Temporal dynamics in biotic and functional recovery following mining David J. Eldridge

12 páginas.- 5 figuras.- referencias.- Additional supporting information may be found in the online version of the article at the publisher’s website.Human-induced disturbance has substantially influenced the structure and function of terrestrial ecosystems globally. However, the extent to which multiple ecosystem functions (multifunctionality) recover following anthropogenic disturbance (ecosystem recovery) remains poorly understood. We report on the first study examining the temporal dynamics in recovery of multifunctionality from 3 to 12 years after the commencement of rehabilitation following mining-induced disturbance, and relate this information to changes in biota. We examined changes in 57 biotic (plants, microbial) and functional (soil) attributes associated with biodiversity and ecosystem services at four open-cut coal mines in eastern Australia. Increasing time since commencement of rehabilitation was associated with increases in overall multifunctionality, soil microbial abundance, plant productivity, plant structure and soil stability, but not nutrient cycling, soil carbon sequestration nor soil nutrients. However, the temporal responses of individual ecosystem properties varied widely, from strongly positive (e.g. litter cover, fine and coarse frass, seed biomass, microbial and fungal biomass) to strongly negative (groundstorey foliage cover). We also show that sites with more developed biota tended to have greater ecosystem multifunctionality. Moreover, recovery of plant litter was closely associated with recovery of most microbial components, soil integrity and soil respiration. Overall, however, rehabilitated sites still differed from reference ecosystems a decade after commencement of rehabilitation. Synthesis and applications. The dominant role of plant and soil biota and litter cover in relation to functions associated with soil respiration, microbial function, soil integrity and C and N pools suggests that recovering biodiversity is a critically important priority in rehabilitation programs. Nonetheless, the slow recovery of most functions after a decade indicates that rehabilitation after open-cut mining is likely to protracted.This project was supported by funding from the New South Wales (NSW) Department of Planning and Environment (DPIE). T.P., T.R. and B.H. were supported by Umwelt (Australia) Pty. Ltd. and The Australian Umwelt Research Program (grant C27038), B.W. by the NSW Environment Trust (2017/RD/0095). M.D-B. is supported by a Ramón y Cajal grant (RYC2018-025483-I), a project from the Spanish Ministry of Science and Innovation (PID2020-115813RA-I00), and a project PAIDI 2020 from the Junta de Andalucía (P20_00879). We thank Carmen Castor (University of Newcastle) for field support, Laura Castaneda-Gomez, Giles Ross, Chaturika Daulagala (Western Sydney University), the Environmental Analytical Research and Carbon Laboratories (University of New England) and the DPIE Soil and Water Environmental Laboratory (Yanco) for laboratory support. Open access publishing facilitated by University of New South Wales, as part of the Wiley - University of New South Wales agreement via the Council of Australian University Librarians.Peer reviewe

Changes in Soil Microbial Atributes and Nutrient Status in Response to Environmental Plantings of Acacia and Eucalyptus in South-Eastern Australia

Land clearing and agricultural activities in Australia have significantly disturbed and affected natural ecosystems, particularly soil and biodiversity. Therefore, restoring these landscapes can help improve and protect soil condition and biodiversity. Environmental plantings of native trees and shrubs have been established on agricultural lands in Australia to restore ecosystem functions and to restore and protect biodiversity degraded by agricultural activities. Although some work exists on the extent of the ecosystem recovery, assessment of soil microbial attributes (i.e., microbial activity and functional diversity) in these plantings may provide a useful indication of restoration status. The overall aims of this study were: 1) to understand how microbial activity and soil properties are spatially distributed under main tree species used in environmental plantings, 2) to expand the understanding of how environmental plantings, and time since their establishment, affects soil microbial activity, functional diversity and soil properties, 3) to determine if the recovery to soil conditions found under extant remnant woodland are achievable, 4) to determine if there are any predictable links between soil chemical properties and soil microbial attributes due to tree plantings, 5) to determine if the main plant genus used in environmental plantings (Eucalyptus and Acacia trees), and their age, affect soil microbial attributes and soil properties, and 6) to assess the extent to which manipulation of the soil microbial population can influence the rate and magnitude of microbial recovery under environmental plantings and pasture soil. To achieve these aims, a chronosequence of environmental plantings was examined which had been established between 1993 and 2005 adjacent to pasture and remnant woodland, at three separate study locations on contrasting soil types in New South Wales. Microbial activity and functional diversity were examined along with total organic carbon (TOC), total nitrogen (TN), extractable phosphorus (P), soil pH and electrical conductivity (EC) in the pastures, environmental plantings and remnant woodlands. Soil microbial activity was mostly confined to the zone under the tree canopy of A. pendula and E. camaldulensis and in the upper 20 cm of the soil. The relative activity of the microbes and levels of TOC, TN and P declined with increasing soil depth. Microbial functional diversity in soils under trees in the environmental plantings became more similar to that of the remnant woodland with increasing age of the environmental plantings. However, after more than two decades, microbial and soil conditions under the plantings had not achieved conditions observed in the remnant woodland soil. Mixed species plantings of Eucalyptus and Acacia were also found to have a more profound impact on soil microbial activity and functional diversity than it did on the range of other soil properties. By manipulating the microbial population in an environmental planting receptor soil, it was observed that either mixing with 10% -
 20% remnant woodland soil, or inoculating soil with a 1:5 soil water extract derived from a remnant woodland soil, was effective in recovering microbial functional diversity in the soils of environmental plantings. However, neither the soil mixing treatments nor soil inoculation treatments had any significant effect on the microbial functional diversity in the adjacent pasture soil. For large scale field application, this study supports soil inoculation as a feasible approach to improving soil recovery under environmental plantings, but only after the plantings are established presumably due to the provision of suitable substrate to support the woodland microbial population. Overall, environmental plantings can be considered as an effective approach to enhance soil microbial recovery in degraded agricultural landscapes, and this can be further enhanced by manipulating and augmenting the soil microbial population under plantings