阿什河流域6种人工林叶片-凋落物-土壤系统的养分分配与利用格局

【目的】分别从人工林叶片、凋落物、土壤养分含量及化学计量比的差异,叶片-凋落物养分重吸收的差异,土壤有效养分及其活化的差异等方面,探究黑龙江阿什河流域6种人工林生态系统的养分吸收与利用策略,明确人工针叶林和阔叶林间以及不同树种间叶片-凋落物-土壤系统养分分配格局的差异,从养分优化利用和养分资源合理配置的角度考虑,推断适宜的互补树种,为流域森林景观的恢复和人工林的经营提供依据。【方法】以东北林业大学实验林场森林培育实验站次生林带状皆伐后营造的位置相近、立地条件基本一致的29年生红松、长白落叶松、红皮云杉、水曲柳、黄檗、胡桃楸人工林为研究对象,通过野外调查取样,室内使用碳氮分析仪测定叶片、凋落物、土壤C含量,使用凯氏定氮仪测定叶片和凋落物的N含量,硫酸-高氯酸消化-钼锑抗比色法测定叶片和凋落物的P含量,连续流动分析仪测定土壤的N含量、铵态氮($NH_{4}^{+}-N$)及硝态氮($NO_{3}^{-}-N$)含量,硫酸-高氯酸消化-钼锑抗比色法测定土壤的P含量,HCl-H₂SO₄浸提法测定土壤的有效磷含量。运用生态化学计量学的研究方法,分析各林分叶片-凋落物-土壤系统的养分含量及其生态化学计量特征,确定各凋落物营养的重吸收及土壤有效养分的供应特征。【结果】①针叶林叶片P含量(1.55 g/kg)显著低于阔叶林叶片P含量(2.02 g/kg)(P<0.05, F=16.92,df=1)。针叶林土壤C、P含量(47.75、1.17 g/kg)显著低于阔叶林土壤C、P含量(76.35、1.47 g/kg)(P<0.05, F_{C 含量}=75.15, F_{P 含量}=9.91,df=1)。6种林分中,水曲柳林叶片的N含量(19.64 g/kg)(P<0.05, F=5.26,df=5)、凋落物C、N、P含量(P<0.05, F_{C 含量}=2.34, F_{N 含量}=1.60, F_{P 含量}=6.74,df=5)和土壤的C、N、P含量(P<0.05, F_{C 含量}=154.84, F_{N 含量}=14.21, F_{P 含量}=53.55,df=5)均相对较高。红皮云杉林叶片P含量(1.30 g/kg)(P<0.05, F=36.71,df=5),长白落叶松林凋落物C含量(P<0.05, F=2.34,df=5),红松林凋落物N含量(P<0.05, F=1.60,df=5)均相对较低。②针叶林叶片碳磷质量比(C/P)值(314.84)显著高于阔叶林叶片C/P值(251.03)(P<0.05, F=20.43,df=1),阔叶林土壤C/P值(53.20)显著高于针叶林土壤C/P值(40.71)(P<0.05, F=15. 38,df=1)。6种林分中,红皮云杉林叶片C/P值(359.24)较高(P<0.05, F=35.02,df=5),水曲柳林叶片碳氮质量比(C/N)值(24.15)相对较低(P<0.05, F=11.42,df=5)。胡桃楸林土壤C/N值(19.82)显著高于长白落叶松林土壤的C/N值(5.62)(P<0.05, F=12.40,df=5)。③针叶林元素重吸收率为N的(25.31%)>P的(14.41%)。阔叶林P重吸收率(29.84%)显著高于针叶林P重吸收率(14.41%)(P<0.05, F=7.30,df=1)。6种林分中,水曲柳N重吸收率(P<0.05, F=13.66,df=5)、黄檗P重吸收率(P<0.05, F=60.40,df=5)相对较高。④阔叶林土壤有效P含量及有效P比率(11.74 mg/kg、8.22×10 ^-3)显著小于针叶林(16.59 mg/kg、14.24×10 ^-3)(P<0.05, F_{有效P含量}=7.32, F_{有效P比率}=11.84,df=1)。6种林分中,红松林和胡桃楸林土壤对N的活化能力相对较强,红松林和长白落叶松林土壤有效P的供应能力及其活化能力相对较强。【结论】针叶林叶片P元素利用率高,元素重吸收率为N>P。阔叶林土壤C、P含量较高、有效P积累能力弱、有效P含量及比例均显著低于针叶林,但其P的重吸收率显著高于针叶林。从优化养分资源角度考虑,针叶树种与阔叶树种混交,如红松与水曲柳、长白落叶松与水曲柳混交可以弥补针叶纯林养分分配与利用格局上的不足。

Nutrient distribution and utilization patterns in six plantations leaf-litter-soil system in the Ashi River Basin

