Enhancing Habitat & Biodiversity Values of Farm Forestry

Farm forestry is commonly undertaken with multiple-objectives in mind. In fact, numerous studies of participating landholder attitudes have revealed that environmental and aesthetic goals consistently rank higher than commercial ones. Habitat provision/wildlife conservation and farm beautification/personal satisfaction are often highly ranked objectives, with timber and revenue production less so. Small-scale farm forestry participants are commonly more willing to try new and innovative approaches, as they attempt to integrate commercial and environmental objectives – goals that have until recently been considered ‘mutually exclusive’.   There are now a number of scientifically recognized principles to help achieve this integration, via the enhancement of habitat and biodiversity values in tree plantations of any scale. These principles are based on years of research by ecologists into the needs and interactions of native animals and plants in the Australian agricultural context and are described and promoted in a recent RIRDC publication by Salt et al., (2004) entitled ‘Trees and Biodiversity: A guide for Australian farm forestry’.  The principles are grouped into 5 themes and their order of presentation is intended to match the planning process of a farm forestry investment. Improved biodiversity outcomes can be achieved at each step of the operation, however, as the themes are all related and interconnected, a combination of efforts across the themes over time is likely to make more significant additions to a farm’s habitat and biodiversity values. Underlying these themes and principles are two fundamental concepts central to the conservation of biodiversity. These are Habitat Suitability – understanding and meeting the basic needs of particular target native animals and plants, and Non-Replaceability – our inability to truly replace natural ecosystems such as patches of remnant native vegetation.  The themes and principles include: 

Location: relates to where to situate a planting and involves the principles of adjacency, connectivity, landscape context and protection of waterways. If remnant vegetation or riparian zones exist on site, a planting could be designed to seal the edges, expand the area, or connect it to other significant native vegetation features in the surrounding landscape.  

 Configuration: relates to the principles of the size and shape of plantings. Larger plantings may provide more resources for wildlife, and shapes that have less edge to area, such as rounded or circular plantings, may provide better habitat than long, thin plantings. For windbreaks and shelterbelts, at least 5 rows is considered a good start.  

Composition: relates to the species being planted. Native species are superior to exotics for the provision and enhancement of habitat and biodiversity values. Mixed-species plantings are considered more likely to provide the habitat requirements of a wider range of animal species, and local species are preferable as they poses the features to which local animals are adapted, and have less chance of creating weed or ‘genetic pollution’ issues. Particular attention should be paid to correct site : species matching, as there may also be production benefits via potential complementarities, where mixed species can make more efficient use of the site resources.  

 A variety of appropriate local species and different life-forms and foliage types can all enhance habitat and biodiversity values

Complexity: is about variety in a planting, and involves the principles of structural complexity, time and age of a planting, and patchiness. Habitat and biodiversity values can be enhanced via the inclusion of vegetation layers (groundcovers, climbers, shrubs, mid and upper canopy); different foliage types and densities; and structures such as logs, rocks, large living hollow bearing trees, remnant vegetation patches, standing dead trees and nest boxes. Integrating dams, firebreaks or other clearings into a planting, staging plantings over several years, permanent retention of some plantation trees to create ‘old growth’ elements, and creating decadence in some living trees can all help to create a patchy, or variable, landscape over space and time. 

Incorporating coarse woody debris,

Ecological Management: involves the principles of monitoring biodiversity, adaptive management, simulating natural disturbance and variability in management actions. It is important to make an effort to record changes to biodiversity over time, to review what is and isn’t working, and change your practices accordingly via a ‘learning by doing’ process. Attempting to understand and mimic the natural forest processes and disturbances relevant to a particular style of planting is likely to produce the most sustainable outcomes. Variety in management is a form of ‘risk-spreading’ – it creates different opportunities for different species by avoiding applying the same management actions in the same way all the time. Timing, method and intensity of activities such as thinning, pruning, harvesting and weed control could be considered here.  

In addition to planting, managing some areas for natural regeneration, as above, can enhance biodiversity values.

Growers seeking to create or improve the environmental outcomes of a farm forestry planting should consider the above themes and principles at the planning or post-implementation stage. Essentially, in order to create or enhance native habitat and biodiversity values in a farm forestry planting, a grower should be thinking of the concept of ‘bio-mimicry’ - ways of making the planting more closely achieve the natural attributes and appearance of an intact native forest. Finally, it is important to recognize that there is no singular answer or approach for enhancing habitat and biodiversity values, with the site specific nature of the aims and context of any particular planting determining which factors can or should be adopted.      J. Meadows, April 2005.   

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