The hill area on which the Monterey pines are planted has a soil warning of “filled/weak ground”.
So what could happen to the “filled/weak ground” if the Western Springs pines are clear-felled as proposed?
According to a pine industry expert on clear-felled slopes, the roots of pinus radiata hold the soil for the first year after harvest, but then quickly rot. Between year two and year six the resulting slopes are highly vulnerable. Foresters typically replant a new crop of radiata seedlings within a year of harvest, but these do nothing to hold the soil for the first couple of years. By year three to four, their roots are getting established, and by year five to six, they are doing a pretty good job.
However, clear-felling has a second effect on the soil. While a canopy of mature forest intercepts about a third of rainfall rather than reaching the ground, clear-felling removes that protection. Result: the soil is wetter and more prone to slips in heavy rain, this triggers a process that, through time, makes the slope more vulnerable if a severe storm comes along.
On flatter land, such risks are minimal. However, Western Springs is on steep land, what Crown research institute Scion calls “erodible steep land terrain”. That is, Western Springs forest is on land which, once cleared, is liable to shed mud and debris flows during storms. Council’s proposal for the Western Springs forest is to plant slow -growing natives. So the window of vulnerability will be much greater than six years.
The Chair of the Waitemata Local Board has made an unsubstantiated claim that if the Western Springs forest is not clear-felled, the forest path would be unsafe to use for 50 years.
In a well-managed forest, trees progress through their life cycles and sometimes fail - that is natural and normal. In the last Category two storm there were a large number of very large and extremely valuable park trees in Western Springs Park which fell over. Yet no one is suggesting that we need to clear-fell the rest of the park trees in Western Springs Park in case they fall down.
Some of the trees in the forest that are predisposed to failure will fail during high wind events. It's the wind that will cause these failures. The trees are extremely unlikely to fail when it's not extremely windy. They are normally safe and sound. Otherwise they would fail on a normal day. And that doesn't tend to happen.
To condemn them all will not only be unnecessary, it will destablise the steep slope, destroy soil structure and cause harmful run-off into Motions Creek. Clear felling will also destroy up to 70% of the currently regenerating native bush which contains maturing pururi, rimu, totara, kanuka and many species and significant specimens of mature ferns.
The solution is clear. Each tree with a recognised predisposition to failure that can fall or fail onto a target (track or house), can be managed: felled, pruned or strengthened - or the target moved. The track can be made safe and leave the rest of the trees to live out their lives - that could be many more years.
The money that would be spent on this 'large' clear-felling project could instead be used to appoint a skilled forester to manage the forest over a period of years to see out the pines and caretake the conversion of the forest to a native forest - a vision that we all share.
At present, council is moving ahead with obtaining consent for their clear-felling plan without 'consultation'. Residents have been shut out of the process, having to rely on 2016 documents that have been superseded by a 400-page report that is not being circulated to all stakeholders.
Residents will have 10-20 days to make a submission, but only if they can find out when the resource consent is lodged. Residents understand they are not entitled to be informed by council when the application is lodged.
Why the secrecy? Why this refusal to cooperate with residents? We all share the vision of a mixed podocarp forest in our ‘hood’. We want to work with council to achieve this. We call on Waitemata Local Board and council to trust in, and work with its ratepayer residents! We are looking for volunteers and supporters with an interest in tree preservation. Please email me. (WENDY GRAY)