北方典型杨树人工林能量分配与碳水通量模拟

发布时间：2018-02-27 10:07

  本文关键词： 杨树人工林 能量分配 表层阻力 Biome-BGC模型 气候变化 碳水通量　出处：《北京林业大学》2016年博士论文　论文类型：学位论文

【摘要】：在中国北方地区,杨树因具有生长迅速、生产力和生物量高等特点而在碳汇林业中发挥着重要的作用,但该高耗水性树种在固碳的同时也会消耗掉大量的水分；在当前气候变化和该地区水资源短缺的现状下,进一步探究该地区大面积杨树人工林的耗水特性和其对周边生态系统可利用水分的潜在影响,评价其对半干旱环境的适应性以及预测其碳水通量对未来气候变化的响应,对于合理应对气候变化、制定长期林业规划和实行科学经营有着十分重要的意义。本研究基于涡度相关(eddy covariance, EC)系统和微气象系统对北京市大兴区杨树(Populous euramericana cv. "74/76")人工林生态系统与大气间碳、水和能量通量长期连续地监测,研究了该生态系统在不同气候条件下能量分配与蒸散发(ET)的动态变化以及生物物理控制机制,利用碳水通量观测数据对Biome-BGC模型进行了参数敏感性分析、参数优化和模拟结果的验证和评价,以及探讨了Biome-BGC模型在杨树人工林碳水通量研究中的适用性。主要研究成果如下：(1)在年际尺度上,杨树人工林的能量分配与蒸散发(ET)响应于气候干旱,存在着显著的湿润与干旱年份间的差异,其中LE/(Rn-G)从湿润年份的0.62下降到干旱年份的0.53,波文比(β)则从0.83上升至1.57；对应地,干早年份中的日平均ET(2.23±1.30 mm/day)低于湿润年份约17%；在季节尺度上,能量分配和ET的动态变化响应于季节性干旱胁迫,水分供应(降水与灌溉之和)则是其主要的影响因素。(2) 表层阻力(Rs)响应于气候干旱,其中干旱年份的Rs:LAI高于湿润年份(71.2sm-1LAI-1)约50%,气候阻力(R,)和空气动力学阻力(Ra)并未表现出干湿年份间的差异,均值分别为74.6 s m-1和23.2 s m-1；在季节尺度上,季节性干旱胁迫则显著地影响着Rs和尺i的变化,总体上表现为干旱胁迫时段的Rs和尺,要高于非胁迫时段。(3) 冠层分离指数(Ω)及偏相关分析结果表明,Rs是控制杨树人工林能量分配和ET的主导因素,即使在湿润年份也是如此；β与ET分别与Rs呈正相关(二阶相关系数SOCC:0.905～0.965)和负相关(SOCC:-0.518～-0.293)关系,且Rs在干旱年份中对β和ET的控制作用要显著强于湿润年份,其中Rs对ET的控制作用会随着土壤水分状况的改善而增强；β与尺,呈负相关关系(-0.667～-0.614),也表现出类似于其与Rs的干湿年份间差异,Ra只在湿润年份中与β有负相关关系；而Ri和Ra对ET的影响远小于Rs,且在干湿年份中不同的土壤水分条件下有所不同。(4) 杨树人工林在干旱和湿润年份中的作物干旱系数(LE/LEeq)分别为0.68和0.81,表明无论在干旱还是湿润年份,该生态系统均受限于有限的水资源；由于其ET消耗了所有的自然降水(在干旱和湿润年份中均如此),同时在干旱年份中还需要灌溉,导致该地区地下水无法得到补给；因此,从长远来看,该地区大面积栽植的杨树人工林,会因其高耗水性而潜在威胁到其周边生态系统和生境的用水。(5) Biome-BGC模型中影响杨树人工林生态系统碳水通量的主要生理生态参数有SLA. k, LWT、LWC:TWC、FLNR、CGPSC:LC、gsmax、wint和LFG；优化后模型对各碳水通量模拟的准确性方面表现为ET NEE GPP ER,在模拟值与实测值的吻合程度上NEE GPP ET ER;而相较于未优化的模型,参数优化对碳水通量模拟准确性的提升程度上表现为ERGPPETNEE,而对模拟值与实测值的吻合能力的提升程度上则表现为ETERGPPNEE。(6) 在未来气候变化条件下,气温升高(+2、+4、+6℃C)使杨树人工林的MR和Tr增强,而使GPP、GR、HR、NPP和Es减弱；除了Tr,GPP、MR、 GR、HR、NPP和Es均随大气CO2浓度的升高(升至650 ppm、860 ppm)而提高；降水的增加则提高了所有的碳水通量。单独大气CO2浓度上升对杨树人工林碳水通量的影响作用要强于单独气温上升和降水增加各自的作用,碳水通量对不同气候变化情景的响应则是基于三种作用的叠加；其中在三种因素均上升的未来气候变化情景中,杨树人工林的碳水通量较当前气候下的均有不同程度的提高。
[Abstract]:In the Chinese northern region, because of the rapid growth of poplar, the characteristics of higher productivity and biomass in carbon forestry plays an important role, but the high water consumption of tree species in carbon sequestration will also consume large amounts of water; in the current climate change and water resources in this area is short of water. The characteristics and on the surrounding ecological system can utilize the potential effects of water consumption to further explore the area of poplar plantation, evaluate the semi-arid environment adaptability and the prediction of the carbon and water fluxes in response to climate change, to reasonably adapt to climate change, to develop long-term forestry planning and implementation of scientific management is very important the significance of this study. Based on the eddy covariance (eddy covariance EC) system and micro meteorological system in Beijing city of Daxing District poplar (Populous euramericana cv. 74/76) plantation ecosystem and Gas carbon, water and energy fluxes in long-term continuous monitoring of the ecological system with energy distribution and steaming in different climate conditions (ET) and the dynamic changes of biophysical control mechanism of Biome-BGC model parameter sensitivity analysis was conducted using water and carbon flux data, verification and evaluation of parameter optimization and simulation results well, the applicability of Biome-BGC model in water flux of Poplar Plantation in Lin Tan. The main research results are as follows: (1) at the annual scale, energy distribution and evaporation of Poplar Plantation distribution (ET) in response to drought, there are differences between the humid and arid year significantly, the LE/ (Rn-G) decreased from 0.62 to 0.53 years of drought wet years, Povenby (beta) has increased from 0.83 to 1.57; the dry year, the average