滨海沙地木麻黄人工林细根生物量及其动态研究

2005年1月到11月对福建省惠安县赤湖林场不同林龄木麻黄人工林细根的生物量及其动态特征进行了研究.结果表明,24a生木麻黄林细根生物量分别占其地下部分生物量和林分总生物量的53.1%和3.8%;活细根的生物量随林龄的增大而逐渐增加,至30a林龄时达到最大值12.373thm-2,而后逐渐下降,死细根的生物量则呈现一直增大的趋势,木麻黄人工林细根的生物量与林分地上部分的生长具有显著的相关关系;细根生物量具有明显的季节动态,各林龄无论活细根还是死细根都表现为双峰型,3a生和18a生的活细根出现在1月和7月,而12a生出现在3月和7月,对于死细根,12a生和18a生的两个峰值出现在3月和7月,5a生则出现在7月和11月.各林龄木麻黄防护林活、死细根密度垂直分布呈单峰型,最大值出现在表层的0~10cm土层中,后随土层厚度增加逐渐减少,其中5a林龄细根生物量随土层深度增加而减少表现最为明显.在0~10cm土层中的活、死细根生物量分别占全部活细根生物量的51.9%和死细根生物量的53.3%,活细根生物量的84.6%和死细根生物量的82.8%分布在0~30cm的土层中.以后随着林龄的增加,表层土壤中细根生物量的比重降低而深层的比重增加.图3表2参31

Fine Root Biomass and Dynamics of Casuarina equisetifolia Plantations on Coastal Sandy Soil

Fine root biomass and its dynamic characteristics of different aged Casuarina equisetifolia plantations on coastal sandy soil were studied in the Chifu Forestry Farm of Huian County, Fujian. The results showed that the fine roots of 24-year-old plantation accounted for 53.1% of the total underground biomass and 3.8% of the total amount of plantation, respectively; the standing crop of living fine roots increased as the forest aging until its maximum reached 12.373 t hm-2 at 30-year-old, then decreased gradually, while the biomass of dead fine roots increased all along as the forest aging. The fine roots biomass had remarkable correlation with the growth of the above-ground. The fine roots biomass was found with remarkable seasonal dynamics that the standing crop of living and dead fine roots of different aged plantations both were shown with double peaks, while the maximum occurred in different seasons for different aged plantations. The maximum of living fine roots of 5-and 18-year-old plantations occurred separately in January and July, while those of 12-year in March and July. As to the dead fine roots, those of 12-and 18-year occurred in March and July, and 5-year in July and November. The vertical distribution of living and dead fine roots at soil depth was shown with single peak for C. equisetifolia plantations, being concentrated at 0~10 cm, and then decreased with depth gradually. This trend was obvious for 5-year-old plantation. The biomasses of living and dead fine roots at 0~10 cm accounted for 51.9% and 53.3% of the totals, respectively. The 84.6% of living and 82.8% of dead fine roots concentrated at the depth of 0~30 cm. The proportion of fine roots decreased in topsoil and increased in deep soil along with aging of the forest. Fig 3, Tab 2, Ref 31