Question: The protected national park located in the undefined region in the north of the state of New South Wales, Australia preserves significant plant and animal populations found in what forests? 

Context paragraphs:
Mount Nothofagus National Park: The Mount Nothofagus National Park is a protected national park located in the Northern Rivers region of New South Wales, Australia.  The 2180 ha park is located approximately 634 km north of Sydney and can be located via Kyogle via the Bruxner Highway and the Summerland Way.

Washpool National Park: The Washpool National Park is a protected national park located in the New England region of New South Wales, Australia.  The 58678 ha park is situated approximately 520 km north of Sydney, inland from Grafton .  The park has two campgrounds and is managed by the NSW National Parks & Wildlife Service.  It was established in 1983 to preserve the significant plant and animal populations found in the Washpool and Gibraltar Range forests.

Willi Willi National Park: The Willi Willi National Park is a protected national park located on the North Coast region of New South Wales, Australia.  Gazetted in 1996, the 29870 ha park is situated 325 km northeast of Sydney and 60 km west of Wauchope .

Oxley Wild Rivers National Park: The Oxley Wild Rivers National Park is a protected national park that is located in the Northern Tablelands region of New South Wales, Australia.  The 145223 ha park is situated 445 km north of Sydney and is named in memory of the Australian explorer John Oxley, who passed through the area in 1818 and is one of the largest national parks in New South Wales.

Bouddi National Park: The Bouddi National Park is a protected national park that is located in the Central Coast region of New South Wales, in eastern Australia.  The 1532 ha national park is situated 46 km northeast of Sydney.  A section of the national park extends into the Tasman Sea, creating fully protected land, shore and marine habitats.  The park contains one of the last temperate rainforests on the Central Coast, Fletchers Glen.

Mount Clunie National Park: The Mount Clunie National Park is a protected national park that is located in the Northern Rivers region of New South Wales, Australia.  The 1426 ha park is situated approximately 631 km north of Sydney and can be located via Kyogle via the Bruxner Highway and the Summerland Way.  The park's north-eastern limits define the state border between New South Wales and Queensland.

Culgoa National Park: The Culgoa National Park is a protected national park that is located in the north-west region of New South Wales, in eastern Australia.  The 35239 ha national park is located approximately 660 km northwest of Sydney.  The nearest town is Brewarrina , 120 km away.  The park's northern boundary is defined by part of the state border between New South Wales and Queensland.

Mallanganee National Park: The Mallanganee National Park is a protected national park located in the Northern Rivers region of New South Wales, Australia.  The 1144 ha park is located approximately 570 km north of Sydney and can be located via Kyogle via the Bruxner Highway and the Summerland Way.

New England (New South Wales): New England or New England North West is the name given to a generally undefined region in the north of the state of New South Wales, Australia about 60 kilometres (37 miles) inland, that includes the Northern Tablelands (or New England Tablelands) and the North West Slopes regions.

New England National Park: The New England National Park is a protected national park located on the Northern Tablelands in the New England region of New South Wales, Australia.  The 67303 ha park was created in May 1935 and is situated approximately 560 km north of Sydney, and 10 km south of Waterfall Way, just 85 km east of Armidale and 65 km west of Coffs Harbour.  The closest village to New England National Park is Ebor, located 20 km away.

Supporting paragraphs: Washpool National Park New England (New South Wales)
Answer: Washpool and Gibraltar Range forests