【作者】 何淑勤；

【导师】 宫渊波；

【作者基本信息】 四川农业大学 ， 水土保持与荒漠化防治， 2019， 博士

【摘要】 人类干扰及不合理的资源开发利用,导致岷江上游干旱河谷区原有的生态防护功能、涵养水源能力降低,自然灾害频繁,水土流失加剧,生态系统退化严重。在我国生态脆弱区以植被建设为主的系列生态环境建设工程的实施背景下,适宜植被恢复模式的选择显得尤为必要和迫切。因此,本研究针对岷江上游生态环境建设的需求和水土保持研究的科学问题,在野外调查基础上,以岷江上游山地森林-干旱河谷交错带为研究对象,开展不同植被恢复模式下土壤理化性质的变化、土壤有机碳动态、水源涵养功能和土壤保持功能等方面的研究;筛选适合于山地森林-干旱河谷交错脆弱带的植被恢复模式,以期为山地森林-干旱河谷退化生态系统的恢复和重建提供理论依据。主要研究结果如下:（1）不同植被恢复模式土壤含水量均在7月最高,4月最低;土壤平均容重大小依次为荒草地、岷江柏-油松幼林、刺槐林、天然次生林、岷江柏幼林、沙棘+金花小檗灌丛。天然次生林、岷江柏幼林和荒草地模式以粗粉粒和物理性粘粒为主,分别占79.97%、72.96%和70.64%;沙棘+金花小檗灌丛模式以砂粒和物理性粘粒为主,分别占46.53%和27.7%;刺槐林和岷江柏-油松幼林模式以砂粒和粗粉粒为主,分别占75.33%和70.7%。除荒草地和刺槐林模式外,其余植被恢复模式均满足不均匀系数（Cu）>5,且曲率系数（Cs）在1-3范围的条件,属于级配良好土壤。沙棘+金花小檗灌丛模式土壤有机质含量、全氮含量、有效磷含量平均值均最高,分别为47.53 g kg^-1、4.94 g kg^-1和8.19 mg kg^-1,其次是天然次生林模式;天然次生林模式土壤速效钾最高,而刺槐林、荒草地模式均较低。不同植被恢复模式均以>2 mm粒径土壤风干团聚体含量为主,约占团聚体数量的60%。天然次生林模式以>2 mm和<0.25 mm粒径水稳性团聚体为主,其他植被恢复模式土壤水稳性团聚体分布均以<0.25 mm粒径为主,且不同土层平均含量均超过50%。天然次生林模式,粒径>0.25 mm的团聚体保存几率最大,土壤团聚体稳定性指数最高;刺槐林模式粒径>0.25 mm的团聚体保存几率最小,土壤团聚体稳定性指数也最低。（2）沙棘+金花小檗灌丛模式土壤总有机碳含量、活性有机碳含量、活性有机碳密度、总有机碳密度、非活性有机碳含量、非活性有机碳密度均最高,而刺槐林和荒草地模式均较低。与0-10 cm土层相比较,活性有机碳含量在10-20 cm和20-40 cm土层分别减少了31.40%和32.08%,非活性有机碳含量分别减少了29.89%和45.31%,总有机碳密度却分别增加了71.34%和195.29%。除沙棘+金花小檗灌丛和天然次生林模式土壤有机碳密度高于我国各森林类型(44-264t C hm^-2)的平均水平,其余植被恢复模式均低于这一数值,研究区植被恢复的土壤碳汇潜力较大。不同植被恢复模式土壤活性有机碳有效率表现为:沙棘+金花小檗灌丛>天然次生林>荒草地>岷江柏幼林>刺槐林>岷江柏-油松幼林,总体水平偏低（平均为0.26）。不同植被恢复模式土壤碳库管理指数介于48.31-251.56间,总体表现为:沙棘+金花小檗灌丛>天然次生林>岷江柏幼林>岷江柏-油松幼林>荒草地>刺槐林。轻组有机碳、颗粒有机碳和易氧化有机碳含量均在沙棘+金花小檗灌丛、天然次生林模式下较高,刺槐林模式较低,各组分均能较好地表征研究区不同植被恢复模式的土壤状况。（3）不同降雨条件下穿透雨量和透流率均表现为:岷江柏幼林>沙棘+金花小檗灌丛>岷江柏-油松幼林>刺槐林>天然次生林。茎干流总体表现为岷江柏幼林和沙棘+金花小檗灌丛模式茎干流较高,且随着降雨量的增加,以乔木为主的植被干流量的较灌木和混交林更为敏感。不同植被恢复模式降雨截留量变化范围1.331-3.824 mm,截留量占总降雨的25.49%-26.62%。天然次生林模式截留率均最大,在不同降雨条件下分别为50.32%、37.31%和25.49%,岷江柏幼林截留率均最小,分别为26.61%、17.51%和10.35%。不同植被恢复模式中,枯落物现存量大小依次是天然次生林>刺槐林>岷江柏-油松幼林>岷江柏幼林>沙棘+金花小檗灌丛>荒草地。不同植被恢复模式枯落物半分解层占现存总量比例均在60%以上,且均大于未分解层占现存总量比例,其中岷江柏幼林最高（79.89%）,天然次生林最低（60.66%）。刺槐林和天然次生林模式枯落物最大持水量较大,分别为53.25 t hm^-2和53.22 t hm^-2,岷江柏-油松幼林模式次之,荒草地最小。不同植被恢复模式枯落物半分解层持水量均大于未分解层,且持水量与浸水时间间呈对数、幂函数、线性和指数函数等关系;而枯落物未分解层、半分解层的吸水速率与浸泡时间均呈幂函数关系。不同植被恢复模式土壤有效贮水力表现为:沙棘+金花小檗灌丛>天然次生林>岷江柏-油松幼林>荒草地>刺槐林>岷江柏幼林。沙棘+金花小檗灌丛、天然次生林模式土壤入渗性能较强,考斯加可夫公式可较好拟合各植被恢复模式土壤入渗过程。（4）采用熵权法,从无机粉粘粒类、有机胶体类、水稳性团聚体类、土壤有机物类角度,基于<0.05 mm土壤颗粒含量、<0.002 mm土壤颗粒含量、结构性颗粒指数、土壤团聚状况、土壤团聚度、土壤分散率、>0.25 mm水稳性团聚体含量、>0.5 mm水稳性团聚体含量、结构体破坏率、平均重量直径、有机质含量等11个指标,构建了山地森林-干旱河谷区生态交错带土壤抗蚀性评价指标体系,得出:天然次生林、岷江柏幼林、沙棘+金花小檗灌丛三种模式总体抗蚀性较好,且天然次生林的抗蚀性分别为刺槐林和荒草地的1.48倍和1.39倍。土壤化学性质对研究区土壤抗蚀性影响较为敏感。不同植被恢复模式土壤抗冲指数随着冲刷时间延长总体上均呈增大的变化趋势,天然次生林模式土壤抗冲指数最大,为5.477,岷江柏幼林模式次之,荒草地最小。不同植被恢复模式土壤抗冲指数不仅与土壤颗粒特性有关,还与土壤有机质和活性有机碳含量呈显著或极显著正相关关系。不同植被恢复模式地表径流量和侵蚀产沙量大小均表现为荒草地最大,天然次生林地最小,且荒草地显著高于其他植被恢复模式。（5）选择枯落物现存量、枯落物最大持水量、枯落物分解强度、土壤有机质、全氮、有效磷、速效钾、土壤容重、毛管孔隙、土壤结构性颗粒指数、土壤团聚度、土壤分散率、稳定性指数、不均匀系数、曲率系数、风干团聚体分形维、土壤初渗速率、土壤稳渗速率、水稳性团聚体分形维、土壤结构体破坏率、土壤抗冲指数、土壤活性有机碳、土壤非活性有机碳、颗粒态有机碳、易氧化有机碳、碳库指数等26个指标构建了山地森林-干旱河谷交错带不同植被恢复模式土壤生态功能评价指标体系。采用熵权法和逼近理想点决策相结合的方法,综合相对近似度和贴近度获得不同植被恢复模式土壤生态功能评价结果,按照由优到劣依次为:天然次生林、岷江柏幼林、沙棘+金花小檗灌丛、岷江柏-油松幼林、刺槐林和荒草地。基于灵敏度稳定性分析结果,确定为天然次生林、岷江柏幼林和沙棘+金花小檗灌丛是适宜于山地森林-干旱河谷交错带植被恢复模式。更多还原

