As our Biological Integrity page points out, restoration to what used to exist before Europeans arrived in California is impossible, no matter what point in pre-contact history you aim for. So the definition of restoration–a return of something to a former, original, normal, or unimpaired condition–leads us to pursue going after “unimpaired” with regards to nutrient, mineral and water cycles. The biodiversity that has been lost cannot be replaced. It is gone for good, at least from the perspective of humans. Perhaps long into the future, biodiversity will again be on the increase, but we are talking geological time. In fact, soil itself is so depleted that to imagine ever reaching a “maximum” state seems impossible.
Globally, there is not one biological community that is in better shape than it was at the dawn of agriculture. In 10,000 years, humanity has destroyed the biodiversity and fecundity of millions of years of evolution and weathering. Therefore, the primary goal of humans for the rest of our time here on earth, should be restoration of the soil. [i]
And aside from mechanistic energy-intensive techniques, or very precise manipulation of plant communities, it is very difficult to build soil without biological integrity. So it should be the focus of restoration, which would not only lead to soil-building and healthier nutrient and water cycles, it also would create more complex community dynamics (see below).
Along many creeks in our bigger region, especially where mining of gravel has taken place, dense stands of arundo or tamarisk have sprung up, the natural world’s way of revegetating severe disturbance. While willow and mule fat are still present throughout the region, “invasives” have stepped in to fill the role of prolific pioneer species. Is there a succession (defined below) to another community at some point, or are we locked into a pattern where ongoing degradation–precisely what makes these invasives thrive–ensures the proliferation of these non-native plants? From the perspective of life’s desire to create more life and more complexity, a non-diverse dense stand of arundo is better than almost no plants at all. This is that type of natural restoration that deals with an emergency situation. Nature just wants to stop the erosion and start building up organic matter again, ASAP.
So from a land management perspective, vegetated soil beats bare soil, and therefore revegetation, even of non-natives, is better than desertification. Better yet is revegetation with perennial plants, whose roots go deeper and hold water and carbon longer. The goal, however, ought to be as diverse a mix of native perennials and annuals as you’ve ever seen, with mature oaks and other native trees creating a significant canopy over the land.
Ecological succession is the process by which the structure of a biological community evolves over time. Two different types of succession—primary and secondary—have been distinguished. Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment.
Primary and secondary succession both create a continually changing mix of species within communities as disturbances of different intensities, sizes, and frequencies alter the landscape. The sequential progression of species during succession, however, is not random. At every stage certain species have evolved life histories to exploit the particular conditions of the community. This situation imposes a partially predictable sequence of change in the species composition of communities during succession. Initially only a small number of species from surrounding habitats are capable of thriving in a disturbed habitat. As new plant species take hold, they modify the habitat by altering such things as the amount of shade on the ground or the mineral composition of the soil. These changes allow other species that are better suited to this modified habitat to succeed the old species. These newer species are superseded, in turn, by still newer species. A similar succession of animal species occurs, and interactions between plants, animals, and environment influence the pattern and rate of successional change.[ii]
Restoration of degraded lands can be more successful if the causes of succession and their driving mechanisms are identified. Also, knowing the likely successions in a local plant community can be very valuable to a restoration plan. Observing what happens after disturbances, introductions of new species or a lot more of ones already present, changing weather patterns, and targeting weedy species for removal are just a few of the dozens of dynamics to monitor as you engage in restoring land. Years of these observations will make future planning easier, but the complexities of the natural world are impossible to know. Educated guesses based on site-specific monitoring, historical information and some background reading on each species is our current approach.
Of all biological processes, the relationships between species may very well be the most important. Even within mature and relatively stable low-pollution communities, species composition, age structure, populations and much more are in a state of flux due to varying weather patterns alone. There are obviously hundreds (millions?) of factors beyond the scope of human understanding. This never-ending development of relationships is called community dynamics, and it is the foundation of a healthy world. The more simple the community becomes, the fewer relationships there are, the less dynamic and less resilient the entire community. Simple communities are counter-evolution, the opposite goal of restoration, and they are caused by the vast majority of human activities, especially agriculture, mining, urbanization and chemical pollution.
Restoration. It is a never-ending process, and the sooner we humans get on board with it, the less painful the future looks for our descendants.
i Even the most ardent supporter of global commerce and modern convenience, when presented with the full analysis, in their terms–economics–can’t reasonably argue that restoration is not essential to our continued existence. For example, restoration of one watershed in Utah using beavers as primary agents of change, provides free benefits not obtainable via any human technology. The analysis summary states: “If beaver populations reached their regional potential, the annual value of benefits could reach well into the tens, even hundreds of millions [of dollars].” These services include sediment retention, delayed stream flow, riparian, wetland, and aquatic habitat restoration, pollutant removal, water temperature stabilization, flood resilience and recreation.