马尾松与湿地松人工林生物量动态及养分循环特征

对乡土树种马尾松和引进外来树种湿地松人工林的生物量动态变化、养分积累与分配以及养分循环特征进行比较 ,结果表明 :在林分生长发育早期 ,马尾松生长慢 ,而湿地松生长快 ,生长发育后期马尾松生长速度比湿地松快。马尾松人工林生物量的数量成熟年龄为 36 a,采伐利用时的最大生物量为 4 34t/ hm2 ;湿地松的为 2 6 a,采伐利用时的最大生物量为 338t/ hm2。湿地松人工林各器官和总的养分积累量均高于马尾松 ,其中养分的总积累量是马尾松的 2倍多 ,树干高达 5倍多。在采伐利用时 ,不管是全树利用还是仅利用干材 ,同马尾松相比 ,湿地松林将带走更多的养分 ,对地力的养分消耗量更大。同时 ,湿地松林养分循环速率低 ,周转时间长 ,需要的养分多 ,比马尾松林维持地力的能力差。因此 ,在湿地松人工林的经营管理过程 ,更应处理好养地与用地之间的关系 ,否则会造成林地生产力的下降

Comparison of biomass dynamic and nutrient cycling between Pinus massomiana plantation and Pinus elliottii plantation

This paper investigated the biomass dynamics, and the accumulation, distribution and cycling of nutrients in Pinus massomiana and Pinus elliottii plantations. Pinus massomiana is a native species while Pinus elliottii is introduced to the region. The results showed that the growth of P. massomiana plantation was slower than that of P. elliottii during the juvenile stage. However, the trend was reversed in the later stage of the stand development, i.e., P. massomiana grew faster than did P. elliottii. The biological maturity of P. massomiana for biomass production was determined to be 36 years, with a total biomass of 434 t/hm~(2) at that age. The biological maturity of P. elliottii for biomass production was 26 years with a total biomass of 338t/hm~(2). The total nutrient accumulation and the nutrient content in different organs were significantly higher in P. elliottii than in P. massomiana, e.g., the total nutrient accumulation and the nutrient content in the bole were twice and five times as high in P. elliottii as in P. massomiana, respectively. Consequently, the harvesting of P. elliotti, whether it is the whole tree or just the tree trunk, will remove more nutrients from the site and thus have more negative impact on the site productivity than the harvesting of P. massomian. Furthermore, the rate of nutrient cycling was lower and thus the period of nutrient cycle was longer in the P. elliotti plantation than in P. massomian. Consequently, P. elliotti was less able to maintain the site productivity than was P. massomian. Therefore, more efforts should be made to maintain the site productivity in managing P. elliotti plantations. Otherwise the site quality will deteriorate.