Seed Germination Responses to Seasonal Temperature and Drought Stress Are Species‐Specific but Not Related to Seed Size in a Desert Steppe: Implications for Effect of Climate Change on Community Structure

Investigating how seed germination of multiple species in an ecosystem responds to environmental conditions is crucial for understanding the mechanisms for community structure and biodiversity maintenance. However, knowledge of seed germination response of species to environmental conditions is still scarce at the community level. We hypothesized that responses of seed germination to environmental conditions differ among species at the community level, and that germination response is not correlated with seed size. To test this hypothesis, we determined the response of seed germination of 20 common species in the Siziwang Desert Steppe, China, to seasonal temperature regimes (representing April, May, June, and July) and drought stress (0, −0.003, −0.027, −0.155, and −0.87 MPa). Seed germination percentage increased with increasing temperature regime, but Allium ramosum, Allium tenuissimum, Artemisia annua, Artemisia mongolica, Artemisia scoparia, Artemisia sieversiana, Bassia dasyphylla, Kochia prastrata, and Neopallasia pectinata germinated to \u3e60% in the lowest temperature regime (April). Germination decreased with increasing water stress, but Allium ramosum, Artemisia annua, Artemisia scoparia, Bassia dasyphylla, Heteropappus altaicus, Kochia prastrata, Neopallasia pectinata, and Potentilla tanacetifolia germinated to near 60% at −0.87 MPa. Among these eight species, germination of six was tolerant to both temperature and water stress. Mean germination percentage in the four temperature regimes and the five water potentials was not significantly correlated with seed mass or seed area, which were highly correlated. Our results suggest that the species‐specific germination responses to environmental conditions are important in structuring the desert steppe community and have implications for predicting community structure under climate change. Thus, the predicted warmer and dryer climate will favor germination of drought‐tolerant species, resulting in altered proportions of germinants of different species and subsequently change in community composition of the desert steppe

Enhanced bioremediation of triclocarban-contaminated soil by Rhodococcus rhodochrous BX2 and Pseudomonas sp. LY-1 immobilized on biochar and microbial community response

Triclocarban (TCC), an emerging organic contaminant (EOC), has become a severe threat to soil microbial communities and ecological security. Here, the TCC-degrading strain Rhodococcus rhodochrous BX2 and DCA-degrading strain Pseudomonas sp. LY-1 (together referred to as TC1) were immobilized on biochar to remove TCC and its intermediates in TCC-contaminated soil. High-throughput sequencing was used to investigate the microbial community structure in TCC-contaminated soil. Analysis of co-occurrence networks was used to explore the mutual relationships among soil microbiome members. The results showed that the immobilized TC1 significantly increased the removal efficiency of TCC from 84.7 to 92.7% compared to CK (no TC1 cells on biochar) in 10 mg/L TCC liquid medium. The utilization of immobilized TC1 also significantly accelerated the removal of TCC from contaminated soil. Microbial community analysis revealed the crucial microorganisms and their functional enzymes participating in TCC degradation in soil. Moreover, the internal labor division patterns and connections of TCC-degrading microbes, with a focus on strains BX2 and LY-1, were unraveled by co-occurrence networks analysis. This work provides a promising strategy to facilitate the bioremediation of TCC in soil, which has potential application value for sustainable biobased economies

Response of temperate forest ecosystem services to rainfall: A case study in the forest nature reserves of northern China

In the context of global climate change, temperate forests in climate-sensitive areas are inevitably affected. To deepen the understanding of the impact on precipitation changes into the relationship between key ecosystem services (ESs), this study selected net primary productivity (NPP), soil conservation (SC) and water yield (WY) of temperate forest in northern China as objects, and the Spearman correlation test and redundancy analysis were applied to analyze the response of ESs relationship to precipitation gradient. The results show that precipitation is the meteorological factor with the greatest impact (contribution 21.2%, p<0.01) on ESs and their relationships in temperate forests. The 600-700 mm precipitation gradient is the key turning point in the change of ESs relationship of WY with NPP and SC. This indicates that attention should be paid to the spatial variation of the 600-700 mm precipitation region in the future warm-wet in northern China, which should be used as a dividing line of forest management and policy development. Based on the results, future restoration projects in northern temperate forest should focus on (1) in areas with less than 600-700 mm of precipitation, attention should be paid to the selection of tree species for afforestation to maintain regional water balance; (2) in areas with more than 700 mm of precipitation, soil and water conservation projects need to be planned, especially in mountainous area. The research can not only support the management of temperate forest ecosystems in northern China, but also provide reference to other forest ecosystems to cope with climate change

SUMOylation of DEC1 Protein Regulates Its Transcriptional Activity and Enhances Its Stability

