黑土区春小麦产量对积雪覆盖的响应研究基于季节性冻土冻融过程调控的视角

Response of spring wheat yield to snow cover in the black soil region: A perspective from the regulation of freezing and thawing processes of seasonally frozen soil

  • 摘要: 为揭示黑土区季节性积雪—季节性冻土—粮食生产的联动关系, 以春小麦为研究对象, 采用积雪控制试验, 设置积雪覆盖和无积雪覆盖两个处理, 通过测定春小麦产量以及季节性冻土冻融期的0~100 cm土壤温度和土壤水分动态变化过程, 探究季节性冻土冻融过程(冻融形成发育、土壤水热状况)在调控春小麦产量对积雪覆盖响应方面的潜在作用。结果发现: 季节性冻土融化阶段的春小麦播种—出苗期10 cm土壤水分、出苗—四叶期20 cm土壤水分以及冻融期10 cm土壤冻融循环频率等土壤水分和土壤冻融循环频率参数是影响黑土区春小麦产量的主要因子, 表现为黑土区春小麦产量随土壤融化阶段的播种—出苗期10 cm土壤水分、融化期10 cm土壤冻融循环频率增加而显著提高(P<0.05) , 而随土壤融化阶段的出苗—四叶期20 cm土壤水分、冻结期10 cm土壤冻融循环频率增加而显著降低(P<0.05)。枯水年份, 上述季节性冻土的土壤水分和土壤冻融循环频率参数对积雪覆盖响应不敏感, 因此, 枯水年黑土区春小麦产量对积雪覆盖无显著响应。研究结果为东北黑土区应对全球气候变化、维持粮食安全生产提供科学依据。

     

    Abstract: Seasonal snow and seasonally frozen soil are sensitive to climate change in middle-high latitude regions. Changes in seasonal snow associated with climate change could alter the freezing and thawing processes of seasonally frozen soil. Thus, these modifications may have important consequences on agricultural production by affecting the soil environment (e.g., moisture, temperature, and nutrients). However, the effects of seasonal snow on seasonally frozen soil and their association with food production remain unknown, especially in assessing the impacts of climate change on sustainable agricultural development and food security in the black soil region. This study was designed to explore how seasonally frozen soil regulates spring wheat yield in response to snow cover in an agroecosystem. To achieve this goal, we conducted a snow manipulation experiment in spring wheat fields, composed of snow cover treatment and snow free treatment. Immediately after each snowfall, we manually removed snow using shovels to maintain a snow-free condition in the snow free treatment plots, whereas snow was left undisturbed in the snow cover treatment plots. We measured spring wheat yield, soil temperature dynamics, and soil moisture dynamics in the 0−100 cm soil profile during the soil freezing and thawing periods. Soil freeze-thaw cycle frequency was determined by using soil temperature data. The results showed that spring wheat yield increased with soil moisture at a depth of 10 cm at the spring wheat sowing to seedling stage, and soil freeze-thaw cycle frequency at a depth of 10 cm during the soil thawing period. In contrast, the spring wheat yield decreased with soil moisture at a depth of 20 cm at the spring wheat seedling to four-leaf stage, and soil freeze-thaw cycle frequency at a depth of 10 cm during the soil freezing period. Furthermore, the soil moisture parameters (soil moisture at a depth of 10 cm at the spring wheat sowing to seedling stage and at a depth of 20 cm at the spring wheat seedling to four-leaf stage during the soil thawing period) and soil freeze-thaw cycle frequency parameters (soil freeze-thaw cycle frequency at a depth of 10 cm during the soil freezing/thawing period) explained 74.3%−77.6% and 77.8%−78.7% of the variance in the spring wheat yield in both the snow free and snow cover treatments, respectively. However, spring wheat yield was not related to soil temperature in the 0−100 cm soil profile, soil freezing duration, or soil thawing duration. Thus, the spring wheat yield was regulated by the above-mentioned soil moisture parameters and soil freeze-thaw cycle frequency parameters of seasonally frozen soil, and it did not respond to snow cover in the dry year. Therefore, the response of spring wheat yield in the dry year to snow cover was not significant in the black soil region. These results might provide insight into the potential role of seasonally frozen soil (development of soil freezing and thawing processes, soil temperature, and soil moisture regime) in regulating spring wheat yield in response to snow cover and improve the understanding of the relationship between seasonal snow-seasonally frozen soil and food production in the black soil region of Northeast China during climate change.

     

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