短轮伐毛白杨人工林耗水规律及作物系数曲线构建.pdf
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1、doi:10.11707/j.1001-7488.LYKX20230190短轮伐毛白杨人工林耗水规律及作物系数曲线构建*李玲雅1,2,3邸楠4刘金强1,2,3赵小宁1,2,3邹松言5付海曼6席本野1,2,3(1.林木资源高效生产全国重点实验室北京 100083;2.干旱半干旱地区森林培育和生态系统研究国家林业和草原局重点实验室北京 100083;3.北京林业大学省部共建森林培育与保护教育部重点实验室北京 100083;4.内蒙古大学生态与环境学院呼和浩特 010021;5.重庆市林业投资开发有限责任公司重庆 401147;6.国家林业和草原局产业发展规划院北京 100010)摘要:【目的】明确
2、短轮伐毛白杨人工林在轮伐期内的长期耗水规律并构建(基础)作物系数曲线,为毛白杨人工林节水灌溉与经营管理提供依据。【方法】对充分供水下 26 年生毛白杨人工林的蒸腾(Tr)、土壤蒸发(Es)和林分蒸散(ET)进行连续监测,同时获取气象因子、茎干直径日增长量(DGR)、叶面积指数(LAI)和地下水位数据,并计算参考作物潜在蒸散量(ET0)、基础作物系数(Kcb)和作物系数(Kc)。【结果】1)林分每年的主要生长阶段不同,但 57 月均生长最快,该时期林木的直径生长量占生长季总生长量的 69%88%,ET 累积量占生长季 ET 总量的 47%61%。根据轮伐期内林分的平均 DGR 和 LAI 季节动
3、态,可将毛白杨人工林生长阶段划分为生长前期、发展期、生长中期和生长末期,其对应时段分别为 4 月初4 月中旬、4 月中旬6 月中旬、6 月中旬8 月中旬和 8 月中旬10 月末。2)林分 Tr、Es和 ET 存在明显的季节变化,但变化模式在不同林龄上存在较大差异;另外,林分 Tr 的季节变化与 ET0仅在 36 年生林分中显著正相关(P 0.05)、Es 和 ET0 的正相关(P 0.05)只出现在 2 年生和 6 年生林分中,但 ET 和 ET0在所有林龄林分中均存在正相关关系(P 0.05)。林分年总 ET 和 Tr 随林龄增加分别呈指数(P 0.001)和线性升高(P=0.004),林分
4、Es则逐渐降低但在 6 年生林分中突然大幅度升高;ET 中的 Tr 和 Es 占比分别逐年升高和降低,并在 56 年生林分中趋于稳定。3)Kcb和 Kc的季节变化特征在不同林龄林分中也存在明显差异,二者的季节变化不受地下水位影响,但其在36 年生林分中受 LAI 的控制(P 0.05),且 Kcb(R2=0.440.87)和 Kc(R2=0.420.77)与 LAI 间均可建立较好的定量关系模型。此外,依据 Kcb和 Kc的变化规律和划分的林木生长阶段,构建了毛白杨人工林的(基础)作物系数曲线和列表。【结论】毛白杨林分蒸散、蒸腾和蒸发的季节动态特征存在年际变化,ET0的波动是控制耗水季节动态的
5、重要因子,但控制方式因耗水组分和林龄而异。毛白杨生长阶段可划分为 4 个时期,且每年 57 月为林分水分管理的关键时期。构建的毛白杨人工林(基础)作物系数曲线、列表和预测模型,可用于林分耗水量的估算,帮助制定和优化灌溉制度。此外,研究结果不仅可为其他树种的高效水分管理提供借鉴,而且还能帮助深化认识人工林的水分关系。关键词:蒸腾;蒸散;土壤蒸发;毛白杨;人工林;水分管理中图分类号:S718.43文献标识码:A文章编号:10017488(2023)10007613Water Consumption Pattern and Crop Coefficient Curve Construction of
6、 Short-rotationPopulus tomentosa PlantationsLi Lingya1,2,3Di Nan4Liu Jinqiang1,2,3Zhao Xiaoning1,2,3Zou Songyan5Fu Haiman6Xi Benye1,2,3(1.State Key Laboratory of Efficient Production of Forest ResourcesBeijing 100083;2.Key Laboratory for Silviculture and Forest Ecosystem Research in Arid-and Semi-Ar
7、id Region of National Forestry and Grassland AdministrationBeijing 100083;3.Key Laboratory for Silviculture and Conservation of Ministry ofEducation,Beijing Forestry UniversityBeijing 100083;4.School of Ecology and Environment,Inner Mongolia UniversityHohhot 010021;5.ChongqingForestry Investment and
8、 Development CompanyChongqing 401147;6.Industrial Development Planning Institute of National Forestry and GrasslandAdministrationBeijing 100010)Abstract:【Objective】This study aims to clarify the long-term water consumption pattern of short-rotation Populus tomentosaplantation during the rotation per
