Influence of El Niño on the Production of Spring Kimchi Cabbage in South Korea

국내 노지 봄배추 생산량에 대한 엘니뇨 영향

Abstract

El $Ni{\tilde{n}}o$ would cause extreme weather conditions, which would result in a negative impact on crop production. The objective of this study was to assess the impact of El $Ni{\tilde{n}}o$ on spring kimchi cabbabe production for the period from 1981- 2016 in South Korea. In this study, years with less than 1.0 Oceanic $Ni{\tilde{n}}o$ index were classified into non El $Ni{\tilde{n}}o$ years. The other years were classified as El $Ni{\tilde{n}}o$ years. The national average production of spring kimchi cabbage in El $Ni{\tilde{n}}o$ years ($3,800kg\;10a^{-1}$) tended to be less than that in non El $Ni{\tilde{n}}o$ years ($4,016kg\;10a^{-1}$). However, there was no significant differences (p = 0.078) in the production between these groups of years. The averaged production of spring kimchi cabbage of El $Ni{\tilde{n}}o$ end years ($3,707{\pm}331kg\;10a^{-1}$) was less than those of El $Ni{\tilde{n}}o$ start years and non El $Ni{\tilde{n}}o$ years by 186 and $309kg\;10a^{-1}$, respectively. Still, such difference was not significant statistically (p=0.127), either. In contrast, there were provinces where the production of spring kimchi cabbage had significant differences by El $Ni{\tilde{n}}o$ occurrence. For example, El $Ni{\tilde{n}}o$ end years had significantly less spring kimchi cabbage production than El $Ni{\tilde{n}}o$ start years and non El $Ni{\tilde{n}}o$ years in Gangwon (p=0.038) and Gyeongbuk (p=0.053) provinces. It appeared that differences in cabbage production resulted from short sunshine duration, which merits further analysis on the impact of extreme weather condtions during El $Ni{\tilde{n}}o$ years on crop production.

본 논문에서는 1981년 이후 중간 강도 이상의 엘니뇨가 발생한 해의 노지 봄배추의 단위면적당 생산량의 변화를 분석하였다. 엘니뇨가 발생한 해(n=16)의 전국 평균 노지 봄배추의 생산량은 $4,016{\pm}342kg\;10a^{-1}$으로 미발생한 해(n=20)의 전국 평균 노지 봄배추의 생산량($3,800{\pm}370kg\;10a^{-1}$)보다 단위면적당 216kg 적었지만, 통계적으로는 유의하지 않았다(t=1,812, p=0.078). 또한, 엘니뇨가 종료한 해의 전국 평균 노지 봄배추의 생산량이 엘니뇨가 시작한 해와 엘니뇨가 미발생한 해보다 낮은 경향을 보였지만, 이 또한 통계적으로 유의하지 않은 것으로 분석되었다(df=2, f=2.195, p=0.127). 하지만, 강원도와 경상북도에서는 엘니뇨가 종료한 해의 노지 봄배추의 단위면적당 생산량은 통계적으로 유의하게 엘니뇨가 시작한 해와 엘니뇨가 미발생한 해보다 줄어드는 것으로 분석되었다. 이러한 원인으로 노지 봄배추 재배기간의 일조부족 현상이 1차적으로 조사되었으나, 앞으로 작물기상환경 측면에서 엘니뇨 발생이 작물생산성에 미치는 영향에 대한 추가 연구가 필요할 것이다.

Fig. 1. El Niño and La Niña years, and intensities based on Oceanic Niño Index (ONI). Events are defined as 5 consecutive overlapping 3-month periods at or above the +0.5℃ anomaly for warm (El Niño) events, and at or below the -0.5℃ anomaly for cold (La Niña) events.

Fig. 2. Yearly changes of nationally averaged production of spring kimchi cabbage (a) downloaded from the Korean Information Service and (b) after removing the residuals according to the increase tendency of production from 1981 through 2016.

Table 1. Averaged production of spring kimchi cabbage and regression analysis of changes of the production of spring kimchi cabbage from 1981 through 2016 according to administrative districts

Table 2. Comparison of the production of spring kimchi cabbage between El Niño years and non El Niño years

Table 3. Comparison of the production of spring kimchi cabbage between El Niño start years, El Niño end years, and non El Niño years