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20 December 2021, Volume 42 Issue 12

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Mechanism on the Formation of Climate Change Impact Chain and Its Responses

PAN Zhi-hua, HUANG Na, ZHENG Da-wei

2021, 42(12):  985-997.  doi:10.3969/j.issn.1000-6362.2021.12.001

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Once climate change brings various stresses and disturbances on the receptor system, the receptor system will transfer these stresses and disturbances to other systems through its connection with them, resulting in the continuous extension of climate change effects in time and space, forming a complex climate change impact chain. At present, studies on the impacts of climate change mostly focus on the direct impacts, while the indirect impacts are rarely considered. The incomplete understanding of the impact transmission of climate change is one of the main constraints in addressing climate change. It is of great significance to explore the formation mechanism of the impact chain of climate change. This research analyzed the characteristics of climate change impacts, explored the formation mechanism of climate change impact chains, defined the connotation and classification of climate change impact chains, clarified the impact levels of climate change, and proposed ways to cope with climate change impact chains. The results showed that the impacts of climate change were extensive, different, persistent, transferable, transformable, and sometime sudden. When climate change acted on the direct receptors, the impacts of climate change would be transmitted along the food chain in the ecosystem, along the industrial chain in the economic system, and along the social relationship chain in the social system. The transmission of impact chain took the form of material flow, energy flow and information flow. The impacts of climate change always rose from low to high levels, along changes in resource endowments to natural production, economic production systems and social systems. It is believed that the effective control or cutting off of the transmission of adverse impacts of climate change can effectively reduce the impact risks and losses of climate change. The impact chain of climate change and its formation mechanism provide ideas and approaches for people to deal with climate change comprehensively.

Effect of Subsoil Plowing on Soil Bacterial Diversity in Potato Fields in Mountainous Areas of Southern Ningxia

YUE Heng, LI Shan-shan, DUAN Ya-xin, LIU Ji-hu, MA Nan, KANG Jian-hong, LU Xing-li

2021, 42(12):  998-1008.  doi:10.3969/j.issn.1000-6362.2021.12.002

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A field experiment during May 3 and October 8, 2019 using Illumina MiSeq high-throughput sequencing methods systematically was conducted to examine the impact mechanisms of three different farming tillage methods (CT, traditional tillage; STD, subsoiling tillage with 30cm soil depth; and STS, subsoiling tillage with 50cm soil depth) on the composition and diversity of soil bacterial communities in potato fields in the mountainous area of southern Ningxia. The seasonal variation of soil enzyme activities, total nitrogen content, organic carbon content, and soil bacterial community composition and diversity were also analyzed. The results showed that: (1) the activities of soil enzymes showed seasonal changes during the entire growth period of potatoes under different tillage methods. STS could significantly increase the activity of urease by 12.9% as compared with CT. When compared with STD and CT, STS could significantly increase the activity of invertase by 17.1% and 56.1%, respectively. As compared with STD and CT treatment, STS increased the activity of catalase by 27.5% and 16.7%, respectively. Additionally, subsoiling treatment could be benefit for the improvement of soil organic carbon content, and total nitrogen content; (2) Sphingomonas belonged to the dominant genus under different tillage treatments in the potato field. Meanwhile, STD significantly increased the relative abundance of Sphingomonas by 24.3% as compared with CT. As compared with CT, STD increased the Simpson index by 0.72%. When compared to the CT treatment, STS significantly increased Shannon index by 6.4%, and Chao 1 value by 35.1%, respectively; (3) Redundancy analysis showed that Shannon index and richness index (Chao1 value) were significantly positively correlated with the activity of soil urease, and soil total nitrogen content. Stepwise regression analysis showed that soil total nitrogen content was the primary factor influencing soil bacterial richness and diversity under different farming methods in the mountainous area of southern Ningxia. Therefore, STS might be the superior farming method for maintaining the high yield of potatoes due to the improvements of the activities of soil enzymes, soil properties, the richness and diversity of soil bacterial community in the area.

