Organic Production, Turnover and Mineral Cycling in Woodlands

Abstract

Summary 1. A distinction is made between the production of tree trunks (economic) and the production of all kinds of primary organic matter (biological) by woodland plants capable of photosynthesis. 2. Yield tables, quality class and site index are considered to be reasonably satisfactory indicators of trunk wood production, but their value as indicators of biological production has not been demonstrated. 3. Some factors, namely geographical, weather, edaphic, genetical, management and biotic, are considered in relation to their influence on economic production. 4. Attention is drawn to the relative paucity of data on biological production. 5. The available information of woodland biomass suggests that the greatest biomass of the world's forests exceeds 500 times 103 kg. of oven‐dry material per hectare. 6. The annual accumulation of plant material in woodland ecosystems can be very rapid, up to about 20 kg./ha. when growth is active. The bulk of the organic matter is in tree trunks but where decomposition is slow large amounts of organic matter are present as litter on the forest floor. 7. Biomass change is considered an unsuitable measure of biological production since it is affected greatly by tree harvesting. 8. Net primary production is regarded as a better measure of biological production. Some of the more serious sources of error in determining net primary production are emphasized. Generally net primary production is underestimated because of failure to take into account the removal of photosynthate by animals and because of infrequent sampling so that the production of plant parts such as inflorescences is missed. 9. Woodlands are shown to be one of the most productive terrestrial communities, giving a range of annual production as 103 kg./ha., from 5 for fir forests of the northern taiga in the U.S.S.R. to 33 in tropical rain forests. The capacity of forests to produce large amounts of organic matter annually is attributed to the large root and leaf mass which permit relatively full use to be made of the soil and incident solar energy. 10. A large part of the organic matter produced by woodland plants is broken down by the secondary producers. Associated with the annual turnover of organic matter in woodlands, nutrient elements circulate through woodland ecosystems. The annual retention of nutrient elements within the biomass is much less than what is returned to the soil by litter fall. Taking a hard beech forest in New Zealand as an example, the woodland plants have an annual uptake as kg. per hectare of potassium, calcium, magnesium, phosphorus and nitrogen of 34, 84, 12, 3‐3 and 40 respectively, but about 30, 74, 11, 2–6 and 37 are returned annually in the litter fall. 11. The annual cycle of mineral elements is regarded as a polycyclic system affected by various input and output factors. The loss of nutrients through the harvesting of tree boles, for instance, is relatively small compared to the addition of nutrients in precipitation. 12. Soil changes resulting from the variable balance in the fact...

Variabilité spatiale des réserves de nutriments dans les humus et les sols d’un massif forestier (Fougères, France)

“…It was for that reason that Ovington [33] criticised short term studies and emphasised that changes with time were not as great as papers indicated, due to faulty experimental layout. Anderson [2] concluded that over a whole rotation, the effect on soil may not be as significant as suggested by data analyses of samples taken in early to mid-rotation.…”

“…There was no significant effect of the type of stand on nutrient stocks. Present understanding of the effects of tree species on soil fertility remains very incomplete and there is no complete agreement on a species ranking with respect to their potential effects on soil fertility [2,25,33,42]. Time is often a limiting factor in these studies, as the impact of species on soil characteristics at a time scale of a few decades is often significant only in the first 10 cm of the topsoil [5].…”

Fitomassa epigéa da mata ciliar do rio Mogi-Guaçu, Itapira - SP

“…O resultado encontrado é bastante inferior ao das florestas tropicais em geral. Segundo Ovington (1965), a média para florestas temperadas é de 154 t.ha -1 , enquanto para florestas tropicais variam entre 300 a 650 t.ha -1 (McWillian et al 1993). Comparando com cerrados, formação vegetal originalmente adjacente à mata ciliar, verifica-se que esta apresenta fitomassa muito superior.…”

The Use of Mineral Nutrients for Biomass Production by Young Birch Stands and Stands Vitality in Different Forest Growing Conditions

“…In essence, forest is a self-regulatory system, which intensively regenerates organic matter. As an example mentioned the highly productive beech stand in New Zealand, where the annual consumption of K, Ca, Mn, P and N is accordingly 34, 84, 12, 3 and 40 kg·ha -1 , with the amount of the same elements produced annually by forest litter and residues 30, 74, 2, 6 and 37 kg·ha -1 , correspondingly [2].…”

“…E-mail: mudrite.daugaviete@silava.lv. mineral nutrient cycling in forest ecosystems is done by the British researcher J. D. Ovington [2] with the following conclusions: woodlands as a producer of both commercial timber (economic aspect) and all types of organic matter (biological aspect) should be considered the most unique ecosystems, functioning on an advanced level. In essence, forest is a self-regulatory system, which intensively regenerates organic matter.…”