【Abstract】 Due to human disturbance and unreasonable resources development and utilization,the original ecological protection function of arid river valley in the upper reaches of the Minjiang River and the ability to conserve water resources have reduced,the soil and water loss was quite serious,degradation of ecosystem is serious and the ecological environment is extremely fragile.Under the background of the implementation of a series of ecological environment construction projects based on vegetation construction in ecologically fragile areas,the selection of suitable vegetation restoration patterns is particularly necessary and urgent.Therefore,this study is aimed at the needs of ecological environment construction in the upper reaches of the Minjiang River and the scientific issues of soil erosion research.Based on the field investigation,the mountain forest-dry valley interlaced zone is taken as the research object,soil physical and chemical properties,soil organic carbon dynamics,water conservation function and soil conservation function under different vegetation restoration patterns were studied,obtaining a vegetation restoration model suitable for mountain forests-arid valleys and fragile zones in order to provide a theoretical basis for the restoration and reconstruction of degraded ecosystems in mountain forests and arid valleys.The main findings are as follows:（1）The soil water content of different vegetation restoration patterns was the highest in July and the lowest in April.The average soil bulk density was in the order of grassland（G）,Minjiang cypress-pinus tabulaeformis（MP）,Locust forest（LF）,natural secondary forest（NSF）,Minjiang cypress（M）,Seabuckthorn and Berberis wilsonii Hemsl（S）.The patterns of NSF,M and G were dominated by coarse silt and physical clay,which accounted for 79.97%,72.96%and 70.64%,respectively.Sand grains and physical clay dominated the pattern of S accounting for 46.53%and27.7%,respectively.The patterns of LF and MP are mainly sand grains and coarse silt,accounting for 75.33%and 70.7%respectively.The dispersion degree of soil particles is low,the deflection is larger,the peak state value is higher,and the imbalance degree of particle distribution is different in the pattern of G and LF.In addition to the G and LF pattern,the remaining vegetation restoration patterns meet the soil inhomogeneity coefficient（Cu）>5,and the curvature coefficient（Cs）in the range of 1-3,belong to the well-equipped soil.The soil organic matter content,total nitrogen content and effective phosphorus content were the highest in the pattern of S,respectively,47.53 g kg^-1,4.94 g kg^-1 and 8.19 mg kg^-1,followed by NSF pattern.The NSF pattern has the highest available potassium,while the pattern of LF and G is lower.The particle size of>2 mm is mainly in soil non-waterstable aggregate for the different vegetation restoration patterns,accounting for about 60%of all the aggregates.The particle sizes of>2 mm and<0.25 mm were mainly in soil waterstable aggregate for NSF pattern,and the particle size of<0.25 mm was mainly for the other vegetation restoration patterns.The average aggregate contents of<0.25 mm particle size were more than 50%in different soil layers,and the average aggregate contents of<0.25 mm particle size was up to 89%for the LF pattern.For the NSF pattern,the preservation probability of soil aggregates in the particle size of>0.25 mm was the highest,and the stability index was also the highest.For the M pattern,the preservation probability of soil aggregates in the particle size of>0.25 mm and the stability index was also the lowest.