摘要: 目的基于土壤质量指数（SQI），研究华北落叶松林不同混交方式对土壤肥力质量的影响，为其合理经营和地力恢复提供理论依据、�/sec> 方法该研究以河北省塞罕坝林场华北落叶松纯林（落叶松纯林）、华北落叶松白桦混交林（落桦混交林）和华北落叶松樟子松混交林（落樟混交林）为研究对象，采集和分析0 ~ 20 cm土层的土壤进行土壤理化性质、生物性质的调查研究，利用SQI法进行土壤肥力质量评价。建立SQI包括3个步骤：采用主成分分析法筛选最小数据集（MDS），利用非线性得分函数计算MDS指标得分，利用加权求和模型计算SQI、�/sec> 结果不同混交方式间土壤理化和生物性质存在不同程度的差异。与落叶松纯林相比，落桦混交林的土壤理化和生物性质有了明显改善；落樟混交林的土壤理化状况较差，土壤生物性质与落叶松纯林没有明显差异。在17个土壤肥力质量指标中，MDS由土壤微生物生物量氮、全磷、氨�?个指标组成。不同混交方式间SQI差异显著，表现为落桦混交林（0.59� > 落叶松纯林（0.47� > 落樟混交林（0.39）、�/sec> 结论土壤肥力质量在不同混交方式下差异显著，塞罕坝机械林场落叶松白桦混交林有利于改善土壤肥力。利用指数法建立SQI进行土壤肥力质量评价，可为其他树种或其他地区的森林土壤质量评价提供借鉴、�/sec>

关键诌�
• 华北落叶杽�/a> /
• 混交枖�/a> /
• 土壤质量指数/
• 评价

Abstract: ObjectiveIn this study, soil quality index (SQI) was used to evaluate the effects of different mixed modes on soil fertility quality in Larix principis-rupprechtiiforests, in order to provide theoretical basis for proper management and soil fertility recovery. MethodThe pure Larix principis-rupprechtiistands (LP), mixed Larix principis-rupprechtiiand Betula platyphyllastands (BL), and mixed Larix principis-rupprechtiiand Pinus sylvestrisvar. mongolicastands (ML) were selected as the research objects in Saihanba Mechanical Forest Farm of Hebei Province, northern China. The soils of 0�?0 cm soil depths were collected and analyzed to investigate the soil physicochemical and biological properties. SQI was used to evaluate soil fertility quality. SQI was determined in three steps by selecting a minimum data set (MDS) through principal component analysis, scoring the MDS indicators using non-linear scoring functions, and integrating the indicator scores into a SQI using the weighted additive equation. ResultThere were different degrees of differences in soil physicochemical and biological properties among different mixed modes. Compared with LP, the soil physicochemical and biological properties of BL were significantly improved. The soil physicochemical conditions in ML were worse than those in LP. And there were no obvious differences in soil biological properties in ML and LP. The MDS consisted of soil microbial biomass nitrogen, total phosphorus, and ammonia nitrogen among 17 soil fertility quality indicators. There were significant differences in the SQI among three mixed modes, which were showed as: BL (0.59) > LP (0.47) > ML (0.39). ConclusionThe soil fertility quality differed significantly among varied mixed modes. The mixed Larix principis-rupprechtiiand Betula platyphyllastands in Saihanba Mechanical Forest Farm can improve soil fertility. Soil fertility quality evaluation based on SQI by indexing approach can provide the basis for evaluating forest soil quality of other species and regions.

Key words:
• Larix principis-rupprechtii/
• mixed forests/
• soil quality index/
• evaluation

�?nbsp; 1最小数据集指标(MDS)的得分倻�/p>

不同小写字母表示不同混交方式间差异显�?P< 0.05)，LP. 落叶松纯林；BL. 落桦混交林；ML. 落樟混交林。下同。Different lowercase letters indicate significant differences among varied mixed modes atP< 0.05 level. LP, pureLarix principis-rupprechtiiforest; BL, mixedLarix principis-rupprechtiiandBetula platyphyllaforest; ML, mixedLarix principis-rupprechtiiandPinus sylvestrisvar.mongolicaforest. The same below.

