-
土壤是森林生态系统的重要组成成分[1],也是维持林木健康生长的必要基质,其养分含量大小直接影响林木生长速度和质量[2]。在林地中由于养分输入、输出以及林木自身养分循环而表现出明显的垂直分布特征,且因养分类型不同具有显著差异[3],这种异质性影响整个生物学和生态学过程[4]。有关垂直方向养分的研究一般将土层划分为0~20、20~40、40~60和60~100 cm等4个层次[5],表土层作为整个土体的最上面,养分含量大小对林木生长和评价土壤肥力状况更有代表性,忽略对表土层更细致的研究,不利于精准地描述土壤养分垂直分布格局。栽植密度是营林措施中一项重要且容易操作的措施,密度大小不仅影响林分结构[6]、树冠大小[7]及各器官养分含量[8],进而影响林木对土壤养分的吸收[9];还会影响凋落物生物量及分解速率[10],最终对土壤养分状况产生深刻影响。很多学者对栽植密度与土壤养分含量之间的关系开展了研究[11-12]。有研究表明:马尾松Pinus massoniana林地土壤养分含量随密度增大而降低[13]。不同学者研究结论不尽相同,可能是由于研究对象、栽植密度及林龄不同所造成的。预计到2050年,人工林将提供75%的工业木材,其中50%由速生丰产林提供[14-15]。杨树Populus在中国的栽植面积已达850万hm2[16]。毛白杨Populus tomentosa适应性较强,具有扩大引栽栽培范围的潜力[17],S86品种相对于其他品种有较高的木材量[18]。目前,关于栽植密度对毛白杨S86的影响大多数为地上部分的研究[19]。人工林具有速生、短轮伐期、长期单一化栽植等特点,地力容易出现单一化问题[9]。为此,本研究以10年生毛白杨S86为研究对象,比较3种栽植密度林地土壤6个土层(0~5,5~10,10~20,20~40,40~60和60~100 cm)的养分情况,阐明在不同栽植密度下毛白杨土壤养分的差异情况,为人工林林地土壤的管理及施肥提供有效指导。
-
试验地位于河北省威县苗圃场。该地属于华北平原中部,地势平坦,海拔30~50 m。年均气温为13.0 ℃,最低气温在1月,为-2.5 ℃,最高气温在7月,为27.0 ℃。气候为暖温带大陆性半干旱季风气候,全年日照总时数为2 574.8 h,无霜期198.0 d,平均降水量为497.7 mm,降水主要集中在7-8月。
-
选择三倍体毛白杨无性系S86为试验材料,于2007年4月挑选长势大致相同的2年生毛白杨无性系幼苗(平均胸径为6.1 cm,树高为5.8 m)进行造林,栽植毛白杨时林地土壤养分概况为:有机质8.60 g·kg-1,全氮0.58 g·kg-1,碱解氮87.8 mg·kg-1,有效磷8.1 mg·kg-1,速效钾90.0 mg·kg-1,总孔隙度46.7%,田间持水量为26%。采用单因素完全随机设计。栽植密度3个水平(行距×株距),分别为2 m × 2 m(T1)、4 m × 3 m(T2)、4 m × 5 m(T3)。T1每行11株,T2每行7株,T3每行4株,分别为2行,3次重复共9个小区。小区以南北走向为长,东西走向为宽,保护行的栽植密度为4 m × 3 m,设置2行。表 1为2016年3种栽植密度下毛白杨生长状况统计。
表 1 3种栽植密度下毛白杨S86生长状况
Table 1. Growth status of P. tomentosa S86 under three different planting densities
栽植密度(行距×株距) 树高/m 胸径/cm 蓄积量/(m3.hm-2) 凋落物量/(3hm-2) T1(2 m × 2 m) 14.60 ± 0.25 c 12.10 ± 0.31 b 157.97 ± 7.78 a 0.69 ± 0.14 b T2(4 m × 3 m) 18.08 ± 0.12 b 13.80 ± 0.24 a 86.80 ± 12.65 b 0.74 ± 0.18 a T3(4 m × 5 m) 21.04 ± 0.35 a 13.90 ± 0.13 a 64.75 ± 11.82 c 0.79 ± 0.04 a 说明:同列不同小写字母表示不同栽植密度毛白杨生长状况差异显著(P<0.05) -
2016年11月中旬收集土样,随机选取试验小区中央位置的5株树木,在其东侧80 cm处定点取样。先剥开凋落物,用土钻分别取(0~5、5~10、10~20、20~40、40~60和60~100 cm)6个土层土壤样品,将每个小区5个取样点土层的40~60和60~100 cm的2个土层的5个土样分别混为1个样品,土层0~5、5~10、10~20和20~40 cm土样不混合。
另采集3种栽植密度的凋落物,具体方法为每个小区取5个面积为60 cm × 60 cm凋落物样点,烘干称量得凋落物质量(表 1)。样品经室内风干、研磨、过筛后测定土壤养分。有机质采用重铬酸钾外加热法,碱解氮采用扩散法,有效磷采用钼锑抗比色法,速效钾采用火焰光度计法测定[20]。
-
采用Excel 2010计算和整理数据并进行图表绘制。数据间的方差分析(one-way ANOVA)、多重比较(Ducan检验法)采用SPSS 20.0进行分析。
-
10年生毛白杨S86林地土层养分所占比例随土层深度增加而减少,从土层0~20 cm占整个土层的69%~79%减少到60~100 cm土层仅占4%~7%(图 1)。养分所占比例在0~5、5~10和10~20 cm有一定的区别,特别是碱解氮在3个土层间有明显差异,0~5 cm土层所占比例高达41%~45%。
图 1 图 1常量元素迁移率随土壤剖面的变化图
Figure 1. Variation of constant element with soil profile
-
