Saturday, March 1, 2014

Can Exotic Norfolk Island Pines be Beneficial ?‏

Osprey Nest in a Norfolk Island Pine
Various coastal communities and parks may remove, kill or ban the planting of Norfolk Island Pine (NIP). This is due to their being non-native, because of the potential hazard in storm-prone areas, and to results of the hard freeze of 1989 in more northern areas, when a number of Norfolk Island pines died. 

In response I offer my personal experience from SW FL. I live on Manasota Key in Englewood, FL, in Charlotte County, just north of Punta Gorda through which hurricane Charlie passed on Aug. 13, 2004. It was a very narrow but strong storm and caused the loss of many trees including Australian pines. To my knowledge few NIP were blown down! Instead, perhaps due to their conical shape (largest at the bottom and rather pointed at the top) and strong trunk and roots the trees survived. Many of the branches were wrenched off but they re-grew due to trunk sprouting. A report on tree damage caused by hurricane Charlie on Sanibel Island provides a remarkable photo of a NIP trunk with no branches left. Although the report recommends against planting of NIP, they provide no evidence of tree fall. 

Eagle's Nest in NIP: S. Manasota Key
We have a tall NIP immediately over our house built in the mid 50's and I have never lost a minutes sleep worrying about the tree coming down. This tree does produce cones almost every year and the fertile seeds do produce seedlings, which are however very easy to pull up. Apparently this reproduction is somewhat unusual. 

As a retired biologist I spend a lot of time studying how to improve wildlife habitat under the conditions imposed by human occupation of the landscape. Norfolk Island pines are ideal for providing nesting habitat for ospreys and eagles along the S FL coasts where humans dominate the ground level of the habitat. So if you want raptors to nest you must provide tall trees. If you dogmatically eliminate exotic trees such as these Norfolk Island pines which are ideal nesting habitat, you will have few if any nesting raptors since there are not any native trees which will survive and grow to a sufficient height within a reasonable time frame to serve this purpose. Data are scarce but it may take slash pines in this area more than 100 years to reach a size adequate for eagle nests. These tall Norfolk Island pines also provide useful habitat for other birds and animals, they grow fast, and they occupy a small ground footprint relative to their height. I would not recommend "topping" them since the regrowth may overbalance the tree and provide an area of weakness when exposed to strong winds. 

Norfolk Island Pine with Osprey Nest, Manasota Key
I suggest that the rigid dogma of "evil exotics" be replaced by a more pragmatic and wildlife-friendly philosophy which in specific instances uses exotics IF they provide more benefits than problems. Every plant, both native and exotic, should be carefully evaluated for its advantages for wildlife before planting or removal. For example, the killing of Australian pines within Stump Pass State Park caused a nesting eagle pair to leave and re- nest in a Norfolk Isl pine in a private yard just outside the park, where the homeowner subsequently cut the tree down because of the nuisance of people coming to watch the eagles! 

Bill Dunson

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