Figure 1.Scores of minimum data set indicators

下载: 全尺寸图牆�/a> 幻灯牆�/a>

�?nbsp; 2华北落叶松纯林和混交林中土壤质量指数(SQI)变化

Figure 2.Changes of soil quality index in pure and mixedLarix principis-rupprechtiiforest

下载: 全尺寸图牆�/a> 幻灯牆�/a>

�?nbsp; 1样地基本特征

Table 1.Basic information for the sample plots

混交方式 Mixing mode	坡度 Slope degree/(°)	坡向 Slope aspect	海拔 Elevation/m	株数密度/(株·hm�?) Plant density/ (tree·ha�?)	郁闭�?br/>Canopy density	平均胸径 Average DBH/cm	平均树高 Average tree height/m
落叶松纯枖�br/>PureLarix principis-rupprechtiiforest	9	西北，西，西卖�br/>Northwest, west, southwest	1 598	1 195	0.77	20.28	15.88
落桦混交枖�br/>MixedLarix principis-rupprechtiiand Betula platyphyllaforest	12	西北，西 Northwest, west	1 588	1 289	0.73	18.20	14.90
落樟混交枖�br/>MixedLarix principis-rupprechtiiand Pinus sylvestrisvar. mongolicaforest	11	西北，西卖�br/>Northwest, southwest	1 589	1 328	0.83	19.08	15.32

下载: 导出CSV

�?nbsp; 2落叶松纯林和混交林中土壤理化性质变化

Table 2.Changes of soil physicochemical properties in pure and mixedLarix principis-rupprechtiiforests

指标 Indicator	落叶松纯枖�br/>PureLarix principis- rupprechtiiforest	落桦混交枖�br/>MixedLarix principis-rupprechtii andBetula platyphyllastand	落樟混交枖�br/>MixedLarix principis-rupprechtiiand Pinus sylvestrisvar.mongolicaforest
质量含水� Mass moisture content/%	16.06 ± 0.91ab	17.96 ± 0.93a	14.45 ± 0.56b
pH	6.34 ± 0.05ab	6.24 ± 0.03b	6.39 ± 0.04a
有机� Organic C/(g·kg�?)	29.17 ± 1.27b	34.35 ± 1.84a	24.71 ± 1.35c
全氮 Total N/(g·kg�?)	1.97 ± 0.12b	2.77 ± 0.26a	1.56 ± 0.12b
全磷 Total P/(g·kg�?)	0.31 ± 0.01b	0.38 ± 0.01a	0.26 ± 0.01c
氨氮 Ammonia N/(mg·kg�?)	10.26 ± 1.09a	12.44 ± 1.11a	9.51 ± 0.90a
硝氮 Nitrate N/(mg·kg�?)	2.20 ± 0.25b	2.90 ± 0.27a	1.75 ± 0.17b
有效� Available P/(mg·kg�?)	2.91 ± 0.11ab	3.37 ± 0.21a	2.81 ± 0.20b
注：不同小写字母表示不同混交方式间差异显�?P< 0.05)，数值为平均� ± 标准误。下同。Notes: different lowercase letters mean significant differences among varied mixed modes atP<0.05 level. Values are mean ± standard error. The same below.

