New Zealand Journal of Agricultural Research abstracts
Sustainability of New Zealand high-country pastures under contrasting
development inputs. 7. Environmental gradients, plant species selection, and
diversity
D. SCOTT
AgResearch
P.O. Box 60
Lincoln, New Zealand
Abstract The change in plant species relative abundance under
different fertiliser and management inputs over 19 years is reported for two
grazed multiple-species trials on a Pukaki/Tekapo high-country soil. One trial
was 30 combinations of 5 superphosphate rates (0-500 kg ha-1
yr-1) x 3 stocking rates x 2 stocking methods, and the second was 31
combinations of S, P (0-100 kg ha-1 yr-1), and
micronutrient fertilisers. Both were overdrilled with a 25-species pasture
mixture. There was rapid initial separation in relative abundance of species,
principally according to fertiliser level. Main features were Hieracium
pilosella remaining dominant in the absence of fertiliser; the initial
success of Trifolium hybridum; the dominance and long-term persistence
of Lupinus polyphyllus at low fertiliser inputs; the transition to
Dactylis glomerata dominance at high fertiliser inputs following a
legume phase, in the middle years; the slow vegetative increase of Trifolium
ambiguum to become dominant in most of the moderate and high fertiliser
treatments in the second decade; and the increase of Bromus tectorum in
later years. Species distributions were predominately determined by P
fertiliser rates, or P by S fertiliser interactions. The effects of different
grazing managements on late spring pasture composition were small during the
first decade but increased over time, with the principal changes under moderate
to high rate set-stocking. Diversity considerations showed that the number of
vascular plants in a plot (n), or their proportional distribution in
biomass (k diversity), gave only a weak and inconsistent correlation
with secondary production (mean sheep carrying capacity), or its stability (CV
of annual grazing capacity), after fertiliser and grazing management treatment
effects were considered. The only significant trend was in one trial where
production tended to be inversely related to the number of plant species (2.2%
decrease per species).
Keywords New Zealand; high-country; species selection;
sustainability; biodiversity; Lupinus polyphyllus; Trifolium
ambiguum; T. hybridum; T. repens; T. pratense;
Hieracium pilosella; Festuca rubra; Dactylis glomerata;
Bromus tectorum
New Zealand Journal of Agricultural Research, 2001, Vol. 44: 59-90
0028-8233/01/4401-0059 $7.00/0 (c) The Royal Society of New Zealand
2001
PDF file of entire paper: medium quality (7415K); (scanned from paper original: notes about this process)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
