Moni Christophe, Silvennoinen Hanna, Kimball Bruce A, Fjelldal Erling, Brenden Marius, Burud Ingunn, Flø Andreas, Rasse Daniel P
1Norwegian Institute for Bioeconomy Research - NIBIO, Høgskoleveien 7, 1430 Ås, Norway.
2U.S. Arid-Land Agricultural Research Center, USDA, Agricultural Research Service, 21881 North Cardon Lane, Maricopa, AZ 85138 USA.
Plant Methods. 2019 Jan 19;15:3. doi: 10.1186/s13007-019-0387-y. eCollection 2019.
Global warming is going to affect both agricultural production and carbon storage in soil worldwide. Given the complexity of the soil-plant-atmosphere continuum, in situ experiments of climate warming are necessary to predict responses of plants and emissions of greenhouse gases (GHG) from soils. Arrays of infrared (IR) heaters have been successfully applied in temperate and tropical agro-ecosystems to produce uniform and large increases in canopy surface temperature across research plots. Because this method had not yet been tested in the Arctic where consequences of global warming on GHG emission are expected to be largest, the objective of this work was to test hexagonal arrays of IR heaters to simulate a homogenous 3 °C warming of the surface, i.e. canopy and visible bare soil, of five 10.5-m plots in an Arctic meadow of northern Norway.
Our results show that the IR warming setup was able to simulate quite accurately the target + 3 °C, thereby enabling us to simulate the extension of the growing season. Meadow yield increased under warming but only through the lengthening of the growing season. Our research also suggests that, when investigating agricultural systems on the Arctic, it is important to start the warming after the vegetation is established,. Indeed, differential emergence of meadow plants impaired the homogeneity of the warming with patches of bare soil being up to 9.5 °C warmer than patches of vegetation. This created a pattern of soil crusting, which further induced spatial heterogeneity of the vegetation. However, in the Arctic these conditions are rather rare as the soil exposed by snow melt is often covered by a layer of senescent vegetation which shelters the soil from direct radiation.
Consistent continuous warming can be obtained on average with IR systems in an Arctic meadow, but homogenous spatial distribution requires that the warming must start after canopy closure.
全球变暖将影响全球的农业生产和土壤碳储存。鉴于土壤-植物-大气连续体的复杂性，有必要开展气候变暖的原位实验，以预测植物的响应以及土壤温室气体（GHG）排放。红外（IR）加热器阵列已成功应用于温带和热带农业生态系统，可使研究地块的冠层表面温度均匀大幅升高。由于该方法尚未在预计全球变暖对温室气体排放影响最大的北极地区进行测试，因此本研究的目的是测试红外加热器的六边形阵列，以模拟挪威北部北极草甸中五个10.5米地块的地表（即冠层和可见裸土）均匀升温3°C。
我们的结果表明，红外加热装置能够相当准确地模拟目标升温+3°C，从而使我们能够模拟生长季的延长。变暖条件下草甸产量增加，但这只是通过生长季的延长实现的。我们的研究还表明，在研究北极地区的农业系统时，在植被建立后开始升温很重要。事实上，草甸植物的不同出苗情况破坏了升温的均匀性，裸土斑块比植被斑块温度高出9.5°C。这形成了土壤结皮模式，进一步导致了植被的空间异质性。然而,在北极地区，这种情况相当罕见，因为融雪暴露的土壤通常覆盖着一层衰老植被，使土壤免受直接辐射。
在北极草甸中，红外系统平均可以实现持续稳定的升温，但要实现均匀的空间分布，则需要在冠层闭合后开始升温。
