Environmental plantings’ influence on microbial attributes and soil properties in Australia.

Abstract

<p>Native trees and shrubs planted in large contiguous blocks (environmental plantings) have been established on agricultural lands in Australia to reinstate ecosystem functions and protect the biodiversity that has been degraded by agricultural activities. Limited work exists on the extent of the ecosystem recovery, but the assessment of microbial attributes (i.e. microbial activity and functional diversity) in these plantings may provide an indication of status. This study investigated how environmental plantings, and time since their establishment, affects aforementioned soil microbial attributes, &#160;to determine if the recovery to conditions found under extant remnant woodland were achievable. We compared changes in microbial functional diversity and activity along with total organic carbon (TOC), total nitrogen (TN), extractable phosphorous (P), soil pH, and electrical conductivity (EC) between environmental plantings established for 17 and 27 years, a paired adjacent pasture, and nearby remnant native woodland at Gunnedah, New South Wales. The results indicated that microbial activity under the trees, compared to that of pasture, increased by 20%&#8211;93% with increasing tree age. The ordination distance of microbial functional diversity declined between environmental plantings and remnant woodland as the age of the environmental planting increased, which was indicative of microbial functions becoming similar to that in the remnant vegetation with time. Soil P levels under trees were significantly higher compared to pasture and also increased with increasing planting age. However, TOC and TN levels under environmental plantings remained similar to pasture. These results suggest that microbial attributes and soil nutrient status of the investigated environmental plantings were on a trajectory of change from that of the pasture systems toward that of the remnant vegetation, but that full ecosystem recovery had not yet been achieved, even after 27 years.</p><p>Keywords: Environmental plantings, Microbial activity, Microbial functional diversity, Soil organic carbon, Soil nutrients</p>