The response of root traits to precipitation change of herbaceous species in temperate steppes

• Published in: Functional ecology Vol. 33; no. 10; pp. 2030 - 2041
• Main Authors: Zhou, Meng, Wang, Jing, Bai, Wenming, Zhang, Yushi, Zhang, Wen‐Hao, Weiser, Martin
• Format: Journal Article
• Language: English
• Published: London Wiley Subscription Services, Inc 01.10.2019
• Subjects: Annual precipitation; Artemisia frigida; Biological evolution; Climate change; Experiments; first two‐order roots; Grasslands; intraspecific variation; Leymus chinensis; Morphology; Organic chemistry; Plant growth; Plastic properties; Plasticity; Precipitation; precipitation gradients; root traits; Roots; Species; Steppes; Structure-function relationships; temperate grasslands; water addition
• ISSN: 0269-8463; 1365-2435
• DOI: 10.1111/1365-2435.13420

Plasticity of root traits plays an important role in plant growth and survival under changing climate. Shift in precipitation is one of the most pertinent global change factors driving changes in structure and function of grasslands. However, few studies have investigated intraspecific variation of root traits in response to precipitation change under field conditions. We conducted a 10‐year simulated increased precipitation experiment in a temperate grassland and a 700‐km regional scale transect along a precipitation gradient ranging from 144.23 to 412.29 mm in northern China. The morphological, chemical and anatomical traits of the first two‐order roots were determined on 15 common herbaceous species in the manipulation experiment and two regionally common species (Leymus chinensis, Artemisia frigida) along a precipitation gradient. We found that most of the root traits of the herbaceous species exhibited no significant responses to water addition. The two regionally common species adjusted their root traits at sites with the annual precipitation lower than certain value, that is 250 and 160 mm for L. chinensis and A. frigida, respectively. These results indicate that root traits of the herbaceous species exhibit little plasticity in response to precipitation change and that the adjustment of root traits occurs when the range of annual precipitation exceeds a certain threshold. Root traits of L. chinensis and A. frigida varied differently both in manipulation experiment and along the precipitation gradient. Root traits of L. chinensis were relatively constant, while A. frigida adjusted their morphological root traits in response to water addition. Moreover, L. chinensis showed higher specific root length (SRL) and area, and root N contents at sites with annual precipitation lower than c. 250 mm. In contrast, A. frigida displayed thicker roots with lower SRL and area at sites with annual precipitation lower than c. 160 mm. Our results showed that root traits of herbaceous species in temperate grasslands exhibited little plasticity and that different species have evolved diverse adaptive strategies in response to precipitation change. These novel findings provide valuable information to predict responses of temperate grasslands to future climate change. 摘要 根系性状的种内变异反映了植物对变化环境的适应策略，是植物在变化环境中生存和生长的关键因素。降水变化是影响草地生态系统结构和功能重要的全球变化因子之一。然而，很少有研究探讨在野外条件下草原植物根系性状对降水变化的响应。本研究利用在内蒙古温带草原开展的野外长期（10年）增加降水控制实验和沿着从东到西的自然降水梯度(412.3–144.2 mm)设置的长约700 km的样带，分别选取了15种常见草本物种和2种区域广布种为研究对象，对其根系形态性状、化学性状和解剖结构进行测定，以期探讨草原植物对降水变化的适应策略。我们的研究结果发现：1）内蒙古典型草原植物的大部分根系性状对增加降水无显著响应，少数几个物种通过改变某几个根性状来适应降水的改变。沿着自然降水梯度，只有当降水量改变到一定程度之后，物种的表型性状才会有适应性调整。这些结果表明，内蒙古典型草原植物根系性状对降水变化响应的敏感性较小，可以适应一定范围的降水变化。2）在增加降水实验中，羊草的根系性状对增加降水无显著响应，而增加降水使冷蒿的比根长和比表面积降低而组织密度升高。沿着自然降水梯度，羊草在降水量低的样点有较高的比根长、比表面积和根N浓度，有较低的组织密度和C：N比，而冷蒿在降水量低的样点有较高的根系直径，和较低的比根长和比表面积。此结果表明，不同的物种通过多样的根系性状调整策略来适应降水的变化。 综上所述，内蒙古温带草原植物的根系性状对降水变化的响应敏感性较小，且不同植物种通过不同的表型调整策略来适应降水的变化。本研究为理解和预测温带草原植物对未来气候变化的响应提供了重要的理论基础。 A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.