Diminished Response of Arctic Plants to Warming over Time

Abstract

The goal of this study is to determine if the response of arctic plants to warming is consistent across species, locations and time. This study examined the impact of experimental warming and natural temperature variation on plants at Barrow and Atqasuk, Alaska beginning in 1994. We considered observations of plant performance collected from 1994–2000 “short-term” and those from 2007–2012 “long-term”. The plant traits reported are the number of inflorescences, inflorescence height, leaf length, and day of flower emergence. These traits can inform us about larger scale processes such as plant reproductive effort, plant growth, and plant phenology, and therefore provide valuable insight into community dynamics, carbon uptake, and trophic interactions. We categorized traits of all species monitored at each site into temperature response types. We then compared response types across traits, plant growth forms, sites, and over time to analyze the consistency of plant response to warming. Graminoids were the most responsive to warming and showed a positive response to temperature, while shrubs were generally the least responsive. Almost half (49%) of response types (across all traits, species, and sites combined) changed from short-term to long-term. The percent of plants responsive to warming decreased from 57% (short-term) to 46% (long-term). These results indicate that the response of plants to warming varies over time and has diminished overall in recent years.

Greater temperature sensitivity of plant phenology at colder sites: implications for convergence across northern latitudes

“…Conversely, temperature sensitivity of vegetative growth may be greater at lower Arctic sites because reproductive strategies involved in vegetative growth may be under stronger selection in sub‐ and low‐Arctic ecosystems with dense, closed canopies (Wookey et al ., ; Parsons et al ., ). The differences between our results and those of previous syntheses indicate that not all plant traits will respond in the same way to environmental change (Shaver & Kummerow, ; Arft et al ., ; Barrett et al ., ; Kremers et al ., ).…”

Plant phenological responses to a long‐term experimental extension of growing season and soil warming in the tussock tundra of Alaska

“…Growth in Ledum and Eriophorum was highly constrained by nutrients in the late‐season (Chapin & Shaver, ). Earlier phenology may cause a feedback mechanism by which nutrient limitation is further exacerbated, thereby limiting productivity (Kremers et al ., ). Our results provide evidence that an earlier onset of the growing season alone will not result in increased growth.…”

Shrub growth and expansion in the Arctic tundra: an assessment of controlling factors using an evidence-based approach

“…Recognising these uncertainties, the recent negative NDVI trends could be driven by complex environmental controls on shrubs beyond simple temperature metrics, such climatic extremes, and/or discrete disturbance events (Phoenix and Bjerke 2016). A progressive decline in the relationship between air temperature and NDVI since 1982 (Piao et al 2014, Kremers et al 2015 further supports the role of controls beyond air temperature.…”