Publications

SARS-CoV-2 has been found in soil and aquatic environments in addition to aerosols. SARS-CoV-2 enters the soil from various sources, including organic amendments and waste irrigation water. The virus counts and virulence in soil depend on spillover routes and soil properties. Organic matter (OM) and clay minerals protect and enable SARS-CoV-2 to survive for longer periods in soil. Therefore, life forms residing in soil may be at risk, but there is a paucity of scientific interest in such interactions. With this perspective, we aim to provide a new viewpoint on the effects of SARS-CoV-2 on soil microbes. In particular, we present a conceptual model showing how successive mutations within soil animals having the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) may change its characteristics and, thus, enable it to infect micro- and macroorganisms and be transferred by them. SARS-CoV-2 particles could be adsorbed on mineral or OM surfaces, and these surfaces could serve as encounter sites for infectious attacks. SARS-CoV-2 accumulation in soil over time can perturb bacteria and other microbes, leading to imbalances in microbial diversity and activities. Thus, SARS-CoV-2 and its interactions with biotic and abiotic soil components should be a future research priority.

No abstract is provided for this article.

Intensification of farming since the Green Revolution has led to large increases in yield but has also increased anthropogenic greenhouse gas emissions. Here, by providing a global comprehensive cradle-to-gate quantification from seed to yield, we show that the global warming potential (GWP) of conventional agriculture of grain crops has increased eightfold from 1961 to 2020, whereas the sustainability index (SI) has decreased threefold. Tillage, synthetic fertilizers and irrigation together accounted for 90% of the increased GWP, linked to tenfold increases in fertilization and groundwater use and more than doubled mechanized and irrigated areas. We highlight regions with high GWP and low SI, such as South Asia, and project further threefold increases in agriculture GWP by 2100 compared with 2020 (3.3 ± 0.73 PgCO2e) driven by declined use efficiency of the inputs. Green energy and climate-smart agriculture techniques can reduce the projected GWP in 2100 to 2.3 PgCO2e and increase the SI fourfold. The authors provide a global, cradle-to-gate quantification of the changes in the global warming potential and sustainability index of conventional agriculture from 1961 to the 2020s. They show an eightfold global warming potential increase and threefold decrease in sustainability index, largely due to tillage, fertilizer use and irrigation.

Aim Significant progress has been made in understanding the links between biodiversity and ecosystem functioning in both experimental and real-world ecosystems. Yet, we have limited understanding to which extent biodiversity affects ecosystem functioning in natural heterogeneous environments and whether changes in ecosystem functions are related to changes in species richness and/or turnover. Here we (1) quantify the contribution of diversity to variation in ecosystem functioning (i.e., the diversity effect) in heterogeneous environments and (2) test whether spatial variation in species richness and/or turnover between communities mediate effects of environmental heterogeneity on the diversity effect. Location Two tropical elevational gradients: Andes (Ecuador) and Mt. Kilimanjaro (Tanzania). Time period Current. Taxa studied Multiple: plants, oribatid mites, springtails, ants and birds. Methods We expand an analytical framework based on the Price equation to quantify the relative contribution of species richness or turnover to variation in ecosystem functioning within and across ecosystem types. We applied this framework using data on seven ecosystem functions collected in six ecosystem types on two tropical elevational gradients. Results We found a consistent increase in the diversity effect on ecosystem functioning with increasing environmental heterogeneity. Both species richness and turnover contributed similarly to the diversity effect. The increase in the diversity effect with environmental heterogeneity was solely based on the variation in species richness. The effect of species turnover was unrelated to environmental heterogeneity. Main Conclusions Our proposed framework enables the quantification of BEF relationships at large spatial scales and across various ecosystem types. It expands on previous studies by allowing comparisons among naturally assembled communities along environmental gradients. By applying our framework to two tropical systems, we show that changes in species richness and turnover contribute similarly to variations in ecosystem functioning across both elevational gradients. However, species richness is particularly important in mediating the effects of environmental heterogeneity on ecosystem functioning.