Effect of Chelating Agent HIDS on Summer Squash Seedlings under Sub-Optimal Temperature

WU Yue-sheng, JIAO Dong, LI Ling-zhi, ZHANG Wei, GAO Qing-lan, CHANG Ling-shan, ZHANG Jie-chun, LI Hai-ping

2021, 42(12):  1009-1019.  doi:10.3969/j.issn.1000-6362.2021.12.003

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In this experiment, summer squash variety' Nongyuan No.1' was used as experimental material, and seven treatments were set up: suitable temperature treatment (day/night 25℃/16℃, CK), watering 1/3 times Yamazaki cucumber formula; Suboptimal temperature treatment (day/night 16℃/8℃, TCK), watering 1/3 times Yamazaki cucumber formula. Under sub-optimal temperature conditions, 1/3 times Yamazaki cucumber formula was used to prepare nutrient solution with HIDS concentration of 100, 400, 700, 1000, 1300mg·L−1(T1, T2, T3, T4 and T5 treatments, respectively). After 18 days of indoor culture in artificial climate, the effects of HIDS on the growth index, osmotic adjustment substances in leaves and MDA of summer squash seedlings were analyzed. The results showed that the growth status, antioxidant enzyme activity and photosynthetic capacity of summer squash treated with TCK were worse than those treated with CK. Under suboptimal temperature, HIDS treatment with different concentrations can alleviate the inhibition of suboptimal temperature on the growth of summer squash seedlings, and the optimum concentration is 700mg·L−1 (T3). Compared with TCK treatment, the leaf area per plant, fresh and dry weight of the whole plant, soluble protein, proline content, POD, SOD and CAT activities are significantly increased, and MDA content is significantly decreased. The total amount of chlorophyll, photosynthetic rate, transpiration rate, stomatal conductance increased significantly; The Fv/Fm, ΦPSⅡ, Fv'/Fm', ETR, qP and NPQ decreased, alleviate the damage caused by suboptimal temperature to photosynthetic organs of summer squash. Therefore, adding suitable concentration of HIDS can improve the adaptability of summer squash seedlings to suboptimal temperature by promoting the accumulation of biomass and osmotic adjustment substances in leaves, reducing the degree of cell membrane lipid peroxidation, and improving the activity of antioxidant enzymes and photosynthetic capacity, and when the concentration of HIDS is 700mg·L−1, each index is closest to CK treatment.

Spatiotemporal Changes of Double Cropping Rice Phenology in South China and Relationship with Climatic Conditions

LI Wei-guang, HOU Mei-ting, ZHANG Jing-hong, CHE Xiu-fen, CHEN Xiao-min

2021, 42(12):  1020-1030.  doi:10.3969/j.issn.1000-6362.2021.12.004

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In order to explore the sensitivity of rice growth and development to climate change, and to estimate the contribution of climate change and varieties change to the change of rice phenology in South China, the phenological and meteorological observation data of double cropping rice planting in South China from 1981 to 2013 were selected for analysis. Theil-Sen estimation linear tendency rate and Mann-Kendall trend significance test were used to analyze the change trend and spatial distribution characteristics of double cropping rice phenology. Different from other regions, the sowing date of early rice in South China is ahead of schedule and the mature period of late rice is delayed slightly. The vegetative growth period of early and late rice was shortened, while the reproductive growth period was prolonged. The length of vegetative and reproductive growth periods of early rice and late rice increased with the increase of precipitation and sunshine hours, and decreased with the increase of temperature; the length of growth period was shortened by 0.5−4.7 days when the average temperature increased by 1℃. The analysis of the contribution rate of climate change and varieties to the impact of rice phenology showed that the influence of varieties change on the long-term length of early and late rice was greater than that of climate change. In the past 30 years, early rice tended to choose the varieties with long vegetative and reproductive growth period, late rice tends to choose varieties with short vegetative growth period and long reproductive growth period.