下载: 导出CSV

�?nbsp; 3落叶松纯林和混交林中土壤生物性质变化

Table 3.Changes of soil biological properties in pure and mixedLarix principis-rupprechtiiforests

指标 Indicator	落叶松纯枖�br/>PureLarix principis- rupprechtiistand	落桦混交枖�br/>MixedLarix principis-rupprechtii andBetula platyphyllaforest	落樟混交枖�br/>MixedLarix principis-rupprechtiiand Pinus sylvestrisvar. mongolicaforest
PLFA总量 Total PLFAs/(nmol·g�?)	36.38 ± 1.38b	51.66 ± 3.34a	32.52 ± 1.67b
细菌 Bacteria/(nmol·g�?)	20.32 ± 0.78b	30.00 ± 2.05a	18.00 ± 0.98b
真菌 Fungi/(nmol·g�?)	3.64 ± 0.11b	4.92 ± 0.30a	3.41 ± 0.16b
放线� Actinomycete/(nmol·g�?)	3.79 ± 0.19b	5.67 ± 0.49a	3.31 ± 0.18b
微生物生物量� Microbial biomass C/(mg·kg�?)	334.55 ± 12.77ab	372.28 ± 16.46a	316.13 ± 9.98b
微生物生物量� Microbial biomass N/(mg·kg�?)	42.63 ± 2.24b	52.92 ± 3.18a	38.31 ± 2.16b
蔗糖� Invertase/(mg·g�?.h�?)	49.01 ± 2.20ab	56.66 ± 3.66a	44.62 ± 3.87b
脲酶 Urease/(mg·g�?.h�?)	0.23 ± 0.01b	0.36 ± 0.03a	0.21 ± 0.01b
酸性磷酸酶 Acid phosphatase/(nmol·g�?.h�?)	774.82 ± 76.25b	1 064.93 ± 105.86a	721.65 ± 56.77b

下载: 导出CSV

�?nbsp; 4主成分因子旋转载荷矩阵、特征值与方差贡献玆�/p>

Table 4.Rotated factor loading matrix, eigenvalue and variance explained of principal component analysis

指标 Indicator	主成� Principal component
	1	2	3
质量含水� Mass moisture content	0.794	0.368	�?.011
pH	�?.087	�?.234	�?.946
有机� Organic C	0.785	0.446	0.337
全氮 Total N	0.800	0.493	0.275
全磷 Total P	0.067	0.895	0.171
氨氮 Ammonia N	0.813	�?.021	0.463
硝氮 Nitrate N	0.888	0.292	�?.094
有效� Available P	0.813	0.285	0.246
PLFA总量 Total PLFAs	0.739	0.588	0.244
细菌 Bacteria	0.726	0.601	0.253
真菌 Fungi	0.617	0.682	0.135
放线� Actinomycete	0.736	0.561	0.194
微生物生物量� Microbial biomass C	0.909	0.349	�?.057
微生物生物量� Microbial biomass N	0.875	0.433	0.08
蔗糖� Invertase	0.927	0.158	0.118
脲酶 Urease	0.545	0.749	0.075
酸性磷酸酶 Acid phosphatase	0.875	0.301	0.265
特征� Eigenvalue	9.524	4.075	1.676
方差贡献� Variance contribution rate/%	56.025	23.973	9.860
累积方差贡献� Cumulative variance contribution rate/%	56.025	79.998	89.858
注：粗体的因子载荷表示高因子载荷，粗体并加下划线的因子载荷对应入选最小数据集的指标。Notes: boldface factor loadings are considered highly weighted. Boldface and underlined loading values correspond to the indicators included in the MDS.

下载: 导出CSV

�?nbsp; 5高因子载荷指标间的相关�?/p>

Table 5.Correlation coefficients for highly weighed variables

土壤指标 Soil indicator	硝氮 Nitrate N	微生物生物量碲�br/>Microbial biomass C	微生物生物量�?br/>Microbial biomass N	蔗糖酵�br/>Invertase	酸性磷酸酶 Acid phosphatase
硝氮 Nitrate N	1.000	0.909	0.912	0.886	0.820
微生物生物量� Microbial biomass C	0.909	1.000	0.947	0.894	0.900
微生物生物量� Microbial biomass N	0.912	0.947	1.000	0.880	0.930
蔗糖� Invertase	0.886	0.894	0.880	1.000	0.854
酸性磷酸酶 Acid phosphatase	0.820	0.900	0.930	0.854	1.000

下载: 导出CSV

[2]陈立�? 陈祥�? 段文�? 落叶松人工林凋落物与土壤肥力变化的研究[J]. 应用生态学�? 1998, 9(6):581�?86.