9、iod and construct a(basic)crop coefficient curve,so as to provide a basis for water-savingirrigation and management of P.tomentosa plantation.【Method】We continuously monitored the transpiration (Tr),soilevaporation(Es),and stand evapotranspiration(ET)of 26-year-old P.tomentosa plantations under suff
10、icient water supply.At thesame time,we also collected data of meteorological factors,daily trunk growth(DGR),leaf area index(LAI),and groundwaterlevel,and further calculated reference crop potential evapotranspiration(ET0),basic crop coefficient(Kcb),and crop coefficient(Kc).收稿日期:20230506;修回日期:20230
11、828。基金项目:国家重点研发计划课题(2021YFD2201203)。*席本野为通讯作者。第 59 卷 第 10 期林业科学 Vol.59,No.102 0 2 3 年 1 0 月SCIENTIA SILVAE SINICAEOct.,2 0 2 3【Result】1)The main growth stages of the stand were different each year,but the growth rate was the fastest from May to July,during which the diameter growth of trees in this
12、period accounted for 69%88%of the total growth in the whole growth season,and the cumulative ET accounted for 47%61%of the total ET in the whole growth season.According to the average DGR andLAI seasonal dynamics of stand during the rotation period,the growth stages of P.tomentosa plantation were di
13、vided into the earlygrowth stage,development stage,middle growth stage,and late growth stage,and the corresponding periods were from early Aprilto mid-April,from mid-April to mid-June,from mid-June to mid-August,and from mid-August to the end of October,respectively.2)The results showed that there w
14、ere significant seasonal changes in Tr,Es,and ET in the stand,but the change patterns were quitedifferent in different stand ages.In addition,the seasonal variation of stand Tr was significantly positively correlated with ET0 onlyin 36-year-old stands(P0.05),and there was positive correlation betwee
15、n Es and ET0(P0.05)only in 2-year-old and 6-year-oldstands,but there was a positive correlation between ET and ET0 in all stand ages(P0.05).The annual total ET and Tr increasedexponentially(P0.001)and linearly(P=0.004)with the increase of stand age,respectively,while the stand Es gradually decreased
16、with the plant age,but suddenly increased significantly in the 6-year-old stand.The proportions of Tr and Es in ET increased anddecreased yearly,respectively and tended to be stable in 56-year-old stands.3)There were significant differences in seasonalvariation characteristics of Kcb and Kc in diffe
17、rent stand ages.The seasonal variation of Kcb and Kc was not affected by groundwaterlevel,however,it was controlled by LAI in 36-year-old stands(P0.05).Moreover,both Kcb(R2=0.440.87)and Kc(R2=0.420.77)could establish an excellent quantitative relationship model with LAI.In addition,we constructed th
