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Jerzy Szejgis

Candidature

PhD Candidate

Thesis Title

Causes and consequences of biogeochemical mismatches during drought

Research Project

Drought is a widespread, complex phenomenon that is occurring more frequently and at greater magnitudes due to climate changes. Drought occurs in periods of reduced rainfall, often compounded by increased temperatures, causing high soil moisture deficit. The lack of water imposes significant stress on soil organisms and plants resulting in reduced activity and population densities or biomass production. At the same time, lower soil water availability forces microbes to reduce their activity, and, as a consequence, many soil processes are disrupted and proceed at a lower rate or, under prolonged or severe drought, are inhibited.

Drought, therefore, has broad consequences for carbon (C), nitrogen (N) and phosphorus (P) dynamics. Without a constant input of organic matter, the ecosystem cannot maintain itself. The differential effect of drought on C and nutrient dynamics can cause biogeochemical decoupling where ecosystem demand for nutrients is higher than inputs or due to an imbalance in the supply of C relative to N and P. This affects microbiomes and plant health, reducing biodiversity and causing degradation of the ecosystem.

To provide a better understanding and knowledge of drought as a phenomenon, its effects on abiotic and biotic factors, and possible actions to better manage ecosystems to promote drought resistance and resilience I will conduct a series of experiments. My research will focus on patterns of drought impacts across a climatic and environmental gradient, and biogeochemical shifts during environmental stress.

Publication

Szejgis J, Carrillo Y, Jeffries TC, Dijkstra FA, Chieppa J, Horn S, Bristol D, Maisnam P, Eldridge D, Nielsen UN, (2024) 'Altered rainfall greatly affects enzyme activity but has limited effect on microbial biomass in Australian dryland soils', Soil Biology and Biochemistry, vol.189, Article no.109277

Szejgis J, Nielsen UN, Dijkstra FA, Carrillo Y, (2024) 'Prolonged drought moderates flood effects on soil nutrient pools across a rainfall gradient', Soil Biology and Biochemistry, vol.193, art. no.109404

Maisnam P, Jeffries TC, Szejgis J, Bristol D, Singh BK, Eldridge DJ, Horn S, Chieppa J, Nielsen UN, (2023) 'Severe Prolonged Drought Favours Stress-Tolerant Microbes in Australian Drylands', Microbial Ecology, vol.86, no.4, pp 3097 - 3110

Supervisors

A/Prof. Uffe Nielsen, Dr. Yolima Carrillo, A/Prof. Feike Dijkstra