Transient changes in transpiration, and stem and soil CO2 efflux in longleaf pine (Pinus palustris Mill.) following fire-induced leaf area reduction
Transient changes in transpiration, and stem and soil CO2 efflux in longleaf pine (Pinus palustris Mill.) following fire-induced leaf area reduction
复制标题
DOI：
10.1007/s00468-011-0574-6
复制
发表时间：
2011-12-01
影响因子：
2.3
通讯作者：
Mitchell, Robert J.
中科院分区：
文献类型：
--
作者：
Clinton, Barton D.;Maier, Chris A.;Mitchell, Robert J.
在20年生长叶松中，我们研究了通过冠层烧焦减少活叶面积（A（L））对树干液流的短期影响（Q; kg H2O h（-1）），单位叶面积蒸腾量（E-L; mm day（-1））、茎CO2排放量（R-stem; mumol m（-2）s（-1））和土壤CO2排放量（R-soil; mumol m（-2）s（-1））。在两个位置（1.3米或BH，和基地的活冠-BLC）的R-茎和Q进行了测量，和R-土壤进行了测量，使用15个开放系统室在每个情节。使用在BLC测量的Q估计治疗前后的E-L，并估计烧焦前后的AL。我们预计Q减少烧焦的树木相比，控制减少A（L）。我们预计，由于叶面积减少，BLC和BH的R-茎和R-土壤在烧焦后会减少，这将减少对茎和根的碳供应。烧焦使A（L）减少77%。在烧焦之前，BH的Q在烧焦树和对照树之间相似。在灼烧之后，对照和灼烧树之间的Q没有不同;然而，与对照树相比，E-L在灼烧之后立即增加3.5倍。烧焦树中E-L的变化与VPD（D）的变化一致，而对照树在处理后5天内表现出更多的解耦。到研究结束时，与对照树相比，烧焦树的两个茎位置的R茎减少到15-25%。最后，我们发现，烧焦导致延迟和暂时的R-土壤增加，而不是减少。焦枯后，气孔导度没有变化，但E-L增大，表明焦枯后气孔导度发生了较大的调整。烧焦和对照树之间的R-茎的差异表明，烧焦后茎碳水化合物逐渐下降。一个强大的R-土壤反应的情况下，可能是由于非限制性供应的根淀粉在初夏。
In 20-year-old longleaf pine, we examined short-term effects of reduced live leaf area (A(L)) via canopy scorching on sap flow (Q; kg H2O h(-1)), transpiration per unit leaf area (E-L; mm day(-1)), stem CO2 efflux (R-stem; mu mol m(-2) s(-1)) and soil CO2 efflux (R-soil; mu mol m(-2) s(-1)) over a 2-week period during early summer. R-stem and Q were measured at two positions (1.3-m or BH, and base of live crown-BLC), and R-soil was measured using 15 open-system chambers on each plot. E-L before and after treatment was estimated using Q measured at BLC with estimates of AL before and after scorching. We expected Q to decrease in scorched trees compared with controls resulting from reduced A(L). We expected R-stem at BLC and BH and R-soil to decrease following scorching due to reduced leaf area, which would decrease carbon supply to the stem and roots. Scorching reduced A(L) by 77%. Prior to scorching, Q at BH was similar between scorch and control trees. Following scorching, Q was not different between control and scorch trees; however, E-L increased immediately following scorching by 3.5-fold compared to control trees. Changes in E-L in scorched trees corresponded well with changes in VPD (D), whereas control trees appeared more decoupled over the 5-day period following treatment. By the end of the study, R-stem decreased to 15-25% in scorched trees at both stem positions compared to control trees. Last, we found that scorching resulted in a delayed and temporary increase in R-soil rather than a decrease. No change in Q and increased E-L following scorching indicates a substantial adjustment in stomatal conductance in scorched trees. Divergence in R-stem between scorch and control trees suggests a gradual decline in stem carbohydrates following scorching. The absence of a strong R-soil response is likely due to non-limiting supplies of root starch during early summer.