investment( tectonic lift or volcanic energy), or to put it another way it was a massive energy investment. And the ongoing maintenance investment is small change( erosion), a lower energy investment. The mountain is more durable because the initial investment was very energy costly. But the maintenance investment( erosion) is long and typically requires a lot less energy.
By contrast comparatively less energy is invested in growing a tree or a blade of grass, but their ongoing maintenance investment is higher. I’ m not at all suggesting the investment in a mountain or a tree are equal 11. I’ m saying the rate at which Nature turns over its investment is based on the level of initial investment. The rate of maintenance investment for mountain ranges is millennia to centuries; forests centuries to decades; and prairies decades to annual. The maintenance investment is based on the energy needed to develop the systems in whole and the rate at which it is expected to turn over and made anew.
But there is a second aspect to the anticipated ROI on the investment Nature makes in building something. When the object or system does eventually succumb to the change( i. e. when it erodes, decomposes, or turns over, etc.) its
decomposed or eroded state provides the capital for the investment in a new object or system. Those minerals eroding out of the mineral bank of a mountain are being used to feed other types of systems or the development of a new system or object. They might collect along a mountain stream bank and provide the nutrients needed for growing a riparian habitat system. Or maybe those minerals wash all the way to an ocean and feed a marine estuary. Either way, the ROI is recycled as capital into another system or, as in the case of forests and prairies, it is invested on site in perpetuation of the existing system. 12
The two pieces of the ROI work together. Nature doesn’ t typically invest in relatively low cost systems and then invest costly maintenance energy without still getting something for it. Using our examples, prairie is a pretty low‐cost initial investment, but fires are pretty expensive maintenance investments. Nature gets more from the fire than turning over the prairie. The maintenance investment cost of fire on a prairie, or in a forest for that matter, leads to locking up a LOT of carbon in the soil of the system. A net positive effect for Nature. To put it differently, when Nature does invest in high cost( energy) maintenance it’ s getting a pretty good value for the investment.
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Nature does apply the basic principle of accounting, credits equal debits, but the accounting at an ecosystem level is really complex.
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An ecologist once shared with me that it’ s as if nature was stingy. Once Nature has invested in something it tries to eke out as much value as it can get from its investment.
6 | LEARNING FROM NATURE