Effects of large fires on boreal forests of China : historical reconstruction and future prediction through landscape modeling

Includes vita.Boreal forests of China store about 350 Tg tree biomass carbon, which is approximately 24–31 [percent] of the total forest carbon storage in China, and thus, play an important role in maintain national carbon balance. Long-term fire exclusion and climate warming have foster larger and more severe fires. On 1987 May 6, a catastrophic fire, known as the Black Dragon Fire, occurred in this region, and burned 1.3 million ha. This fire is among the top five of such megafires ever recorded in the world, resulting in high degree of tree mortality and reset forest succession stage for most burned stands. Forests have grown back since, with much more homogeneous age classes and composition, which post new ecological risks and challenges. It is predicted that the warming will continue in the next century, and thus uncertainties exist in future fire regimes and vegetation response under novel climate. Chapter II estimate the burn severity and carbon emissions from the Black Dragon fire. I combined field and remote sensing data to map four burn severity classes and calculated combustion efficiency in terms of the biomass immediately consumed in the fire. Results of this chapter showed that 1.30 million hectares burned and 52 [percent] of that area burned with high severity. The emitted carbon dioxide equivalents (CO2e), accounted for approximately 10 [percent] of total fossil fuel emissions from China in 1987, along with CO (2 [percent] - 3 [percent] of annual anthropogenic CO emissions from China) and non-methane hydrocarbons (NMHC) contributing to the atmospheric pollutants. This study provides an important basis for carbon emission estimation and understanding the impacts of megafires. Chapter III developed a novel framework to spatially reconstruct the post-fire time-series of forest conditions after the 1987 Black Dragon fire of China by integrating a forest landscape model (LANDIS) with remote sensing and inventory data. I derived pre-fire (1985) forest composition and the megafire perimeter and severity using remote sensing and inventory data. I simulated the megafire and the post-megafire forest recovery from 1985-2015 using the LANDIS model. I calibrated the model and validated the simulation results using inventory data. I demonstrated that the framework was effective in reconstructing the post-fire stand dynamics and that it is applicable to other types of disturbances. Chapter IV investigated the effects of future fire regimes on boreal forests of China under a warming climate. I simulated species composition and distribution changes to the year 2100 using a coupled forest dynamic model (LANDIS PRO) and ecosystem process model (LINKAGES). I focused on two possible fire regimes (frequent small fires and infrequent large fires). Results of this chapter showed that climate warming and fires strongly affected tree species composition and distribution in the boreal forests of China. Climate warming promoted transitions from boreal species to pioneer and temperate species. Fire effects acted in the same direction as climate change effects on species occurrences, thereby catalyzing climate-induced transitions. Frequent small fires exerted stronger effects on the species composition shifts than infrequent large fires. The combined effects of climate warming and fire on the shifts in species composition will accumulate through time and space and can induce a complete transition of forest type, and alter forest dynamics and functions.Includes bibliographical reference

Carbon cycle responses to climate change across China's terrestrial ecosystem: Sensitivity and driving process

International audienc

Investigations of the Mechanical Properties and Durability of Reactive Powder Concrete Containing Waste Fly Ash

Waste fly ash (WFA) with pozzolanic activities may be advantageous to the mechanical properties of reactive powder concrete (RPC) when WFA partially replaces cement in RPC. In this study, RPC specimens with 0–25% WFA were prepared under the curing temperatures of 0, 20, and 40 °C for 3 to 120 days. The flowability of fresh RPC, the mechanical strengths, and the NaCl freeze–thaw damage were investigated. Additionally, the following carbonation depths after different NaCl freeze–thaw cycles and the leaching amount of toxic metal elements were also determined experimentally. The results indicated that the incorporation of WFA could decrease the slump flow of fresh RPC due to the relatively smaller particle size of WFA. With an increase in the WFA content, the early-age flexural and compressive strengths first exhibited an increasing and then decreasing trend. However, WFA will always deteriorate the long-term mechanical properties, and both flexural and compressive strengths can be reduced by up to 25% when cured for 120 days. A higher temperature (i.e., 40 °C) was found to benefit the mechanical properties, especially when cured for 3 days. The RPC with 10% WFA exhibited the optimum salt-freezing resistance with an approximately 30% reduction in the mass loss rate when the NaCl freeze–thaw cycles reached 300. The improvement in durability can be attributed to a more compact microstructure of RPC with WFA through microscopic observations. The relationships between the mass and mechanical strength loss rates can be expressed through positive correlation quadratic functions. The carbonation depth decreased following a quadratic function with increasing mass ratios of WFA and NaCl freeze–thaw cycles. The leaching amounts of Cr and Zn increased with increasing WFA content over time, and the cumulative values reached equilibrium at 5 months

