基于多种同位素模型的侧柏林生态系统蒸散组分定量拆分

doi:10.13287/j.1001-9332.202106.023

摘要/Abstract

摘要： 为了全面认识森林生态系统蒸散各组分及其对蒸散的贡献率在日尺度上的变化规律,本研究利用同位素稳态和非稳态假设理论结合水同位素分析仪系统,对生长季侧柏林生态系统蒸散各组分进行了定量拆分和比较。结果表明: 4个测定日(2016年8月5、8、10、11日)不同来源水体的¹⁸O都呈现表层土壤水氧同位素组成(δ_S)＞枝条水氧同位素组成(δ_X)＞大气水汽氧同位素组成(δ_V),说明三者可能因同位素分馏效应表现出明显的差异。土壤蒸发水汽氧同位素组成(δ_E)在日尺度上为-26.89‰～-59.68‰,整体上呈现出先上升后下降的变化趋势;森林生态系统蒸散水汽氧同位素组成(δ_ET)为-15.99‰～-10.04‰,稳态(ISS)下植物蒸腾水汽氧同位素组成(δ_T-ISS)为-12.10‰～-9.51‰,而非稳态(NSS)下植物蒸腾水汽氧同位素组成(δ_T-NSS)为-13.02‰～-7.23‰,在日时间尺度上δ_ET与δ_T-NSS全天的变化趋势一致,在11:00—17:00 δ_ET、δ_T-ISS与δ_T-NSS三者的变化趋势近似一致。总体上,植物蒸腾量对蒸散量的贡献率表现为F_T-ISS 79.1%～98.7%,而F_T-NSS 88.7%～93.7%。这表明研究区土壤蒸发耗水远小于植被蒸腾耗水,植被蒸腾在林地蒸散中起主导作用。

关键词: 稳定同位素, 植物蒸腾, 土壤蒸发, 非稳态假设, 定量拆分

Abstract: To fully understand the changes in the evapotranspiration components in forest ecosystem and their contribution to evapotranspiration at daily scale, we used the hypothesis theory of isotopic steady state and non-steady state combined with the water isotope analyzer system to quantitatively split and compare the evapotranspiration components of Platycladus orientalis ecosystem during the growing season. Results showed that the ¹⁸O of water from different sources during the four mea-surement days (August 5, 8, 10, 11, 2016) all showed surface soil water and oxygen isotope composition (δ_S) > branch water and oxygen isotope composition (δ_X) > atmospheric water vapor oxygen isotopes composition (δ_V), with obvious differences due to the isotope fractionation. Oxygen isotopes composition of soil evaporated water vapor (δ_E) was between -26.89‰～-59.68‰ at the daily scale, showing a pattern of first rising and then decreasing. The oxygen isotopic composition of evapotranspiration water vapor in forest ecosystem (δ_ET) was between -15.99‰～-10.04‰. The oxygen isotopic composition of transpired water vapor under steady state(δ_T-ISS) was between -12.10‰～-9.51‰. The oxygen isotopic composition of transpired water vapor under non-steady state (δ_T-NSS) was between -13.02‰～-7.23‰. δ_ET and δ_T-NSS had the same changing trend throughout the day at the daily scale, while the trend of δ_ET, δ_T-ISS and δ_T-NSS was approximately the same during 11:00-17:00. In general, the contribution rate of plant transpiration to total evapotranspiration showed that F_T-ISS was between 79.1%-98.7%, and F_T-NSS was between 88.7%-93.7%. Our results suggested that water consumption through soil evaporation was far less than that of vegetation transpiration in the study area, and that vegetation transpiration dominated forest evapotranspiration.

Key words: stable isotope, plant transpiration, soil evaporation, non-steady-state assumption, quantitative partitioning

武昱鑫, 张永娥, 贾国栋, 王渝凇, 余新晓. 基于多种同位素模型的侧柏林生态系统蒸散组分定量拆分[J]. 应用生态学报, 2021, 32(6): 1971-1979.

WU Yu-xin, ZHANG Yong-e, JIA Guo-dong, WANG Yu-song, YU Xin-xiao. Quantitative separation of evapotranspiration components of Platycladus orientalis ecosystem based on multiple isotope models[J]. Chinese Journal of Applied Ecology, 2021, 32(6): 1971-1979.

