-
林下植被可以增加人工林生态系统生物多样性和养分周转率,但其在维持森林生态系统结构和功能方面的作用通常被忽视[1],特别是在传统森林管理方式中,常采用林下植被去除的方式来减少树木和下层群落之间的空间资源竞争[2]。然而,林下植被可通过改变土壤生物化学过程,如微生物活性和组成、碳和其他营养物质的周转,进而影响森林生态系统长期的生产力和稳定性[3]。以往研究表明,林下植被完整时,土壤养分、微生物量、酶活性和土壤呼吸均高于林下植被移除[4-5]。因此,在人工林的经营管理中,林下植被的保留比去除可能更有利于森林土壤地力的提高,但目前林下植被管理对土壤生化过程的影响发生机制仍不清楚,需要开展更多的研究工作。
土壤酶是由植物根系或微生物产生,对土壤碳(C)、氮(N)和磷(P)等养分变化具有一定的灵敏性,其常被用作衡量土壤质量状况的关键指标[6]。土壤酶活性可以反映底物利用率、微生物和植物对养分的需求,同时也在一定程度上影响植物和微生物在土壤环境变化时维持其养分平衡的策略[7]。Xu等[8]通过研究我国东部南北样带沿线的9个森林生态系统中的土壤酶活性及其化学计量比,结果发现,土壤酶化学计量比能很好的反映微生物的营养需求和环境中营养物质的供应状况。因此,开展土壤酶化学计量的研究为理解土壤中养分的周转、循环和平衡过程提供了新途径[9]。目前,有关林下植被去除的相关研究主要集中于土壤酶活性,且研究结果存在较大差异。有研究表明,林下植被去除显著降低了土壤C含量和微生物生物量,同时也促使土壤水解酶活性降低[10];而Liu等[11]发现,去除林下植被对桉树人工林生态系统土壤酶活性无显著影响。因此,林下植被去除对人工林生态系统土壤酶活性的影响研究还需进一步探索,而且,从土壤酶化学计量的角度探究林下植被去除对土壤养分特征的相关研究相对较少,相关过程的研究可能对人工林养分维持及调控具有重要的指导意义。
杉木(Cunninghamia lanceolata (Lamb.) Hook.)广泛分布于我国南方,是主要经济树种之一,种植面积约占全国人工林面积的30%[12]。杉木能够高效吸收土壤养分进而决定了其速生特性[13],而林下植被去除可能会进一步改变杉木人工林中土壤水分和养分有效性,最终影响土壤酶活性[10],以往研究更多关注土壤酶活性变化,而从土壤酶化学计量比的角度探讨林下植被去除对土壤养分特征的影响研究较少。因此,本研究以养分较贫瘠的杉木人工林为研究对象,通过测定土壤C、N、P含量及5种C、N、P水解酶活性,计算养分-酶化学计量比,并进一步分析土壤理化性质与酶活性及其化学计量比的相关性,进而揭示亚热带杉木人工林林下植被去除和保留的土壤养分和酶活性的响应特征,为林下植被管理对土壤质量影响的评估提供参考。
-
表1表明:在不同土层中,UR处理的SWC、SOC、TN、TP、NH4+-N、NO3−-N均显著低于UP处理,不同处理的pH值差异不显著;除pH值外,UR和UP处理的理化性质均表现为腐殖质层含量最高,5~10 cm土层最低;UR处理的SOC、NO3−-N、TN、NH4+-N含量和UP处理的SOC、NO3−-N含量均在3个土层间差异显著;UP处理腐殖质层的SWC、TN、NH4+-N含量显著高于0~5、5~10 cm土层,而0~5 cm与5~10 cm土层间差异不显著。
表 1 不同林下植被处理对杉木人工林土壤理化性质的影响
Table 1. Effects of different understory vegetation treatments on physical and chemical properties of Chinese fir plantation soil