3种栽植密度的毛白杨S86林地土壤有机质质量分数分别为1.72~8.57 g·kg-1(T1)、5.20~15.44 g·kg-1(T2)、4.58~14.86 g·kg-1(T3),且随土层深度的增加而减少(图 2)。0~5,5~10和10~20 cm有机质质量分数随土层变化较为缓慢,20~40,40~60和60~100 cm随土层增加下降较明显。方差分析显示:土层深度对有机质质量分数有显著影响(P < 0.05),0~5和5~10 cm土层有机质质量分数差异不显著,但均显著高于其他土层,10~20、20~40和60~100 cm之间有机质质量分数差异显著(P < 0.05)。有机质质量分数随栽植密度和土层变化而变化。0~5、20~40、40~60和60~100 cm土层,有机质质量分数从大到小依次为T2、T3、T1,0~5 cm土层,T2和T3有机质质量分数分别较T1增加80.16%和73.40%;5~10和10~20 cm土层,有机质质量分数从大到小依次为T3、T2、T1(图 2)。总的来说,T1有机质质量分数显著低于T2和T3。
-
毛白杨S86林地碱解氮质量分数为6.8~142.7 mg·kg-1(图 3),随土层深度的增加而减少。土层对碱解氮质量分数影响显著(P < 0.05),各土层之间(除60~100 cm)差异显著(P < 0.05)。3种栽植密度下碱解氮质量分数在0~5、10~20、20~40、40~60和60~100 cm土层从大到小依次为T2、T3、T1(图 3);碱解氮质量分数在5~10 cm土层从大到小依次为T3、T2、T1。随土层深度增加,不同栽植密度间碱解氮质量分数差异越来越小,可能由于冬季淋溶作用较弱的原因所导致。
-
3种栽植密度的毛白杨S86林地土壤有效磷质量分数分别为1.3~6.1 mg·kg-1(T1)、1.5~12.4 mg·kg-1(T2)和2.5~11.7 mg·kg-1(T3),随土层深度增加,有效磷质量分数呈下降趋势(图 4),从0~5 cm土层占整个土层的31%~37%减少到60~100 cm土层仅占4%~8%(图 1)。栽植密度对有效磷质量分数影响显著(P < 0.05)。0~5 cm土层有效磷质量分数大小依次为:T2(12.4 mg·kg-1)、T3(11.7 mg·kg-1)、T1(6.1 mg·kg-1),T1显著低于T2和T3。有效磷质量分数在土层5~10、10~20和20~40 cm表现为3条有差异的曲线(图 4)。多重比较结果表明:T2显著高于T1和T3,T1和T3差异不显著;40~100 cm土层T3显著高于T1和T2(P < 0.05)。
-
速效钾质量分数随土层增加呈下降趋势(图 5)。5~10 cm土层速效钾质量分数显著高于10~20 cm(P < 0.05),与0~5 cm土层差异不显著,20~40、40~60和60~100 cm土层间速效钾质量分数差异不显著。T2的土壤速效钾质量分数最高,为60.3~278.1 mg·kg-1。T1速效钾质量分数小于T2和T3(图 5)。方差分析表明:栽植密度对土壤速效钾质量分数无显著影响(P>0.05)。
-
10 a后毛白杨S86林地土壤养分质量分数发生变化,碱解氮和有效磷降低,栽植密度越大降低的程度越明显,特别是碱解氮,在T1处理下降低了60%(表 2)。表明随林龄增加,毛白杨从土壤中吸收越来越多的氮素来供地上部分生长,从而导致土壤氮库储量和供氮能力的下降。
表 2 10 a前后毛白杨S86林地土壤养分质量分数
Table 2. Soil nutrient (mean) content in P. tomentosa S86 stand before and after 10 years
年份 处 w有机质/(g.kg-1) w碱解氮/(mg.kg-1) w有效磷/(mg.kg-1) w速效钾/(mg.kg-1) 2016 T1 5.5 ± 0.1 c 34.8 ± 0.1c 3.3 ± 0.1 c 113.0 ± 0.1a T2 9.2 ± 0.1 a 53.3 ± 0.1b 6.6 ± 0.1 b 157.0 ± 0.2 a T3 10.0 ± 0.1 a 45.9 ± 0.1 b 5.2 ± 0.1 c 150.0 ± 0.2 a 2007 8.6 ± 0.1b 87.8 ± 0.1 a 8.1 ± 0.1 a 90.0 ± 0.2 b 说明:数据为平均值±标准差,同列不同字母表示不同处理间差异显著(P<0.05) 速效钾质量分数增加,增加的幅度和栽植密度相关,T2增加幅度最大;有机质质量分数在T1处理下降低了3.12 g·kg-1,在T2和T3处理下分别增加了0.64和1.39 g·kg-1。
Planting densities and vertical soil nutrients in a Populus tomentosa stand
-
摘要:
目的 研究栽植密度对毛白杨Populus tomentosa林地土壤养分的影响。 方法 在3种不同栽植密度[行距×株距分别为2 m×2 m(T1)、4 m×3 m(T2)和4 m×5 m(T3)]下,对10年生毛白杨速生丰产林试验地0~5、5~10、10~20、20~40、40~60和60~100 cm共6个土层的有机质、碱解氮、有效磷和速效钾质量分数进行了分析。栽植密度对土壤养分的影响用单因素分析法,数据间的多重比较用Ducan法。 结果 0~20 cm土层有机质、碱解氮、有效磷和速效钾所占比例分别为69%、79%、71%和74%;不同栽植密度下土壤养分质量分数不一致:T2栽植密度下有机质在0~5 cm处最高,为15.44 g·kg-1,显著高于T1,在5~20 cm土层处3栽密度间有机质差异显著(P < 0.05),大小依次为T3、T2、T1,在20~100 cm土层处T1显著低于T3和T2(P < 0.05);碱解氮在T2下为14.5~142.7 mg·kg-1,高于T1和T3(除5~10 cm);有效磷为1.3~12.4 mg·kg-1,5~40 cm土层T2显著高于T1和T3(P < 0.05),40~100 cm土层大小依次为T3、T2、T1;栽植密度对速效钾无显著影响(P>0.05)。 