参考文献

[1] 张永芳, 邓珺丽, 关德新, 等. 松嫩平原潜在蒸散量的时空变化特征. 应用生态学报, 2011, 22(7): 1702-1710 [Zhang Y-F, Deng J-L, Guan D-X, et al. Spatiotemporal changes of potential evapotranspiration in Songnen Plain of Northeast China. Chinese Journal of Applied Ecology, 2011, 22(7): 1702-1710]
[2] 罗伦, 余武生, 万诗敏, 等. 植物叶片水稳定同位素研究进展. 生态学报, 2013, 33(4): 1031-1041 [Luo L, Yu W-S, Wan S-M, et al. Advances in the study of stable isotope composition of leaf water in plants. Acta Ecologica Sinica, 2013, 33(4): 1031-1041]
[3] Dongmann G, Nürnberg HW, Förstel H, et al. On the enrichment of H₂¹⁸O in the leaves of transpiring plants. Radiation and Environmental Biophysics, 1974, 11: 41-52
[4] Cooper LW, Deniro MJ. Covariance of oxygen and hydrogen isotopic compositions in plant water: Species effects. Ecology, 1989, 70: 1619-1628
[5] 程立平, 刘文兆. 黄土塬区几种典型土地利用类型的土壤水稳定同位素特征. 应用生态学报, 2012, 23(3): 651-658 [Cheng L-P, Liu W-Z. Characteristics of stable isotopes in soil water under several typical land use patterns on Loess Tableland. Chinese Journal of Applied Ecology, 2012, 23(3): 651-658]
[6] Wang P, Yamanaka T, Li XY, et al. Partitioning evapo-transpiration in a temperate grassland ecosystem: Numerical modeling with isotopic tracers. Agricultural and Forest Meteorology, 2015, 208: 16-31
[7] Good SP, Soderberg K, Guan K, et al. δ²H isotopic flux partitioning of evapotranspiration over a grass field following a water pulse and subsequent dry down. Water Resources Research, 2014, 50: 1410-1432
[8] Wen XF, Yang B, Sun XM, et al. Evapotranspiration partitioning through in-situ oxygen isotope measurements in an oasis cropland. Agricultural and Forest Meteorology, 2016, 230: 89-96
[9] Zhang YC, Shen YJ, Sun HY, et al. Evapotranspiration and its partitioning in an irrigated winter wheat field: A combined isotopic and micrometeorologic approach. Journal of Hydrology, 2011, 408: 203-211
[10] Xu Z, Yang HB, Liu FD, et al. Partitioning evapotranspiration flux components in a subalpine shrubland based on stable isotopic measurements. Botanical Studies, 2008, 49: 351-361
[11] 孙守家, 孟平, 张劲松, 等. 华北低丘山区栓皮栎生态系统氧同位素日变化及蒸散定量区分. 生态学报, 2015, 35(8): 2592-2601 [Sun S-J, Meng P, Zhang J-S, et al. Variation of vapor oxygen isotopic composition and partitioning evapotranspiration of oak woodland in the low hilly area of North China. Acta Ecologica Sinica, 2015, 35(8): 2592-2601]
[12] 张永娥, 余新晓, 陈丽华, 等. 北京山区侧柏林蒸散组分δ¹⁸O的确定及定量区分. 水土保持学报, 2017, 31(1): 122-126 [Zhang Y-E, Yu X-X, Chen L-H, et al. Determining δ¹⁸O value of evapotranspiration components and partition total evapotranspiration of Platycladus orientalis forest in Beijing Mountains Area. Journal of Soil and Water Conservation, 2017, 31(1): 122-126]
[13] 彭文丽, 赵良菊, 谢聪, 等. 黑河上游青海云杉森林生态系统蒸散发分割. 冰川冻土, 2020, 42(2): 629-640 [Peng W-L, Zhao L-J, Xie C, et al. Evapotranspiration partitioning of the Picea crassifolia forest ecosystem in the upper reaches of the Heihe River. Journal of Glaciology and Geocryology, 2020, 42(2): 629-640]
[14] Wei X, Wei ZW, Wen XF. Evapotranspiration partitioning at the ecosystem scale using the stable isotope method: A review. Agricultural and Forest Meteorology, 2018, 263: 346-361
[15] Farquhar GD, Cernusak LA. On the isotopic composition of leaf water in the non-steady state. Functional Plant Biology, 2005, 32: 293-303
