Department of Geography and the Environment , University of North Texas , 1155 Union Circle #305279 , Denton , Texas 76203 , United States.
Department of Environmental Science , Baylor University , 1 Bear Place #97266 , Waco , Texas 76798 , United States.
Environ Sci Technol. 2019 Sep 3;53(17):10092-10101. doi: 10.1021/acs.est.9b02844. Epub 2019 Aug 22.
Urban trees could represent important short- and long-term landscape sinks for elemental carbon (EC). Therefore, we quantified foliar EC accumulation by two widespread oak tree species- (post oak) and (live oak)-as well as leaf litterfall EC flux to soil from April 2017 to March 2018 in the City of Denton, Texas, within the Dallas-Fort Worth metropolitan area. Post oak trees accumulated 1.9-fold more EC (299 ± 45 mg EC m canopy yr) compared to live oak trees (160 ± 31 mg EC m canopy yr). However, in the fall, these oak species converged in their EC accumulation rates, with ∼70% of annual accumulation occurring during fall and on leaf surfaces. The flux of EC to the ground via leaf litterfall mirrored leaf-fall patterns, with post oaks and live oaks delivering ∼60% of annual leaf litterfall EC in fall and early spring, respectively. We estimate that post oak and live oak trees in this urban ecosystem potentially accumulate 3.5 t EC yr, equivalent to ∼32% of annual vehicular EC emissions from the city. Thus, city trees are significant sinks for EC and represent potential avenues for climate and air quality mitigation in urban areas.
城市树木可能是元素碳（EC）的重要短期和长期景观汇。因此，我们在 2017 年 4 月至 2018 年 3 月期间，在达拉斯-沃斯堡大都市区内的德克萨斯州丹顿市，对两种广泛分布的橡树物种（朴树）和（湿地松）的叶片 EC 积累以及叶片凋落物 EC 通量到土壤进行了量化。朴树的 EC 积累量是湿地松的 1.9 倍（299±45mg EC m 树冠 yr），而湿地松的 EC 积累量为（160±31mg EC m 树冠 yr）。然而，在秋季，这些橡树物种的 EC 积累率趋同，年积累量的约 70%发生在秋季和叶片表面。通过叶片凋落物向地面输送 EC 的通量与叶片凋落物模式相吻合，朴树和湿地松分别在秋季和早春将年凋落物 EC 的约 60%输送到地面。我们估计，这个城市生态系统中的朴树和湿地松每年可能会积累 3.5 吨 EC，相当于城市每年车辆 EC 排放量的约 32%。因此，城市树木是 EC 的重要汇，是城市地区气候和空气质量缓解的潜在途径。
