EPOW - Ecology Picture of the Week

What is a Hoop Pine Worth?

Plantation of Hoop Pine (Araucaria cunninghamii),
Family Araucariaceae
Chambers Park, Queensland, Australia

Explanation:  This part of Chambers Park rainforest in Queensland, Australia, had been logged and planted with a monoculture of hoop pines.  Was it worth it?  What are hoop pines worth?

First, what is a hoop pine?  It is a species of Araucaria, a genus of trees found native to the southern hemisphere.  According to a signboard I encountered in Lamington National Park in Queensland, the genus name Araucaria comes from the name of an indigenous tribe of Chile where the first species of this genus was described (Araucaria cunninghamii, the feature of this week's photos).  The specific epithet (the "species name") of cunninghamii was named after the mid-19th century Australian explorer and botanist Allan Cunningham.

Hoop pines are used for timber and most of their logging comes from plantations such as the one shown here.  

So if the goal is to produce wood, what are the consequences of clearing native rainforests to plant hoop pines in Australia?  Timber plantations can help concentrate wood production to specific sites and greatly increase efficiency of managing and harvesting trees.  Studies have suggested that some monoculture plantations serve better than others for helping protect or provide for other aspects of biological diversity.  For example, Kanowski and others (2005) found that plantations of eucalyptus trees (which are native to Australia) provide poorly for rainforest biodiversity.  

But any plantation can have only minor adverse effects if located within a landscape of native forest, as occurred with this plantation of hoop pines, if the plantation trees are derived locally and not from an exotic genetic source, and if the plantations are managed to eliminate weeds and non-native animals.  Mixed-species plantations, using several species of locally native trees, might serve even better to balance biodiversity conservation with wood production in a rainforest environment.  

But don't overstate the value of plantations for biodiversity; plantations will nearly always be far less diverse than native rainforests and cannot substitute for old, native forest ecosystems.  This is in part because of the absence of non-timber elements in plantations, such as fig trees and other fruit- and seed-bearing trees used by a diversity of wildlife species, and many other more subtle differences in occurrence of fungi, mosses, lichens, invertebrates, and overall forest structure.
  

  
Natural occurrence of hoop pines in Lamington National Park,
southern Queensland, Australia.  This park, in fact, has the largest
protected stand of hoop pine in Australia.
Hoop pines in timber plantations never get this huge!

Kanowski and colleagues found that, compared to native rainforest, hoop pine plantations had only a 52 percent similarity of plant species and 69 percent similarity of bird species.  That is, native rainforests were far more diverse in plants and birds.  This is not surprising but is an important reminder that timber plantations do not replicate or provide for the full array of biodiversity as found in unharvested, native rainforest ecosystems.

Further research is needed to determine optimal mixes of plantations and native rainforests that would serve to maintain the natural biodiversity and also provide for timber and wood production.  

Information:
     Kanowski, J., C. P. Catterall, and G. W. Wardell-Johnson. 2005. Consequences of broadscale timber plantations for biodiversity in cleared rainforest landscapes of tropical and subtropical Australia. Forest Ecology and Management 208(103):359-372.