土壤性质 Soil Properties 处理 Treatment 腐殖质层 Humus layer 土层 Soil layers/cm 0~5 5~10 SWC/% UR 15.95±0.38 Ba 12.26±0.02 Bb 11.64±0.25 Bb UP 17.23±0.80 Aa 13.53±0.24 Ab 12.50±0.06 Ab pH值 UR 5.03±0.02 Aa 5.05±0.01 Aa 4.94±0.02 Ab UP 4.99±0.01 Aa 4.99±0.01 Aa 4.99±0.01 Aa SOC/ (g·kg−1) UR 21.96±2.64 Ba 16.62±1.44 Bb 11.78±0.99 Bc UP 34.07±1.06 Aa 22.65±1.69 Ab 14.94±0.46 Ac TN/ (g·kg−1) UR 1.99±0.06 Ba 1.07±0.01 Bb 0.60±0.01 Bc UP 2.43±0.19 Aa 1.45±0.33 Ab 0.73±0.03 Ab TP/ (g·kg−1) UR 0.90±0.05 Ba 0.85±0.01 Ba 0.66±0.03 Bb UP 0.99±0.01 Aa 0.95±0.07 Aa 0.85±0.01 Aa NH4+-N/(mg·kg−1) UR 9.67±0.42 Ba 7.49±0.11 Bb 5.89±0.13 Bc UP 12.71±1.23 Aa 9.21±0.05 Ab 7.02±0.20 Ab NO3--N/(mg·kg−1) UR 7.60±0.42 Ba 2.37±0.07 Bb 1.12±0.07 Bc UP 9.25±1.06 Aa 3.55±0.23 Ab 1.32±0.06 Ac 注:表中不同大写字母表示同一土层不同处理之间的差异性。不同小写字母表示同一处理不同土层之间的差异(P<0.05)。下同。
Notes: In the table, Different capital letters indicate differences between different treatments of the same soil layer. Different lowercase letters indicate differences between different layers of the same treatment (P<0.05). The same below.图1表明:在不同土层中,UR处理的C/N和N/P与UP处理的差异不显著,而UR处理的C/P在腐殖质层和0~5 cm土层显著低于UP处理;UR和UP处理的C/P和N/P均表现为腐殖质层含量最高,5~10 cm土层最低,但C/N却与之相反;UR和UP处理的N/P在3个土层间差异显著,C/N仅在UR处理的3个土层间差异显著,C/P仅在UP处理的3个土层间差异显著。
-
图2表明:在不同土层中,UR处理的5种酶活性均低于UP处理。在腐殖质层中,UP处理的LAP活性显著高于UR处理,增幅为48%;在0~5 cm土层中,UP处理的CB、NAG和LAP活性显著高于UR处理,增幅分别为38%、53%和32%;在5~10 cm土层中,UR处理的CB和LAP活性显著低于UP处理,降幅分别为45%和18%。在UR处理中,腐殖质层的AP、BG、NAG活性显著高于0~5 cm和5~10 cm土层,但0~5 cm与5~10 cm间差异不显著,而CB和LAP活性在3个土层间均差异显著;在UP处理中,腐殖质层的AP、CB、NAG活性显著高于0~5 cm和5~10 cm土层,但0~5 cm与5~10 cm之间差异不显著,而BG和LAP活性在3个土层间均差异显著。
图 2 不同林下植被处理对杉木人工林土壤酶活性的影响
Figure 2. Effects of different understory vegetation treatments on soil enzyme activity of Chinese fir plantation
图3表明:在3个土层中,UP处理与UR处理的ln(BG+CB)/ln(AP)和ln(NAG+LAP)/ln(AP)差异不显著;UP处理的ln(BG+CB)/ln(NAG+LAP)仅在0~5 cm土层中显著低于UR处理,降幅为16%;UR处理的腐殖质层的ln(BG+CB)/ln(AP)和ln(NAG+LAP)/ln(AP)显著高于0~5 cm和5~10 cm土层,但0~5 cm与5~10 cm间差异不显著;而UP处理的ln(NAG+LAP)/ln(AP)在3个土层间均差异显著,腐殖质层的ln(BG+CB)/ln(AP)显著高于0~5 cm和5~10 cm土层,但UR和UP处理的ln(BG+CB)/ln(NAG+LAP)在腐殖质层显著低于5~10 cm土层,降幅分别为20%和23%。
