Loss of plant functional group diversity has significant repercussions for ecosystem productivity globally. However, our understanding of how this loss of specific functional groups, particularly those providing non-food resources, influences herbivores and, consequently, ecosystem productivity remains limited. To elucidate these, we conducted a series of experiments consisting of (1) a two-factor field experiment, where we manipulated the forb abundance and caterpillar presence to assess their interactive effects on plant productivity and caterpillar performance, (2) a field complementary shelter addition experiment, designed to isolate and evaluate the effects of microclimatic changes resulting from forb removal, and (3) a confirmatory microcosm experiment to validate the field findings under controlled by monitoring the herbivory patterns. Our results show that forb removal significantly decreased the aboveground plant biomass (APB) by 41.3%, but did not affect the APB of sedges. The presence of caterpillars significantly decreased total APB by 16.7% and APB of sedges by 34.8%, but these effects disappeared with forbs removed. Specifically, forb removal significantly increased caterpillar mortality rates by 319% and decreased caterpillar body size by 27.2%, which in turn diminished the herbivory pressure on sedges. Changes in caterpillar performance were correlated with maximum and average soil surface temperatures influenced by forb removal and the addition of shelters. Further investigation by the confirmatory microcosm experiment indicated that the absence of forbs decreased the feeding time of caterpillars and deprived caterpillars of refuge from the midday heat and intense sunlight, ultimately resulting in lower body size and higher larval mortality. Our findings suggest that forb removal disrupts trophic interactions, with potential cascading effects on herbivore populations, plant community structure, and ecosystem productivity. These results underscore the importance of plant functional diversity in maintaining ecosystem stability, especially under changing environmental conditions.

由于人为排水和气候变化,若尔盖泥炭地地下水位普遍下降,并存在着不同排水时长和微区域差异,这些可能会对泥炭地的植物群落变化产生显著的影响。为了准确的评估泥炭地植物群落对不同排水时长和微区域差异的响应,选取了短期排水(S)和长

土壤微生物在陆地生态系统的结构和功能中起着重要的作用。然而，水位下降对土壤微生物垂直分布和其对土壤碳循环的贡献的影响知之甚少。在这里，我们研究了排水6年后不同深度的土壤微生物(细菌、古细菌和真菌)和土壤有机质分布情况。结果表明，中水位处理和低水位处理的土壤有机质含量(SOM)分别显著降低了10.6%和11.2%。同样，中水位处理和低水位处理的水位下降使地下植物生物量(BPB)分别显著降低了43.5%和58.7%。这些变化主要发生在浅层(0-10 cm),浅层中中水位下降使SOM和BPB分别降低了13.4%和48.7%。同样，水位下降显著降低了泉古菌门和酸杆菌门的相对OTU丰富度。然而，水位的下降显著增加了真菌的香农威纳指数。逐步一般线性回归模型结果表明，泉古菌门的相对OTU丰富度可以解释近50%的SOM变化。综上所述，地下植物生物量(与莎草植物APB密切相关)和泉古菌丰度可能是排水泥炭地SOM损失的两个主要因素。鉴于土壤微生物和地下植物生物量对土壤碳动态的重要性，本文所描述的土壤微生物丰度的变化表明，土壤微生物与最近报道的若尔盖泥炭地土壤碳快速损失的关系应该进一步研究。此外，本研究建立一种古菌培养和标记的体系，为进一步研究古菌的周转特征提供基础。

The contribution of CH4 emissions from paddy soils to greenhouse gas emissions is key in the evaluation of future climate change scenarios. Most studies in this field have investigated the effects of elevated CO2 concentrations (e[CO2]s) on CH4 fluxes and methanogenic communities in paddy soils under constant CO2 concentrations ([CO2]s). However, atmospheric [CO2] is gradually increasing and the relationship between future climate change and CH4 emissions from paddy fields is poorly understood. This study explored the responses of CH4 fluxes and methanogenic communities in paddy soils to different e[CO2]s using open-top chambers. The rice biomass, CH4 fluxes, methane production potential, and methanogenic characteristics were analyzed under CK (ambient [CO2]), C-1 (e[CO2] by 120 & mu;mol mol(-1)), and C-2 (e[CO2] by 200 & mu;mol mol(-1)) treatments. The results indicated that the C-1 and C-2 treatments insignificantly increased the CH4 flux in paddy fields. However, the C-1 treatment significantly increased the CH4 flux/biomass at the elongation stage, while the C-2 treatment significantly increased the CH4 flux/biomass at all of the growth stages. The C-1 and C-2 treatments had a positive effect on both methane production potential and methanogenic abundance at all of the growth stages, but this effect was not always significant. In addition, the C-1 and C-2 treatments significantly altered the methanogenic community structure at the elongation stage. Notably, there was a significant linear relationship between the CH4 flux/biomass and [CO2] at all of the growth stages; between the methane production potential and [CO2] at the tillering, elongation, and milk-ripening stages; and between the mcrA gene abundance and [CO2] at the milk-ripening stage. A linear model based on rice biomass, methane production potential, and soil DOC concentration explained 72.7% of the variation in the CH4 fluxes. Overall, the linear relationship between CH4 fluxes and atmospheric [CO2] levels was controlled by the rice biomass, soil carbon substrate, and methanogenic communities.