【Objective】This study aimed to provide a theoretical basis for the recovery of the forest landscape and optimal management of plantations in the Ashi River Basin. The differences in leaf-litter-soil nutrient content and stoichiometric ratio, leaf-litter-nutrient resorption and soil available nutrients and their activation were investigated to explore the nutrient absorption and utilization strategies in plantations of six tree species. Differences in the nutrient distribution patterns between plantations of coniferous and broad-leaved species were also investigated, from the point of rational allocation and optimal utilization of nutrient resources, complementary tree species were inferred. 【Method】The study was conducted at the Forest Cultivation Experiment Station of the Northeast Forestry University in plantations located on secondary forest strip clear cutting land with the same site conditions. The study plantations were 29 years old and contained the following six species: Pinus koraiensis, Larix olgensis, Picea koraiensis, Fraxinus mandshurica, Phellodendron amurense and Juglans mandshurica. Applying the research method of ecological stoichiometry, the nutrient content and stoichiometric characteristics of the leaf-litter-soil system of each plantation were analyzed, and the nutrient resorption of the litter and the supply characteristics of soil available nutrients were confirmed. This was accomplished through field survey sampling and laboratory analysis. A Carbon and nitrogen analyzer was used to determine the carbon (C) content in leaves, litter, and soil and a Kjeldahl instrument was used to determine the nitrogen (N) content in leaves and litter. The soil N content as ammonium nitrogen ($NH_{4}^{+}-N$) and nitrate nitrogen ($NO_{3}^{-}-N$) was determined by using a continuous flow analyzer. Phosphorus (P) content was determined by sulfuric-perchloric acid digestion and molybdenum-antimony colorimetry. The soil P content was determined by sulfuric-perchloric acid digestion and molybdenum-antimony colorimetry. Soil available P was determined by HCl-H₂SO₄ extraction.【Result】① The leaf P content of the coniferous plantations (1.55 g/kg) was significantly lower than that of the broad-leaved plantations (2.02 g/kg) (P < 0.05, F =16.92, df=1) and the C and P content in the coniferous plantations (47.75, 1.17 g/kg) was significantly lower than in the broad-leaved plantations (76.35, 1.47 g/kg) (P<0.05, F_{C content}=75.15, F_{P content}=9.91, df=1). Within all six stands, the leaf N content (19.64 g/kg) (P < 0.05, F =5.26, df=5), C, N and P content in the litter (P < 0.05, F_{C content} =2.34, F_{N content} =1.60, F_{P content} =6.74, df=5) and the soil (P< 0.05, F_{C content} =154.84, F_{N content} =14.21, F_{P content}=53.55, df=5) of the F. mandshurica plantation was higher than those in the other plantations. Leaf P content of the P. koraiensis plantation (1.30 g/kg) (P < 0.05,F =36.71,df=5), litter C content of the L. olgensis plantation (P < 0.05,F =2.34,df=5) and litter N content of the P. koraiensis plantation (P < 0.05,F=1.60,df=5) was lower than those for the other plantations. ② The leaf C/P of the coniferous plantations (314.84) was significantly higher than that of the broad-leaved plantations (251.03) (P < 0.05, F =20.43, df=1) whereas the soil C/P of the broad-leaved plantations (53.20) was significantly higher than that of the coniferous plantations (40.71) (P<0.05, F=15.38, df=1). Within all six stands, the leaf C/P of the P. koraiensis plantation (359.24) was the highest (P < 0.05, F =35.02, df=5), and C/N in the leaves of the F. mandshurica plantation (24.15) was the lowest (P<0.05, F =11.42, df=5). The soil C/N of the J. mandshurica plantation (19.82) was significantly higher than that of the L. olgensis plantation (5.62) (P<0.05, F =12.40, df=5). ③ The N resorption efficiency (25.31%) was significantly higher than the P resorption efficiency (14.41%) in the coniferous plantations and the P resorption efficiency of the broad-leaved plantations (29.84%) was significantly higher than that of the coniferous plantations (14.41%) (P < 0.05, F =7.30, df=1). Within all six stands, the N resorption efficiency of F. mandshurica (P < 0.05, F =13.66, df=5) and the P resorption efficiency of P. amurense (P < 0.05, F =60.40, df=5) were higher than for the litter of the other stands. ④ The ratio of available P content and available P in the broad-leaved plantations (11.74 mg/kg, 8.22×10 ^-3) was significantly lower than that in the coniferous plantations (16.59 mg/kg, 14.24×10 ^-3) (P < 0.05, F_{available P content}=7.32, F_{available P ratio}=11.84, df=1). Within all six stands, the soil activation ability to N of the P. koraiensis plantation and the J. mandshurica plantation was stronger than those that of other plantations, and the soil supply ability and activation ability of available P in the P. koraiensis and the L. olgensis plantations was stronger than in the other plantations. 【Conclusion】The rate of P utilization in the leaves of coniferous plantation trees was higher than that in broad-leaved plantation trees, and the N resorption efficiency was higher than the P resorption efficiency. The C and P content in the soil of the broad-leaved plantations was higher than that of the coniferous plantations, while the available P accumulation ability was weak. The available P content and ratio of the broad-leaved plantations was significantly lower than for the coniferous plantations, but the P resorption efficiency was significantly higher than that for the coniferous plantations. From the point of optimal utilization of nutrients and rational allocation of nutrient resources, coniferous and broad-leaved tree mixes, such as P. koraiensis and F. mandshurica, and L. olgensis and F. mandshurica could create a complementary nutrient allocation and utilization pattern.