Forest plantations in the tropics are becoming increasingly important as a source of wood supply for paper and other wood products. Many countries are now committed to developing plantation forestry and wood-based, value-adding industries as an integral part of their regional and national economic development. An example of a major new development, very relevant to this network, is Vietnam’s ‘Five Million Hectares Reforestation Program’ (5MHRP 1998-2010). Among the strategies for creating sustainable and productive forests are large-scale plantation forests: 1 million ha for pulp, 400 000 ha for plywood, 200 000 ha for solid wood and 200 000 ha for...
The main objective of this paper is to provide a critical appraisal of the research results and practical implications arising from the Brazilian part of CIFOR Network project ‘Site management and productivity in tropical plantation forests’ to the network as a whole. The Brazilian project was set up in Itatinga district, Sao Paulo State, Brazil in 1995 with the objective of evaluating the effect of site management practices (ranging in intensity from minimum to intensive management regimes) on soil fertility, nutrient cycling, nutrition and productivity of a stand of Eucalyptus grandis. We have shown that minimum cultivation and retention of...
Since 1998 an experiment has been conducted in the Congo to evaluate harvesting methods with respect to sustainable management of eucalypt plantations. The results showed: (1) a marked negative effect on tree and stand growth when all slash materials were removed; (2) a risk of nutrient leaching after harvesting due to the high rate of decomposition of organic residues; (3) a production of inorganic nitrogen in the surface soil layer which depends on slash management; and (4) a high rate of nitrification and a risk of N losses in the early stage of stand development.
Since 1978, a study has...
Effects of intensive site management operations on nutrient capital and stand growth were studied in a stand of Eucalyptus grandis in South Africa. Macronutrient pools in the standing crop, belowground biomass, forest floor and soil were determined. The forest floor on this site is a large store for nutrients, particularly N, P and Ca. Nutrient additions and removals resulting from fertilisation, wood harvesting, slash burning and slash manipulation were quantified. Stem wood harvesting has a moderately small effect on the capital of most macronutrients in the system. Slash burning results in comparatively large losses from N and P pools (440...
Effects of site management practices on Eucalyptus urophylla plantation establishment and productivity on degraded soils in southern China were evaluated. Tree growth in the treatment where all organic matter was removed and weeds were periodically controlled was better than in the whole tree harvest treatments because of reduced weed competition. Intercropping with N-fixing trees increased tree growth 69 months after planting and increased litterfall 36 months after planting. Retention of harvest residue increased foliar N and P concentration in leaves and tree growth. Retention of residue also increased the amount of litterfall in the new plantation. Application of N, P...
Impacts of site management practices on the productivity of Eucalyptus tereticornis and E. grandis in industrial plantations have been investigated at four forest sites in Kerala State, southwest India. Management practices studied were: (I) harvest residue management; (2) nutrient additions; (3) weed control; and (4) legume cover cropping. Significant removal of nutrients from eucalypt plantations occurs through harvest of wood and removal of other aboveground biomass. Conservation of nutrients on site through retention of harvest residues and/or nutrient addition will be required to ensure sustained productivity. Retention of harvest residues had no effect on soil total C, N and P...
Impacts of alternative strategies for managing harvest residues in second rotation Eucalyptus globulus plantations are being examined at sites of contrasting soil fertility in southwestern Australia. Treatments being examined in a randomised block experiment are complete harvest residue removal, residue retention, increased residue and residue burning. We studied: (I) decomposition rates of harvest residues and their associated nutrient release rates; (2) impact of treatments on soil carbon and nutrient stores; (3) dynamics of soil N mineralisation and; (4) nutrient uptake and tree growth. Results up to 7 years after stand re-establishment following harvest of the first plantation rotation are reported....
This paper presents the early results of the effect of harvesting and site management on the growth of a second rotation Acacia mangium plantation at PT Musi Hutan Persada, South Sumatra, Indonesia. Impacts of various harvest and residue management options, including litter and slash removal, whole tree harvest, only stems of commercial size removal, and double slash retention were examined. Growth responses to application of N, P, K fertilisers and Ca were studied in another set of experiments. At age 2 years, the complete removal of litter and slash from the site reduced tree height, stem diameter and stem volume...
This paper reports progress on effects of inter-rotation site management of Acacia mangium plantations in Riau Province, Sumatra, Indonesia. Growth of the previous stand in relation to soil is discussed. Pre-harvest tree biomass and nutrient content measurements indicate the 7-year, first rotation crop (R1) had an aboveground live standing biomass of 151 t ha-1 made up of 71% stem wood (> 7 cm top diameter), 17% branches and stem (< 7 cm end diameter), 8% bark, 4% foliage, and 0.2% flowers/pods. Total nutrients per hectare in these components were 593 kg N, 16 kg P, 357 kg K, 254 kg...
Encouraged by the implementation of the national forestry development program, public and private investors are establishing Acacia plantations for industrial wood production in South Vietnam. These operations are mostly small to medium enterprises. Their expectations of productivity from short rotation (6-7 years) pulpwood plantations are high but the knowledge and technology required for high and sustained production are inadequate. This paper describes a project on site management and productivity of Acacia auriculiformis plantations in the south of Vietnam. The project aims to investigate the effect of various management options including harvesting intensity organic matter retention, vegetation management and nutrient management...
