CRDPI, Centre de Recherche sur la Durabilité et la Productivité des Plantations Industrielles, BP 1291, Pointe Noire, Republic of Congo.
Ann Bot. 2011 Jul;108(1):221-30. doi: 10.1093/aob/mcr102. Epub 2011 May 13.
Despite their importance for plant production, estimations of below-ground biomass and its distribution in the soil are still difficult and time consuming, and no single reliable methodology is available for different root types. To identify the best method for root biomass estimations, four different methods, with labour requirements, were tested at the same location.
The four methods, applied in a 6-year-old Eucalyptus plantation in Congo, were based on different soil sampling volumes: auger (8 cm in diameter), monolith (25 × 25 cm quadrate), half Voronoi trench (1·5 m(3)) and a full Voronoi trench (3 m(3)), chosen as the reference method.
With the reference method (0-1m deep), fine-root biomass (FRB, diameter <2 mm) was estimated at 1·8 t ha(-1), medium-root biomass (MRB diameter 2-10 mm) at 2·0 t ha(-1), coarse-root biomass (CRB, diameter >10 mm) at 5·6 t ha(-1) and stump biomass at 6·8 t ha(-1). Total below-ground biomass was estimated at 16·2 t ha(-1) (root : shoot ratio equal to 0·23) for this 800 tree ha(-1) eucalypt plantation density. The density of FRB was very high (0·56 t ha(-1)) in the top soil horizon (0-3 cm layer) and decreased greatly (0·3 t ha(-1)) with depth (50-100 cm). Without labour requirement considerations, no significant differences were found between the four methods for FRB and MRB; however, CRB was better estimated by the half and full Voronoi trenches. When labour requirements were considered, the most effective method was auger coring for FRB, whereas the half and full Voronoi trenches were the most appropriate methods for MRB and CRB, respectively.
As CRB combined with stumps amounted to 78 % of total below-ground biomass, a full Voronoi trench is strongly recommended when estimating total standing root biomass. Conversely, for FRB estimation, auger coring is recommended with a design pattern accounting for the spatial variability of fine-root distribution.
尽管地下生物量及其在土壤中的分布对植物生产很重要，但估计地下生物量及其分布仍然很困难且耗时，并且不同的根系类型没有一种可靠的单一方法。为了确定最佳的根系生物量估计方法，在同一地点测试了四种具有不同劳动力需求的方法。
这四种方法应用于刚果一个 6 年生的桉树种植园中，其基础是不同的土壤采样体积：螺旋钻（直径 8 厘米）、岩芯（25×25 厘米的正方形）、半 Voronoi 沟（1.5 立方米）和全 Voronoi 沟（3 立方米），后者被选为参考方法。
使用参考方法（0-1 米深），细根生物量（FRB，直径<2 毫米）估计为 1.8 t ha（-1），中根生物量（MRB，直径 2-10 毫米）估计为 2.0 t ha（-1），粗根生物量（CRB，直径>10 毫米）估计为 5.6 t ha（-1），树桩生物量估计为 6.8 t ha（-1）。对于这种 800 株/公顷的桉树种植密度，地下总生物量估计为 16.2 t ha（-1）（根：叶比等于 0.23）。FRB 的密度非常高（0.56 t ha（-1）），位于表层土壤（0-3 厘米层），随着深度的增加（50-100 厘米），密度大大降低（0.3 t ha（-1））。不考虑劳动力需求因素，四种方法之间 FRB 和 MRB 没有显著差异；然而，半 Voronoi 沟和全 Voronoi 沟更适合估计 CRB。当考虑劳动力需求时，最有效的方法是螺旋钻取芯法，用于 FRB，而半 Voronoi 沟和全 Voronoi 沟分别是 MRB 和 CRB 的最适合方法。
由于 CRB 加上树桩占地下总生物量的 78%，因此在估计总立根生物量时强烈建议使用全 Voronoi 沟。相反，对于 FRB 估计，建议使用螺旋钻取芯法，并设计考虑细根分布空间变异性的模式。