-
图4表明:杉木人工林土壤的C、N、P水解酶活性之间呈极显著正相关。土壤酶活性及化学计量比与土壤理化性质之间的相关分析(表2)表明:AP、BG、CB、NAG、LAP 5种酶活性及ln(BG+CB)/ln(AP)、ln(NAG+LAP)/ln(AP)与SWC、SOC、TN、TP、NH4+-N、NO3−-N、C/P、N/P呈显著或极显著正相关,与C/N呈极显著负相关;土壤ln(BG+CB)/ln(NAG+LAP)与C/N呈极显著正相关,但与SWC、SOC、TN、TP、NH4+-N、NO3−-N、C/P、N/P呈极显著负相关(P<0.05);土壤酶活性及其化学计量比与pH相关不显著。
表 2 土壤酶活性和酶化学计量比与土壤理化性质之间的 Pearson相关分析
Table 2. Pearson correlation analysis between soil enzyme activity and enzyme stoichiometric ratio and soil physical and chemical properties
土壤性质
Soil properties土壤酶活性 Soil enzyme activity 土壤酶化学计量比 Soil enzyme stoichiometric ratio AP BG CB NAG LAP ln(BG+CB)/
ln(NAG+LAP)ln(BG+CB)/
ln(AP)ln(NAG+LAP)/
ln(AP)SWC 0.952** 0.919** 0.912** 0.942** 0.936** −0.697** 0.894** 0.924** pH值 0.252ns 0.161ns 0.189ns 0.124ns 0.172ns −0.198ns 0.234ns 0.222ns SOC 0.812** 0.773** 0.769** 0.746** 0.908** −0.634** 0.761** 0.793** TN 0.902** 0.867** 0.867** 0.881** 0.940** −0.734** 0.862** 0.908** TP 0.646** 0.507* 0.532* 0.496* 0.660** −0.515* 0.530* 0.576* NH4+-N 0.788** 0.812** 0.824** 0.796** 0.931** −0.700** 0.816** 0.856** NO3--N 0.921** 0.944** 0.940** 0.960** 0.974** −0.728** 0.938** 0.964** C/N −0.698** −0.649** −0.659** −0.681** −0.636** 0.688** −0.643** −0.720** C/P 0.795** 0.801** 0.783** 0.773** 0.904** −0.624** 0.781** 0.805** N/P 0.910** 0.912** 0.902** 0.929** 0.943** −0.750** 0.904** 0.945** 注:ns处理在P>0.05水平上的差异不显著; *处理在 P<0.05水平上的显著性差异;**处理在 P<0.01水平上的显著性差异; ***处理在 P<0.001水平上的显著性差异。
Notes: There was no significant difference in ns treatment at P>0.05. * significant difference in treatment at P<0.05; ** treatment at P<0.01 level of significant difference; *** treatment was significantly different at the P<0.001 level.
