Forest Management

Forest Management and White Cypress Silviculture

 

The supply of white cypress sawlogs to the cypress sawmilling industry from State forests and Crown timbered lands is the responsibility of State Forests of NSW.  Forest management practices delivered by Forests NSW are aimed at managing the whole forest system to achieve a variety of outcomes including:

-     The maintenance of healthy and dynamic forests, with minimal
  soil erosion;

-     To provide a sustainable supply of forest products;

-     To ensure the conservation of flora fauna and soils;

-     To provide for a range of cultural, recreational and
  educational pursuits.

The primary means of achieving these objectives are through:

-     Implementation of silvicultural practices
  (through non-commercial thinning and commercial harvesting);

-     Fire management;

-     Domestic grazing;

-     Weed/pest control;

-     Infrastructure such as visitor facilities, fencing, dams,
   roads and trails.

Silvicultural intervention aims to improve timber productivity while maintaining a  functioning forest ecosystems that promotes a diverse vegetation structure and allows for specific habitat requirements. 

Cypress silvicultural objectives that promote a healthy forest ecosystems and future timber production include:

a)      promoting regeneration

b)     encouraging the growth of selected trees by reducing the number of trees per hectare by culling trees with poor form and growth potential

White Cypress (Callitris glaucophylla) has a number of characteristics which sets it apart from other commercially important Australian timber species.  These include;

Ø       Given suitable climatic conditions, it regenerates prolifically from
    seed and stocking rates of many thousands per hectare are the norm;

Ø       It is fire sensitive;

Ø       It is a competition tolerant species which will regenerate under
    the forest canopy.

The species regeneration capacity and tolerance can lead the development of extremely dense stands in which growth virtually ceases but individual tree mortality does not occur.  This condition is known as "lock up" and such stands will not produce commercial timber nor develop into a healthy stand with diverse understorey.

State Forests of NSW has undertaken research to develop silvicultural practices to optimise both yields and size of sawlogs produced from Cypress forests.  To optimise timber production and maintain a healthy functioning forest ecosystem requires;

-   Non-commercial thinning of regeneration to a predetermined stocking rate to minimise competition and avoid "lock up"

-   one or more commercial thinnings to further optimise the growth on retained stems and to create an open canopy to encourage the next wave of regeneration

-   once regeneration is well established a commercial harvest to release the young regeneration from competition from the mature trees.

The stylised diagram portrays this nominal silviculture for a stand of White Cypress.

This approach should be interpreted for each stand and having regard to the overall objectives of forest management.  In many of the western forests White cypress is often not the sole tree species making up the forest, and there may be a range of circumstances requiring harvesting to be limited, excluded or modified.

 

For example:

-          Tree retention for stand structure and condition, specific ecological considerations (eg koala presence, "old grey"), and "seed tree" retention.

-          Forest management can be used to target specific ecosystem outcomes.   An example may be the generation and maintenance of a more open grassy understorey to favour a particular suite of species to address problems such as woodland bird decline.

-          A stand that is not in nominal condition (perhaps due to environmental circumstances or past management actions), or lacks adequate regeneration, may need specific silvicultural treatment.

 

Grazing, fire management and control of pests and weeds are other key tools in Cypress forest management.  Domestic and natural grazing is monitored to limit impact on cypress regeneration and other understorey plants.  Control of rabbits and noxious weeds contribute to a healthy forest system.  Fuel management through burning is generally not favoured as white cypress is fire sensitive but may be used where specific environmental diversity or habitat outcomes cannot be achieved by other means.

 

A number of studies have confirmed that the cypress silviculture can deliver ecological and timber outcomes. For example, cypress harvesting in the Pilliga was shown to not disadvantage the Pilliga koala population. Non-commercial thinning dense cypress regeneration generated a substantial biodiversity response at Western Plains Zoo.