The ecological importance of moss ground cover in dry shrubland
restoration within an irrigated agricultural landscape matrix
Abstract
1. Kānuka (Kunzea serotina, Myrtaceae) dryland shrubland
communities of the lowland plains of South Island (Te Wai Pounamu) New
Zealand (Aoteoroa) contain a ground cover largely consisting of mosses,
predominantly Hypnum cupressiforme. There has been no previous
study of the role of mosses in this threatened habitat which is
currently being restored within a contemporary irrigated and
intensively-farmed landscape that may be incompatible with this
component of the ecosystem. 2. The aim of the present study was to
investigate the influence of moss ground cover on hydrology, nitrogen
(N) availability and vascular plant interactions, and in relation to
nutrient spillover from adjacent farmland. Experimental work was a
combination of glasshouse experiments and field-based studies. 3.
Extremes of soil temperature and moisture were found to be mediated by
the moss carpet, which also influenced N speciation; available N
declined with moss depth. The moss layer decreased the amount of
germination and establishment of vascular plants but, in some cases,
enhanced their growth. Spillover of mineral nitrogen and phosphate from
farmland enhanced invasion of exotic grasses which may have benefited
from conditions provided by the moss carpet. 4. Synthesis: We found the
moss layer to be crucial to ecosystem functioning in these dry habitats
with low nutrient substrate. However, when the moss layer is accompanied
by nutrient spillover it has the potential to increase exotic weed
encroachment. Our results emphasise the importance of non-vascular plant
inclusion in restoration schemes but also highlights the importance of
mitigating for nutrient spillover.