daily ET (2.23 + 1.30 mm/day) less than about 17% in wet years; season On the scale, seasonal drought stress response dynamic change of energy distribution and ET (precipitation and irrigation, water supply and) is the main influence factors. (2) surface resistance (Rs) in response to drought, the drought year Rs:LAI was higher than that of wet years (71.2sm-1LAI-1) (about 50% climate resistance R) and aerodynamic resistance (Ra) did not show the difference between wet and dry years, the average was 74.6 s M-1 and 23.2 s M-1; in the season scale, seasonal drought stress significantly affects the change of Rs and I scale, the overall performance of the drought stress time and Rs to feet. Higher than that of the non stress period. (3) canopy separation index (q) and partial correlation analysis showed that Rs is a dominant factor to control the energy distribution of Poplar Plantation and ET, even in wet years; beta and ET were positively correlated with Rs (correlation coefficient of two order SOCC:0.905 ~ 0.965) and Negative correlation (SOCC:-0.518 ~ -0.293), and Rs in dry year in control effect on beta and ET is significantly stronger than the wet year, the control effect of Rs on ET will be enhanced with the improvement of soil moisture; beta and feet, negative correlation (-0.667 ~ -0.614), also showed differences dry and wet year is similar to the Rs, Ra only in wet years and beta has negative correlation; and the effects of Ri and Ra on ET far less than Rs, and different soil moisture conditions in dry and wet years under different. (4) crop drought coefficient of Poplar Plantation in arid and humid year the (LE/LEeq) were 0.68 and 0.81, showed that both in dry or wet years, the ecological systems are subject to limited water resources; because the ET consumed all the natural precipitation (both in arid and humid year), while in drought years also need irrigation, resulting in The groundwater can not get supplies; therefore, in the long run, poplar plantation area planted in the area, because of its high water consumption and the potential threat to the surrounding ecosystem and habitat water. (5) the Biome-BGC model in the influence of carbon and water fluxes of main physiological and ecological parameters of Poplar Plantation Ecosystem SLA. K, LWT, LWC:TWC, FLNR, CGPSC:LC, gsmax, wint and LFG; the accuracy of the simulation model of carbon and water fluxes after optimizing the performance for the ET NEE GPP in ER, the simulation results fit the degree of NEE GPP ET ER with the measured values; and compared to the non optimized model, parameter optimization to improve the degree of simulation the accuracy of carbon and water fluxes on the performance of ERGPPETNEE, and the simulation value is consistent performance for the ETERGPPNEE. to improve the degree of the ability and the measured value (6) in the future climate change conditions, temperatures (+2, +4, +6 C C) made of poplar plantation MR And the GPP, enhanced Tr, GR, HR, NPP and Es decreased; in addition to Tr, GPP, MR, GR, HR, NPP and Es decreased with the increasing atmospheric CO2 concentrations (up to 650 ppm, 860 ppm) increased; the increase of precipitation increased carbon and water fluxes all alone. Atmospheric CO2 concentration rose a stronger effect on Yang Shuren forest carbon and water fluxes increase their effect on individual temperature rise and precipitation, carbon and water fluxes response to different climate change scenarios is the superposition of three effects which are based on; a rise in three factors of future climate change scenarios, improve the carbon and water fluxes of Poplar Plantation than under the current climate in varying degrees.

【学位授予单位】：北京林业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S792.11
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本文编号：1542214