Studying methanogenesis in paddy fields under future climate change scenarios is important for carbon sequestration and reduction in agroecosystems. Most studies have investigated the effects of elevated CO2 concentrations (e[CO2]) on CH4 emissions in paddy fields under a constant CO2 concentration ([CO2]). However, the increase in the [CO2] in the atmosphere is a gradual process rather than an abrupt increase, and the [CO2] in the atmosphere has remained high and relatively constant. In this research, we explored the differences in methanogenesis in paddy fields under gradually and abruptly e[CO2] using open-top chambers (OTCs). CH4 flux, soil physicochemical properties, enzyme activities, methane production potential (MPP), and methanogenic (mcrA gene) characteristics were analyzed under CK (ambient [CO2]), C1 (gradually e[CO2] by 200 μmol mol−1), and C2 (abruptly e[CO2] by 200 μmol mol−1) treatments. The results showed that the C1 and C2 treatments significantly promoted the cumulative amount of CH4 emissions (CAC) by 63.3% and 86.5%, respectively, and significantly increased the CAC/yield by 30.8% and 47.3%, respectively, compared with the CK treatment. In addition, the C1 and C2 treatments increased the DOC concentration, enzyme activities (urease, invertase, and catalase), MPP, and mcrA gene abundance in paddy soils. Notably, CAC/yield, shoot biomass, and soil seasonal average urease activity under the C2 treatment were increased by 12.6%, 12.2%, and 3.0%, respectively, compared with those in C1. The methanogenic activity of the C2 treatment was significantly increased by 24.1% and 24.4% during the tillering and grain-filling stages, respectively, and the methanogenic abundance of the C2 treatment was significantly increased by 53.9% and 72.2% during the tillering and elongation stages, respectively, compared with that of C1. Therefore, it is inappropriate to ignore the fact that [CO2] increases gradually and to only examine the effects of high e[CO2] on agroecosystems. © 2023 Elsevier Ltd

Carbon sequestration is the primary function of biochar. Hence, it is necessary to design biochar with high carbon (C) retention and low C loss. In this study, three P compounds, including KH2PO4, Ca(H2PO4)2, and NH4H2PO4, were premixed with corn stalk (1:4, w/w), aiming to produce biochars (CSB+K, CSB+Ca, and CSB+N) with high C sequestration and slow release of P at three temperatures (300, 500, and 700 °C). The addition of all P sources obviously increased C retention, with the order of NH4H2PO4 (65.6-83.5%) > Ca(H2PO4)2 (60.4-78.2%) > KH2PO4 (50.1-76.1%), compared with the pristine biochar (47.8-73.6%). The addition of Ca(H2PO4)2 and KH2PO4 led to an increase in aromaticity and graphitization, as evidenced by H/C, FTIR, Raman and XPS analysis, whereas an opposite result occurred on CSB+N. Furthermore, all three phosphates reduced C loss of biochars with H2O2 oxidation, and CSB+Ca showed the best effect. Ca(H2PO4)2 and KH2PO4 pretreated biochars had higher resistance to K2Cr2O7 oxidation and thermal treatment. In contrast, the C loss of NH4H2PO4-added biochar at 500 and 700 °C with K2Cr2O7 oxidation was increased by 54% and 36%, respectively. During the pyrolysis process, Ca(H2PO4)2 was transformed into insoluble Ca2P2O7, leading to the lowest P release rate of CSB+Ca. This study indicates that co-pyrolysis of corn stalk and Ca(H2PO4)2 is optimal for increasing C retention, enhancing C stability and improving slow-release performance of P regardless of pyrolysis temperature.

Invertebrate herbivory is suggested to modulate community shifts caused by climate warming in grasslands. However, experimental evidence is lacking, especially in high elevation areas. We examined the interactive effect of experimental warming and the grassland caterpillar Gynaephora alpherakjj, a typical invertebrate herbivorous insect with sedge preference, on the structure of plant community in a sedge-dominated alpine meadow in the Tibetan Plateau. We manipulated both herbivore and temperature in a full factorial field experiment using passive warming chambers over one plant-growing season. Results show that simulated warming significantly increased the aboveground plant biomass (APB) of forbs and total APB, while the presence of caterpillars significantly decreased sedge APB and total APB. The increase in consumption of sedges by caterpillars under warmed conditions can largely be ascribed to the increase in feeding time of caterpillars. Importantly, the presence of caterpillars significantly decreased the APB ratio of sedges to forbs in the warmed but not in the unwarmed chambers. These results suggest that with a warming climate, invertebrate herbivory could accelerate community shifts from sedge dominance to forb dominance in only one plant-growing season in the Tibetan alpine meadow. This shift would reduce the biomass of high-quality forage and further threaten animal husbandry in this area. Considering the harm of G. alpherakjj to grasslands, its population should be controlled more strictly under the global warming scenario.

Water table decline is one of the most serious environmental problems in the peatland in the Qinghai-Tibetan Plateau. However, the effect of water table decline on the structure of aboveground arthropod communities is still not clear. We investigated changes in the abundance of different arthropod groups, and estimated the abundance, height, and biomass of the plant community in a soil water table reduction experiment to reveal the effect of water table decline on the arthropod community structure. The effect of water level decline on herbivorous arthropods varied according to the feeding habits. Specifically, water table decline treatment decreased the abundance of grass-preferring herbivores but increased the abundance of forb-preferring herbivores. However, the density of predators (e.g., spiders) did not change significantly. The variations in arthropod communities were correlated with the increase in forbs and leaf nitrogen content in the water table decline treatments. Our experiment demonstrated that the effect of water table decline on plant communities cascades upwardly to alter the arthropod community. Such trophic interactions should be considered in studies aimed at predicting shifts in the arthropods communities in a changing climate.