Belowground Tree Biomass Research Articles

Carbon and nitrogen pools in an old-growth, Norway spruce mixed forest in eastern Finland and changes associated with clear-cutting

The amount of carbon (C) and nitrogen (N) removed in stems after clear-cutting a forest in eastern Finland is compared with ecosystem pools (above- and below-ground tree and understorey vegetation biomass+ organic layer +0–60 cm mineral soil layer) and fluxes before clear-cutting. The tree stand was an old-growth mixed coniferous forest dominated by Norway spruce. The ecosystem pools of C and N before clear-cutting were 175 536 and 2848 kg ha −1, respectively. Most (62%) of the C was in living vegetation, mainly trees (60%), whereas most of the N pool was in the soil (80%). C and N pools in understorey vegetation were small (<2% of ecosystem pools) and those in dead tree compartments were somewhat greater (C: 8%; N: 4%). The annual net uptake (defined as net accumulation in tree biomass+aboveground litterfall) of C by trees was 2013 kg ha −1 and that of N was 16.1 kg ha −1. The annual return to the forest floor as aboveground litterfall was 958 kg ha −1 of C and 12 kg ha −1 of N, corresponding to 48 and 75% of annual net uptake, respectively. During clear-cutting, some 239 m 3 ha −1 of stemwood (overbark) were removed from the site, corresponding to 32% (C) and 3.0% (N) of the pre-harvest ecosystem pools; branches and foliage were left on site. The pool of C in living vegetation was reduced by 89% and that of N by 81% while the C pool in dead vegetation increased fourfold and that of N somewhat less. Our results indicate that clear-cutting will affect the C and N pools and fluxes of forest ecosystems significantly, even though some living trees are left on site.

Integration of remotely sensed radar imagery in modeling and mapping of forest biomass and net primary production

New remote sensing programs provide the opportunity to optimize the connection of remotely sensed data with key parameters in measuring and modeling net primary production (NPP). Synthetic aperture radars (SARs) are discussed in terms of their ability to measure more directly certain parameters related to NPP. The purpose of this paper is to introduce SAR-based methodologies and results for (1) deriving parameters which may be considered input datasets for NPP models and (2) the subsequent application of an aboveground annual NPP (ANNP) model for these datasets. Derivations are land cover and biophysical parameters including forest height, aboveground forest tree biomass (and carbon fraction), and belowground coarse root biomass (and carbon fraction). An allometric ANPP model is applied to demonstrate the applicability of these SAR-derived datasets to NPP modeling. Results are regional quantifications and mapped distributions of forest height, above and belowground tree biomass (and carbon fraction), aboveground ANPP, and the relationship of forest stage to production.

Root biomass of a dry deciduous tropical forest in Mexico

The deciduous tropical dry forest at Chamela (Jalisco, Mexico) occurs in a seasonal climate with eight rainless (November through June) and four wet months (700 mm annual precipitation). The forest reaches a mean height of 10 m. Tree density in the research area was 4700 trees per ha with a basal area at breast height of 23 m2 per ha. The above-and below-ground biomass of trees, shrubs, and lianas was 73.6 Mg ha−1 and 31 Mg ha−1, respectively. A root:shoot biomass ratio of 0.42 was calculated. Nearly two thirds of all roots occur in the 0–20 cm soil layer and 29% of all roots have a diameter of less than 5 mm.