Differentiated embryo-chondrocyte expressed gene 1 (DEC1, also known as sharp2, stra13, or BHLHB2) is a mammalian basic helix-loop-helix protein that is involved in many aspects of gene regulation through acting as a transcription factor. Changes in DEC1 expression levels have been implicated in the development of cancers. Using COS-7 cell, we showed that DEC1 can be modified by the small ubiquitin-like modifiers, SUMO1, 2 and 3. Two major SUMOylation sites (K159 and K279) were identified in the C-terminal domain of DEC1. Substitution of either K159 or K279 with arginine reduced DEC1 SUMOylation, but substitution of both K159 and K279 abolished SUMOylation, and more protein appeared to be retained in the cytoplasm compared to wild-type DEC1. The expression of DEC1 was up-regulated after serum starvation as previously reported, but at the same time, serum starvation also led to more SUMOylation of DEC1. In MCF-7 cells SUMOylation also stabilized DEC1 through inhibiting its ubiquitination. Moreover, SUMOylation of DEC1 promoted its repression of CLOCK/BMAL1-mediated transcriptional activity through recruitment of histone deacetylase1. These findings suggested that posttranslational modification of DEC1 in the form of SUMOylation may serve as a key factor that regulates the function of DEC1 in vivo

Legacy effects from historical grazing enhanced carbon sequestration in a desert steppe

Legacy effects are the ecological inheritances produced by preceding actions, which have been underlined more on agricultural land use, wildfire, invasive and removal species, forest management, and extreme climates in previous research; however, very few studies have shown concern toward the grazing legacy effects on key ecosystem functions such as the carbon cycle. A nested random block design was employed in 2012, with historical grazing as the block factor and precipitation as a nested factor, to explore the regulatory mechanisms on the carbon fluxes in a desert steppe. This long-term grazing practice had exerted unique legacy effects on community composition through increasing the proportion of Stipa breviflora Griseb. (P-stipa) by 61.53%, and decreasing species richness (R-sp) by 30.70%, cover by 21.87%, aboveground biomass (AGB) by 31.34%, and carbon allocation (the ratio of ANPP/BNPP) by 15.18%. Moreover, plants had differential adaptations to herbivores. Remarkably, these grazing legacies indirectly promoted plant photosynthesis (GEE) and carbon gain (NEE). Precipitation, as expected, accounted for the variability of GEE by 43% and NEE by 33%. The results revealed that precipitation controlled the magnitude of carbon fluxes while grazing legacies offset the adverse effects of current grazing and, therefore, mediated carbon sequestration. (C) 2014 Elsevier Ltd. All rights reserved

China’s grassland ecological compensation policy achieves win-win goals in Inner Mongolia

Approximately 10% of China’s grasslands are severely degraded and 90% of them are overgrazed. To protect ecosystems and boost human well-being, payments for ecosystem services programs have been implemented to generate win-win outcomes for pastoralists and the grasslands. Taking a payment for ecosystem services program in Damao County, Inner Mongolia as an example, our study evaluated the ecological effects of the Grassland Ecological Compensation Policy (GECP) based on historical trends at the pixel, parcel, and county levels. We also evaluated the socioeconomic effects of GECP using both objective and subjective well-being at the household level. Our results show that: (1) at the pixel level, the percentages of additionally increased Normalized Difference Vegetation Index (NDVI) and Net Primary Production (NPP) were 93.4% and 93.3% after GECP implementation, corresponding to the average additional effects of 0.08 and 58.99 g C/m ^2 , respectively. At the parcel level, the GECP additionally increased NDVI between 0.02–0.17 (average of 0.08) and increased NPP between 28.36–115.15 (average of 60.30) g C/m ^2 , respectively. At the county level, the GECP additionally increased grassland NDVI and NPP by 0.07 (∼3.4% annually) and 53.63 g C/m ^2 (∼4.5% annually) from 2008 to 2020, respectively; and (2) the GECP implementation significantly improved pastoralists’ objective well-being ( P < 0.01) while the effects on subjective well-being indices were mixed. Our results also show that GECP effects on objective and subjective well-being significantly differ from households with large rangeland to those with small rangeland. We further discussed the experience, challenges, and opportunities of GECP. The long-term sustainability of GECP, particularly socioeconomic sustainability, still remains challenging and relies on guiding pastoralists to find alternative livelihoods. For future research and policy improvement, we call for the establishment of a better policy compensation mechanism that jointly considers the ecological effectiveness, economic efficiency, and social equity

Strengthening and fracture mechanisms of Fe–20Ni–14Cr–2Cu alumina-forming austenitic steel during creeping

The strengthening and fracture mechanisms of Fe–20Ni–14Cr–2Cu alumina-forming austenitic (AFA) steel during creeping at 973 K/130 MPa were systematically investigated. Microstructural observations show that during creep after priorly aged at 973 K for different times, three main types of precipitates, i.e., Laves, B2-NiAl, and σ phases, are found in Fe–20Ni–14Cr–2Cu AFA steel. Laves and B2-NiAl phases dispersed in austenitic matrix contribute to the creep properties of AFA steel due to their small particle sizes, while the coarsening of hard-brittle σ phase in δ-ferrite region seems to be the main reason for creep failure. The Fe–20Ni–14Cr–2Cu AFA steel priorly aged for 1000 h possesses excellent creep property at 973 K with the minimum steady-state creep rate of 7.64 × 10–6 s−1 and the longest creep life of 329.5 h. The contribution of Laves and B2-NiAl phases to creep strength of AFA steel at 973 K/130 MPa after priorly aged for 1000 h is 261.2 MPa