Chen L X, Chen X W, Duan W B. Larch litter and soil fertility[J]. Chinese Journal of Applied Ecology, 1998, 9(6): 581�?86. [3]Bone J, Barraclough D, Eggleton P, et al. Prioritising soil quality assessment through the screening of sites: the use of publicly collected data[J]. Land Degrad Develop, 2014, 25(3): 251�?66. doi:10.1002/ldr.2138 [4]闫德�? 刘永�? 张幼�? 落叶松人工林土壤养分动态[J]. 东北林业大学学报, 2003, 31(3):16�?8.

Yan D R, Liu Y J, Zhang Y J. Dynamic of soil nutrients under larch plantation[J]. Journal of Northeast Forestry University, 2003, 31(3): 16�?8. [5]程旭, 吴彦�? 刘广�? �? 迹地更新营造白桦、落叶松混交林试验[J]. 河北林业科技, 2005(2):12�?2.

Cheng X, Wu Y Q, Liu G Y, et al. Experiment on renewal of site to build mixed birch and larch forest[J]. The Journal of Hebei Forestry Science and Technology, 2005(2): 12�?2. [6]刘世�? 李春�? 落叶松人工林养分循环过程与潜在地力衰退趋势的研究[J]. 东北林业大学学报, 1993, 21(2):19�?4.

Liu S R, Li C Y. Nutrient cycling and stability of soil fertility in larch plantation in the eastern part of northern China[J]. Journal of Northeast Forestry University, 1993, 21(2): 19�?4. [7]范辉�? 杉木、拟赤杨混交对杉木持续生长的影响[J]. 林业科学研究, 2001, 14(4):455�?58. doi:10.3321/j.issn:1001-1498.2001.04.018

Fan H H. Influence of miture with Alniphyllum fortuneion sustainable growth of Chinese fir[J]. Forest Research, 2001, 14(4): 455�?58. doi:10.3321/j.issn:1001-1498.2001.04.018 [8]Nakajima T, Lal R, Jiang S. Soil quality index of a crosby silt loam in central Ohio[J]. Soil and Tillage Research, 2015, 146(part B): 323�?28. [9]Qiu X C, Peng D L, Wang H B, et al. Minimum data set for evaluation of stand density effects on soil quality in Larix principis-rupprechtiiplantations in North China[J/OL]. Ecological Indicators, 2019, 103: 236�?47 [2021�?1�?2]. https://doi.org/10.1016/j.ecolind.2019.04.010. [10]骆东�? 白洁, 谢德�? 论土壤肥力评价指标和方法[J]. 土壤与环�? 2002, 11(2):202�?05.

Luo D Q, Bai J, Xie D T. Research on evaluation norm and method of soil fertility[J]. Soil and Environmental Sciences, 2002, 11(2): 202�?05. [11]Raiesi F. A minimum data set and soil quality index to quantify the effect of land use conversion on soil quality and degradation in native rangelands of upland arid and semiarid regions[J/OL]. Ecological Indicators, 2017, 75: 307�?20 [2020�?2�?9]. http://dx.doi.org/10.1016/j.ecolind.2016.12.049. [12]Guo L L, Sun Z G, Zhu O Y, et al. A comparison of soil quality evaluation methods for Fluvisol along the lower Yellow River[J/OL]. Catena, 2017, 152: 135�?43 [2020�?2�?0]. http://dx.doi.org/10.1016/j.catena.2017.01.015. [13]Dose H L, Fortuna A, Cihacek L J, et al. Biological indicators provide short term soil health assessment during sodic soil reclamation[J/OL]. Ecological Indicators, 2015, 58: 244�?53 [2020�?2�?1]. http://dx.doi.org/10.1016/j.ecolind.2015.05.059. [14]覃其�? 曹继�? 李军, �? 马尾松人工幼林土壤肥力变化及其综合评价研究[J]. 中南林业科技大学学报, 2013, 33(3):64�?9.

