Figure 4.5 Relatively few species can tolerate the special conditions of salt marshes, but those that do create ecosystems of great importance. Salt marshes buffer upland areas from ocean storms. They also export large amounts of organic matter to adjacent estuaries, which constitutes a key component of the estuarine food web.

      (Trish Hartmann/Flickr/CC BY 2.0)

The economic values of ecosystems for both goods and services were compiled and a grand tally of their economic value estimated by multiplying a value‐per‐hectare figure for each major type of ecosystem by the total global area of that ecosystem (Costanza et al. 1997a). The estimate of $33 trillion per year was considered an average figure because of the nature of various uncertainties within a range of $16 to $64 trillion. To put these figures in perspective, the gross national products of all the world’s nations totaled about $18 trillion at that time.

       Spiritual Values

The journeys people make to natural ecosystems, to places where the hand of humanity is hard to detect, are often too profoundly important to be reduced to dollars and cents (Fig. 4.6). The forty days Moses spent in the desert, the walkabouts of Australian Aborigines, and perhaps the night you spent watching the tide ebb and flood are periods of spiritual recreation and revitalization that many people find of immeasurable value. For some people, particularly those who are pantheistic (i.e. believe that God is nature and nature is God), ecosystems provide far more than an aesthetic setting for these experiences. The ecosystems themselves, with their depth and complexity, are a source of inspiration, a vehicle for feeling connected to something larger and more permanent than one’s self. It is notable that all the world’s major religions advocate respect and stewardship for “creation.”

Figure 4.6 Many people visit natural ecosystems to feel a sense of spiritual renewal, for example by walking this path in Japan.

      (Sean Pavone/Shutterstock)

       Scientific and Educational Values

      Ecology has become a very sophisticated science, but we still cannot hope to understand an ecosystem fully. This dilemma is apparent when you think of ecology as the apex of a pyramid with biology as the next layer below, earth sciences such as geology and climatology forming the third layer, chemistry the fourth, and physics the foundation. Of course, ecologists do not need an intimate familiarity with quantum physics to be effective, but they do need a basic understanding of thermodynamics, electromagnetic radiation, and many other aspects of physics. In contrast, a physicist can be highly successful and understand nothing about ecology. The fact that ecosystems integrate so many phenomena makes them a focal point for scientists trying to monitor how the Earth is changing, particularly in response to human activities. This feature also means that ecosystems are fascinating models for researchers interested in complex systems, for example by modeling how carbon moves through ecosystems to better predict global climate change (Harris et al. 2014).

      Ecosystems are also wonderful models for showing children and adults how everything in the environment can be connected to everything else. Drawing lines between boxes to represent the functional relationships of those boxes can become an extremely complex exercise. Alternatively, it can be as simple as drawing lines between the sun, a plant, and an animal to form a food chain and then adding more boxes and lines to create a food web. How did that cup of coffee you are drinking get into your hands? In short, we can all learn a great deal from ecosystems.

       Ecological Values

      The ecological interactions that are the basis of ecosystems are absolutely fundamental to life. Try to imagine a planet where dead things did not decompose, where water was not filtered through forests, or where plants did not replenish oxygen. Consequently, it is not really profound or insightful to say that ecosystems have ecological value. Nevertheless, it is extraordinary how often we try to place the well‐being of humanity over the well‐being of the ecosystems on which our lives ultimately depend.

Do all ecosystems have equal ecological value? No. Obviously, a large salt marsh will usually provide more ecological values than a small salt marsh, and, similarly, a dominant type of ecosystem such as spruce–fir forests will have more total ecological value than an uncommon type of ecosystem such as caves. Certain types of ecosystems may have a significantly greater importance to other nearby ecosystems than we would predict based on their area. We can call these keystone ecosystems, analogous to using the term keystone species for species with disproportionately significant ecological roles (Chapter 3; deMaynadier and Hunter 1997). The long narrow shorelines where aquatic and terrestrial ecosystems intersect are an excellent example of this (Fig. 4.7). Keystone ecosystems can also shape disturbance regimes that affect large areas by either inhibiting or facilitating the spread of a disturbance. To take two examples: a river can inhibit the spread of a fire, while certain types of woodlands that burn easily can facilitate the spread of fires to other ecosystems. Some of these keystone ecosystems are very small but have effects over large areas, for example, a cave that harbors a wide‐ranging colony of bats or a small pool that provides essential water for animals in a sizable landscape (M.L. Hunter 2017 ; Hunter et al. 2017; see Fig. 4.4).