（2）The content of soil organic carbon,soil labile organic carbon（LOC）,soil organic carbon density of LOC,soil organic carbon density,soil inactive organic carbon（NLOC）and soil organic carbon density of NLOC were the highest in the pattern of S,while the indexes of LF and G patterns were lower.Compared with the 0-10cm soil layer,the content of LOC in the 10-20cm soil layer and the 20-40cm soil layer decreased by 31.40%and 32.08%respectively,and the content of NLOC decreased by 29.89%and 45.31%respectively,and the soil organic carbon density increased by 71.34%and 195.29%respectively.Soil organic carbon density of S pattern and NSF pattern was higher than the average level of the forest type in China(44-264t C hm^-2),and the other vegetation recovery patterns were lower than this value.The results showed that the soil carbon sink potential of the different vegetation restoration pattern is greater in the study area.The efficiency ratios of the labile organic carbon in different vegetation restoration patterns was as following:S>NSF>G>M>LF>MP,and the overall level was low and the average value was only 0.26.The carbon pool management index ranged from 48.31 to 251.56for the different vegetation restoration patterns,and was as following:S>NSF>M>MP>G>LF.The content of light fraction organic carbon（LFOC）,The particulate organic content（POC）and soil readily oxidizable organic carbon（ROC）content were higher in the patterns of S and NSF,and the pattern of LF was lower.Each component of soil organic carbon could better characterize the soil condition of different vegetation restoration patterns in the study area.（3）Under different rainfall conditions,both the through-fall quantity and through-fall ratio showed as follows:M>S>MP>LF>NSF.The stemflows were higher for the patterns of M and S,and with the increase of rainfall,the stemflow of arbor dominated vegetation was more sensitive than that of shrub and mixed forest.The range of rainfall interception were from1.331mm to 3.824mm for the different vegetation restoration patterns,and the interception accounted for 25.49%-26.62%of the total rainfall.The interception rates of NSF were the highest（50.32%,37.31%and25.49%,respectively）,and the interception ratio of M were the lowest（26.61%,17.51%and 10.35%,respectively）.Under different vegetation restoration patterns,the litter stock of the litter was in the order of NSF>LF>MP>M>S>G.Under different vegetation restoration patterns,the proportion of semidercomposed litter layer in the existing total was greater than that of undecomposed litter layer,which were more than 60%,among which the pattern of M was the highest,accounting for 79.89%,and the pattern of NSF was the lowest,accounting for 60.66%.The maximum water holding capacity of litter in LF and NSF pattern was 53.25 t hm^-2 and 53.22 t hm^-2,respectively,followed by that in MP pattern,and the maximum water holding capacity of litter in G was the least.The semi-decomposed litter layer of different vegetation restoration patterns had a higher water holding capacity than that of the undecomposed litter layer,and the relationship between water holding capacity and time of soaking showed mutiple relevance such as logarithmic,power function,linear and exponential function.The relationship between water absorption rate and time of soaking for the undecomposed layer and semi-decomposed layer of litters showed power functions under different vegetation restoration patterns.Soil available moisture storage capacity showed the order of S>NSF>MP>G>LF>M under different vegetation restoration patterns.The soil permeability was strong for the patterns of S and NSF.The soil infiltration process can be fitted by Kostiakov formula for all vegetation restoration patterns.