with different investments in processes such as photosynthesis and biosynthesis. The precise level of investments, however, is conditional on the limiting process and is ultimately determined dynamically by competition and predation within the emergent community of the water column. We show how an increase in temperature can intensify nutrient limitation by altering organisms' interactions, and reduce relative cell‐size in the community. Further, we anticipate that a combination of temperature and resource limitation reduces ecosystem efficiency at capturing carbon due to strengthening of the microbial loop. By explicitly representing the effects of temperature on traits responsible for growth, we demonstrate how changes on the individual level can be scaled up to trends at the ecosystem level, helping to discern direct from indirect effects of temperature on natural plankton communities.
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- Award ID(s):
- 1848576
- PAR ID:
- 10448819
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Limnology and Oceanography
- Volume:
- 64
- Issue:
- 4
- ISSN:
- 0024-3590
- Page Range / eLocation ID:
- p. 1627-1640
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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