Spatial variation and understorey competition effect of Pinus radiata fine roots in a silvopastoral system in New Zealand |
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| Authors: | MK Gautam DJ Mead SX Chang PW Clinton |
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| Institution: | (1) School of Resources, Environment and Society, Australian National University, 0200 Canberra, Australia;(2) Silviculture Advisor, Golden Bay, New Zealand;(3) Department of Renewable Resources, University of Alberta, , Centre for Enhanced Forest Management, 4–42 Earth Sciences Building, T6G 2E3 Edmonton, Canada;(4) New Zealand Forest Research Institute Ltd, Christchurch, New Zealand |
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| Abstract: | In designing agroforestry systems, the combination of tree genotype (orspecies) and pasture species and the spatial arrangement
of trees are importantconsiderations. The spatial variation of fine root length density (FRLD) ofthree radiata pine (Pinus radiata D. Don) genotypes,referred to here as clone 3, clone 4 and seedlings, was studied in athree-year-old temperate silvopastoral
experiment. The genotypes were plantedwith three understorey types: ryegrass (Lolium perenne)mixed with clovers (Trifolium spp), lucerne(Medicago sativa), and control (bare ground). Also fineroot distribution of both tree and pasture species with soil depth and inrelation to
tree row (0.9 m north or south of and within the rippedtree row) was studied. Greater FRLD was found in clonal than in seedling
treesin the bare ground treatment but not in the two pasture treatments, and in the0–0.1 m but not in the 0.1–0.2 or 0.2–0.3m
soil layers. Clonal trees had a greater ability to develop a moreextensive root system, especially in the 0–0.1 m soil layer,but
that advantage disappeared when they were planted with pasture species sincecompetition from the pasture species was most
severe in the 0–10cm layer. The FRLD of lucerne was greater than that ofryegrass/clovers, consistent with the greater aboveground
biomass production oflucerne. Pasture species FRLD was greater on the south (wetter) than on thenorth side of the ripline
or in the ripline. The interception of prevailingsoutherly rain-bearing wind by tree crowns resulted in the south side beingwetter
than the north side. Results indicated that production and distributionof fine roots of both tree and pasture species responded
to changes in themicroclimate. We suggest that to optimize pasture/tree biomass productionplanting trees in the north-south
direction is better than in the east-westdirection at the studied site.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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| Keywords: | Fine root length density (FRLD) Genotype Microsite Ripping Root distribution Tree-pasture interaction |
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