Integrated Deep Neural Networks-Based Complex System for Urban Water Management

Although the management and planning of water resources are extremely significant to human development, the complexity of implementation is unimaginable. To achieve this, the high-precision water consumption prediction is actually the key component of urban water optimization management system. Water consumption is usually affected by many factors, such as weather, economy, and water prices. If these impact factors are directly combined to predict water consumption, the weight of each perspective on the water consumption will be ignored, which will be greatly detrimental to the prediction accuracy. Therefore, this paper proposes a deep neural network-based complex system for urban water management. The essence of it is to formulate a water consumption prediction model with the aid of principal component analysis (PCA) and the integrated deep neural network, which is abbreviated as UWM-Id. The PCA classifies the factors affecting water consumption in the original data into three categories according to their correlation and inputs them into the neural network model. The results in the previous step are assigned weights and integrated into the form of fully connected layer. Finally, analyzing the sensitivity of the proposed UWM-Id and comparing its performance with a series of commonly used baseline methods for data mining, a large number of experiments have proved that UWM-Id has good performance and can be used for urban water management system

Coping strategies mediate the association between stigma and fertility quality of life in infertile women undergoing in vitro fertilization-embryo transfer.

10.1186/s12905-021-01525-9BMC Womens Health211386

Responses of Korean Pine to Proactive Managements under Climate Change

Proactive managements, such as the resistant and the adaptive treatments, have been proposed to cope with the uncertainties of future climates. However, quantifying the uncertainties of forest response to proactive managements is challenging. Korean pine is an ecologically and economically important tree species in the temperate forests of Northeast China. Its dominance has evidently decreased due to excessive harvesting in the past decades. Understanding the responses of Korean pine to proactive managements under the future climates is important. In this study, we evaluated the range of responses of Korean pine to proactive managements under Representative Concentration Pathway (RCP) 8.5 scenarios from four General Circulation Models (GCMs). We coupled an ecosystem process-based model, LINKAGES, and a forest landscape model, LANDIS PRO, to simulate scenarios of management and climate change combinations. Our results showed that the resistant and the adaptive treatment scenarios increased Korean pine importance (by 14.2% and 42.9% in importance value), dominance (biomass increased by 9.2% and 25.5%), and regeneration (abundance <10 years old increased by 286.6% and 841.2%) throughout the simulation. Results indicated that proactive managements promoted the adaptability of Korean pine to climate change. Our results showed that the variations of Korean pine response to climate change increased (ranging from 0% to 5.8% for importance value, 0% to 4.3% for biomass, and 0% to 85.4% for abundance) throughout the simulation across management scenarios. Our result showed that regeneration dictated the uncertainties of Korean pine response to climate change with a lag effect. We found that the effects of proactive managements were site-specific, which was probably influenced by the competition between Korean pine and the rare and protected broadleaf tree species. We also found that the adaptive treatment was more likely to prompt Korean pine to migrate into its suitable habitats and promoted it to better cope with climate change. Thus, the adaptive treatment is proposed for Korean pine restoration under future climates

Stigma predicting fertility quality of life among Chinese infertile women undergoing In Vitro Fertilization-Embryo Transfer.

Journal of Psychosomatic Obstetrics & Gynecology43135-4

Stigma predicting fertility quality of life among Chinese infertile women undergoing in vitro fertilization–embryo transfer

Objective To investigate stigma and fertility quality of life (FertiQoL) and identify predictors of FertiQoL in Chinese infertile women undergoing in vitro fertilization–embryo transfer (IVF-ET). Methods A descriptive correlational design was adopted to investigate the association between stigma and FertiQoL in 588 infertile women undergoing IVF-ET. The personal information questionnaire, Infertility Stigma Scale (ISS) and FertiQoL tool were used to measure study variables. Results The mean scores of ISS and FertiQoL were 62.59 (SD = 21.58) and 63.64 (SD = 13.72), respectively. There were significant differences of ISS scores among participants with different educational level, residence, occupation, religious belief, financial condition, age group, duration of infertility and infertility treatment, while significant differences of the FertiQoL scores were found in participants with different insurance status, determinism of etiology, infertile type, duration of infertility treatment and cycles of IVF-ET. Pearson’s correlation analysis showed stigma was negatively correlated with FertiQoL (r = −0.081 to −0.669, p < .05). The self-devaluation (β = −0.290, p < .001), social withdrawal (β = −0.237, p < .001), family stigma (β = −0.217, p < .001) and insurance status (β = 0.066, p=.035) were identified as the significant predictor of FertiQoL accounting for 43.5% of variance. Conclusions The stigma was significantly associated with FertiQoL in infertile women undergoing IVF-ET with higher level of stigma predicting poorer FertiQoL. More psychological support should be provided to infertile women to reduce stigma and improve FertiQoL