（4）By entropy-weighing method,from the point of view of inorganic silt-clays,organic colloid,water-stable aggregates and soil organic matter,evaluation indicators system of the soil anti-erodibility was established based on 11 indexes such as the<0.05 mm soil particles content,<0.002 mm soil particles content,soil structural index,soil aggregation condition,soil aggregation degree,soil dispersion rate,waterstable aggregate content of>0.25 mm particle size,waterstable aggregate content of>0.5 mm particle size,damage rate of soil structure,average weight diameter and soil organic matter content in a mountain forest-arid valley area.The results showed that the soil anti-erodibility of three patterns（NSF,M,S）was the better for all vegetation restoration patterns.Soil anti-erodibility of NSF was 1.48 times and1.39 times of patterns of LF and G respectively.Soil chemical properties were sensitive to soil anti-erodibility in the study area.Index of soil anti-scourability increased with the extension of scour time under different vegetation restoration patterns.Index of soil anti-scourability was the highest（5.477）for the pattern of NSF,followed by M pattern,and the index of soil anti-scourability of G pattern was the lowest.Index of soil anti-scourability was not only related to soil particle characteristics,but also has significant or extremely significant positive correlation with soil organic matter content and soil active organic carbon content under different vegetation restoration patterns.The surface runoff and sediment yield of G pattern was the highest and the surface runoff and sediment yield of NSF pattern was the lowest,and the pattern of G was significantly higher than the other vegetation restoration patterns.（5）Evaluation indicators system of soil ecological function was established based on 26 indexes such as the litter stock of the litter,the maximum water holding capacity of litter,litter decomposition intensity,soil organic matter content,soil total nitrogen,soil available phosphorus,soil available potassium,soil bulk density,capillary porosity,soil structural index,soil aggregation degree,soil dispersion rate,stability index,Cu,Cs,fractal dimension of non-waterstable aggregate,soil initial infiltration rate,soil steady infiltration rate,fractal dimension of waterstable aggregate,soil structural index,damage rate of soil structure,the index of soil anti-scourability,LOC,NLOC,POC,ROC and carbon management index.By the combined methods of entropy-weighing and technique for order preference by similarity to an ideal solution,the results of soil ecological function evaluation were obtained by integrating relative approximation degree and proximity degree under different vegetation restoration patterns.The order from good to bad as follows:NSF,M,S,MP,LF and G for all vegetation restoration patterns.Based on the results of sensitivity and stability analysis,it was determined that the patterns of NSF,M,S were suitable for vegetation restoration in mountainous forest-arid valley ecotone.更多还原