华北高唐地区4种常见树木叶片水力学和等水特性分析

Analysis of hydraulic and isohydraulic characteristics of leaves of four common trees in Gaotang area of North China

【目的】研究相同环境中不同树种采取的水分适应策略多样性,为适地适树造林提供参考。【方法】在山东省高唐地区选取分别在根系分布深度、材性和生长速度方面有着较大差异的4个典型适生树种,元宝枫、紫叶李、毛白杨和刺槐。比较了4个树种叶片的水力学特性和等水评价,其中水力学特性包括栓塞脆弱性参数,压力−容积(PV)曲线参数,水力结构和功能性状。【结果】结果表明,适应相同的环境的不同树种采取的水分适应策略差异较大,其中紫叶李和元宝枫的水分适应策略较为保守,而刺槐和毛白杨则采取了较为冒险的水分适应策略:浅根性散孔材速生树种紫叶李,其叶片栓塞抗性最强(栓塞脆弱性P_(50)为−2.67 MPa),用水安全性非常高(水力安全边际HSM为1.57 MPa),水分适应策略较为保守;浅根性散孔材慢生树种元宝枫,其叶片偏向于等水调节(水力学面积为0.049 MPa^(2)),可以在水分胁迫时更早的关闭气孔来维持叶片水势和膨压稳定,由于P_(50)比较高而HSM比较低,表现出了低抗栓塞能力和低水力安全性,叶水势的调节范围较窄,但其高Huber值(Hv)显示其具有较高的抗旱性,采用了较为保守的水分适应策略;浅根性环孔材速生树种刺槐,其叶片偏向不等水调节方式,抗栓塞能力较强,叶水势调节范围较广,水分适应策略较为冒险;深根性散孔材速生树种毛白杨,栓塞抗性不强,用水安全系数接近极限(HSM为0.002 MPa),其叶片维持膨压能力最强(膨压损失点水势ψ_(tlp)为−3.36 MPa),确保其在缺水情况下从土壤深处获取水分,采取的水分适应策略较为冒险。【结论】综上所述,树木可以采用不同的水力学特性、等水特性、形态结构特征,应用不同的水分适应策略来适应相同的环境,这种水分适应策略的多样性有利于维持生态系统的稳定性。

[Objective]This paper aims to study the diversity of water adaptation strategies adopted by different tree species in same environment to provide reference for better silviculture of tree species in the suitable sites.[Method]We selected four typical suitable tree species with great differences in root distribution depth,wood properties and growth speed,they were Acer truncatum,Prunus cerasifera,Populus tomentosa and Robinia pseudoacacia and planted in Gaotang region,Shandong Province of North China.We compared the hydraulic traits and isohydraulic evaluation of the leaves of these four species.The hydraulic traits included embolism vulnerability parameters,pressure-volume(PV)curve parameters,hydraulic structure and functional properties.[Result]Different species selected varied water adaptation strategies to adjust to the same environment.Among them,P.cerasifera and A.truncatum owned more conservative water adaptation strategies,while R.pseudoacacia and P.tomentosa adopted more adventurous water adaptation strategies;P.cerasifera is a fast-growing tree species with shallow-rooted diffuse-porous wood,it had the strongest leaf embolism resistance(embolism vulnerability P_(50) was−2.67 MPa).Meanwhile,the water safety of P.cerasifera was very high(hydraulic safety margin HSM was 1.57 MPa),the water adaptation strategy was conservative;A.truncatum is a slow-growing tree species with shallowrooted diffuse-porous wood,its leaves inclined to isohydraulic regulation(the hydraulic area was 0.049 MPa_(2)).When drought stress was encountered,the stomata can be closed early to keep the leaf water potential and turbulence stable.Its P_(50) was relatively high and HSM was relatively low,showing low antiembolism ability and low hydraulic safety.The adjustment range of leaf water potential was narrow.Its high Huber value(Hv)showed that it had high drought resistance.A more conservative water adaptation strategy had been adopted by it.R.pseudoacacia is a kind of fast-growing tree species,its leaves were inclined to aniso-hydraulic regulation,having strong anti-embolism ability,the range of leaf water potential was wide,and the water adaptation strategy was more adventurous.P.tomentosa is a fast-growing tree species with deep-rooted diffuse-porous wood and low sieve resistance.The water safety factor was close to limit(HSM was 0.002 MPa).Its leaves owned the strongest ability to maintain turgor pressure(water potential at turgor pressure loss point ψ_(tlp) was−3.36 MPa),to ensure that they can get water from the deep soil in case of water shortage,the water adaptation strategy is more risky.[Conclusion]In summary,trees can adopt different hydraulic characteristics,isohydraulic characteristics,morphological and structural characteristics,and apply different water adaptation strategies to adapt to the same environment.The diversity of water adaptation strategies is conducive to maintaining the stability of the ecosystem.