林下植被去除对杉木人工林土壤酶活性及其化学计量比的影响
Effects of Understory Vegetation Removal on Soil Hydrolytic Enzyme Activity and Stoichiometric Ratio of Chinese Fir Plantation
-
摘要:
目的 通过对比杉木人工林林下植被去除与保留的土壤理化性质和酶活性特征,探讨林下植被管理对杉木人工林土壤质量的影响。 方法 以亚热带杉木人工林为研究对象,采用配对试验设计,对8块样地进行林下植被保留(UP)和林下植被去除(UR)2种处理,测定土壤的理化性质和5种水解酶活性,计算土壤养分-酶化学计量比,并进一步分析土壤理化性质与酶活性及其化学计量比的相关性。 结果 林下植被去除显著降低土壤腐殖质层、0~5 cm、5~10 cm土层的含水量(SWC)、有机碳(SOC)、总氮(TN)、总磷(TP)、铵态氮(NH4+-N)和硝态氮(NO3−-N)养分含量,也抑制了0~5、5~10 cm土层的半纤维素酶(CB)和亮氨酸基肽酶(LAP)活性,林下植被去除与保留均对酸性磷酸酶(AP)活性影响不显著。5种土壤水解酶活性以及化学计量比与SWC、SOC、TN、TP、有效氮和养分化学计量比均呈显著或极显著相关,且土壤的C、N、P水解酶活性之间呈极显著正相关,ln(BG+CB)/ln(NAG+LAP)、ln(BG+CB)/ln(AP)和ln (NAG+LAP)/ln(AP)分别与土壤C/N、C/P和N/P呈极显著正相关。 结论 林下植被去除降低了土壤水分、全量养分、有效养分含量和酶活性(CB、LAP),且土壤水分、养分及其化学计量比与酶活性及其化学计量比的关系极为密切,这些指标可能是影响土壤酶活性及其化学计量比的重要因子。 Abstract:Objective By comparing the characteristics of soil physical and chemical properties and enzyme activity of understory vegetation removal and retention in the Chinese fir (Cunninghamia lanceolata) plantation to study the effect of understory vegetation management on the soil quality of Chinese fir plantation. Method Taking subtropical Chinese fir plantation as the research object, and by using a paired test design, two plots of understory vegetation retention (UP) and understory vegetation removal (UR) were treated on 8 plots to determine the physical and chemical properties of the soil and the activities of five hydrolase. The soil nutrient-enzyme stoichiometric ratio was calculated, and the correlation between soil physical and chemical properties and enzyme activity and its stoichiometric ratio were analyzed. Result The understory vegetation removal significantly reduced the water content (SWC), organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) nutrient contents in soil humus layer, 0−5 cm and 5−10 cm soil layers and also inhibited the cellobioside (CB) and leucine aminopeptidase (LAP) enzyme activity of 0−5 cm and 5−10 cm soil layers. Understory vegetation removal and retention had no significant effect on acid phosphatase (AP) enzyme activity. The activities and stoichiometric ratios of the five soil hydrolyzing enzymes were significantly or very significantly correlated with SWC, SOC, TN, TP, available nitrogen and nutrient stoichiometric ratios, and the soil C, N and P hydrolase activities were extremely significant positive interrelated. The ln(BG+CB)/ln(NAG+LAP), ln(BG+CB)/ln(AP) and ln (NAG+LAP)/ln(AP) were respectively related to soil C/N, C/P and N/P which showed a very significant positive correlation. Conclusion Understory vegetation removal will reduce soil moisture, total nutrients, available nutrients and enzyme activity (CB, LAP). The nutrients and their stoichiometric ratio are closely related to enzyme activity and its stoichiometric ratio. These indicators may be important factors affecting soil enzyme activity and its stoichiometric ratio. -
表 1 不同林下植被处理对杉木人工林土壤理化性质的影响
Table 1. Effects of different understory vegetation treatments on physical and chemical properties of Chinese fir plantation soil
