不同林龄华北落叶松人工林生物量及营养元素分布特征

The biomass and nutrient distribution in Larix principis-ruppechtii Magyr plantations at different forest age

为揭示华北落叶松人工林的养分特征,以山西太岳山好地方林场3种林龄(15年生、26年生、40年生)华北落叶松人工林为研究对象,采用样地调查和实测生物量的方法,测定乔木层不同器官、林下植被层和凋落物层生物量、营养元素积累量和年存留量及土壤营养元素(C、N、P、K)含量.结果显示:1)华北落叶松人工林的总生物量由林龄从小到大的顺序分别为61.89、175.81、163.15/t/hm^2.各层生物量分配规律为乔木层>凋落物层>草本层>灌木层.2)华北落叶松人工林乔木层树皮中的C含量最高,树根最低;N、P、K含量中树叶最高,树干最低.随着林龄增加,土壤中有机质和全N含量逐渐减少,全P和全K逐渐增加.3)15年生、26年生和40年生华北落叶松人工林营养元素的总积累量分别为26.12×103、77.29×103、69.60×103 kg/hm^2;随着林龄增加,林下植被层的营养元素积累量先增加后减小,凋落物层逐渐增加.4)26年生华北落叶松人工林林木营养元素年存留量最高.各器官中年存留量最高为树干,最低为树叶和树皮.综上,与15年生和40年生相比,26年生华北落叶松人工林的生物量、营养元素积累量和年存留量较高,因此应定期对林龄较高的华北落叶松人工林进行间伐,使林下生境条件得到改善,林下植被多样性增加,达到维持华北落叶松人工林生态系统稳定和可持续经营的目的.

This study aimed to interpret the nutrient utilization to provide theoretical basis for forest management through investigating the biomass and the content, concentrations and distribution patterns of four nutrient elements（C, N, P and K） in Larix principis-ruppechtii Magyr plantations at the Haodifang Foresty Station of Taiyue Mountain, China. We investigated the biomass, the content, concentration of nutrient elements and annual nutrient retention in the layers of tree, shrub, grass, litter and soil in L. principis-ruppechtii plantations of different forest age（15-year-old, 26-year-old and 40-year-old）. The results showed a total biomass of 61.89 t/hm^2, 175.81 t/hm^2 and 163.15 t/hm^2 respectively in the L. principis-ruppechtii plantation stands of 15, 26, and 40 years. The biomass was in the order of tree layer litter layer herb layer shrub layer. The concentration of C in different components of L. principis-ruppechtii was in the order of bark branch leaves stem root. The concentrations of N, P and K was as leaves branch bark root stem. Soil organic matter and K decreased with stand age, whereas the concentrations of N and P increased. The total nutrient retention among the three stands were 26.12 × 10^3kg/hm^2, 77.29 × 10^3 kg/hm^2 and 69.60 × 10^3 kg/hm^2, respectively. With the stands growth, the nutrient accumulation decreased in the forest fl oor layer, but increased in the the litter fl oor layer. The annual nutrient retention in 26-year-old L. principisruppechtii plantations was the highest. Among all tree organs, the stem had the highest annual nutrient retention amounts but the leaves and bark had the lowest. In contrast to the 15-year-old and 40-year-old plantations, 26-year-old L. principisruppechtii plantations had higher biomass, concentration of nutrient elements and annual nutrient retention. For a stableecosystem and sustainable management, the L. principis-ruppechtii plantations of older ages should be thinned regularly to improve the light, water and soil condition in the forest and increase vegetation diversity.