Beneath the Surface – Land or Water

Finally, in 2020’s “Science of the Forest” has progressed to connections with “Science of the Soil”. Aldo Leopold in his essay The Last Stand published in Outdoor America in 1942 recognized this connection in the early days of forest management.  It only took eighty years of scientific experimentation to understand his concept the health of the microflora of the soil (bacteria, molds, fungi, insects, and burrowing animals) “constitute half the environment of a tree”. We have gone through the same scenario with the tall grass prairies and the value of the soils that their original plant community created.   Perhaps, we must consider this knowledge of the forest/prairie and apply it to the aquatic environment of the same. Just as we have applied our forest/soil knowledge to preservation and forest practices we need to apply it to our lake management.

Leopold also knew the connection between a forest wilderness and old growth trees as a place where the relationship between forest health and the accumulated soils below would be a secret to the way we should manage our forest. He knew the value of selective cutting rather than clearcutting in maintaining the productivity of the soil. Whether it be prairies or forests, nutrients and fertility lie in the soil below and are channeled up through the plant and animal community efficiently unless there is a drastic change, such as intensive farming of the prairie and clearcutting of a forest. Perhaps the same is occurring in lakes …are  the nutrients accumulated in the sediment over tens of thousands of years and released to the lake critical to the health of a lake?

One would expect it to be the same for a lake.  Have we learned the lessons of what happened ecologically to our prairies and our forest to apply it to our lakes? Or will the economic incentives that have despoiled the prairie and forest continue to occur in our lakes and rivers.

The organisms that live in and around a lake, like the plants and animals that live in the forest, are part of the lake’s rhythm of connectiveness. Most of these organisms eventually return to the bottom soil and provide nutrients to be recycled up the food chain the next growing season. Yet, just like every farm field on the landscape is different, so is the lake and where it is located. Lakes in country with fertile soil will produce a greater and wider diversity of organisms unless the runoff from the upland creates an environment where the lake’s excess nutrients cannot be absorbed into lake’s evolutionary recycling.  Wisconsin lakes that are surrounded by fertile lands that created wealth and urban communities have succumbed to the values of economic gain that have led to the changes and disturbances where nutrient are now in excess.

One must understand a lake’s ability to withstand disturbances under the pressure of economic gain and change. In Northern Wisconsin lakes nutrients are limited in the soils of the surrounding forest, lake bottoms and wetlands. These nutrients entering the natural lake’s cycling are limited and the pressures of economic gain and change can have a greater impact. In our attempts to protect and manage the resources of our Northern lakes we have made … and continue to make many mistakes … that are continuing to break the connectiveness that time has made. Just as agricultural science began understanding the soil of the farm field and started to add fertilizer and pesticides to increase production this pattern has been played out in the management of our pristine lakes of the Northwoods.

For example, the practice of stocking walleye and muskellunge, that is now exceeding 100 years of operation, was to increase the production of the harvestable crop- fish. We should have realized by now it has not worked. Early science and experience in hatchery that produced and stocked 2-3” fingerlings were just added food for 5 to 7” two-year-old fish of most every species including the stocked muskellunge  . There is no evidence that this large expense in increasing production of a harvestable crop of these game fish as adults has occurred.

But after 65 years of this type of production a move to hatchery rearing and stocking of extended growth or bigger fish was the answer to greater of productivity of harvestable fish. Now after 12-13 years of this effort we find very few of these produced fish again have recruited into a harvestable crop. Should we ask what this most recent effort has done to the health of natural population of not only the stocked species but to all species and the organisms that support them?

The other aspect of fish management reacting to the economic demand for more harvestable fish was the assumption humans had overharvested the fish and that limiting harvest of natural population by regulation was the answer. This aspect of fish management originated in the depletion and disruption of the native fish of the Great Lakes by commercial fishing to feed the ever-increasing human population in the port cities of the same lakes in beginning in the mid 1800’s. In general, the reduction of bag limits and the increase in size limit, has been carried into the management of the inland fisheries in the 1900’s. As a result, of this continued fish management practice we have created a culture of sports fisherman who practice catch and release and seek only the trophy believe this is the answer to conservation of our fisheries.

Yet this too has not worked. Fish management to protect the large spawning walleye  and harvest the slow growing smaller fish to preserve the fishery is not working. Our fish scientists proclaim our walleye population is at the tipping point where the species presence itself may be at risk. Perhaps it is time to REALLY rethink how the production of a fishery is tied to restoring the channeling of nutrients from bottom soils through the food chain that further maintains water quality is the answer. It is time to shift fish management to be a part of a lake’s sustaining ecosystem of saving all the parts and stop tinkering with a single or two species of fish.

It is not only an answer to creating a sustainable fishery again but also an answer to the plethora of exotics that we are exposing our lakes from our  increasing economic necessity to develop and use lakes. A healthy and functioning lake is the best defense against exotics becoming established. In the long run a healthy lake, just like a healthy farm or forest that understands the soil beneath and connects it to the growing environment above, is the key to its sustainability.  Native species and habitats will prevail, and exotic populations will decline and reverse. Our pristine lakes of the Northwoods are where an understanding of the natural processes of ecology that have evolved over time can still be applied to resist disturbances under the pressure of economic gain and change.