Question

Why can deciduous trees stay in winter without making food

Answer 1

In places where the ground freezes in winter, or dries out in the summer (e.g., Mediterranean climates), shedding leaves is an excellent adaptive strategy to prevent water stress. This is because the trade-off necessary to photosynthesize is that a plant has to open the stomates on its leaves, which allows water to quickly escape the plant. Therefore, if the ground is too dry or the water in the ground is tied up in the form of ice, rapid photosynthesis cannot happen without drying out the plant. Losing leaves does halt photosynthesis, but it is far better than getting air embolisms in the water-conducting vessels of the stem.