Prediction of Potential Distribution of Diaphorina citri Kuwayama in China under Future Climate Change Scenarios of CMIP6

YAO Jun-meng, LIU Dan, DUAN Li-cheng, CAI Zhe

2021, 42(12):  1031-1041.  doi:10.3969/j.issn.1000-6362.2021.12.005

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Based on the climate data in 1970−2000 and the distribution data of Diaphorina citri Kuwayama in China, the main climatic indices affecting the distribution of Diaphorina citri Kuwayama were identfied by maximum entropy model (Maxent), including temperature seasonality standard deviation, precipitation of driest month(mm), precipitation of coldest quarter(mm), average maximum temperature in January(℃), average maximum temperature in September (℃), average maximum temperature in October(℃) and average minimum temperature in August (℃). The MaxEnt model was reconstructed by the 7 main climatic indices to estimate the impact of climate change on the potential distribution of Diaphorina citri Kuwayama in China. The results showed that climate prediction mode selection of CMIP6 had significant impacts on prediction of the distribution of Diaphorina citri Kuwayama. The overall prediction distribution of Diaphorina citri Kuwayama was the highest in the CanESM5 mode, and the lowest in the BCC-CSM2-MR mode. It showed that the single mode had a greater uncertainty. Affected by climate change, multi-mode ensemble prediction showed that the potential suitable areas in the 2081−2100 for Diaphorina citri Kuwayama would increase significantly compared with in the 1970−2000, from 18.8% (SSP126 scenario) to 55.7% (SSP585 scenario). In the 2081−2100, the potential high suitable area would increase significantly from 78.3% (SSP126 scenario) to 177% (SSP585 scenario). The northern boundary of the suitable distribution shifted northward to about 32°N (SSP126 scenario) and 37°N (SSP585 scenario), while the actual northern boundary was at 30°N in the 1970−2000.This study indicated that climate change would be very beneficial to the spread of Diaphorina citri Kuwayama and threaten the ecological security of citrus-producing in China. The main citrus producing provinces, especially the areas where Diaphorina citri Kuwayama had not been found, need to be vigilant and strengthen the prevention of Citrus Huanglongbing.

Construction of Meteorological Grade Index for Summer Maize Lodging

LI Shu-yan, XUE Chang-ying, ZHANG Shou-lin, REN Li-wei, CHEN Dao-pei, WEI Qing-wei

2021, 42(12):  1042-1056.  doi:10.3969/j.issn.1000-6362.2021.12.006

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Strong wind and precipitation are the direct external conditions that induce maize lodging. In order to accurately define the lodging degree of summer maize under different wind and rain conditions, the data of maize regional variety tests in Hebi city from 2003 to 2019 was used. The wind speed (extreme max. or max.wind speed) and precipitation were extracted according to the recorded lodging time. The quantitative relationship between lodging percentage and meteorological conditions was analyzed, and the summer maize lodging meteorological grade index was constructed. The validations of the indices were conducted using agricultural meteorological observation data and lodging disaster data in the literatures. Firstly, according to the correlations between the lodging percentage and precipitation at different time scales, the “process rainfall” that had a significant impact on lodging was determined as the total amount of precipitation from 1 day before the occurrence of the lodging to 1 hour during the lodging process. R2 of the regression equation between the determined "process rainfall" and the lodging percentage was 0.924. According to the threshold of "process rainfall" of 15mm, the types of lodging disaster weather were classified into "strong wind type" and "wind and rain type". After classification, the fitness between wind speed and lodging percentage for two weather types was significantly improved. The regression equations between meteorological conditions and lodging percentage for two weather types were established. Then, the meteorological factors thresholds for three lodging grades (slight, moderate and severe) were determined responding to the lodging percentage standards 5%, 10%, and 20%, respectively. For the "strong wind type", the indices of light grade were the extreme maximum wind speed between 14m•s⁻¹ and 25m•s⁻¹or the maximum wind speed between 8m•s⁻¹ and 16m•s⁻¹. The indices of moderate grade were the extreme maximum wind speed higher than 25m•s⁻¹ or the maximum wind speed higher than 16m•s⁻¹. For the "wind and rain type", 15mm≤"process rainfall"＜40mm and the extreme maximum wind speed≥11m•s⁻¹ or the maximum wind speed≥5m•s⁻¹ was moderate grade；The indices of severe grade were the "process rainfall" higher than 40mm and extreme maximum wind speed higher than 15m•s⁻¹ or the maximum wind speed higher than 7m•s⁻¹. The validation results of the meteorological grade indices of maize lodging showed that 73% of the judged grades were consistent with the actual disaster grades, and 27% were different by one grade. The indices could provide a reference for meteorological early warning of lodging and guide agricultural production to prevent and reduce disasters.

