Intensive agriculture development and achievement to higher profitability has inflicted permanent damage on agroecosystems. Rapid deterioration of structure and functional properties in agroecosystems has intensified the need for research on agroecosystem health and management. To assess the health status of wheat agroecosystems in the agricultural lands of Bandar-e-Turkmen county (Golestan province, Iran), we were used the variables of weed and natural enemies biodiversity, soil health (carbon and organic matter, microbial respiration, earthworm, soil salinity, and acidity), environmental indexes (environmental effects of pesticides (EIQ) and nitrate leaching) and vegetation indexes (RVI, cultivar type, and grain yield). In this study, thematic layers were prepared in ArcGIS and overlayed according to three scenarios. Then final layer was classified into three classes of health. Based on the results, only 8.47% (5 fields) were located in the first health class. These fields were characterized by high grain yield, low weed biodiversity, minimal pesticides use, optimal soil conditions, high RVI, and the presence of earthworms and natural enemies. Also, we found that 42 fields (71.19%) were placed in the second health class. Increase of biodiversity and population of weeds, lower grain yield, and reducing the quantity and quality of soil variables were important factors that reduced the health degree of these fields. Based on the results, 20.34% of the area (12 fields) in the central and western parts of the county was placed in the unhealthy class. It seems that increasing the environmental restrictions, including salinity higher than 6 ds/m, high weed diversity, increasing the consumption of harmful and dangerous pesticides with high environmental impact, and less grain yield than the potential of cultivars, were the main reasons for placing these fields in the unhealthy class. Also, the most important factors of decreasing the health degree of fields, frequency of weeds, increasing consumption of chemical pesticides, low soil organic matter, absence of earthworms, and decreasing grain yield were identified. Generally, management of weeds, implementation of crop rotation, preservation of plant residues on the soil surface, and development of conservation agriculture can help to improve the health indicators of wheat agroecosystems.
Reclaimed water irrigation has emerged as a critical alternative in agricultural regions facing water scarcity. However, soil pollution with microplastics (MPs) greatly increases the exposure risk and toxic effects of reclaimed water contaminations, such as phthalate esters (PAEs). A field experiment consisting of soil column pots evaluated the feasibility of using PAEs-contaminated water to irrigate oats (Avena sativa L.) in drought seasons. Three irrigation regimens based on soil matric potential thresholds (-10 kPa, -30 kPa, -50 kPa) explored the impact of PAE-contaminated water on oat physiology and environmental pollution in soil with and without MPs contamination. The results showed that treating oats at the SMP of -30 kPa boosted shoot biomass by 3.1%-14.0% compared to the drought condition at -50 kPa, and the root biomass of oats was significantly increased. The physiological metrics of oats indicated that irrigation at -50 kPa induced drought stress and oxidative damage in oats, particularly during the milk stage. Different irrigation treatments influenced the accumulation of PAEs in plants, soil, and leachate. The ratios of leachate to irrigation water in -10 kPa treatment with and without MPs addition were 1.18% and 4.48%, respectively, which aggravated the accumulation of pollutants in deep soil layers and may cause groundwater pollution. MPs pollution in soil increased the content of PAEs in the harvested oats and reduced the transport and accumulation of PAEs in deep soil layers (20-50 cm) and leachate. The coupling of PAEs in irrigation water with soil MPs pollution may exacerbate plant damage. However, the damage can be minimized under the scheduled irrigation at -30 kPa which could balance crop yield and potential risks.
Under the influence of global change, precipitation amounts and extreme precipitation frequency during nongrowing seasons in mid -high latitude grasslands have been increasing. However, the ecological effects of nongrowing season precipitation in the desert steppe have long been overlooked due to an insufficient understanding of the correlative mechanisms linking non -growing season precipitation to plant growth. Therefore, a 3year non -growing season precipitation manipulation experiment was conducted to reveal the response of desert steppe plants to non -growing season precipitation changes. Our study indicates that, by influencing water budget and availability, non -growing season precipitation directly or indirectly impacted community structure, plant biomass allocation, and water -carbon utilization intensity. Adaptive strategies of communities and plants included: Dominant species enhanced their dominance in the community to adapt to non -growing season precipitation changes. Stipa krylovii exhibited different biomass allocation strategies in response to nongrowing season precipitation variations. Plants in the precipitation shading plots tended to allocate biomass to the roots, while those in the precipitation increase plots favored aboveground development. Persistent drought during the growing season intensified early insufficient development of plants in the precipitation shading plots. Upon entering the wet period, plants in the precipitation shading plots shifted into a compensatory growth mode with high water -carbon activity intensity, while those in the precipitation increase plots entered a moderate growth mode with relatively low water -carbon activity intensity. Additionally, our study found that the regulatory effects of non -growing season precipitation were more pronounced in the growing seasons with less precipitation in the early to middle stage. Moreover, increased non -growing season precipitation enhanced plant water use efficiency (WUE) and strengthened their resilience to drought conditions. Our study suggests that the ecological role of non -growing season precipitation may be further highlighted in the future climate change pattern. Given the worldwide increase in frequency of extreme precipitation events, particular vigilance should be paid to the underlying long-term adverse effects of severe droughts during the non -growing season. Our findings provide new insights and valuable experimental observational evidence for the climate change impact assessment and response in xerophytic grassland ecosystems.
The detrimental effects of plastic and microplastic accumulation on ecosystems are widely recognized and indisputable. The emergence of biodegradable plastics (BPs) offers a practical solution to plastic pollution. Problematically, however, not all BPs can be fully degraded in the environment. On the contrary, the scientific community has demonstrated that BPs are more likely than conventional plastics (CPs) to degrade into micro/ nanoplastics and release additives, which can have similar or even worse effects than microplastics. However, there is very limited information available on the environmental toxicity assessment of BMPs. The absence of a toxicity evaluation system and the uncertainty regarding combined toxicity with other pollutants also impede the environmental toxicity assessment of BMPs. Currently, research is focused on thoroughly exploring the toxic effects of biodegradable microplastics (BMPs). This paper reviews the pollution status of BMPs in the environment, the degradation behavior of BPs and the influencing factors. This paper comprehensively summarizes the ecotoxicological effects of BPs on ecosystems, considering animals, plants, and microorganisms in various environments such as water bodies, soil, and sediment. The focus is on distinguishing between BMPs and conventional microplastics (CMPs). In addition, the combined toxic effects of BMPs and other pollutants are also being investigated. The findings suggest that BMPs may have different or more severe impacts on ecosystems. The rougher and more intricate surface of BMPs increases the likelihood of causing mechanical damage to organisms and breaking down into smaller plastic particles, releasing additives that lead to a series of cascading
Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 degrees C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness.