Four years of experimental warming do not modify the interaction between subalpine shrub species

Global warming changes biomass and C:N:P stoichiometry of different components in terrestrial ecosystems

Global warming has significantly affected terrestrial ecosystems. Biomass and C:N:P stoichiometry of plants and soil is crucial for enhancing plant productivity, improving human nutrition, and regulating biogeochemical cycles. However, the effect of warming on the biomass and C:N:P stoichiometry of different components (plant, leaf, stem, root, litter, soil, and microbial biomass) in various terrestrial ecosystems remains uncertain. We conducted a comprehensive meta-analysis to investigate the global patterns of biomass and C:N:P stoichiometry responses to warming, as well as interaction relationships based on 1399 paired observations from 105 warming studies. Results indicated that warming had a significant impact on various aspects of plant growth, including an increase in plant biomass (+16.55%), plant C:N ratio (+4.15%), leaf biomass (+16.78%), stem biomass (+23.65%), root biomass (+22.00%), litter C:N ratio (+9.54%) and soil C:N ratio (+5.64%). However, it also decreased stem C:P ratio (-23.34%), root C:P ratio (-12.88%), soil N:P ratio (-14.43%) and soil C:P ratio (-16.33%). The magnitude of warming was the primary drivers of changes of biomass and C:N:P stoichiometry. By establishing the general response curves of changes in biomass and C:N:P ratios with increasing temperature, we demonstrated that warming effect on plant, root, and litter biomass shifted from negative to positive, whereas that on leaf and stem biomass changed from positive to negative as temperature increased. Additionally, the effect of warming on root C:N ratio, root biomass, and microbial biomass N:P ratios shifted from positive to negative, whereas the effects on plant N:P, leaf N:P, leaf C:P, root N:P ratios, and microbial biomass C:N ratio changed from negative to positive with increasing temperature. Our research can help assess plant productivity and optimize ecosystem stoichiometry precisely in the context of global warming.

Temperature sensitivities of vegetation indices and aboveground biomass are primarily linked with warming magnitude in high-cold grasslands

Incessant argument on whether temperature sensitivity of aboveground biomass is primarily linked with temperature itself (local air temperature and increased magnitudes in air temperature) or other environmental variables restrains our capability to exactly forecast upcoming alterations in grass yield and high-quality development of animal husbandry in high-cold areas. Consequently, since May 2010, a field warming trial with open-top containers was achieved in high-cold grasslands at three elevations (i.e. 4313, 4513 and 4693 m) of the Tibet. The temperature sensitivities of normalized different vegetation indices (Q1_NDVI), soil adjusted vegetation indices (Q1_SAVI) and aboveground biomass (Q1_AGB) were detected in 2014-2015 and 2017-2018. Temperature itself had the greatest exclusive impacts on the Q1_NDVI, Q1_SAVI and Q1_AGB. Vegetation indices itself or aboveground biomass itself had the second greatest exclusive impacts on the Q1_NDVI, Q1_SAVI or Q1_AGB. The exclusive impact of vegetation indices itself or aboveground biomass itself was less than one-tenth that of temperature itself. Water availability and elevation & duration (elevation and warming length) only had exclusive impacts on the Q1_NDVI and Q1_SAVI. The total exclusive impact of water availability and elevation & duration on the Q1_NDVI or Q1_SAVI was around 11-12 % equivalent to that of temperature itself. Vegetation indices/aboveground biomass itself, water availability and elevation & duration had interactive impacts with temperature itself on the Q1_NDVI, Q1_SAVI or Q1_AGB. Compared to local air temperature, increased magnitudes in air temperature had the greater exclusive effects on the Q1_NDVI, Q1_SAVI and Q1_AGB. Consequently, temperature sensitivities of vegetation indices, and aboveground biomass were primarily linked with temperature itself (especially warming magnitude), and adjusted by water availability, vegetation indices/aboveground biomass itself, elevation and warming length in high-cold grasslands of the Tibet.

Differences in Bifenthrin and Fipronil Susceptibility Among Invasive Latrodectus spp. (Araneae: Theridiidae) and Nontarget Spiders in Japan

Prompt responses to invasive Latrodectus spiders introduced unintentionally are needed worldwide due to their medical and ecological importance. Latrodectus species are chemically controlled using pyrethroid insecticides despite concerns about the ecological impacts of these compounds on biodiversity/ecosystems. Here, the relative sensitivities (acute toxicity: 48-h LC50) of Latrodectus hasseltii Thorell and Latrodectus geometricus C.L. Koch from Japan to the conventional neurotoxic insecticide bifenthrin (pyrethroid) and a new candidate insecticide, fipronil (phenylpyrazole), were examined. Acute residual toxicity tests of these compounds in two nontarget spiders (Parasteatoda tepidariorum C.L. Koch (Araneae: Theridiidae), Badumna insignis L. Koch (Araneae: Desidae)) were conducted for comparison. To test whether bifenthrin and fipronil toxicities differed among the four spiders, corresponding species sensitivity distributions (SSDs) were compared, and hazardous concentrations were determined. Sensitivity (especially in the nontarget species) was two to four orders of magnitude higher for bifenthrin than for fipronil. The SSD patterns of the two insecticides differed significantly, with the spider communities being more sensitive to bifenthrin than to fipronil. The lethal bifenthrin concentration for Latrodectus may reduce spider populations by over 70-90%. If L. hasseltii (established throughout Japan) is targeted for effective population suppression rather than L. geometricus (with a limited distribution range) using the specified insecticide concentration (LC50 value) for fipronil, less than 20% of spider communities will be impacted. Chemical operations aimed at the effective population management and subsequent eradication of invasive Latrodectus spiders while supporting local biodiversity conservation would benefit from considerations of fipronil dosages and target species sensitivities.