A long-term field experiment was established in 1996 in southeast Queensland to: (I) examine the impacts of slash management, fertilisation and cover crops on tree growth and nutrient status; (2) quantify the effects on soil properties; and (3) contribute to the CIFOR international network of long-term experiments designed to develop management practices which would aid sustained productivity for forest plantations in tropical environments. This paper reports the major research findings in the first 6.4 years of the experiment.
Retention of slash increased stem volume by 22% at age 6.4 years, compared with the treatment in which the slash was removed....
A 37-year-old pine plantation was harvested. An experiment was established at the site with three levels of logging residue retention and two levels of weed control. By age 10 years retaining harvest residue increased pine volumes by 10 m³ ha-1 and weed control increased production by another 20 m³ ha-1. Growth differed between genetic family, but there was no genetic family x residue treatment interaction. Retention of logging residue without weed control increased the amount of carbon in the soil at age 5 years, but carbon levels decreased to pre-planting levels by age 10 years.
In southern US, most of...
Study objectives are to measure the influence of various site management treatments on the productivity of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations over a rotation. A second-rotation C. lanceolata plantation was established using five site preparation treatments on the cleared area of first-rotation C. lanceolata. In the first four years after treatment, trees on the plots treated with double slash (BL3) grew the best. Five to 6 years after treatment, tree growth in double slash treatment (BL3) still remained the best, but no significant difference in tree growth was found among different treatments. Two years after treatment, average soil...
Models available to predict growth of forest plantations include: process-based, architectural and growth and yield models, each dealing with a particular aspect of the forest production. As a part of plantation sustainability research in Congo, these three approaches are being tested. Among them, the growth and yield model (EUCALYPT-Dendro) aims at: (I) assessing stand production under different silvicultural options, and (2) evaluating the risks of nutrient deficiencies for different harvesting strategies. This chain of models includes three modules: a single tree distance independent model assesses the tree and stand growth; a set of stem taper and biomass equations evaluates wood...
Plantations in the tropics and subtropics with fast-growing species are intensively managed over short rotation cycles with the expectation of high yield. While their potential growth rates are high they also increase demand on soil resources. The greatest impact from management inputs occurs during operations associated with harvesting, site preparation, planting and silviculture. This CIFOR partnership project was initiated to address some of those issues.
The original governing concept of the project is that inter-rotation management phase of plantation is a period of great risks (damage and depletion of resources) but also a period of great opportunity (to conserve and...
Since 1978, 42 000 ha of clonal Eucalyptus plantations have been established around Pointe-Noire. The dynamics of the biogeochemical cycles of nutrients after afforestation of native savannas have been studied for a few years to assess the influence of Eucalyptus plantations on soil nutrient capitals. The work presented here is a part of this general investigation (Laclau 2001). The objective was to quantify nutrient retranslocations in the stemwood of a Eucalyptus clone throughout the whole rotation. Stemwood was studied because it represents the major sink of nutrients for this clone.
Sampling occurred in 1-, 2-, 3-, 4-, 5-, 6- and...
In recent years, there has been a growing interest in developing methods to estimate carbon fluxes and sequestration from ecosystems. Following the Kyoto Protocol, carbon sequestration from growing forests may be accounted to help countries to meet their CO2 emissions targets. Studies on the role of forests in the sequestration of carbon have been facilitated by developments in micrometeorological methods such as eddy covariance (EC), that allows continuous and long-term measurements of water and CO2 fluxes between the forest and the atmosphere (e.g. Aubinet et al. 2000, Berbigier et al. 2001). These measurements provide valuable information to assess the functional...
Nutrient release by weathering of soil minerals is one of the major fluxes for calculating nutrient accurate budgets for forest soils. In extensively managed sites, atmospheric deposits and weathering determine the resilience of the ecosystem, in terms of soil capacity for forest growth. In more intensively managed plantations, weathering remains an input difficult to quantify. For sustainability purposes, it is ecologically and economically necessary to optimise the soil nutrients and supply additional nutrients when necessary for production.
Unfortunately, this flux cannot be measured directly. For years, soil scientists used controlled experimental approaches for estimating weathering. It is now generally recognised...
More than 40 000 ha of Eucalyptus have been planted on the savannas around Pointe-Noire (Congo). In order to improve the productivity of these plantations, breeders have developed genetically improved planting stock that is more productive. For some years, the clones of natural hybrids (E. PF1 and E. tereticornis x E. grandis) originally planted, have been replaced by the clones of artificial hybrid E. urophylla x E. grandis (UG). Some UG clones achieve a MAI 507 higher than E. PF1 1-41, the most productive clone of natural hybrids. This increase in biomass production may lead to a higher nutrient uptake...
Data on standing biomass, mean annual increment of carbon stock, and nutrient accumulation in 40 industrial plantations at 21 sites in 11 countries are summarised. Aboveground biomass and mean annual increment of carbon near the harvest age, of these plantations ranged from 44 to 324 t ha-1 and from 3.1 to 22.9 tC ha-1 yr-1, respectively. Plantations managed on a short rotation are expected to accumulate carbon rapidly. However, there are large variations of biomass accumulation depending on site conditions. There is concern about the potential decrease of productivity caused by nutrient loss by intensive and repeated harvesting. It is...