土壤性质 Soil Properties 处理 Treatment 腐殖质层 Humus layer 土层 Soil layers/cm 0~5 5~10 SWC/% UR 15.95±0.38 Ba 12.26±0.02 Bb 11.64±0.25 Bb UP 17.23±0.80 Aa 13.53±0.24 Ab 12.50±0.06 Ab pH值 UR 5.03±0.02 Aa 5.05±0.01 Aa 4.94±0.02 Ab UP 4.99±0.01 Aa 4.99±0.01 Aa 4.99±0.01 Aa SOC/ (g·kg−1) UR 21.96±2.64 Ba 16.62±1.44 Bb 11.78±0.99 Bc UP 34.07±1.06 Aa 22.65±1.69 Ab 14.94±0.46 Ac TN/ (g·kg−1) UR 1.99±0.06 Ba 1.07±0.01 Bb 0.60±0.01 Bc UP 2.43±0.19 Aa 1.45±0.33 Ab 0.73±0.03 Ab TP/ (g·kg−1) UR 0.90±0.05 Ba 0.85±0.01 Ba 0.66±0.03 Bb UP 0.99±0.01 Aa 0.95±0.07 Aa 0.85±0.01 Aa NH4+-N/(mg·kg−1) UR 9.67±0.42 Ba 7.49±0.11 Bb 5.89±0.13 Bc UP 12.71±1.23 Aa 9.21±0.05 Ab 7.02±0.20 Ab NO3--N/(mg·kg−1) UR 7.60±0.42 Ba 2.37±0.07 Bb 1.12±0.07 Bc UP 9.25±1.06 Aa 3.55±0.23 Ab 1.32±0.06 Ac 注:表中不同大写字母表示同一土层不同处理之间的差异性。不同小写字母表示同一处理不同土层之间的差异(P<0.05)。下同。
Notes: In the table, Different capital letters indicate differences between different treatments of the same soil layer. Different lowercase letters indicate differences between different layers of the same treatment (P<0.05). The same below.表 2 土壤酶活性和酶化学计量比与土壤理化性质之间的 Pearson相关分析
Table 2. Pearson correlation analysis between soil enzyme activity and enzyme stoichiometric ratio and soil physical and chemical properties
土壤性质
Soil properties土壤酶活性 Soil enzyme activity 土壤酶化学计量比 Soil enzyme stoichiometric ratio AP BG CB NAG LAP ln(BG+CB)/
ln(NAG+LAP)ln(BG+CB)/
ln(AP)ln(NAG+LAP)/
ln(AP)SWC 0.952** 0.919** 0.912** 0.942** 0.936** −0.697** 0.894** 0.924** pH值 0.252ns 0.161ns 0.189ns 0.124ns 0.172ns −0.198ns 0.234ns 0.222ns SOC 0.812** 0.773** 0.769** 0.746** 0.908** −0.634** 0.761** 0.793** TN 0.902** 0.867** 0.867** 0.881** 0.940** −0.734** 0.862** 0.908** TP 0.646** 0.507* 0.532* 0.496* 0.660** −0.515* 0.530* 0.576* NH4+-N 0.788** 0.812** 0.824** 0.796** 0.931** −0.700** 0.816** 0.856** NO3--N 0.921** 0.944** 0.940** 0.960** 0.974** −0.728** 0.938** 0.964** C/N −0.698** −0.649** −0.659** −0.681** −0.636** 0.688** −0.643** −0.720** C/P 0.795** 0.801** 0.783** 0.773** 0.904** −0.624** 0.781** 0.805** N/P 0.910** 0.912** 0.902** 0.929** 0.943** −0.750** 0.904** 0.945** 注:ns处理在P>0.05水平上的差异不显著; *处理在 P<0.05水平上的显著性差异;**处理在 P<0.01水平上的显著性差异; ***处理在 P<0.001水平上的显著性差异。
Notes: There was no significant difference in ns treatment at P>0.05. * significant difference in treatment at P<0.05; ** treatment at P<0.01 level of significant difference; *** treatment was significantly different at the P<0.001 level. -
[1] 何艺玲, 傅懋毅. 人工林林下植被的研究现状[J]. 林业科学研究, 2002, 15(6):727-733. doi: 10.3321/j.issn:1001-1498.2002.06.015 [2] Wagner R G, Little K M, Richardson B, et al. The role of vegetation management for enhancing productivity of the world’s forests[J]. Forestry, 2006, 79(1): 57-79. doi: 10.1093/forestry/cpi057 [3] Powers R F, Busse M D, McFarlane K J, et al. Long-term effects of silviculture on soil carbon storage: does vegetation control make a difference[J]. Forestry, 2013, 86(1): 47-58. doi: 10.1093/forestry/cps067 [4] Li Y F, Zhang J J, Chang S X, et al. Long-term intensive management effects on soil organic carbon pools and chemical composition in Moso bamboo (Phyllostachys pubescens) forests in subtropical China[J]. Forest Ecology and Management, 2013, 303: 121-130. doi: 10.1016/j.foreco.2013.04.021 [5] Wu J P, Liu Z F, Huang G M, et al. Response of soil respiration and ecosystem carbon budget to vegetation removal in Eucalyptus plantations with contrasting ages[J]. Scientific Reports, 2014, 4: 6262. [6] Nannipieri P, Trasar-Cepeda C, Dick R P. Soil enzyme activity: a brief history and biochemistry as a basis for appropriate interpretations and meta-analysis[J]. Biology and Fertility of Soils, 2018, 54(1): 11-19. doi: 10.1007/s00374-017-1245-6 [7] Burns R G, DeForest J L, Marxsen J, et al. Soil enzymes in a changing environment: Current knowledge and future directions[J]. Soil Biology and Biochemistry, 2013, 58: 216-234. doi: 10.1016/j.soilbio.2012.11.009 [8] Xu Z W, Yu G R, Zhang X Y, et al. Soil enzyme activity and stoichiometry in forest ecosystems along the North-South Transect in eastern China (NSTEC)[J]. Soil Biology and Biochemistry, 2017, 104: 152-163. doi: 10.1016/j.soilbio.2016.10.020 [9] Cui Y X, Fang L C, Deng L, et al. Patterns of soil microbial nutrient limitations and their roles in the variation of soil organic carbon across a precipitation gradient in an arid and semi-arid region[J]. Science of the Total Environment, 2019, 658: 1440-1451. doi: 10.1016/j.scitotenv.2018.12.289 [10] Yang Y, Zhang X Y, Zhang C, et al. Understory vegetation plays the key role in sustaining soil microbial biomass and extracellular enzyme activities[J]. Biogeosciences, 2018, 15(14): 4481-4494. doi: 10.5194/bg-15-4481-2018 [11] Liu Z F, Wu J P, Zhou L X, et al. Effect of understory fern (Dicranopteris dichotoma) removal on substrate utilization patterns of culturable soil bacterial communities in subtropical Eucalyptus plantations[J]. Pedobiologia, 2012, 55(1): 7-13. doi: 10.1016/j.pedobi.2011.07.014 [12] Wang Q K, Wang S L, Zhang J W. Assessing the effects of vegetation types on carbon storage fifteen years after reforestation on a Chinese fir site[J]. Forest Ecology and Management, 2009, 258(7): 1437-1441. doi: 10.1016/j.foreco.2009.06.050 [13] 盛炜彤, 范少辉. 杉木及其人工林自身特性对长期立地生产力的影响[J]. 林业科学研究, 2002, 15(6):629-636. doi: 10.3321/j.issn:1001-1498.2002.06.001 [14] 鲁如坤. 土壤农业化学分析方法[M]. 北京: 中国农业科技出版社, 2000. [15] Saiya-Cork K R, Sinsabaugh R L, Zak D R. The effects of long-term nitrogen deposition on extracellular enzyme activity in an Acer saccharum forest soil[J]. Soil Biology and Biochemistry, 2002, 34(9): 1309-1315. doi: 10.1016/S0038-0717(02)00074-3 [16] Wang F M, Zou B, Li H F, et al. The effect of understory removal on microclimate and soil properties in two subtropical lumber plantations[J]. Journal of Forest Research, 2014, 19(1): 238-243. doi: 10.1007/s10310-013-0395-0 [17] 李 程, 尤业明, 唐佐芯, 等. 碳源输入量变化对河南宝天曼锐齿栎林土壤酶活性的影响[J]. 