水土保持研究

为揭示滨海盐碱地林地土壤生态化学计量特征及其群落物种多样性,以山东寿光机械林场5种纯林和4种混交林为研究对象,运用生态化学计量手段,对比分析营林过程中林地间土壤营养元素差异和群落物种多样性变化,并通过CCA和RDA排序探讨了影响植物多样性的关键因子。结果表明:(1)各林地0—20 cm表层土壤有机碳(SOC)和全氮(N)占整个剖面的41.76%～54.56%和40.51%～51.46%,全磷(P)除旱柳林外其余林地各层无显著差异,全钾(K)在0—60 cm土层无明显分层规律,表层SOC和N可作为表征盐碱地林地最敏感的养分指标。(2)造林后林地土壤C/N由逐渐降低演变为先升高后降低的分布规律,C/P,N/P,N/K由先降低后升高的分布特征呈逐渐降低的分布规律,C/K,P/K无明显变化,造林前后均呈逐渐降低趋势。盐碱地养分含量普遍偏低,N和P对滨海盐碱地存在不同程度的限制,纯林更易受到N,P养分的限制。(3)各林地土壤养分间具有极显著非线性耦合关系,SOC,N,P与K相互影响,SOC,N与P相互影响,SOC,N间表现为相互促进、协同增长的正相关关系。(4)林地灌草群落大致可分为3个类群,其中耐盐碱植物的分布与P有效性关系密切相关,一年生草本喜肥沃土壤,多年生草本更倾向于低养分土壤。灌草层植物多样性与土壤K和C/N呈显著正相关关系。综上,滨海盐碱地林地养分含量普遍偏低,旱柳林、黑杨林、白蜡臭椿林和皂角臭椿林,蓄肥保墒效果优越,可以改善盐碱地土壤贫瘠现象,造林还可以改变养分在不同土层的吸收利用及分布规律,且N和P对滨海盐碱地存在不同程度的限制。各林地土壤养分及生态化学计量比间呈极显著耦合关系,同时生态化学计量特征又影响盐碱地灌草植物的分布与多样性变化。

In order to reveal the characteristics of soil stoichiometry and species diversity in coastal saline-alkali land forestland, five pure forests and four mixed forests in Shouguang mechanical forest farm of Shandong Province were selected as the research sites. Ecological stoichiometry was used to compare and analyze the difference of soil nutrient elements and change of species diversity among woodlands in the process of plantation. The CCA and RDA were used to explore the key factor on species diversity. The results show that:(1)the surface soil organic carbon(SOC)and total nitrogen(N)of 0—20 cm layer in different forestlands accounted for 41.76%～54.56% and 40.51%～51.46% of the whole section; there was no significant difference in total phosphorus(P)among all the forestland layers except upland Salix matsudana; there was no obvious stratification rule of total potassium(K)in 0—60 cm soil layer; surface soil organic carbon and total nitrogen can be used as the most sensitive fertility index in forestlands;(2)after afforestation, C/N in forestlands evolved from gradually decreasing to first increasing and then decreasing; the distribution characteristics of C/P, N/P and N/K present the decrease and then increase to gradual decrease; C/K and P/K are no significant change, but show the decreasing trend before and after afforestation; the nutrient content of saline-alkali soil is generally low, and total nitrogen and total phosphorus have different limits on coastal saline-alkali land; pure forests are more restricted by nitrogen and phosphorus nutrients;(3)soil nutrients in each forestland have a highly significant nonlinear coupling relationship with each other; SOC, N, P and K interact with each other, SOC, N and P interact with each other, and SOC and N show the positive correlation of synergistic growth;(4)the plant community can be roughly divided into three groups, among which the distribution of salt-tolerant plants is closely related to the availability of P; annual herb prefers the fertile soil, while perennial herb prefers the low-nutrient soil; there is a significant positive correlation between species diversity and soil K and C/N. In conclusion, the nutrient content of coastal saline-alkali forestland is generally low. The effects of Salix matsudana, Populus deltoides, Fraxinus chinensis-Ailanthus altissima and Gleditsia sinensis-Ailanthus altissima forest lands on soil fertility are both excellent, which can alleviate the soil barrenness of saline-alkali land. Afforestation can change the absorption, utilization and distribution of nutrients in different soil layers, and N and P have different degrees of restrictions on coastal saline-alkali land. Soil nutrients and ecostoichiometry in each forestland have a highly significant nonlinear coupling relationship with each other. And ecostoichiometry also affects the distribution and diversity of shrub and grass plants in saline alkali land.