结论 10年生毛白杨林地土壤养分富集在0~20 cm土层,栽植密度为2 m(行距)×2 m(株距)的养分低于栽植密度为4 m×3 m和4 m×5 m,养分质量分数随栽植密度和不同土层的变化而变化。 Abstract:Objective To explore the effects of planting densities on soil nutrients of different soil layers for a Populus tomentosa plantation. Method 10-year-old S86 clones were used to study the soil nutrient characteristics with three planting densities (T1:2 m×2 m; T2:4 m×3 m; and T3:4 m×5 m) for six soil layers (0-5, 5-10, 10-20, 20-40, 40-60, and 60-100 cm). In mid-October 2016, soil samples were collected, and the contents of carbon (C), available nitrogen (N), available phosphorus (P), and available potassium (K) were determined and in total there were 3 treatments with 3 replicates, then one-way ANOVA and Duncan's multiple comparison tests were used to determine significant differences. Result The proportions of nutrients in the 0-20 cm layer compared to the 0-100 cm layer were:C(69%), N(79%), P(71%), and K (74%). The content of soil nutrients varied for the three planting densities. The highest C content found in T2 (15.44 g·kg-1 in the 0-5 cm layer) was significantly higher (P < 0.05) than T1; the C content in the 5-20 cm layer was significantly different (P < 0.05) than other densities in the order of T3 > T2 > T1; and in the 40-100 cm layer, the T1 content was significantly lower (P < 0.05) than other densities. The N content in T2 was 14.5-142.7 mg·kg-1. The P content was 1.3-12.4 mg·kg-1 with the content of T2 being significantly higher (P < 0.05) than other layers from 5-40 cm; however, in the 40-100 cm layers the content was T3 > T2 > T1. Planting density, though, had no significant effect on K content (P>0.05). Conclusion Nutrient content varied according to planting density and soil layers with the soil nutrient content of 10-year-old P. tomentosa clone S86 gathered in the 0-20 cm layer for the 2 m×2 m density having a lower nutrient content than the 4 m×3 m and 4 m×5 m densities. -
Key words:
- soil science /
- vertical soil nutrient /
- planting density /
- Populus tomentosa forest
-
图 1 图 1常量元素迁移率随土壤剖面的变化图
Figure 1 Variation of constant element with soil profile
表 1 3种栽植密度下毛白杨S86生长状况
Table 1. Growth status of P. tomentosa S86 under three different planting densities
