It turns out at that time of the year, in the summer, that birch was sending more carbon to fir than fir was sending back to birch, especially when the fir was shaded.
마침 그 실험이 진행된 여름에는 자작나무가 전나무에게 탄소를 좀 더 보내는 때였어요. 전나무가 햇빛을 못 받는 경우라면 특히요.