Reestablishment of ecological functioning by mulching and termite invasion in a degraded soil in an Australian savanna

• Published in: Soil biology & biochemistry 2010-10, Vol.42 (10), p.1825-1834
• Main Author: Dawes, Tracy Z.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biochemistry and biology; biodegradation; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Decomposition; dry season; ecological function; Ecosystem function; Fundamental and applied biological sciences. Psychology; insect ecology; Isoptera; land restoration; Macroporosity; Mulch; mulching; nitrogen; Physical properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; plant litter; Rehabilitation; savannas; soil ecology; soil fertility; soil organic carbon; soil pore system; Soil science; Soil structure; soil water; soil water retention; Structure, texture, density, mechanical behavior. Heat and gas exchanges; termite mounds; Termites; Termiticide; Tropical savanna; tropical soils; vegetation cover; Water storage
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2010.06.023

Soil degradation is a major source of ecological dysfunction in both natural and agricultural landscapes. Termites are key mediators of tropical soil structure and function, but there has been little experimental evaluation of their potential in soil rehabilitation. This study investigated if termite activity can be used as a tool to improve the properties and function of degraded soil in tropical Australia, through mulch addition. A 2 × 2 randomised block design was used, with mulch (bare [B] or mulched [M] plots) and termiticide (termite [T] or non-termite [NT] plots) as factors. Over 4.5 years I tested the hypothesis that the MT plots would show greatest increase in (i) soil macroporosity, (ii) total soil surface carbon and nitrogen, (iii) litter decomposition, (iv) soil water storage and (v) plant cover, and (vi) greatest reduction in soil strength. MT treatment plots showed a 46% and 45% increase in soil macroporosity and plant cover, respectively, and a 25% reduction in soil strength compared with MNT plots. Compared with B treatments (BT, BNT), macroporosity and plant cover were 98% and 60% higher, respectively and soil water storage increased by up to 15%. Termites contributed to 58% of litter loss in MT plots over the transitional/dry season period. Mulching doubled soil carbon and nitrogen levels. This research demonstrates termite-mediated processes can be initiated and maintained in degraded soil, thereby improving soil structure and key ecosystem functions. Termites may represent a valuable biological resource for promoting tropical soil restoration, through incorporating techniques that promote their activity into tropical soil rehabilitation management.