☔️ Water series: Interactions of flora with water and climate: Difference between revisions

==Water and ecosystems==

As much as we vertebrates need to regulate our bodies salinity by peeing, “transpiration” help plants evacuate the excess of soil water they pump from the ground to convey nutrients through their roots.<ref>Plants roots actually absorbes water thanks to osmotic laws, by the use of metabolic energy in cells to increase the salts’ concentration inside the roots, so that the soil water is less concentrated and gets in. However, this process called “active” is less important that of the “passive” absorption of water caused by the leaves’ transpiration that creates a suction from bottom to top, throughout the plants tissues.

</li><li>https://en.wikipedia.org/wiki/Ocean_acidification</li></ul></ref>

Depending on the geography of the land where it falls down, this evaporated water would have different effects on the land and ecosystem. Afterward, water will pursue the “hydrologic cycle”<ref name="wikisource" />, either by running back to oceans, evaporating, or being fixed for a time<ref>The residence time of water depends on where it is stored: see table (approximations).

source: https://en.wikipedia.org/wiki/Water_cycle#Residence_times</ref> as groundwater or ice. However, much more water is stored than actually moving through this cycle. Among the effects of rain on land, erosion is the most double-edged one. Erosion happens when water falls on a surface that is either already saturated with water, or simply waterproof (artificial covered soils or agricultural compact soil); making urbanisation and agriculture foster floods and erosion of the soil, which could destroy vegetation and the humus soil layer, thus entire ecosystems. Erosion is however the process that let seawater and fresh water to grab nutrients (salts) from the rocks it runs on, allowing the life soup to stay rich and salty.

Along with the climate and geography of the land, the way water is distributed affects greatly what type of ecosystems would exist: if water is scarce and hidden in the ground (deserts), saturating the air and the soil (equatorial and continental forests), flooding vegetation permanently (wetlands) or frozen with the soil as permafrost (toundra and taïga); water “decides” who will thrive and where. In most of those ecosystems, the plants growing thanks to water will have an important retro-effect on water distribution: when rain falls on vegetation, a share of it will never reach the soil and be captured by leaves, while the excess of water that the soil can’t absorb wont run away, because tree trunks and plants will slow it down. Combined with plants inner water, we can state that vegetation is like a big sponge slowing the water from joining streams and rivers locally, thus regulating floods and erosion.<ref name="wikisource" />