Climate-driven changes in biomass allocation in pines
Climate-driven changes in biomass allocation in pines
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DOI：
10.1046/j.1365-2486.2000.00338.x
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发表时间：
2000-06-01
影响因子：
11.6
通讯作者：
Carey, EV
中科院分区：
文献类型：
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作者：
DeLucia, EH;Maherali, H;Carey, EV
人类活动导致的未来气温升高可能会增加大气的水蒸气压不足（VPD）。了解树木对 VPD 空间变化的响应可以增强我们预测树木如何响应这一重要变量的时间变化的能力。使用已发表的值，我们测试了理论预测，即随着 VPD 的增加，针叶树相对于茎（边材）中的导水组织会减少对光合组织（叶子）的投资。随着VPD的增加，松属植物的叶/边材面积比(A(L)/A(S))显着降低，但冷杉、黄杉、铁杉和云杉的叶/边材面积比(A(L)/A(S))显着降低，并且松树的平均A(L)/A(S)显着低于其他针叶树(松树：0.17 m(2) cm(-2)；非松树：0.44 m(2) cm(-2))。因此，松树通过改变地上形态来适应日益增加的干旱，而非松树针叶树却没有。造成水力传导率损失 50% 的平均水势，松树为 -3.28 MPa，非松树针叶树为 -4.52 MPa，这表明松树比其他针叶树更容易受到木质部栓塞的影响。对于黄松，高 VPD 下 A(L)/A(S) 的减少增加了向叶子提供水分的能力，而不会增加木质部栓塞的风险。该变量的低 A(L)/A(S) 和可塑性可能会增强松树的耐旱性。然而，随着 VPD 的增加以及生物量分配从叶子到茎的相关转变，A(L)/A(S) 降低，这表明随着气候变暖，松树可能会消耗更多的光合产物来构建和支撑结构质量，并携带更少的叶面积。
Future increases in air temperature resulting from human activities may increase the water vapour pressure deficit (VPD) of the atmosphere. Understanding the responses of trees to spatial variation in VPD can strengthen our ability to predict how trees will respond to temporal changes in this important variable. Using published values, we tested the theoretical prediction that conifers decrease their investment in photosynthetic tissue (leaves) relative to water-conducting tissue in the stem (sapwood) as VPD increases. The ratio of leaf/sapwood area (A(L)/A(S)) decreased significantly with increasing VPD in Pinus species but not in Abies, Pseudotsuga, Tsuga and Picea, and the average A(L)/A(S) was significantly lower for pines than other conifers (pines: 0.17 m(2) cm(-2); nonpines: 0.44 m(2) cm(-2)). Thus, pines adjusted to increasing aridity by altering above-ground morphology while nonpine conifers did not. The average water potential causing a 50% loss of hydraulic conductivity was -3.28 MPa for pines and -4.52 MPa for nonpine conifers, suggesting that pines are more vulnerable to xylem embolism than other conifers. For Pinus ponderosa the decrease in A(L)/A(S) with high VPD increases the capacity to provide water to foliage without escalating the risk of xylem embolism. Low A(L)/A(S) and plasticity in this variable may enhance drought tolerance in pines. However, lower A(L)/A(S) with increasing VPD and an associated shift in biomass allocation from foliage to stems suggests that pines may expend more photosynthate constructing and supporting structural mass and carry less leaf area as the climate warms.