The use of motorized vehicles is OPTIONAL and MAY be allowed by the property owner. Futher, participating in this program  REQUIRES the public accessible lands are open for a varitey of activities including hunting.  Notice I said "public", not "members in good standing". 

http://dnr.wi.gov/forestry/ftax/mfl.htm

Obligations

• Submit management plan
  Note: Beginning November 1, 2005, all MFL management plans must be prepared either by a certified plan writer or a DNR Forester.
• Follow management plan
• Pay annual tax on land as follows:

  Year Entered	Open	Closed
  1987 - 2004	$0.83	$1.95
  2005 and later	$1.46	$7.28

• On open land, permit public access for hunting, fishing, cross-country skiing, sight-seeing, and hiking.
• Adopt sound management practices
• Submit cutting notice before harvesting; unauthorized cutting is subject to a maximum of $1,000 fine
• Submit cutting report after harvesting
• Report accurate volumes of timber harvested
• Pay yield tax based on current rates at time of harvest
  Note: For most MFL lands enrolled under the law in 2005 and thereafter, no yield tax will be assessed on timber harvested during the first five years the lands are enrolled. However, a yield tax will be assessed, regardless of when the timber is harvested, on the following MFL lands enrolled under the law in 2005 and thereafter: those converted from FCL; those renewed into MFL at the end of the original FCL order period; those renewed into MFL at the end of the original MFL order period; and those that are the result of pre 2005 MFL lands being withdrawn and redesignated because additions are no longer allowed to pre 2005 orders.
• Apply post-harvest treatment
• Permit field inspections

http://dnr.wi.gov/forestry/ftax/FAQ3.htm

Are the Forest Tax Lands "open" for public access?

Some of the land under forest tax laws is open for public access. Each law has different public access provisions.

All Forest Crop Law (FCL) lands are open to the public for hunting and fishing. For any other uses, landowner permission is required.

Under the Managed Forest Law (MFL), landowners have the right to keep some lands closed to public access. Lands that remain open to public access are available for hunting, fishing, cross-country skiing, hiking and sightseeing. The law is specific about these permitted activities. Some activities not permitted under the law include motorized vehicles, permanent tree stands, picking berries or mushrooms, and trapping. The landowner may allow these activities but without permission you may be violating trespass laws.

Keep in mind, these are private lands. You should always respect the landowner's rights and wishes. Use good hunter ethics. Hunters don't have to obtain permission to use "open" tax law lands but should be courteous and considerate of the landowner. By building a relationship with the property owner chances are you'll enjoy your hunting experience. In many cases open lands are a part of a larger property. Landowners may prefer to direct hunters safely across their property to "open" lands.