Our hypothesis that there would be a reduction in the total soil carbon pool that was directly proportional to the aboveground tree biomass killed was not supported. The gradient of change in live aboveground biomass created in this study: +6% (C), to -6% (NO), to -32% (O50), to -78% (OG), to -100% (ALL) may be indicative of a progression of sudden oak death on the oak girdled plots. Following the initial girdling during the summer of 2008, we found a rapid decline in respiration rate (approximately 50%) on the OG and ALL plots (Levy-Varon et al. 2011). This finding was comparable to reported values for fully girdled plots in other studies (Hogberg et al. 2001; Högberg et al. 2009; Olsson et al. 2005; Subke et al. 2004). A buffered soil respiration response along with almost double the survival rate on the O50 plots Quercus compared to OG plots suggested a possible threshold effect for this type of disturbance et al. 2011). This threshold effect is not evident in differences of soil carbon storage in the second year after the mimicked attack. The most notable shifts in the proportion of SOC found at each depth interval was observed in the ALL plot (Fig. 4.5) but neither the degree of canopy loss nor the specific genus targeted (Quercus vs other) show strong trends for a reduction in the overall soil carbon pool in the treatment plots. This provides the first estimate for a soil carbon budget at Black Rock Forest. Based on the three control plots, an average of 3.0 ± 0.5 kg C m-2 was found in the upper 30cm of the soil profile (including litter). This is lower than the national average of 5.6 kg C m-2 for southern New York (Kern 1994). The lower SOC is likely a result of our field site being situated on a slope that has shallow, nutrient poor, and very rocky soils. The slope increases erosion and the thin nutrient poor soils make this site less than optimal for tree growth. Unlike nearby regions such as the Catskills NY, the hard basement bedrock of granite and gneiss also reduces the probability of carbon being brought into this system via groundwater. Reductions in forest
Our hypothesis that there would be a reduction in the total soil carbon pool that was directly proportional to the aboveground tree biomass killed was not supported. The gradient of change in live aboveground biomass created in this study: +6% (C), to -6% (NO), to -32% (O50), to -78% (OG), to -100% (ALL) may be indicative of a progression of sudden oak death on the oak girdled plots. Following the initial girdling during the summer of 2008, we found a rapid decline in respiration rate (approximately 50%) on the OG and ALL plots (Levy-Varon et al. 2011). This finding was comparable to reported values for fully girdled plots in other studies (Hogberg et al. 2001; Högberg et al. 2009; Olsson et al. 2005; Subke et al. 2004). A buffered soil respiration response along with almost double the Quercus survival rate on the O50 plots compared to OG plots suggested a possible threshold effect for this type of disturbance et al. 2011). This threshold effect is not evident in differences of soil carbon storage in the second year after the mimicked attack. The most notable shifts in the proportion of SOC found at each depth interval was observed in the ALL plot (Fig. 4.5) but neither the degree of canopy loss nor the specific genus targeted (Quercus vs other) show strong trends for a reduction in the overall soil carbon pool in the treatment plots. This provides the first estimate for a soil carbon budget at Black Rock Forest. Based on the three control plots, an average of 3.0 ± 0.5 kg C m-2 was found in the upper 30cm of the soil profile (including litter). This is lower than the national average of 5.6 kg C m-2 for southern New York (Kern 1994). The lower SOC is likely a result of our field site being situated on a slope that has shallow, nutrient poor, and very rocky soils. The slope increases erosion and the thin nutrient poor soils make this site less than optimal for tree growth. Unlike nearby regions such as the Catskills NY, the hard basement bedrock of granite and gneiss also reduces the probability of carbon being brought into this system via groundwater. Reductions in forest