Qin Q Y, Cao J Z, Li J, et al. Comprehensive evaluation on soil fertility variations in Pinus massonianayoung plantation[J]. Journal of Central South University of Forestry & Technology, 2013, 33(3): 64�?9. [15]孙宇, 李际�? 曹小�? �? 不同龄组杉木生态公益林土壤肥力综合评价[J]. 林业资源管理, 2019(1):57�?2.

Sun Y, Li J P, Cao X Y, et al. Comprehensive evaluation of soil fertility of Cunninghamia lanceolataecological public welfare forests in different age groups[J]. Forest Resources Management, 2019(1): 57�?2. [16]杨晓�? 王海�? 刘玲, �? 东北过伐林区不同林分类型土壤肥力质量评价研究[J]. 生态环境学�? 2012, 21(9):1553�?560.

Yang X J, Wang H Y, Liu L, et al. Evaluation of soil fertility quality under different forest stands in over-logged forest region, northeast China[J]. Ecology and Environmental Sciences, 2012, 21(9): 1553�?560. [17]岳西�? 葛玺�? 王旭�? 基于GIS的黄土丘陵沟壑区土壤质量评价研究:以陕西省长武县为例[J]. 干旱地区农业研究, 2011, 29(3):144�?49.

Yue X J, Ge X Z, Wang X D. GIS-based research on soil quality evaluation in the loess hilly gully region: a case study of Changwu County[J]. Agricultural Research in the Arid Areas, 2011, 29(3): 144�?49. [18]Qi Y B, Darilek J L, Huang B, et al. Evaluating soil quality indices in an agricultural region of Jiangsu Province, China[J]. Geoderma, 2009, 149(3�?): 325�?34. doi:10.1016/j.geoderma.2008.12.015 [19]Cheng J J, Ding C F, Li X G, et al. Soil quality evaluation for navel orange production systems in central subtropical China[J/OL]. Soil and Tillage Research, 2016, 155: 225�?32 [2019�?2�?1]. https://doi.org/10.1016/j.still.2015.08.015. [20]乔云�? 钟鑫, 苗淑�? �? 基于最小数据集的东北风沙土农田耕层土壤质量评价指标[J]. 水土保持研究, 2019, 26(4):132�?38.

Qiao Y F, Zhong X, Miao S J, et al. Evaluation indicators of soil quality in plough layer of aeolian sandy land in Northeast China based on minimum date set[J]. Research of Soil and Water Conservation, 2019, 26(4): 132�?38. [21]郭剑�? 赵国�? 贾书�? �? 施肥对高寒草原草地质量指数及土壤性质影响的综合评价[J]. 草业学报, 2020, 29(9):85�?3.

Guo J B, Zhao G Q, Jia S G, et al. Comprehensive evaluetion of effects of fertilization on grassland quality index and soil properties in alpine steppe[J]. Acta Prataculturae Sinica, 2020, 29(9): 85�?3. [22]李洁, 滑磊, 任启�? �? 冀西北3种植被恢复类型土壤理化性质差异及肥力评价[J]. 生态环境学�? 2020, 29(8):1540�?546.

Li J, Hua L, Ren Q W, et al. Physicochemical properties difference and fertility evaluation of soil within three types vegetation restoration in northwest Hebei[J]. Ecology and Environmental Sciences, 2020, 29(8): 1540�?546. [23]郝宝�? 艾宁, 刘广�? �? 陕北风沙区不同植被类型土壤养分特征与肥力评价[J]. 福建农林大学学报(自然科学�?, 2020, 49(5):678�?82.

