This evaporation, called transpiration, creates negative pressure in the xylem, pulling watery xylem sap up the tree.

这种蒸发，叫作蒸腾作用，在木质中产生一种负压，把液体的木质树液往树上方拉。

So these are xylem sap feeders.

所以这些是木质部汁液饲养者。

This process, called osmotic movement, creates nutrient-rich xylem sap, which will then travel up the trunk to spread those nutrients through the tree.

这个过程，叫做渗透运动，会产生营养丰富的木质树液，这些树液会沿着树干向上把营养传送到整棵树。

And where these two forces pull the sap, the osmotic movement at the tree's base creates root pressure, pushing fresh xylem sap up the trunk.

这两种力量推动树液向上，树根部的渗透作用也产生树压，把新鲜的木质树液推上树干。