Soil Carbon Fractions and Plant Biomass At Busby Forest.

Forests play an important role in the global carbon cycle since it sequesters carbon that can help offset emissions. Therefore, it is important to assess how much carbon our forests are storing in both soil and trees and how these carbon sinks relate. We inventoried four hundred twenty seven trees belonging to twenty three species at Busby Forest of Lincoln University. We tagged each tree, measured its diameter at breast (DBH) and calculated the corresponding total above ground biomass (TAGB), stem biomass (StemBio), foliage biomass (FolBio), branch biomass (BranchBio) and root biomass (RTB) with allometric equations found in the North America Carbon Project database.  We collected soil samples at 250 locations and measured total carbon (TC) and total nitrogen (TN). Using previous data on total carbon (TC) and its fractions, we developed linear equations relating TC to hydrolyzable carbon (HC), non hydrolyzable carbon (NHC), cold water extractable carbon (CWC) and hot water extractable carbon (HWC). These linear equations were later used to calculate HC, NHC, CWC and HWC at 250 locations where TC and TN were measured, but not these fractions.  Finally, we conducted a Pearson correlation analysis between TC, HC, CWC, HWC, NHC, TN and plant biomass. Results showed that TC was significantly correlated with DBH (p =0.0176, r = 0.15) and FolBio (p=0.0280, r=0.14).  TN was significantly correlated with DBH (p= 0.05, r = 0.12), FolBio(p= 0.01, r =0.15), StemBio (p=0.04, r=0.13), TAGB (p= 0.04, r = 0.12), RTB (p= 0.04, r = 0.12). Carbon fractions could not correlate with branch biomass.  Further studies will be conducted to better understand carbon storage and its relationship with plant biomass at Busby forest.