栽植密度(行距×株距) 树高/m 胸径/cm 蓄积量/(m3.hm-2) 凋落物量/(3hm-2) T1(2 m × 2 m) 14.60 ± 0.25 c 12.10 ± 0.31 b 157.97 ± 7.78 a 0.69 ± 0.14 b T2(4 m × 3 m) 18.08 ± 0.12 b 13.80 ± 0.24 a 86.80 ± 12.65 b 0.74 ± 0.18 a T3(4 m × 5 m) 21.04 ± 0.35 a 13.90 ± 0.13 a 64.75 ± 11.82 c 0.79 ± 0.04 a 说明:同列不同小写字母表示不同栽植密度毛白杨生长状况差异显著(P<0.05) 表 2 10 a前后毛白杨S86林地土壤养分质量分数
Table 2. Soil nutrient (mean) content in P. tomentosa S86 stand before and after 10 years
年份 处 w有机质/(g.kg-1) w碱解氮/(mg.kg-1) w有效磷/(mg.kg-1) w速效钾/(mg.kg-1) 2016 T1 5.5 ± 0.1 c 34.8 ± 0.1c 3.3 ± 0.1 c 113.0 ± 0.1a T2 9.2 ± 0.1 a 53.3 ± 0.1b 6.6 ± 0.1 b 157.0 ± 0.2 a T3 10.0 ± 0.1 a 45.9 ± 0.1 b 5.2 ± 0.1 c 150.0 ± 0.2 a 2007 8.6 ± 0.1b 87.8 ± 0.1 a 8.1 ± 0.1 a 90.0 ± 0.2 b 说明:数据为平均值±标准差,同列不同字母表示不同处理间差异显著(P<0.05) -
[1] TRANGMAR B B, YOST R S, UEHARA G. Application of geostatistics to spatial studies of soil properties[J]. Adv Agron, 1986, 38:45-94. [2] 贺志龙, 张芸香, 郭跃东, 等.不同密度华北落叶松林天然林土壤养分特征研究[J].生态环境学报, 2017, 26(1):43-48. HE Zhilong, ZHANG Yunxiang, GUO Yuedong, et al. Soil nutrient characteristics of natural Larix principis-rupprechtii in different stand density[J]. Ecol Environ Sci, 2017, 26(1):43-48. [3] 张红桔, 马闪闪, 赵科理, 等.山核桃林地土壤肥力状况及其空间分布特征[J].浙江农林大学学报, 2018, 35(4):664-673. ZHANG Hongju, MA Shanshan, ZHAO Keli, et al. Soil fertility and its spatial distribution for Carya cathayensis stands in Lin'an, Zhejiang Province[J]. J Zhejiang A&F Univ, 2018, 35(4):664-673. [4] JOHN R, DALLING J W, HARMS K E, et al. Soil nutrients influence spatial distributions of tropical tree species[J]. Proc Natl Acad Sci USA, 2007, 104(3):864-869. [5] 王华, 陈莉, 宋敏, 等.喀斯特常绿叶阔叶混交林土壤磷钾养分空间异质性[J].生态学报, 2017, 37(24):8285-8293. WANG Hua, CHEN Li, SONG Min, et al. Spatial heterogeneity of soil phosphorous and potassium in a mixed evergreen and deciduous broad-leaved forest in karst region of southwest China[J]. Acta Ecol Sin, 2017, 37(24):8285-8293. [6] HALL S J, MARCHAND P J. Effects of stand density on ecosystem properties of subalpine forests in the southern Rocky Mountains, USA[J]. Ann For Sci, 2010, 67(1):102. [7] 王春胜.西南桦人工中幼林密度效应和秀芝研究[D].北京: 中国林业科学研究院, 2015. WANG Chunsheng. Studies on the Effect of Planting Density and Srtificial Pruning on Young and Middle Aged Betula alnoides[D]. Beijing: Chinese Academy of Forestry, 2015. [8] 肖兴翠, 李志辉, 唐作钧, 等.林分密度对湿地松人工林养分循环速率和利用效率的影响[J].生态学杂志, 2013, 32(11):2871-2880. XIAO Xingcui, LI Zhihui, TANG Zuojun, et al. Effects of stand density on nutrient cycling rate and use efficiency of Pinus elliottii plantation[J]. Chin J Ecol, 2013, 32(11):2871-2880. [9] 刘骏, 杨清培, 余定坤, 等.