Timber plantations

Nutrient cycling in timber plantations in the Amazon has not been studied as much as... 

Homestead agroforestry system provides nearly 50% cash flow to the rural poor (Ahmed 1999). Collectively, homestead agroforestry production system contributes about 70% fruit, 40% vegetable, 70% timber, and 90% firewood and bamboo requirement of Bangladesh (Miah and Ahmed 2003). In addition, the homestead plantations are recognized repositories of non-timber products such as medicinal and aromatic plants, ornamentals, bamboos, khair, lac, honey, cane, murta plants, and grasses. 

Harvesting operations are moving away from virgin forests, and there is an increasing reliance upon plantations as a source of industrial timber, although the development of such plantations is relatively recent. According to the FAO (2001), half of all established plantations are less than 20 years old. It is predicted that future increases in wood demand will be met largely from plantations. 

Fast grown softwood from plantation sources is generally characterized by a high proportion of juvenile wood and often poorly developed heartwood. A fast rate of growth results in wide growth rings, producing low-density timber that exhibits inferior mechanical... 

In summary, there is little reason to be concerned about allelopathy in mixed plantations where walnut is grown for timber as the harvested crop. Allelopathy does appear to be a factor to consider before planting European alder as a nurse crop with black walnut. Black walnut has had no apparent effect on the autumn-olive but is probably responsible for the decline and mortality of the European alder. These results present interesting possibilities for future research on the plant/soil/microbial relationships related to the metabolism of aromatics. 

Such techniques are generally categorized under the term forest vegetation management and involve the use of machinery, fire, and or chemicals during silvicultural practices such as site preparation, weed control for plantation establishment, pine release from overtopping brush, timber stand improvement, etc. 

This chapter considers large-scale industrial tree plantations, as well as small- and medium-scale plantations for timber and land rehabilitation. Aspects that influence plantation sustainability are emphasized, and suggestions are given regarding plantation design and management. 

In summary, in high-yield, short-rotation plantation forestry in rain forest sites such as Jari, and other locations with similar ecological conditions, nutrients are likely to become limiting after the second or third rotation therefore, yields will not be maintained without extra fertilizer inputs. Repeated fertilization can upset soil nutrient balances and alter microbial populations, and it would also pose problems for the economics of producing low-value commodity timbers (see also Jordan, this volume). 

Fig. 7.2 Nitrogen and phosphoms use efficiency of 4-year-old stands of 4 indigenous timber species grown in pure plantation at La Selva Biological Station, Costa Rica.

Other tree communities, planted for commercial and/or erosion and water control purposes are also capable of growing way above the timberline. Pressure in timber demand has stimulated commercial plantations of Monterrey pine (Pinus radiata) and other species in tropical paramos from Venezuela to Ecuador since 1920, between 3000 and 3800 m asl. Most of the 36% of the planted forest area with Monterrey pine in Ecuador is cultivated in the paramo. These man-made forests modify soil nutrient balance (Farley and Kelly, 2004) and, in serving as refuges for mammal herbivores such as rabbits and deer, increase their pressure on existing plants. 

The exhaustion of natural forest resources is forcing industry to come to terms with the corewood of plantation timber. As its properties are better understood industry is finding appropriate end uses that reflect the intrinsic properties of the individual... 

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