Description & Significance

The Brokken property contains a large remnant of fire-dependent oak woodland. Large white, red, and bur oaks, along with scattered white pines, are the dominant canopy trees.  These oaks show evidence that their early growth was under a less dense canopy as their lower limbs have been lost to shading, leaving stubs and scars from the lost limbs.  Additionally, an understory of young  ironwood, basswood, and other small trees has developed. 

The ground layer in many areas is rich in sedges and woodland grasses. 

While prairie and savanna communities have received most of TPE’s attention, oak woodlands also need attention.  The opportunity here is to begin reinvigorating a woodland that still has a flourishing canopy and ground layer before these are lost to overcrowding and invasives.  A smaller portion of the property is dominated by sugar maples.  These portions have little in the understory (including few maple seedlings) probably due to heavy deer browsing.

A comprehensive inventory of the flora will be needed.  So far, a number of sedges and woodland grasses have been recorded based on observations made during  October 2025.  This list needs compiling and supplementing with surveys conducted throughout the rest of the growing season. 

Natural History

Much of this site was formerly owned by the Johnson family who used it to pasture cows and horses. Lower fields were once plowed for a hemp crop but soon abandoned due to poor soil quality. The horse pasture was seeded to smooth brome but many native plants, including some threatened species have returned in the brome sod.

The hillsides were only lightly grazed and hold significant populations of prairie savanna.

The Prairie Enthusiasts St. Croix Valley Chapter has been managing portions of this site since 1999. Much of the red cedar and brush that covered the hills has been removed and a controlled burn program has been initiated.

Management goals at the site are to:

• Restore and maintain oak woodland across the majority of the site. Restore and maintain oak savanna on south-central ridge top.
• Eliminate sapling sized European buckthorn across the site.
• Eliminate greater than 50% of Japanese barberry and common hoptree across the site.
• Full survey of extent of oriental bittersweet and start of control program. Eliminate seed producing stems.
• Full survey of extent of crown vetch. Remove small infestations as discovered.
• Starting in the targeted management units: thin out understory fire-intolerant species (including ironwood, basswood, ash, boxelder, others). Remove non-oak, non-white pine canopy trees which are crowding mature oaks.  Move to other management units as available labor permits.
• Near-yearly prescribed dormant season burns in the first two management units, moving further into other areas as available time and labor permits.
• Develop a comprehensive species list.