Hao B B, Ai N, Liu G Q, et al. Soil nutrient characteristics and fertility evaluation of different vegetation types in aeolian sand region of northern Shaanxi[J]. Journal of Fujian Agriculture and Forestry University (Natural Science Edition), 2020, 49(5): 678�?82. [24]张连�? 赖光�? 孙长�? �? 北京九龙山不同林分土壤肥力诊断与综合评价[J]. 中南林业科技大学学报, 2017, 37(1):1�?.

Zhang L J, Lai G H, Sun C Z, et al. Diagnosis and comprehensive evaluation on soil fertility of different stands in Beijing Jiulong Mountain[J]. Journal of Central South University of Forestry & Technology, 2017, 37(1): 1�?. [25]Imaz M J, Virto I, Bescansa P, et al. Soil quality indicator response to tillage and residue management on semi-arid Mediterranean cropland[J]. Soil and Tillage Research, 2010, 107(1): 17�?5. doi:10.1016/j.still.2010.02.003 [26]扈梦�? 田龙, 吴亚�? �? 塞罕坝华北落叶松人工林间伐和混交改造对大型土壤动物群落结构的影响[J]. 林业科学, 2019, 55(11):153�?62.

Hu M M, Tian L, Wu Y N, et al. Influences of thinning and mixed transformation of Larix principis-rupprechtiiplantations on the community structure of soil macro faunal in Saihanba Area[J]. Scientia Silvae Sinicae, 2019, 55(11): 153�?62. [27]李文�? 吕振�? 黄选瑞, �? 塞罕坝华北落叶松人工林生产力及其空间分布预测[J]. 自然资源学报, 2019, 34(7):1365�?375. doi:10.31497/zrzyxb.20190702

Li W B, Lü Z G, Huang X R, et al. Predicting productivity and spatial distribution of Larix principis-rupprechtiiplantation[J]. Journal of Natural Resources, 2019, 34(7): 1365�?375. doi:10.31497/zrzyxb.20190702 [28]方文�? 蔡琼, 朱江�? �? 华北地区落叶松林的分布、群落结构和物种多样性[J]. 植物生态学�? 2019, 43(9):742�?52. doi:10.17521/cjpe.2018.0244

Fang W J, Cai Q, Zhu J L, et al. Distribution, community structures and species diversity of larch forests in North China[J]. Chinese Journal of Plant Ecology, 2019, 43(9): 742�?52. doi:10.17521/cjpe.2018.0244 [29]刘欣. 华北落叶松不同林型凋落物对土壤性质影响的研究[D]. 北京: 北京林业大学, 2019.

Liu X. Study on the effects of different forest type litters about Larix principis-rupprechtiion the soil properties[D]. Beijing: Beijing Forestry University, 2019. [30]刘欣, 彭道�? 邱新�? 华北落叶松不同林型土壤理化性质差异[J]. 应用与环境生物学�? 2018, 24(4):735�?43.

Liu X, Peng D L, Qiu X C. Differences in soil physicochemical properties between different forest types of Larix principis-rupprechtii[J]. Chinese Journal of Applied & Environmental Biology, 2018, 24(4): 735�?43. [31]张宇�? 彭道�? 间伐对塞罕坝华北落叶松人工林土壤活性有机碳的影响[J]. 应用与环境生物学�? 2020, 26(4):961�?68.

Zhang Y C, Peng D L. Effects of thinning on the soil active organic carbon of Larix principis-rupprechtiiplantations in Saihanba[J]. Chinese Journal of Applied & Environmental Biology, 2020, 26(4): 961�?68. [32]鲍士�? 土壤农化分析[M]. 北京: 中国农业出版�? 2000.

Bao S D. Soil and agricultural chemistry analysis[M]. Beijing: China Agriculture Press, 2000. [33]吴然, 康峰�? 韩海�? �? 山西太岳山不同林龄华北落叶松林土壤微生物特性[J]. 生态学杂志, 2016, 35(12):3183�?190.