Design of Yunnan Walnut Drought Weather Index Insurance Product

QIN Tao, ZHU Cai-xia

2021, 42(12):  1057-1067.  doi:10.3969/j.issn.1000-6362.2021.12.007

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In order to effectively reduce the adverse selection and moral hazard in the traditional forest insurance market, reduce the cost of claims, and improve the efficiency of claims, authors designed drought weather index insurance based on the development of the walnut industry in Yunnan.First of all, the drought index was calculated based on anomaly percentage of annual precipitation.Secondly, the HP filter method was used to calculate the walnut yield reduction rate. Finally, by constructing a regression model to determine the correlation between the drought index and the rate of yield reduction, the pure rate and risk zoning were determined.The time span of the panel data is from 2007 to 2017. Meteorological data and walnut output data come from the China Forestry Statistical Yearbook compiled by the State Forestry Administration, Yunnan Statistical Yearbook compiled by the Yunnan Provincial Statistics Bureau, Yunnan Yearbook compiled by the Yunnan Provincial People's Government, Yunnan Provincial Government Report on National Economic and Social Development and statistical yearbook sharing platform. Others are from The official website of the Yunnan Forestry and Grassland Bureau (http://lcj.yn.gov.cn/) Government Report on National Economic and Social Development of Yunnan Province. At the same time, refer to the relevant data of the 2019 Yunnan Province Climate Bulletin. There are 8 steps in the innovative design of insurance products. (1) Determine the homogeneity of the region, and apply weather index insurance when the homogeneity is high. (2) Determine the drought weather index, based on the impact of precipitation on the growth of walnuts, and refer to the existing drought grade standards, to determine the different drought indexes in the region. (3) Calculate the yield reduction of walnuts due to lack of water, and isolate the impact of precipitation on crop growth potential, that is, isolate the drought weather yield. (4) Quantify the regression relationship between walnut yield reduction rate and drought index, and establish a regression model. (5) Determine the critical value of production reduction due to water shortage and determine the trigger compensation value of insurance. (6) The price of insurance contracts is determined, and the pure rate is determined based on the principle of "equal expected value", and the contract is designed. (7) Feedback on product pilots, and revise and optimize products based on market demand. (8) Market promotion and popularization of products, and do a good job in product publicity. The results showed that the pure premium rate of walnut drought index insurance in different states (cities) in Yunnan is between 1.26% and 34.39%. Cluster analysis found that there are significant differences in the risk loss probability of various states (cities). Among them, Qujing, Pu'er and other areas are in mild ecologically fragile areas with fewer drought disasters, while Zhaotong and Honghe are in strong ecologically fragile areas with more drought disasters. Which provide a theoretical basis for insurance companies to further calculate the rate. Based on the risk zoning cluster analysis of pure premium rate, different states (cities) can set different premium subsidy ratios, so as to improve the premium subsidy policy system. According to the distribution of walnut planting in Yunnan and the regional drought situation, Yiliang county, Zhaotong city, which has a higher pure premium rate in northern Yunnan, Changning county, Baoshan city, which is ecologically fragile in western Yunnan, and Dayao county, Chuxiong prefecture, the "hometown of walnuts in China" in eastern Yunnan and Yangbi county, Dali prefecture, can conduct pilot projects and optimize insurance products based on feedback from actual conditions.