林业科学研究, 2018, 31(4):23-30. [18] Feng J, Turner B L, Wei K, et al. Divergent composition and turnover of soil organic nitrogen along a climate gradient in arid and semiarid grasslands[J]. Geoderma, 2018, 327: 36-44. doi: 10.1016/j.geoderma.2018.04.020 [19] 曹光球, 费裕翀, 路 锦, 等. 林下植被不同管理措施培育杉木大径材林分土壤酶活性差异及质量评价[J]. 林业科学研究, 2020, 33(3):76-84. [20] Dijkstra F A, Carrillo Y, Pendall E, et al. Rhizosphere priming: a nutrient perspective[J]. Fronties in Microbiology, 2013, 4: 216. [21] Margalef O, Sardans J, Fernandez-Martinez M, et al. Global patterns of phosphatase activity in natural soils[J]. Scientific Reports, 2017, 7(1): 1-13. doi: 10.1038/s41598-016-0028-x [22] Allison S D, Vitousek P M. Responses of extracellular enzymes to simple and complex nutrient inputs[J]. Soil Biology and Biochemistry, 2005, 37(5): 937-944. doi: 10.1016/j.soilbio.2004.09.014 [23] Wu J P, Liu Z F, Wang X L, et al. Effects of understory removal and tree girdling on soil microbial community composition and litter decomposition in two Eucalyptus plantations in South China[J]. Functional Ecology, 2011, 25(4): 921-931. doi: 10.1111/j.1365-2435.2011.01845.x [24] Rosling A, Midgley M G, Cheeke T, et al. Phosphorus cycling in deciduous forest soil differs between stands dominated by ecto- and arbuscular mycorrhizal trees[J]. New Phytologist, 2016, 209(3): 1184-1195. doi: 10.1111/nph.13720 [25] Sinsabaugh R L, Lauber C L, Weintraub M N, et al. Stoichiometry of soil enzyme activity at global scale[J]. Ecology letters, 2008, 11(11): 1252-1264. doi: 10.1111/j.1461-0248.2008.01245.x [26] 乔 航, 莫小勤, 罗艳华, 等. 不同林龄油茶人工林土壤酶化学计量及其影响因素[J]. 生态学报, 2019, 39(6):1887-1896. [27] 曾晓敏, 范跃新, 林开淼, 等. 亚热带不同植被类型土壤磷组分特征及其影响因素[J]. 应用生态学报, 2018, 29(7):2156-2162. [28] 袁 萍, 周嘉聪, 张秋芳, 等. 中亚热带不同森林更新方式生态酶化学计量特征[J]. 生态学报, 2018, 38(18):6741-6748. [29] Liu J L., Yang Z L, Dang P, et al. Response of soil microbial community dynamics to Robinia pseudoacacia L. afforestation in the loess plateau: a chronosequence approach[J]. Plant and Soil, 2018, 423(1-2): 327-338. doi: 10.1007/s11104-017-3516-2 [30] 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 pseudoacacia plantation on the Loess Plateau, China[J]. Soil Biology and Biochemistry, 2019, 134: 1-14. doi: 10.1016/j.soilbio.2019.03.017 [31] Peng X Q, Wang W. Stoichiometry of soil extracellular enzyme activity along a climatic transect in temperate grasslands of northern China[J]. Soil Biology and Biochemistry, 2016, 98: 74-84. doi: 10.1016/j.soilbio.2016.04.008 [32] Zhang W, Gao D X, Chen X, et al. Substrate quality and soil environmental conditions predict litter decomposition and drive soil nutrient dynamics following afforestation on the Loess Plateau of China[J]. Geoderma, 2018, 325: 152-161. doi: 10.1016/j.geoderma.2018.03.027 [33] Dong W Y, Zhang X Y, Liu X Y, et al. Responses of soil microbial communities and enzyme activities to nitrogen and phosphorus additions in Chinese fir plantations of subtropical China[J]. Biogeosciences, 2015, 12(18): 5537-5546. doi: 10.5194/bg-12-5537-2015