This network includes about thirty experimental sites distributed throughout France. Different species are represented (oak, beech, spruce, fir, douglas fir, pine), several of which may co-occur in the same experiment. The age of the stands when the trials were set up varies greatly, as do the amendments used (fertilisers, Ca or Ca-Mg carbonates, gypsum, slag, etc.) and the doses administered (from a few dozen kg to several tonnes per hectare). Expeimental sites vary in size from 1 to 6 hectares, depending on the methods applied, the number of blocks and the size of the plots (from 0.01 to 1 ha). At set-up – and before any amendments were applied, most of the plots underwent a formal "initial condition" assessment. Then, sampling campaigns and physico-chemical analyses (soil, humus, population) were carried out more or less regularly depending on the technical, human and financial resources available. Therefore, the frequency of measurements often varies from one experimetal site to another depending on the parameters monitored, the initial objectives and successive scientific projects related to each experimental site). Different ecosystem components are concerned (soil, humus, individual trees, leaves/needles, the herbaceous layer, etc.). The effects of the amendments on the ecosystem can be deduced from comparisons between plots having received the fertiliser and control plots (ecosystems similar in all respects, but without inputs). Changes in each component and in the global ecosystem can then be studied by comparing the measurements, or scores, recorded during successive survey campaigns. The most commonly performed analyses are: (i) pedological or systematic soil chemical analyses, horizon by horizon; (ii) chemical analyses of humus and evaluation of the quantities of dry matter per hectare; (iii) chemical analyses of leaves or needles, (iv) inventories in the middle of the stands; (v) species inventories for the tree, shrub, herbaceous and moss strata; and, for a few plots, (vi) stand biomass and mineralomass.
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soil fertility, nutrient management, biogeochemical cycles
Temperate species, Quercus sp., Pinus sp., Pseudotsuga menziesii, Abies sp. , Fagus sp.