Environmental Reporting, Ministry for the Environment and Statistics New Zealand
"The rates of death (mortality) of indigenous tree species vary across New Zealand. Changes in the state of the environment (such as from browsing pests, large-scale weather events, or climate change) may change the rates of mortality of particular tree species. This in turn may alter forest processes. Repeated surveys of the distribution of mortality rates can alert us to impacts on our indigenous forests.
This data set relates to the ""Distribution of indigenous trees"" measure on the Environmental Indicators, Te taiao Aotearoa website."
Source: Department of Conservation
Method: "This information comes from 874 survey plots (20m x 20m) distributed across forests on both public conservation land and private land around New Zealand. Each of these plots was first surveyed between 2002 and 2007. All trees with trunk diameters greater than or equal to 2.5cm when measured at 1.35m height (called ‘diameter at breast height’ or DBH) were tagged and identified. The same plots were resurveyed between 2009 and 2014. Any trees present in the first survey but missing from the second were recorded as dead. Any trees that died between surveys were also recorded as dead. Any trees not recorded in the first survey but recorded in the second as having a trunk greater than or equal to 2.5cm DBH were recorded as newly established trees.
Statistical analyses were carried out to assess whether there were spatial patterns in the data and whether these patterns were associated with major environmental gradients, such as latitude and/or modelled soil moisture."