Browsing by Author "Incoll, L. D."

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    Poplar (Populus spp) growth and crop yields in a silvoarable experiment at three lowland sites in England
    (Springer Science Business Media, 2004-01-01T00:00:00Z) Burgess, Paul J.; Incoll, L. D.; Corry, D. T.; Beaton, A.; Hart, B. J.
    In early 1992, a silvoarable experiment, comprising four poplar (Populus spp.) hybrids (at a spacing of 10 m x 6.4 m) and four arable treatments, was established at three contrasting lowland sites in England. By the end of 1998, seven years after planting, the height of the poplar hybrid Beaupré (11.9 m) was greater than those of the hybrids Gibecq, Robusta and Trichobel (8.9-9.8 m). The trees at the most exposed site had the shortest height (9.2 m) and the greatest diameter at breast height (173 mm). Tree growth was also affected by the arable treatments. The height (9.5 m) and diameter (143 mm) of the trees bordered on both sides by a continuous rotation of arable crops were 89% and 79%, respectively, of those bordered on both sides by a regularly cultivated fallow. This result could be explained by competition for water. Across the three sites, in the presence of the trees the yield per unit cropped area, relative to that in the control areas, was an average of 4% less in the first three years and an average of 10% less between years four and six. However the specific responses were dependent on the arable crop. The experiment also included an alternately- cropped arable treatment, where the crop was alternated with a one-year bare fallow. The benefits of a preceding fallow, rather than a cereal crop, for yield were greatest for wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) and least for field beans (Vicia faba L.), peas (Pisum sativum L.) and mustard (Brassica alba L.)
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    Silvoarable agroforestry
    (The Royal Scottish Forestry Society, 1999-01-01) Beaton, A.; Incoll, L. D.; Burgess, Paul J.
    Introduction: A silvoarable system of land management implies the cultivation of trees and arable crops on the same area of land, a system practised quite commonly in southern Europe and in the tropics. The system comprises two components: tree rows, generally one tree wide, and arable alleys, alternating across the field. The first major development of silvoarable practice in the UK took place during the 1960s and 1970s when Bryant & May established extensive poplar plantations on lowland farmland in southern England to supply their own market for match veneer timber (Beaton, 1987). Since the demise of the Bryant Sr May market for match timber in 1978, interest in the potential for silvoarable systems lay dormant until the advent of food crop surpluses in the 1980s.
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    Yield-SAFE: A parameter-sparse, process-based dynamic model for predicting resource capture, growth, and production in agroforestry systems.
    (Elsevier Science B.V., Amsterdam., 2007-04-01T00:00:00Z) van der Werf, Wopke; Keesman, Karel; Burgess, Paul J.; Graves, Anil R.; Pilbeam, David; Incoll, L. D.; Metselaar, Klaas; Mayus, Martina; Stappers, Roel; van Keulen, Herman; Palma, João H. N.
    1. Silvoarable agroforestry (SAF) is the cultivation of trees and arable crops on the same parcel of land. SAF may contribute to modern diversified land use objectives in Europe, such as enhanced biodiversity and productivity, reduced leaching of nitrogen, protection against flooding and erosion, and attractiveness of the landscape. Long-term yield predictions are needed to assess long-term economic profitability of SAF. 2. A model for growth, resource sharing and productivity in agroforestry systems was developed to act as a tool in forecasts of yield, economic optimization of farming enterprises and exploration of policy options for land use in Europe. The model is called Yield- SAFE; from “YIeld Estimator for Long term Design of Silvoarable AgroForestry in Europe”. The model was developed with as few equations and parameters as possible to allow model parameterization under constrained availability of data from long-term experiments. 3. The model consists of seven state equations expressing the temporal dynamics of: (1) tree biomass; (2) tree leaf area; (3) number of shoots per tree; (4) crop biomass; (5) crop leaf area index; (6) heat sum; and (7) soil water content. The main outputs of the model are the growth dynamics and final yields of trees and crops. Daily inputs are temperature, radiation and precipitation. Planting densities, initial biomasses of tree and crop species, and soil parameters must be specified. 4. A parameterization of Yield-SAFE is generated, using published yield tables for tree growth and output from the comprehensive crop simulation model STICS. Analysis of tree and crop growth data from two poplar agroforestry stands in the United Kingdom demonstrates the validity of the modelling concept and calibration philosophy of Yield-SAFE. A sensitivity analysis is presented to elucidate which biological parameters most influence short and long-term productivity and land equivalent ratio. 5. The conceptual model, elaborated in Yield-SAFE, in combination with the outlined procedure for model calibration, offers a valid tool for exploratory land use stud