Storms Could Benefit Forest Biodiversity
Thursday, December 6, 2012 • 6:20pm
After more than three centuries of repeated cutting for timber, firewood, charcoal and conversion to rocky pastures, the forests in New Jersey’s Highlands might get more interesting after the triple-whammy of Hurricane Irene, the 2011 Halloween snowstorm and Superstorm Sandy.
Healthy, large trees have fallen at unprecedented rates in the last two years, each time from a different cause.
Irene turned wetland and floodplain soils to pudding, toppling trees with rampaging floodwaters. The Halloween snowstorm caused huge branches and trunks to split and crack high above ground, creating broken-off “snags.” Sandy pulverized exposed eastern slopes and hilltops with fierce gusts, uprooting trees.
You may think that messy-looking forests need to be cleaned up. But, according to New Jersey Conservation Foundation ecologist Dr. Emile DeVito, this type of devastation has happened a thousand times before in the eastern deciduous forest and can actually be beneficial.
For millennia, Dr. DeVito tells us, natural calamities trigger an ecological process known as “gap-phase succession,” causing an explosion of biodiversity as plants seedlings and saplings compete for light and space.
Today’s forests, which re-grew after being flattened by colonial saws, plows, and oxen, have a chance to regain their natural, undulating micro-topography.
Huge logs and root masses in tangled heaps can support a multitude of animals, plants and fungi. Yellow birch seedlings, wood-boring beetles, pileated woodpeckers, slimy salamanders and many more species will thrive in the newly-disturbed forests.
Light streaming through new gaps in the forest canopy will allow young saplings to rocket skyward and forest shrubs to flower and set seed. Amphibians and invertebrates will breed in temporary ponds created under massive, tipped-up root systems.
Understory bird species will increase if the new forest gaps fill with native leafy plants, insects, flowers, pollinators, and berries. Wood thrushes will lead their fledglings to these sunny gaps, where caterpillars and beetles are abundant. Whip-poor-wills will hunt moths in the moonlight, as the unsuspecting moths fly along chemical trails toward their mates. A Ruffed Grouse may drum on a log, proclaiming a nesting territory within thickets of succulent new growth.
But this picture of a thriving, renewed forest isn’t guaranteed.
The triple threats of over-abundant deer that eat native shrubs and seedlings, “seed banks” of alien invasive plants, and pH-raising invasive earthworms that have depleted the carbon-rich forest humus could foil the natural process that has renewed our native biodiversity since the Ice Age.
If too many deer accumulate in the new gaps and eat emerging native plants, invasive species like stiltgrass, wineberry, bittersweet, barberry and knotweed will win the race for sunlight, water, and nutrients. Invasive plants don’t support a food chain; native insects ignore them as if they were made of nylon. If the gaps in the forest canopy fill with invasives, native biodiversity and the forest itself will likely dissolve into a pile of weeds.
But there are things we can do to tip the balance to favor our native species. One would be to judiciously apply controlled fires - difficult when natural areas are in proximity to suburbia.
Leaving the tangles of fallen logs, tip-up mounds and branches in place will protect some native saplings from being munched by deer. Hopefully, large crops of native plant seeds were dispersed by wind or animals into incipient gaps, to spark a new generation of native forest understory.
Another critically-important action would be for Governor Christie to re-convene the Invasive Species Council and direct them to implement our state’s Invasive Species Plan.
The most critical action would be to seriously reduce deer density in our Highlands forests. Several challenges currently are preventing this from happening. The state has set hunting rules to keep deer density constant in heavily forested zones. In addition, for over 100 years laws have barred deer from having a commodity value, for fear of a black market. Reversing outdated regulations could make the hunting and butchering of deer affordable, and encourage more hunters.
The recent storms have created an opportunity for forest regeneration and an explosion of native biodiversity; the time is now to take actions to foster forest resiliency.
For more information about preserving New Jersey’s land and natural resources, visit the New Jersey Conservation Foundation website at www.njconservation.org or contact me at firstname.lastname@example.org.