112-學測-英文-題組-11-15

$~~~~$ In certain forests, when you look up you will see a network of cracks formed by gaps between the outermost edges of tree branches. It looks like a precisely engineered jigsaw puzzle, each branch growing just perfectly so it almost, 11, touches the neighboring tree. This beautiful phenomenon is called crown shyness.
$~~~~$ Scientists have been discussing crown shyness since the 1920s, proposing 12 explanations for the phenomenon. Some researchers point out that as trees often grow close together, treetops can easily collide and break when swayed by the wind. In order to protect their branches from breakage, trees maintain “shyness gaps”—spaces large enough to prevent them from touching their neighbors.
$~~~~$ Other scientists suggest that plants, like animals, 13 resources—nutrients, water, space, and light. In forested areas with thick tree crowns, there is intense struggle for these resources. Gaps in the treetops resulting from crown shyness may allow trees to increase their 14 light and enhance photosynthesis. Additionally, by having branches that do not touch those of their neighbors, trees may be able to limit the spread of leaf-eating insects, and potentially also the transmission of diseases from tree to tree. 15 decades of investigation, there is no consensus on exactly what causes the beautiful and mysterious phenomenon of crown shyness.