Wu R, Kang F F, Han H R, et al. Soil microbial properties in Larix principis-rupprechtiiplantations of different ages in Mt. Taiyue, Shanxi, China[J]. Chinese Journal of Ecology, 2016, 35(12): 3183�?190. [34]关松�? 土壤酶及其研究法[M]. 北京: 中国农业出版�? 1983.

Guan S Y. Soil enzyme and its research method[M]. Beijing: China Agricultural Press, 1983. [35]Li P, Zhang T, Wang X, et al. Development of biological soil quality indicator system for subtropical China[J/OL]. Soil & Tillage Research, 2013, 126: 112�?18 [2020�?2�?2]. http://dx.doi.org/10.1016/j.still.2012.07.011. [36]Shao G D, Ai J J, Sun Q W, et al. Soil quality assessment under different forest types in the Mount Tai, central Eastern China[J/OL]. Ecological Indicators, 2020, 115: 106439 [2020�?2�?2]. https://doi.org/10.1016/j.ecolind.2020.106439. [37]Askari M S, Holden N M. Indices for quantitative evaluation of soil quality under grassland management[J/OL]. Geoderma, 2014, 230�?31: 131�?42 [2020�?2�?2]. https://doi.org/10.1016/j.geoderma.2014.04.019. [38]秦娟, 唐心�? 杨雪�? 马尾松不同林型对土壤理化性质的影响[J]. 生态环境学�? 2013, 22(4):598�?04.

Qin J, Tang X H, Yang X M. Effects of soil physical and chemical properties on different forest types of Pinus massoniana[J]. Ecology and Environmental Sciences, 2013, 22(4): 598�?04. [39]谷会�? 金靖�? 陈祥�? �? 采伐干扰对大兴安岭北坡兴安落叶松林土壤化学性质的影响[J]. 土壤通报, 2009, 40(2):272�?75.

Gu H Y, Jin J B, Chen X W, et al. Effects of logging disturbance on soil chemical properties of Larix gmeliniforests in the northern slope on Greater Hinggan Mountains[J]. Chinese Journal of Soil Science, 2009, 40(2): 272�?75. [40]丛高, 张志�? 张晋�? �? 长白山不同林型土壤有机碳特征[J]. 水土保持学报, 2019, 33(3):179�?84.

Cong G, Zhang Z D, Zhang J J, et al. Research on characteristics of soil organic carbon in different forest types in Changbai Mountain[J]. Journal of Soil and Water Consevation, 2019, 33(3): 179�?84. [41]牛庆�? 郭宇�? 任子�? �? 坝上地区典型防护林土壤改良效益[J]. 东北林业大学学报, 2019, 47(9):63�?0.

Niu Q H, Guo Y J, Ren Z B, et al. Improvement benefits on soil of typical shelterbelt stands in Bashang Area[J]. Journal of Northeast Forestry University, 2019, 47(9): 63�?0. [42]陈立�? 陈祥�? 史桂�? �? 提高落叶松人工林林地质量的研究[J]. 东北林业大学学报, 1998, 26(3):6�?1.

Chen L X, Chen X W, Shi G X, et al. Study on improving the quality of forest land of larch plantations[J]. Journal of Northeast Forestry University, 1998, 26(3): 6�?1. [43]邹莉, 唐庆�? 王轶. 落叶松、樟子松纯林及混交林土壤微生物的群落分布特征[J]. 东北林业大学学报, 2010, 38(11):63�?4.

Zou L, Tang Q M, Wang Y. Ecological distribution of soil microorganism in pure and mixed forests of Pinus sylvestrisvar . mongolicaand Larix gmelini[J]. Journal of Northeast Forestry University, 2010, 38(11): 63�?4. [44]Zhang W, Xu Y D, Gao D X, et al. Ecoenzymatic stoichiometry and nutrient dynamics along a revegetation chronosequence in the soils of abandoned land and Robinia pseudoacaciaplantation on the Loess Plateau, China[J/OL]. Soil Biology and Biochemistry, 2019, 134: 1�?4 [2020�?2�?1]. https://doi.org/10.1016/j.soilbio.2019.03.017. [45]林达, Dao Ngoc Chuong, 洪森�? �? 间伐对杨树人工林土壤微生物量和氮含量的影响[J]. 森林与环境学�? 2016, 36(4):416�?22.

