The acorns have been arriving at the Kane County Forest Preserve offices since naturalists put out word of the need.
Instead of leaving acorns for the squirrels, local oak tree owners brought them in bags, buckets and bushels. Most are – dutifully – identified by species as red, white, burr, pin, scarlet, white swamp or black, said Ben Haberthur, restoration ecologist with the forest preserve.
The purpose of the acorn collection is to counter the decline of oak trees by propagating new ones from the donated acorns, Haberthur said.
“Regionally, they are declining,” Haberthur said. “An effort has started through Chicago Wilderness to do the mapping [of oak forests] to see how much we’ve lost. … We are not waiting to see the results. We know we have lost them and need to get these oak woodlands back.”
The problem is a lack of oak regeneration, he said.
When oaks drop their acorns, the ones that sprout have a chance of becoming mature trees in oak woodlands. Acorn sprouts are being eaten by deer populations before they have a chance to get big.
“We are seeing the last generation of oaks,” Haberthur said. “There are no baby oaks on the ground.”
The forest preserve district is collecting the acorns at its main office on the top floor of the Fox Valley Ice Arena, 1996 S. Kirk Road, Geneva, until Oct. 12. Donors should identify the type of oak – if they don’t know, they can include a leaf or piece of bark – and the location or address of where the tree is.
Acorns are being sorted, cleaned and dried at the district’s natural resources shop in the Aurora West Forest Preserve in Sugar Grove. They will be stored on a bed of soil in refrigerators and then planted at the facility so they can grow into 2- to 3-year-old trees.
From there, they will be transplanted into woodlands and savannas where they will become the next generation of oaks, Haberthur said.
“We will have to take precautions to stop deer from nipping and preventing the oaks from growing,” he said.
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Preserving oak woodlands is supported by science, Haberthur said.
“Oaks are the most majestic tree native to our area,” he said. “All are a great food source for animals, and they shelter those same animals. They are refuges for bird species, opossums and raccoons.”
It’s important for naturalists to know the species because each type of oak has specific growing needs. A swamp oak, for example, “likes to have its feet wet,” Haberthur said, so it needs to be planted in hydric or wet soil.
Burr oaks are a savanna species that do well in open landscape. Red and white oaks are likely to be in the center of a stand of oaks, with a burr oak on the edge. The black oak prefers drier soil and commonly grows at the top of little hills.
“Oaks can live hundreds of years,” Haberthur said. “What is really amazing is that even after an oak tree falls over, it takes another century – another 100 years – for that tree to provide habitat for insects and small animals before it turns its nutrients back to the earth.”
Oak woodlands are part of the natural heritage of Illinois, prompting Chicago Wilderness to map them in a four-state region. The nonprofit is pioneering a regional, collaborative approach to conservation.
The group recently received a $190,000 grant from the National Forest Service Northeastern Area to map oak woodlands in 18 counties across Illinois – including Kane County – Wisconsin, Indiana and Michigan to measure the loss.
Restoration & Green Infrastructure Coordinator Chris Mulvaney said as many as 90 percent of oaks in McHenry County had been documented in 2005 as lost.
“They are basically following what McHenry County did, taking old maps from the 1800s and find out where there were blocks of forest and woodland,” Mulvaney said. “And then they’re using aerial maps from 1939 when they first started doing aerial photos of the ground. It gives an indication of the broad level of land cover that we have lost over time.”
Mulvaney said the project will tell naturalists how much is left and where it is.
“Given that oaks are so important for wildlife and biodiversity, it will show the scale of the problem,” Mulvaney said. “The results will feed into another part of the project, which is to develop an oak recovery plan, a strategy and plan to reintroduce oaks across the region.”