Old growth trees pierce clouds and catch fog droplets as they do pollutant particles. An old tree collects droplets on perhaps 60 million needles, a surface area of one acre. Fog drip can add 8 inches of precipitation to an ancient forest during the dry months, increasing stream flow when it is most needed. Clear-cutting diminishes the source of water for decades or longer. Temperate, wind-pollinated conifers are among the most genetically variable organisms known.
Genetic diversity provides a natural hedge against insect and disease damage.
But an array of trees, protected by different compounds at different chemical concentrations, diminishes the chances of a general outbreak. Naturally variable varieties can better adapt and survive the unpredictable future climate conditions. Old growth has survived the cycles of the past. The surfaces are also filters for collecting anomalous dust and droplets, whether natural or human-caused pollution. Plant photosynthesis removes carbon dioxide gas from the atmosphere and stores it as biomass in leaves, branches, tree trunks, snagss, downed logs, duf, pots and soil.