人工调控措施下马尾松凋落叶化学质量变化及与分解速率的关系

马尾松凋落叶分解缓慢,促进其凋落物分解,提高养分归还速度,维持地力稳定,已成为马尾松人工林可持续经营中的关键问题。基于此,采用正交试验L_9(3~4)设计,选择菌剂、表面活性剂、不同碳氮营养液和有机肥料4种人工调控因素,在马尾松林下开展凋落叶分解调控试验,以掌握不同调控组合对凋落叶分解速率和化学质量的影响及作用效果等。结果表明:有机肥料和菌剂显著影响马尾松凋落叶分解速率,腐解剂2和鸡粪联合作用更利于分解。马尾松凋落叶在林下自然分解过程中,化学质量参数向着利于分解的方向变化,N、P以积累为主,C/N、C/P、L/N和L/P呈降低态势,人为调控措施加速了这一变化进程;不同调控措施对凋落叶化学质量参数的影响不尽相同,添加有机肥料有利于剩余凋落叶N、P含量升高,C/N、C/P、L/N和L/P的降低;菌剂腐解剂2有利于L/P、C/P的降低;表面活性剂OP-10有利于凋落叶L/N的降低。人工调控下,调控因素可通过改变凋落物化学质量影响其分解速率,N含量和C/N是影响马尾松凋落叶分解速率的主要因素;而P浓度、L/N、C/P、L/P对分解速率的影响不规律或不显著。

Impact of different control measures on leaf litter chemical quality dynamic and its relations with decomposition rate under the pure Pinus massoniana forest

The slow decomposition rate of Pinus massoniana litter is an important problem that results in the nutrient imbalance of soil of P. massoniana forests. Accelerating the nutrient return rate to soil is considered to be an efficient measure to maintain the stability of soil productivity and sustainable management. The aim of this study was to observe the chemical quality change of litter and decomposition rate by altering the decomposition conditions and to assess the effect of different additives on the decomposition rate of P. massoniana litter in field. The regulation factors were microbial inoculants (fungus 1 or microorganisms 1 or microorganisms 2), surface-active agents(Tween 80 or OP-10), carbon and different forms of nitrogen nutrient solution(NaNO₃ or urea or NH₄Cl) and organic fertilizer(chicken manure or oil cake). The experiment was designed using the orthogonal test method of L₉(3⁴). The results indicated that the decomposition rate of P. massoniana litter was influenced significantly by organic fertilizer and microbial inoculants and was fastest under the combined treatment of microorganisms 2 and chicken manure. Under natural conditions, nitrogen and phosphorus would be relatively concentrated in the debris, whereas the ratios of C/N, C/P, lignin/N (L/N) and lignin/P (L/P) would decrease with the decomposition process; this is helpful in terms of accelerating the decomposition rate. Based on this principle, additives could speed up this process according to this principle. The effects of the different additives varied considerably. After the addition of organic fertilizer, the concentrations of nitrogen and phosphorous were raised, and the ratios of C/N, C/P, lignin/N (L/N) and lignin/P (L/P) were reduced. The addition of microbial inoculants resulted in lower C/P and L/P ratios; surface-active agents could help lower the L/N ratio of debris. The litter decomposition rate in all control treatments positively correlated with N concentration and negatively with the C/N ratio, and the leaf litter decomposition rate was not obviously related to its P content, L/N ratio, C/P ratio, and L/P ratio. Under artificial control, the decomposition rate can be affected by changing the litter chemical quality; the N content and C/N ratio were the main factors involved in regulating litter decomposition. The results of the study will provide the theoretical basis and technical support for P. massoniana forest resource management.