乾燥に強いと思われていた種が限界に達する Supposedly drought-tolerant species hit their breaking points
2023-03-27 カリフォルニア大学リバーサイド校(UCR)
Ocotillo growing in the Boyd Deep Canyon Reserve. This is one of the plants moving into lower-elevation territory where other, taller species are declining. (Boyd Reserve)
新たな研究により、気候変動によって植物の移動が、想定外の形で起きていることが明らかになった。
カリフォルニア大学リバーサイド校の研究チームが、ソノラ砂漠の一部で植物が移動する様子を観察し、高温の地域に移動する種類もあると発表した。
研究チームは、より深い土壌水分に頼らない浅い根系を持つ、ブリトルブッシュ、バロウブッシュ、オコティロなどの低木類が、高温地帯に向かって移動していることを発見。それ以外にも、カリフォルニアのジュニパーやパイニオンパインなどの木々は、高地に移動する一方で衰退していることが分かった。
このような変化は、炭素排出量の削減が行われない限り継続する可能性があり、植物の生理学的限界に達すると回復が困難になるという。
<関連情報>
- https://news.ucr.edu/articles/2023/03/27/even-sonoran-desert-plants-arent-immune-climate-change
- https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.14308
植物機能形質が予測する気候変動に伴う不均質な分布のシフト Plant functional traits predict heterogeneous distributional shifts in response to climate change
Tesa R. Madsen-Hepp, Janet Franklin, Shane McFaul, Lisa Schauer, Marko J. Spasojevic
Functional Ecology Published: 23 March 2023
DOI:https://doi.org/10.1111/1365-2435.14308
Abstract
- Climate change is causing the rapid redistribution of vegetation as plant species move to track their climatic optima. Despite a global trend of upward movement in latitude and elevation, there is extensive heterogeneity among species and locations, with few emerging generalizations. Greater generalization may be achieved from considering multidimensional changes in species’ distributions as well as incorporating ecologically relevant functional traits into studies of range shifts.
- To better understand how recent changes in climate are influencing the elevational distribution of plant species and how species’ functional traits mediate distributional changes, we resampled a 2438 m elevation transect spanning a distance of 16 km which encompasses desert scrub, pinyon-juniper woodland, chaparral and coniferous forest plant communities.
- Over the last 42 years, total perennial cover and species’ average cover increased at lower elevations and decreased at higher elevations while average elevational leading-edge increased 116 m and elevational rear edge decreased 84 m. Notably, these changes were mediated by species’ functional traits, where species exhibiting more conservative traits (lower specific leaf area [SLA], greater δ13C, larger seed mass) and taller height shifted upward in their leading-edge range limit, average elevation and trailing edge range limit, while declining in abundance at the median and trailing edge of their range. Species possessing more acquisitive traits (higher SLA, lower δ13C, smaller seed mass) and shorter height shifted downward and increased in abundance at their trailing edge, with increases in their total range size.
- Our results provide clear evidence that heterogeneous range dynamics under recent climate change can be generalized by considering ecologically relevant plant functional traits, and how they respond to localized climate exposure. Furthermore, by documenting changes across a steep elevational gradient comprising a large aridity gradient, we show divergent patterns for plants occupying contrasting positions along the global spectrum of plant form and function, which provides critical insight into how trait-mediated changes under increasing aridity will impact ecosystem functioning.
