The tree carbon storage of urban forests in Auckland is highly variable as displayed in figure one. The average total carbon storage by trees in urban forest plots overall was 31.21 Kg C/m^2.The range of carbon storage was large with storage ranging between 0.31 to 115.64 Kg C/m^2 as displayed in table 1.
The significantly higher carbon storage in the Auckland domain when compared to all other urban forests surveyed (figure 1) this is likely due the Auckland domain being located on the cone of an extinct volcano. This means the soil type will be much more nutrient rich when compared to other urban forests plots and therefore I hypothesis this will have promoted greater carbon storage in the trees established there. Another contributing factor for the Auckland domain forest displaying over twice the carbon storage of all other urban forests tested is the age of trees.Auckland domain is Auckland’s oldest park and is likely to have many more established older trees. This in turn will allow for greater carbon storage as large trees can store 1000 times more carbon than small trees (Nowak, & Crane, 2002).
Comparison of the urban forest to the native forest in New Zealand show a significant difference with the native forest average found being approximately 16.91 ± 1.84 Kg C/m^2 (Coomes.,2005) , this is much lower than the average found in our study of 31.21 Kg C/m^2. The difference in carbon storage is expected as tree carbon storage is dependent on many variables one of which is extent of urbanization. The differences in urban forests when compared to natural leads to the much higher carbon storage the lower density and much higher rates of large trees with greater access to carbon dioxide allows for the thriving of the carbon storage in urban located trees. We can infer this relationship as this is shown in other studies and in ours but at an insignificant level (T statistic 0.252). The insignificant relationship for distance for the CBD is likely due to Auckland having a relatively high percentage of green space.
The average 31.21 Kg C/m^2 of is relatively high value compared to other studies conducted on urban forest in foreign countries for example the average for...