Introduction

Sowing seeds directly onto prepared ground can be a cheap and effective method for establishing trees and shrubs over large areas. In fact, direct seeding can be up to 10 times cheaper than planting for broadscale revegetation.

The establishment of plants by this method is largely controlled by climatic conditions, soil type and weed competition. These factors have a significant bearing on soil moisture, which is vitally important to germination and early survival of seedlings in the field. Seedlings must be protected from grazing by vermin and livestock until they are beyond browsing height.

Other factors that play an important part in determining the success of the method include:

• correct choice of species, e.g. avoidance of frost-sensitive species on a site prone to severe frosts;
• ground preparation to provide a suitable seedbed;
• use of good quality, viable seed;
• correct seeding rates to ensure the required density of seedlings -- too little will lead to disappointment and too much will necessitate extra work for thinning;
• sowing when soil moisture is favourable for seedling germination and establishment; and
• using the correct sowing procedure so that seed is not buried too deeply.

A willingness to experiment is essential when direct seeding, as no one method will suit all situations.

Introduction

Effects of fire on plants, animals and soils are numerous, complex and important. In Australia most types of natural vegetation have evolved to cope with fire and are largely dependent on and shaped by fire. Effects of fire include:

• overheating and thus killing part or all of the above-ground portions of existing plants,
• combustion of plants and litter with the consequent release of nutrients
• loss of some of these nutrients through volatilisation and leaching
• elimination of some growth-inhibiting chemicals and microorganisms
• preparation of seedbeds suitable for germination and rapid early growth of new plants
• release of seed from standing plants
• stimulation of germination in some species such as Acacia
• removal of competing plants and hence the opportunity for new plants to become established
• better availability of nutrients and water to those plants that survive the fire with little or no damage
• exposure of the soil to erosion
• changes in water infiltration and retention

Fire is usually both beneficial and damaging, the net effect depending on circumstances and aims. This article deals only with direct health hazards - injuries caused by overheating, how to cope with them, and how to prevent them.

Introduction

In many temperate regions, blowing and drifting snow jeopardizes public safety and emergency services, interrupts businesses, and increases livestock and wildlife mortality. Snowplows can keep roads open, but annual costs are often high. When roads are subject to recurring snow blockage, a more permanent, cost-effective solution is often needed.

Structural barriers, commonly made of slated or picket fences, are a proven technique for reducing the impact of blowing and drifting snow. These are placed to interrupt blowing snow. With an action similar to a rock placed in a flowing stream, they cause an eddy effect that alters wind speed and direction, allowing snow to settle out.

However, another kind of snow fence, made of living plant materials such as grasses, shrubs and trees, can also be used and has several advantages over man-made structures. Often called living snow fences, they are actually densely planted windbreaks that have been specifically designed and planted to reduce blowing and drifting snow. Like a structural barrier, they cause blowing snow to settle in a designated area. Living snow fences are more cost-effective than structural barriers and provide a wide array of benefits beyond snow control.

Introduction

The true extent of value-adding is a way of thinking...a process, not just processing.

Every aspect of private forest management should be seen as an opportunity to add value. Often it is suggested that additional returns may be possible through the use of portable sawmills and other processing technologies. For private forestry, adding value should take place long before post-harvest processing - it starts with forest management.

The timber industry has traditionally seen only post-harvest timber processing as constituting value-adding. The sawmilling industry's primary concern has been to access the best of the resource and concentrate on adding value to this raw product through sawing/processing. Instead of inheriting this limited definition of value-adding from the timber industry, private forestry needs to adapt the concept to its area of greatest potential returns and expertise, that is, growing quality timber.

Introduction

A high degree of diversity is common in the Tropics, especially in the humid lowlands. In single-species operations, such as the extensive plantations of Pinus spp., natural diversity is irrelevant. But organizations that service a wide variety of users with diverse needs, and ecosystem restoration projects where nature dictates the species to plant, cannot ignore diversity. Poorly known species and species with difficult reproductive characteristics must be accommodated. With a good understanding of biology and ecology, innovative thinking, and a little luck, most of these new species can be collected and grown. In some cases research can provide answers, but for a few species, and for a variety of reasons, consistent collection and processing of viable seeds may be impossible. In a 14-year study of species suitable for revegetation of bauxite mine lands in Trombetas, Brazil, 600 species were evaluated and 160 were grown and outplanted; only 89 taxa demonstrated acceptable survival and growth during the first two years (Knowles and Parrotta 1995).

Introduction

Understanding the relationship between nutrients in the soil and crop productivity is crucial in achieving and maintaining high levels of agricultural productivity. This understanding is especially important for productivity at the lowest possible costs, both economic and ecological. Soil fertility is not an easy concept to define. For the purposes of this paper, we use the definition of soil fertility presented by Anthony Young (Young 1989), "soil fertility...is the capacity of soil to support the growth of plants, on a sustained basis, under given conditions of climate and other relevant properties of land." Notice that this definition goes beyond the simplistic concept of soil content of available nutrients, and allows for other critical aspects of soil fertility such as physical and biological properties.