Lin D, Chuong D N, Hong S X, et al. Effects of thinning intensity and method on soil microbial biomass and nitrogen content in the poplar plantations[J]. Journal of Forest and Environment, 2016, 36(4): 416�?22. [46]Lamb E G, Mengersen K L, Stewart K J, et al. Spatially explicit structural equation modeling[J]. Ecology, 2014, 95(9): 2434�?442. doi:10.1890/13-1997.1 [47]Hu L, Ade L J, Wu X W, et al. Changes in soil C: N: P stoichiometry and microbial structure along soil depth in two forest soils[J]. Forests, 2019, 10(2): 113. doi:10.3390/f10020113 [48]Sun J, Ma B B, Lu X Y. Grazing enhances soil nutrient effects: trade-offs between aboveground and belowground biomass in alpine grasslands of the Tibetan Plateau[J]. Land Degrad Develop, 2018, 29(2): 337�?48. doi:10.1002/ldr.2822 [49]Jing X, Sanders N J, Shi Y, et al. The links between ecosystem multifunctionality and above- and belowground biodiversity are mediated by climate[J/OL]. Nature Communications, 2015, 6: 8159 [2020�?2�?2]. DOI: 10.1038/ncomms9159. [50]Kline R. Principals and practice of structural equation modeling[M]. New York: Guilford Press, 1998. [51]邓绍�? 曾令�? 关强, �? 基于最小数据集的南方地区冷浸田土壤质量评价[J]. 土壤学报, 2016, 53(5):1326�?333.

Deng S H, Zeng L T, Guan Q, et al. Minimum dataset-based soil quality assessment of waterlogged paddy field in South China[J]. Acta Pedologica Sinica, 2016, 53(5): 1326�?333. [52]Nabiollahi K, Golmohamadi F, Taghizadeh-Mehrjardi R, et al. Assessing the effects of slope gradient and land use change on soil quality degradation through digital mapping of soil quality indices and soil loss rate[J/OL]. Geoderma, 2018, 318: 16�?8 [2021�?1�?8]. https://doi.org/10.1016/j.geoderma.2017.12.024. [53]邵森. 山西太岳山针叶林土壤肥力随林龄和营林措施变化特征的研究[D]. 北京: 北京林业大学, 2018.

Shao S. The study on the changes of soil quality in coniferous forest with age and silvicultural measures of Shanxi Taiyue Mountain[D]. Beijing: Beijing Forestry University, 2018. [54]边丽�? 华北落叶松纯林与混交林生长、林下植被和枯落物差异分析[D]. 保定: 河北农业大学, 2018.

Bian L N. Difference of growth, understory vegetation and litter in pure and mixed forests of Larix principis-rupprechti[D]. Baoding: Hebei Agricultural University, 2018. [55]谢博. 针阔混交林中针叶树种枯落物分解所受的化感影响[D]. 杨凌: 西北农林科技大学, 2017.

Xie B. Allelopathic effects of broad-leaf litter on coniferous litter decomposition in coniferous and broadleaved mixed forest[D]. Yangling: Northwest A & F University, 2017. [56]刘增�? 杜良�? 张晓�? �? 黄土高原不同树种枯落叶混合分解效应[J]. 生态学�? 2012, 32(8):2596�?602. doi:10.5846/stxb201103110298

Liu Z W, Du L Z, Zhang X X, et al. Effects of mix-leaf litter decomposition of different trees in the Loess Plateau[J]. Acta Ecologica Sinica, 2012, 32(8): 2596�?602. doi:10.5846/stxb201103110298