细根对竹林-阔叶林界面两侧土壤养分异质性形成的贡献[J].植物生态学报, 2013, 37(8):739-749. LIU Jun, YANG Qingpei, YU Dingkun, et al. Contribution of fine root to soil nutrient heterogeneity at two sides of the bamoo and broad-leaved forest interface[J]. Chin J Plant Ecol, 2013, 37(8):739-749. [10] KUNHAMU T K, KUMAR B M, VISWANATH S. Does thinning affect litterfall, litter decomposition, and associated nutrient release in Acaia mangium stands of Kerala in peninsular India?[J]. Can J Res, 2009, 39:792-801. [11] 董彬, 曹永富, 尉海东.杨树人工林凋落物养分归还功能研究[J].生态科学, 2011, 30(3):257-261. DONG Bin, CAO Yongfu, WEI Haidong. Nutrient return of litterfall in a Populous tremuloides plantation[J]. Ecol Sci, 2011, 30(3):257-261. [12] 孙千惠, 吴霞, 王媚臻, 等.林分密度对马尾松林林下物种多样性和土壤理化性质的影响[J].应用生态学报, 2018, 29(3):732-738. SUN Qianhui, WU Xia, WANG Meizhen, et al. Effects of stand density on understory species diversity and soil physicochemical properties of Pinus massoniana plantation[J]. Chin J Appl Ecol, 2018, 29(3):732-738. [13] FANG Xiangmin, CHRISTENSON L M, WANG Fangchao, et al. Pine caterpillar outbreak and stand density impacts on nitrogen and phosphorous dynamics and their stoichiometry in masson pine (Pinus massoniana) plantations in subtropical China[J]. Can J For Res, 2006, 46(5):601-609. [14] SEDIO R A. From foraging to cropping:the transition to plantation forestry, and implications for wood supply and demand[J]. Unasylva, 2001, 52(20):24-32. [15] TRUAX B, GAGNON D, FORTIER J, et al. Yield in 8-year-old hybrid poplar plantations on abandoned farmland along climatic and soil fertility gradients[J]. For Ecol Manage, 2012, 267:228-239. [16] XI Benye, BLOOMBERG M. WATT M S, et al. Modeling growth response to soil water availability simulated by HYDRUS for a mature triploid Populus tomentosa plantation located on the north China plain[J]. Agric Water Manage, 2016, 176:243-254. [17] 朱之悌.毛白杨遗传改良[M].北京:中国林业出版社, 2006. [18] ZHU Jialei, BO Huijuan, LI Xuan, et al. Effect of soil water and nitrogen on the stand volume of four hybrid Populus tomentosa clones[J]. Forests, 2017, 8(7):250. [19] SONIA C, MIREN D R, HUBERT S. Mixing effect on volume growth of Fagus sylvatica and Pinus sylvestris is modulated by stand density[J]. For Ecol Manage, 2013, 292:86-95. [20] 鲍士旦.土壤农化分析[M].北京:中国农业出版社, 2000:14-111. [21] KIRBY M J. A basis for soil profile modeling in a geomorphic context[J]. Soil Sci, 1985, 36:97-121. [22] 戴奥娜, 刘肖肖, 王兵, 等.丝栗栲林下土壤有机碳及其组分的时空年变化特征[J].