[16] Wen XF, Zhang SC, Sun XM. Recent advances in H₂¹⁸O enrichment in leaf water. Journal of Plant Ecology, 2008, 32: 961-966
[17] Gat JR. Oxygen and hydrogen isotopes in the hydrologic cycle. Annual Review of Earth & Planetary Sciences, 1996, 24: 225-262
[18] Yepez EA, Williams DG, Scott RL, et al. Partitioning overstory and understory evapotranspiration in a semiarid savanna woodland from the isotopic composition of water vapor. Agricultural and Forest Meteorology, 2003, 119: 53-68
[19] Wang LX, Caylor KK, Villegas JC, et al. Partitioning evapotranspiration across gradients of woody plant cover: Assessment of a stable isotope technique. Geophysical Research Letters, 2010, 37: doi: 10.1029/2010GL043228
[20] Macinnis-Ng CMO, Flores EE, Müller H, et al. Rainfall partitioning into throughfall and stemflow and associated nutrient fluxes: Land use impacts in a lower montane tropical region of Panama. Biogeochemistry, 2012, 111: 661-676
[21] Farquhar GD, Cernusak LA. On the isotopic composition of leaf water in the non-steady state. Functional Plant Biology, 2005, 32: 293-303
[22] Zhang YG, Yu XX, Chen LH, et al. Comparison of the partitioning of evapotranspiration: Numerical modeling with different isotopic models using various kinetic fractionation coefficients. Plant and Soil, 2018, 430: 1-22
[23] 徐晓梧, 余新晓, 贾国栋, 等. 基于稳定同位素的SPAC水碳拆分及耦合研究进展. 应用生态学报, 2017, 28(7): 2369-2378 [Xu X-W, Yu X-X, Jia G-D, et al. A review of water and carbon flux partitioning and coupling in SPAC using stable isotope techniques. Chinese Journal of Applied Ecology, 2017, 28(7): 2369-2378]
[24] Williams DG, Cable W, Hultine K, et al. Evapotranspiration components determined by stable isotope, sap flow and eddy covariance techniques. Agricultural and Forest Meteorology, 2004, 125: 241-258
[25] Dubbert M, Cuntz M, Piayda A, et al. Oxygen isotope signatures of transpired water vapor: The role of isotopic non-steady-state transpiration under natural conditions. New Phytologist, 2014, 203: doi: 10.1111/nph.12878
[26] Farquhar GD, Gan KS. On the progressive enrichment of the oxygen isotopic composition of water along a leaf. Plant, Cell and Environment, 2003, 26: 801-819
[27] Sun SJ, Meng P, Zhang JS, et al. Partitioning oak woodland evapotranspiration in the rocky mountainous area of North China was disturbed by foreign vapor, as estimated based on non-steady-state ¹⁸O isotopic composition. Agricultural and Forest Meteorology, 2014, 184: 36-47
[28] Jasechko S, Sharp ZD, Gibson JJ, et al. Jasechko et al. reply. Nature, 2014, 506: 2-3
[29] Good SP, Noone D, Bowen G. Hydrologic connectivity constrains partitioning of global terrestrial water fluxes. Science, 2015, 349: 175-177
[30] 王渝淞, 贾国栋, 张永娥. 北京山区侧柏林蒸散拆分研究. 水土保持学报, 2019, 33(2): 272-278 [Wang Y-S, Jia G-D, Zhang Y-E, et al. Study on the separation of evapotranspiration of Platycladus orientalis forest in Beijing Mountains Area. Journal of Soil and Water Conservation, 2019, 33(2): 272-278]
[31] 杨斌, 谢甫绨, 温学发, 等. 华北平原农田土壤蒸发δ¹⁸O的日变化特征及其影响因素. 植物生态学报, 2012, 36(6): 539-549 [Yang B, Xie F-T, Wen X-F, et al. Diurnal variations of soil evaporation δ¹⁸O and factors affecting it in cropland in North China. Chinese Journal of Plant Ecology, 2012, 36(6): 539-549]