DEEP ECOLOGY

Multi-species Reforestation, Stability and Complexity

In a recent discussion the topic of Deep Ecology came up.  This concept focuses our attention on the fact that humans are not outside observers of the natural world, but are very much a part of it.  The goal of this type of thought is to accept the intrinsic value of all species in an ecosystem, not just those of immediate economic value.  It also focuses our awareness on how human actions, both individual and collective, impact the natural world every species depends on.  In the field of physics this concept is embodied in the uncertainty principle or the observer effect.  In the field of ecology we are participating components not just observers.

Much of human progress has hinged on our ability to select economically valuable species for cultivation and grow them at high densities in mono-crop environments.  My formal education was in marine microbial ecology.  At the time I was in graduate school there was much interest in growing oil rich algae at commercial densities.  The oil shortages of the 1970's were in full swing.  Interest continued even after that particular oil crisis abated since the ability to grow algae as a crop suggested other applications such as commercial culture of clams and oysters.  Anyone who has done this type of work has dealt with the inherent instability of simple biological systems.  In short, population levels tend to oscillate and crash.  Aquaculture has battled this demon since its inception.  We would joke about the old adage that you can recognize a pioneer because he is the one with the arrows sticking out of his back.  In its pioneering days, commercial agriculture spent thousands of years trying to resolve the problem of mono-crop stability and to this day relies heavily on chemical fertilizers, pesticides and herbicides to manage unstable situations.

This brings us to the question of why we would bother with planting dozens of indigenous and endemic species in our reforestation effort when they have little or no economic value.  The centerpiece of the HLH model is koa, a tree of high economic value.  One could argue that sandalwood may have future economic value, but you would be hard pressed to put a dollar value on most of the shrubs and ground covers that are being established throughout the Legacy Forest. To my mind, their value is intrinsic in the complexity they bring to the environment.  Many of these plants provide forage for native birds, but other roles they may have in the environment are not as easily catalogued. 

A lot of research has supported the idea that more complex ecosystems are inherently more stable.  The reasons for this are not always clear.  It is easy to understand why a system with one prey species and one predator species would be unstable, but why would this be true for plants alone?  In a climax forest the relative numbers of the different plant species change very little with time.  These systems tend to be more resistant to pests and catastrophic collapse.  In a way, the mix of native species is sort of an insurance policy or safety net.  Ultimately we are not building a native ecosystem, it is self-assembling.  By planting a wide variety of plants that once were found on the site, we are providing raw materials for natural selection to find its way to a complex and stable ecosystem.  Historical records give us some guidance as to what was here in the past, but what will be here in the future is harder to predict.  Climate change will continue to change what the new balance of species will be.  The only thing we can do as stewards of the land is to provide a diverse pallet of species for the environment to work on.  Now we get to see what nature will do with them.

A couple of books were key in articulating these concepts.  The earliest was Alfred J. Lotka in "Elements of Mathematical Biology" published in 1925.  In 1973 Robert M. May explored the question further in "Stability and Complexity in Model Ecosystems".   

Weathering the Storm

Hawaii Island has stood in the path of tropical storms for a half a million years.  The diverse ecology found in its native forests evolved with the backdrop of those storms exerting its relentless selective pressure.  Early in August we had a tropical storm make landfall on Hawaii Island.  Within our project area we had only minor signs of the storm's passing.  The high rainfall was a welcome addition to what are normally dry summer months. 

Eucalyptus photo taken after the storm Iselle August 26, 2014

The wind damage was primarily to non-native trees such as Eucalyptus.  Eucalyptus trees were blown onto roads and power lines creating more inconvenience than catastrophe.  In other parts of the island, the story was the same.  Native forests have the composition they have because they can withstand occasional brushes with tropical cyclones.

This has been a great year to be a tree.  Over the years we have found that established koa trees can withstand considerable drought conditions.  We've also discovered that given even moderate rainfall during the summer months they will grow before your very eyes.  This has been that kind of year.  Some crew members, like the nursery crew, only get out into the field once in a while.  Every one of them has been amazed at the changes from visit to visit.

Koa photo taken after storm Iselle August 26, 2014

If you haven't been here in a while, you also will be amazed at the growth.  Book a tour and bring a raincoat.

http://www.hawaiianlegacytours.com 

dfox@hlh.co