Approximately 220 million hectares of former croplands are abandoned worldwide, with a quarter of this area located in Russia. In these areas, natural zonal vegetation is developing, and the soils, including soil carbon (C) stocks, are recovering. Accumulated organic C serves as a structural and energetic source for soil microorganisms. Postagricultural soil restoration affects organic matter stability, microbial organic carbon decomposition, and C cycling. We studied a chronosequence of abandoned croplands in the Eastern Siberian forest steppe zone (Haplic Luvisol) to assess the effects of cropland natural restoration on the stability of soil organic matter (SOM) and energy stocks. The energy content and thermal stability of C in the bulk soil, in free and occluded particulate organic matter (fPOM and oPOM), and in mineral-associated organic matter (MAOM) were analysed by thermogravimetry and differential scanning calorimetry as proxies for С available for microbial decomposition. The soils sequestered 0.85 Mg C ha−1 y−1 (0–30 cm) during the first 25 years after abandonment. In abandoned soils, thermally labile C with an activation energy of 69±0.6 kJ·mol⁻¹ accumulated 2.8 times faster than did stable C with a higher energy barrier to combustion (80±0.5 kJ·mol⁻¹). This increased energy availability and microbial activity led to faster C and nutrient cycling in the abandoned soils than in soils of current croplands. MAOM stored 1.7 times more energy per unit of C (42 kJ·g⁻¹ C) than did the free and occluded POM fractions (25 kJ·g⁻¹ C). fPOM was the dominant energy pool for labile C in the restored soil and increased microbial activity. Due to the preferential accumulation of C with lower thermal stability and with greater susceptibility to microbial decomposition in the restored soils, greater CO2 release could occur if these lands are tilled again. The content of thermally stable C also increased in abandoned soils; therefore, we must account for the ecological balance between C sequestration and release after the natural restoration of croplands.

No abstract is provided for this article.

The Kobresia pastures of the Tibetan Plateau represent the world's largest alpine grassland ecosystem. These pastures remained stable during the last millennia of nomadic animal husbandry. However, strongly increased herds' density has promoted overgrazing, with unclear consequences for vegetation and soils, particularly for cycles of carbon (C), nutrients and water. Vegetation-free patches of dead root-mat covered by blue-green algae and crustose lichens (crusts) are common in overgrazed Kobresia pastures, but their effect on C turnover processes is completely unknown. We tested the hypothesis that the crusts strongly affect the C cycle by examining: (i) the long-term C stock measured as soil organic matter content; (ii) medium-term C stock as dead roots; (iii) recent C fluxes analyzed as living roots and CO2 efflux; and (iv) fast decomposition of root exudates. Up to 7.5 times less aboveground and 1.9 times less belowground living biomass were found in crust patches, reflecting a much smaller C input to soil as compared with the non-crust Kobresia patches. A lower C input initially changed the long-term C stock under crusts in the upper root-mat horizon. Linear regression between living roots and CO2 efflux showed that roots contributed 23% to total CO2 under non-crust areas (mean July–August 5.4 g C m−2 day−1) and 18% under crusts (5.1 g C m−2 day−1). To identify differences in the fast turnover processes in soil, we added 13C labeled glucose, glycine and acetic acid, representing the three main groups of root exudates. The decomposition rates of glucose (0.7 day−1), glycine (1.5 day−1) and acetic acid (1.2 day−1) did not differ under crusts and non-crusts. More 13C, however, remained in soil under crusts, reflecting less complete decomposition of exudates and less root uptake. This shows that the crust patches decrease the rates of medium-term C turnover in response to the much lower C input. Very high 13C amounts recovered in plants from non-crust areas as well as the two times lower uptake by roots under crusts indicate that very dense roots are efficient competitors with microorganisms for soluble organics. In conclusion, the altered C cycle in the overgrazing-induced crustose lichens and blue-green algae crusts is connected with strongly decreased C input and reduced medium-term C turnover.

Mediterranean vegetation is frequently subjected to the heat waves with temperature peaks exceeding 45 °C. While the effects of drought on assimilates allocation are deeply studied, little information is available regarding the effects of the acute heat stress on this aspect of the plant physiology. We evaluated the effects of acute heat pulses on plant C internal allocation in Eucalyptus camaldulensis saplings and its transfer into the soil. Shoots of Eucalyptus were subjected to an increase of the air temperatures up to 45 °C. Allocation of C was inferred after pulse labelling of heated and non-heated shoots with 13CO2. Heat pulse lowered the photosynthesis and almost tripled the C losses from shoots through respiration. Assimilated 13C was preferentially allocated to leaf soluble sugar fractions rather than to starch. Heat pulse interrupted 13C allocation to the trunk, roots and soil. 13C allocation to new non labelled leaves was detected in some replicate plants, independently of treatment, suggesting that this process is sink-driven. Although, shoots subjected to the heat pulse modified allocation strategy, “saving” assimilated 13C at a leaf level, the rate of 13C involvement in shoot respiration was restricted by photosynthetic rates measured during the labelling. The results suggest that photosynthetic and non-photosynthetic organs may be constrained to rely on C reserves under elevated temperatures with further negative consequences for C balance in case the duration and frequency of the heat waves will increase as projected by climate change.