18、e(basic)cropcoefficient curve and list of P.tomentosa plantations according to the change patterns of Kcb and Kc and the divided tree growthstages.【Conclusion】The seasonal dynamic characteristics of evapotranspiration,transpiration,and evaporation of P.tomentosastands have interannual changes.The fl
19、uctuation of ET0 is an essential factor in controlling the seasonal dynamics of waterconsumption,but the control mode varies with water consumption components and stand ages.The growth stage of P.tomentosacan be divided into four periods,and the key period of water management in stands is from May t
20、o July every year.The established(basic)crop coefficient curve,list,and prediction model of P.tomentosa plantation can be used to estimate the stand waterconsumption and thereby formulate and optimize the irrigation schedule.In addition,the results can not only provide a referencefor the efficient w
21、ater management of other tree species,but also help deepen the understanding of the water relationship of theplantation.Key words:transpiration;evapotranspiration;soil evaporation;Populus tomentosa;plantation;water management 杨树(Populus spp.)因其生长快、适应性强而成为我国发展速生丰产用材林的主要树种。第九次全国森林资源清查数据显示,我国杨树人工林面积已达7
22、57 万 hm2,占全国人工林总面积的 13.25%,是世界上杨树人工林面积最大的国家。人工林产量与质量的提高很大程度上取决于高效集约栽培技术的应用(Xiet al.,2021)。水分是影响杨树生长的最重要因素(董文怡等,2011;Xi et al.,2016,2021),可通过水分管理的手段来提高杨树人工林的生产力(Gochis et al,2000;李广德,2010;任忠秀等,2011;孙兆地等,2012;席本野等,2012),但人工林水分管理策略的合理制定和高效实施,需依赖对林木耗水规律的准确把握和对林分耗水量的准确估算。林分耗水量系指林木蒸腾、土壤蒸发消耗的水分以及植株体内所含水分的总
23、和。由于植株体内所含水分占比非常小且影响因素较复杂而常忽略不计,因此,林分的耗水量即林分蒸散量(林木蒸腾+土壤蒸发)。目前,国际上较为通用的植物耗水量计算方法是通过参考作物潜在蒸散量(reference crop potentialevapotranspiration,ET0)与作物系数 Kc(crop coefficient)和基础作物系数 Kcb(basal crop coefficient)计算的作物系数法(Allen et al.,1998)。该方法包括单作物系数法及双作物系数法,其中,单作物系数法以作物系数 Kc表示植物耗水量与参考作物耗水量之间的差异,Kc综合反映了植物的物种特异性
24、和土壤蒸发的平均效应。双作物系数法可以区分植物蒸腾和土壤蒸发对植物耗水量的影响,将 Kc分为基础作物系数 Kcb和土壤蒸发系数 Ke两部分,其中,Kcb代表植物蒸腾部分,是表层土壤干燥且根区土壤含水量不构成水分胁迫时植物蒸散量与 ET0的比值。在植物完全覆盖地面时,2种作物系数法计算结果差别不大,而地面被植物部分覆盖的情况下,双作物系数法计算得到的植物耗水量比单作物系数法更接近实测值(樊引琴等,2002)。因此,精确获取作物系数,探明植物耗水变化规律,是实现区域水资源高效利用和制定节水灌溉制度的前提。研究表明,杨树比大田作物及其他阔叶树种具有第 10 期李玲雅等:短轮伐毛白杨人工林耗水规律及作
25、物系数曲线构建77 更高的耗水需求(王彦辉等,2006;Petzold et al.,2011),因此,杨树林地的高效水分管理更加需要获取精准的林分耗水规律和耗水量信息,否则难以在林分最需水的时期给予最适量的水分供给。目前,已有不少杨树耗水特性研究集中于苗木上(方晓娟等,2010;董文怡,2011),且近十几年来,关于杨树人工林的耗水研究也大量开展。例如,李广德(2010)和莫康乐等(2014)分别研究了 45 年生和 13 年生杨树人工林的蒸腾特征,但未关注林地土壤蒸发和蒸散的变化规律;Gochis 等(2000)观测了 13 年生杂交杨人工林的蒸散变化,并构建了用于灌溉管理的 Kc 曲线,
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