Shannon

Shannon National Park near Manjimup in WA's Southern Forests protects 53,500 hectares of magnificent karri, jarrah, and marri forest in the high-rainfall southwest. The park centres on the Shannon River, which flows through old-growth forest in a valley that escaped the intensive timber harvesting that depleted much of the surrounding forest. The Great Forest Trees Drive — a 48 km self-guided drive through the forest — provides access to some of WA's most magnificent trees. The park also protects heathland, wetlands, and coastal forest types, making it one of the most ecologically diverse parks in the southern forests region. The Bibbulmun Track passes through the park, and the Shannon Campsite is one of the trail's most popular overnight stops.

Shannon's tall forest supports exceptional forest-dependent wildlife. Western ringtail possums — threatened and largely dependent on peppermint and karri — are present throughout the forest. The forest red-tailed black cockatoo (Calyptorhynchus banksii naso) nests in old-growth marri, while baudin's black cockatoos feed on karri and marri seeds. Powerful owls hunt through the tall forest at night. The chuditch (western quoll) is present in suitable forest habitats. Tiger snakes — common and venomous — inhabit the wetland margins. The Shannon River supports freshwater fish including southern pygmy perch and western minnow, plus marron (freshwater crayfish). Over 100 bird species have been recorded.

The park protects outstanding examples of southwest forest diversity. Karri (Eucalyptus diversicolor) forests on the wet valley floors contain trees 60–80 metres tall. Marri (Corymbia calophylla) and jarrah (Eucalyptus marginata) cover drier slopes and ridges. Peppermint (Agonis flexuosa) forms dense coastal-style woodland in some sections. The understorey features zamia palms, various ferns, native orchids, and a spring flower display from August through November. The Shannon wetlands and coastal heath zones protect plant communities quite different from the tall forest, adding to the park's exceptional botanical diversity.

Shannon National Park sits in the Leeuwin Block and southern Yilgarn Craton transition zone. Archaean granites and Proterozoic metamorphic rocks underlie the park, deeply weathered under the high rainfall. The Shannon River has carved its valley through these ancient rocks, exposing fresh granitic rock in the river channel. The valley floor accumulates alluvial deposits from periodic floods. The soils transition from the relatively fertile red earths that support karri to the more typical lateritic soils of the broader jarrah forest.

Manjimup receives approximately 900–1,000 mm annual rainfall — the higher end for WA's mainland. Winters are cool, wet, and foggy, with the moisture-laden atmosphere creating the conditions that support the tall forest. Summers are warm (20–27°C) and relatively dry. Spring wildflowers from August through November are rewarding in the heathland sections. The park is accessible year-round but forest tracks can be wet and slippery in winter.

Shannon is within the traditional country of Bibbulmun Noongar people. The tall forest provided timber, food, and shelter for Noongar people for thousands of years. European timber harvesting reached the Shannon valley in the early 20th century. The Shannon Timber Company operated here from the 1940s until the mill closed in 1968. The decommissioned timber mill site is now the Shannon Campsite.

Shannon National Park was created from the former Shannon Timber Company's forest lease after the mill closure. The transition from working timber forest to national park reflects the broader shift in forest management policy that characterised the late 20th century in WA. The Great Forest Trees Drive was developed to provide access to magnificent forest sections.

The Great Forest Trees Drive (48 km) winds through magnificent forest with interpretive stops at large trees and ecological features. The Shannon Campsite — a popular Bibbulmun Track destination — provides camping in old-growth forest. Walking trails through karri forest. Spring wildflowers August–November in the heathland sections. Fishing for marron in the Shannon River (seasonal).

The park is approximately 50 km south of Manjimup, accessible via South Western Highway. The Shannon Campsite has toilets and basic facilities. Manjimup and Pemberton provide accommodation and services. Parks entry fees may apply. Best visited August–November for wildflowers and spring weather.

Phytophthora cinnamomi dieback is a primary threat to the Proteaceae-rich understorey. Western ringtail possum habitat management requires predator control. Fire management in the tall forest is increasingly challenging with climate change-driven conditions. The park's connectivity to adjacent forest reserves is vital for wildlife populations.