浙江农林大学学报, 2018, 35(3):405-411. DAI Aona, LIU Xiaoxiao, WANG Bing, et al. Annual spatial and temporal variations of soil organic carbon and its components in Castanopsis fargesii[J]. J Zhejiang A&F Univ, 2018, 35(3):405-411. [23] 杨晓娟, 王海燕, 刘玲, 等.东北过伐林区不同林分类型土壤肥力质量评价研究[J].生态环境学报, 2012, 21(9):1553-1560. YANG Xiaojuan, WANG Haiyan, LIU Ling, et al. Evaluation of soil fertility quality under different forest stands in over-logged forest region, northeast China[J]. Ecol Environ Sci, 2012, 21(9):1553-1560. [24] 牛小云, 孙晓梅, 陈东升, 等.辽东山区不同林龄日本落叶松人工林土壤微生物、养分及酶活性[J].应用生态学报, 2015, 26(9):2663-2672. NIU Xiaoyun, SUN Xiaomei, CHEN Dongsheng, et al. Soil microorganisms, nutrients and enzyme activity of Larix kaempferi plantation under different ages in mountainous region of eastern Liaoning Province, China[J]. Chin J Appl Ecol, 2015, 26(9):2663-2672. [25] 邱新彩, 彭道黎, 李伟丽, 等.北京市延庆区不同林龄油松人工林土壤理化性质[J].应用与环境生物学报, 2018, 24(2):221-229. QIU Xincai, PENG Daoli, LI Weili, et al. Soil physicochemical properties of Pinus tabuliforms plantations of different ages in Yanqing, Beijing[J]. Chin J Appl Environ Biol, 2018, 24(2):221-229. [26] BO Huijuan, WEN Chunyan, SONG Lianjun, et al. Fine-root responses of Populous tomentosa forests to stand density[J]. Forests, 2018, 9(9):562. [27] 范少辉, 赵建诚, 苏文会, 等.不同密度毛竹林土壤质量综合评价[J].林业科学, 2015, 51(10):1-9. FAN Shaohui, ZHAO Jiancheng, SU Wenhui, et al. Comprehensive evaluation of soil quality in Phyllostachys edulis stands of different stocking densities[J]. Sci Silv Sin, 2015, 51(10):1-9. [28] 刘勇, 李国雷, 李瑞生, 等.密度调控对油松人工林土壤肥力的影响[J].西北林学院学报, 2008, 23(6):18-23. LIU Yong, LI Guolei, LI Ruisheng, et al. Effected of tree density on soil fertility in Pinus tabulaeformis plantations[J]. J Northwest For Univ, 2008, 23(6):18-23. [29] 任丽娜, 王海燕, 丁国栋, 等.林分密度对华北土石山区油松人工林土壤有机碳及养分特征的影响[J].干旱区地理, 2012, 35(3):456-464. REN Lina, WANG Haiyan, DING Guodong, et al. Effects of Pinus tabulaeformis Carr. plantation density on soil organic carbon and nutrients characteristics in rocky mountain area of northern China[J]. Arid Land Geogr, 2012, 35(3):456-464. [30] HERNANDEZ J, PINO A D, VANVE E D, et al. Eucalyputs and Pinus stand density effects on soil carbon sequestration[J]. For Ecol Manage, 2016, 368:28-38. [31] YANAI R D, CURRIE W S, GOODALE L. Soil carbon dynamics after forest harvest:an ecosystem paradigm reconsidered[J]. Ecosystems, 2003, 6(3):197-212. -
链接本文:
https://zlxb.zafu.edu.cn/article/doi/10.11833/j.issn.2095-0756.2020.02.010