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Plastic contamination of ecosystems has increased dramatically over the last decades, raising concerns about the negative impacts of plastic particles on aquatic and terrestrial systems. In recent years, the focus of most research has shifted from large fragments (macroplastic) to micro- (, iForest, 15 (2), ISSN:1971-7458

Since 2010, central Chile has experienced one of the driest decadal-scale droughts of the past thousand years, with annual precipitation deficits of 20-40%. In the Andes, this ‘megadrought’ has manifested in acute reductions in snowpack; streamflow; lake, reservoir and glacier volume; and soil moisture, with knock-on effects especially for agriculture and vegetation productivity. While many studies have characterised such impacts via remote sensing, in-situ measurements and conceptual hydrological modelling, fewer have taken a mechanistic approach, leaving room to improve process understanding and disentangle the complex response of the mountain water cycle. Here we present preliminary results from a modelling study of the propagation of the megadrought in the Cajon del Maipo, to the east of Santiago. We simulate water, energy and carbon fluxes both before and during the drought, using the land-surface model Tethys-Chloris, at 250 m spatial and hourly temporal resolution. We force the model with a new meteorological dataset, CHELSA high-res, and evaluate its performance using in-situ streamflow and glacier mass balance data, as well as snow cover and leaf-area index data from satellite images. We explore in particular how reduced snow cover has affected vegetation dynamics and downstream hydrology to gain insights relevant for a snow-scarce future., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The vitality of Scots pine (Pinus sylvestris L.) is declining since the 1990s in many European regions. This was mostly attributed to the occurrence of hotter droughts, other climatic changes and secondary biotic stressors. However, it is still not well understood which specific atmospheric trends and extremes caused the observed spatio-temporal dieback patterns. In the Swiss Rhone valley, we identified negative precipitation anomalies between midsummer and early autumn as the main driver of sudden vitality decline and dieback events. Whereas climate change from 1981 to 2018 did not lead to a reduced water input within this time of the year, the potential evapotranspiration strongly increased in spring and summer. This prolonged and intensified the period of low soil moisture between midsummer and autumn, making Scots pines critically dependent on substantial precipitation events which temporarily reduce the increased water stress. Thus, local climate characteristics (namely midsummer to early autumn precipitation minima) are decisive for the spatial occurrence of vitality decline events, as the lowest minima outline the most affected regions within the Swiss Rhone valley. Mortality events will most likely spread to larger areas and accelerate the decline of Scots pines at lower elevations, whereas higher altitudes may remain suitable Scots pine habitats. The results from our regional study are relevant on larger geographic scales because the same processes seem to play a key role in other European regions increasingly affected by Scots pine dieback events., Frontiers in Forests and Global Change, 5, ISSN:2624-893X

Severe drought acutely impairs plant hydraulic functioning and impedes processes of carbon (C) and nutrient as well as their allocation. However, how fertilization would modify the allocation of C and nutrient between sink and source organs during drought stress remains largely unknown.We used three-year old potted seedlings of sessile oak and Scots pine in a greenhouse experiment where they were subjected to three different fertilization treatments (non-fertilized, moderate and high fertilization) and two water regimes (well-watered and severe drought) across two consecutive growing seasons. 13C and 15N labeling were labeled to trace the C and nitrogen (N) allocation. Leaf gas exchanges and predawn water potential, biomass of the different plant organs and NSC concentration, as well as relative 13C and 15N allocation to root, stems and leaves were assessed in the two growing seasons.Our results showed that sessile oak grown under fertilization suffered faster from drought and showed earlier death than unfertilized seedlings. Fertilization significantly improved aboveground growth, increased shoot: root ratio and reduced NSC storage in sessile oak. This leads to drought-induced C depletion and increased mortality under severe drought. Progressing drought altered C and N translocation strategies in sessile oak by prioritizing C allocation to and N retention in the roots under moderate fertilization, but not in high fertilization. In sessile oak, seasonal dynamics of C and N allocation is coupled and independent of drought and fertilization. By contrast, fertilization and drought, both had only minor impacts on Scots pine C allocation and the tradeoff of C allocation between growth and reserves, as well as the uptake of added N by root. Severe drought strongly decreased NSC in stem and root of Scots pine, while NSC concentrations in leaf and fine root kept stable and high and at the status of mortality.We conclude that sessile oak shows a more plastic response to environment changes than Scots pine by adjusting its C and N relations on the whole plant level. The impact of fertilization on tree seedlings drought responses seems to be species-specific and is also modified by the degree of drought and fertilization.