the ocean in the form of river runoff. Mongabay: Why do you associate the biotic pump with natural forests rather than with trees in general? Could a monoculture tree plantation act as biotic pump? A palm oil plantation on the island of Sumatra in Indonesia. Such plantations may look like 'forest,' but Gorshkov and Makarieva argue that the biotic pump doesn't work over monoculture plantations as well as over natural forest. Photo by: Rhett A. Butler Victor Gorshkov and Anastassia Makarieva: As with all life processes, the biotic pump is a highly-organized complex process. In order to sustain condensation that keeps the air pressure low on landso that moist winds blow to land from the oceanthere must be intense evaporation from the forest canopy. But evaporation diminishes the amount of moisture in soil. Moisture is additionally lost from soil by gravitational runoff. If all the soil moisture is gone, evaporation stops, and so does the atmospheric moisture transport. This means that a non-trivial balance must be maintained: forest evaporation must be exactly such that it never fully depletes the soil moisture but at the same time is intense enough to ensure that the amount of moisture brought from the ocean by winds compensates moisture losses in the soil. Native species that form natural forest communities have evolved a complex set of genetically encoded biophysical and morphological traits that make the biotic pump possible. These traits took hundred million of years to evolve. For example, the root system of forest trees facilitates both storage and extraction of moisture from soil; biogenic aerosols produced by trees control the intensity of water vapor condensation over the forest; the large height of trees determines the vertical temperature gradient under the canopy, keeping soil evaporation under biotic control; tall trees are also essential for surface friction that does not allow extremely high wind velocities to develop. Thus, natural forests not only create an ocean-to-land moist air flow, but also stabilize this flow at an optimum level and prevent its extreme fluctuations like hurricanes, tornadoes, severe droughts or floods. Species other than plants (bacteria, fungi, animals) are essential for the stability of the forest ecosystem itself. Monocultures or plantations consisting of a random set of plant species do not possess the required set of correlated traits. To give two extremely simplified examples: if one plants cacti, they will evaporate too little and will be unable to keep the atmosphere persistently moist. If one plants eucalyptus, they will evaporate readily but will be unable to prevent soil from drying. In either case, the biotic pump will not work. Generally, information fluxes processed by the natural biota exceed by twenty orders of magnitude the information processing capacity of modern civilization. It is not possible to create a technological analogue of the biotic pump. THE SCIENCE BEHIND THE BIOTIC PUMP THEORY This figure shows the "tug-of-war" between the forest and the ocean for the right to become a predominant condensation zone. In Fig. a: on average the Amazon and Congo forests win this war: annual precipitation over forests is two to