What drives the vegetation restoration in Yangtze River basin, China: Climate change or anthropogenic factors?

Vegetation dynamics and the relations with climate change at multiple time scales in the Yangtze River and Yellow River Basin, China

Wildfire is recognized as a critical Earth system process which affects the global carbon cycle, atmospheric chemistry, and ecosystem dynamics. Estimating the potential impact of future climate change on the incidence of fire requires an understanding of the long-term interactions of fire, climate, vegetation, and human activity. Accordingly, we analyzed the black carbon content and the pollen stratigraphy of sediments spanning the past 12.8 ka from Lake Muge Co, an alpine lake in western Sichuan Province, in order to determine the main factors influencing regional fire regimes. The results demonstrate that wildfires occurred frequently and intensively during the late deglaciation and the early Holocene when the regional vegetation was dominated by deciduous forests. Wildfire occurrence decreased significantly during the Holocene climatic optimum between 9.2 and 5.6 cal ka BP. Overall, the wildfire history of western Sichuan Province is similar to that of the Chinese Loess Plateau and of East Asia as a whole, suggesting that regional-scale fires depended mainly on changes in the intensity of the Asian summer monsoon. In addition, the fire regime of western Sichuan Province may have been influenced by the establishment of human settlement and agriculture in western Sichuan Province and the southeastern Tibetan Plateau after about 5.5 cal ka BP, and by an intensification of cereal cultivation coupled with population expansion in southwestern China during the last two millennia.

Black carbon record of the wildfire history of western Sichuan Province in China over the last 12.8 ka

Objective To reduce the danger for firefighters and ensure the safety of firefighters as much as possible, based on the back propagation neural network (BPNN) the fire sensor multi-sensor information fusion detection system is investigated. Method According to previous studies, the information sources and information processing methods for the design of this study are first explained. Then, the basic structure and flowchart of the research object in this study are designed. Based on the structure diagram and flowchart, the BPNN is selected to fuse the feature layers in this study, and the fuzzy control is selected to fuse the decision layers in this study. The multi-sensor information fusion detection system collects information for the sensors first, processes the collected information, and sends it to the processor of the robot. The processor analyzes and processes the received signal, and transmits the obtained information to the control terminal through the wireless communication system. Results Through the tests in this study, it is found that when the number of hidden layer nodes of the BPNN is 7, the optimal training result is obtained. On this basis, the test of BPNN in this study is performed. The test results show that after 127 iterations, the error of the BPNN reaches the lowest target value, indicating that the BPNN achieves an excellent level of accuracy. The trained BPNN has a running time of 0.0276 s and a mean square error of 0.0013. The smaller the mean square error value is, the higher the accuracy of the BPNN is, which shows that the BPNN meets the high precision requirements of this study. Conclusion The research on the multi-sensor information fusion detection system of fire robots in this study can provide theoretical support for the research on forest fire detection in China. Since the proposed BPNN-based robot is applied to the inspection and processing of forest remaining fire, the results are applicable to the forests of various countries, with a wide range of applications.

/pdf/multi-sensor-information-fusion-detection-system-for-fire-35ua1l6b4l.pdf

Multi-sensor information fusion detection system for fire robot through back propagation neural network.

The invasive species Eupatorium adenophorum is known to influence stand structure and wildfire the hazard in forests. In the current work, we quantitatively examined fire effects in invaded and uninvaded plots in southwestern Sichuan Province, China, with five different forest sites that had different types of dominant species: Pinus yunnanensis, P. yunnanensis–Quercus spp., Keteleeria fortunei, K. fortunei–Quercus spp., and Eucalyptus robusta. We compared the fuel chemistry (moisture, ash, heat value, and ignition point) and fire severity (flame length, fire intensity) under three burning conditions between the invaded and uninvaded plots in each forest sites, and then analyzed the results using multivariate response permutation procedures (MRPP). The burning conditions included: low (fine fuel moisture of 15 % and 5 km/h windspeed), moderate (fine fuel moisture of 10 % and 15 km/h windspeed), and extreme (fine fuel moisture of 5 % and 30 km/h windspeed). With all five sites, the fire severity and fuel loads were clearly significantly higher at the invaded sites. Fire severity was also intensified in the invaded coniferous sites compared to their mixed forest sites. These results indicate that biological invasions may increase the surface fire severity, perhaps through an increase in the heat value, and fuel loads, while reducing the moisture, ash, and ignition point of the understory herbaceous.

Do biological invasions by Eupatorium adenophorum increase forest fire severity

【Objective】 The relationship of forest fires and meteorological factors in last 30 years in Sichuan province was studied.【Method】 21 regions of Sichuan province were statistically analyzed and attributed to three groups:severe fire region,moderate fire region,and mild fire region.Correlation analysis,principal component analysis and regression analysis methods were used to investigate the relationship between occurences of forest fire and metorological factors.【Result】 Forest fires were mainly concentrated in Liangshan Prefecture,Panzhihua City and Ganzi Prefecture in Sichuan,with average annual fire areas of 2 866.99,1 141.84 and 1 129.00 hm2,respectively.These three regions accounted for 61.6% of the total fires based on the number of occurrences and 92.4% based on the fire areas.Wind speed,sunshine time,and rainfall had significant correlation with fires.Dominanting meteorological factors of different regions were different and they changed over time randomly.In addition,extreme climate accounted for some fire events.【Conclusion】 Forest fires in Sichuan province had a decreasing trend over past 30 years,and the fire events were related to wind speed,sunshine time,and rainfall.

Relationship of forest fires and meteorological factors in Sichuan province.

To study the influence of fire disturbance and environmental factors on undergrowth vegetation changes in a Pinus tabulaeformis forest, burned areas of an artificial P. tabulaeformis forest in Liaoheyuan National Forest Park of Pingquan County, Hebei Province were used as research objects. The burned forest was divided into three levels according to the degree of burn:mild, moderate, and severe. And three repeated plots were set. Non-burned forests near the burned area were also used for control plots. A redundancy analysis (RDA) was conducted on undergrowth vegetation and environmental factors in the three degrees of the burned area and the non-burned forest. Analysis also determined the richness index (R), diversity index (H), and evenness index (J). Results showed that undergrowth regeneration after fire was largely influenced by tree mortality rate and slope aspect, but slope and slope position had little effect on important herbs. The importance value for herbs and shrubs showing different degrees of change after fire:compared to control plots the severe burned area had a sharp increase in the number of herbaceous species from 15 to 26 with the number of shrub species increasing from 3 to 6. With an increase in fire intensity, R and H showed an overall increase (P < 0.05); whereas, J decreased (P < 0.05). Thus, growth and changes in undergrowth vegetation after fire were jointly affected by fire and topographic factors with fire being conducive to regeneration of undergrowth vegetation partly.

Chen Feng

Papers

Relationship of forest fires and meteorological factors in Sichuan province.

Fire disturbance and environmental factors for the undergrowth in a Pinus tabulaeformis forest

Potential fire behavior and canopy hazard index of main coniferous forests in Beijing mountain area.