What’s Wrong with Transplanting?

By Eilene Lyon

First, this post is not about putting vegetables in your garden, though I’ll point out that there are many reasons you shouldn’t put non-native ornamentals in your yard.  The problems we have here in the western U. S. with tamarisk and Russian olive are an illustration of what can go wrong.

Rather, I want to point out the problems with using transplanting as a method for dealing with threatened and endangered species, both plants and animals.  I will illustrate with a couple of projects that I have been involved with in my biology career: Brack’s fishhook cactus (aka Brack’s hardwall cactus) and desert tortoise.

Why We Transplant

Let’s face it, 7+ billion human beings have an enormous impact on the natural environment.  We drastically alter where we live, where we grow and gather our food, and where we procure our energy resources and raw materials.  Our seemingly preferred environment consists of a lot of concrete, asphalt, mono-culture crops, and the use of machines, chemicals and other not-naturally-occurring substances.  For some reason, a lot of other living things don’t do so well in such places.

Inconveniently, our continuing development (not as a species, but in terms of construction) has led to many species becoming rare and endangered.  Many of them are only found in a small area and are known as endemics.  Others are found over vast areas, but still need specific environmental elements to survive.

In an effort to alleviate the impact we have on listed species, if they are found to exist in an area slated for development, we scoop them up and move them someplace more suitable (for us, not them).  This is not to be confused with species reintroduction, which is a subject for another time.

Brack’s Fishhook Cactus (BFC) (Sclerocactus cloverae ssp. brackii)

This small, ball-shaped cactus is endemic to San Juan and Rio Arriba counties in northwestern New Mexico.  It is considered a Bureau of Land Management (BLM) sensitive species and New Mexico endangered species.  It grows specifically on sandy/shale soils of the Nacimiento Formation.  Here is an example of the natural habitat of this species.

All ball and barrel cacti are struggling to some extent.  This one happens to live in an area of extensive oil and gas development.  That is not the only thing that threatens the BFC.  Horses and cattle trample them.  Flash floods wash them away.  Rodents and rabbits eat them.  Beetles lay their eggs in them and the growing larvae eat them from the inside out.  Some of them die every year from these impacts.  But oil and gas is unique in that it can wipe out dozens or hundreds at a time when a new well pad, pipeline or road is constructed.

BLM guidelines are designed to minimize this impact by locating development outside of habitat conservation areas whenever possible.  Qualified individuals (such as myself) will conduct pre-planning surveys for the presence of BFC.  If cactus habitat can’t be avoided, the BLM will sometimes grant a permit to transplant them, under the supervision of a trained horticulturalist.

So, what’s wrong with that?  We’re saving cacti, right?  No, we’re not.

The Problem with Transplanting

Before we dig up BFC and move them, we have to find a suitable place to re-plant them.  Usually it isn’t far from the original impact site, therefore, it is still within the general area of development.  The transplant site should have an existing population of BFC, both to prove the suitability of the habitat and to serve as a control.  The site is surveyed and the existing BFC are marked.  Then we do the transplanting and mark those, too.

The process of digging up a cactus and moving it is strike one.  Some will simply not survive the process, regardless of how careful we are.  Strike two is that we have now endangered the existing population by trampling the area, and by possibly placing more cacti in an area than can be sustained with the available resources (e.g. water and soil nutrients).

The third strike is the requirement that we monitor the transplant plots every year.  Again, we are trampling the site just to determine how many BFC died – and many do, both transplant and control.

Desert Tortoise (Gopherus agassizii)

Essentially the same process I’ve described for the BFC is sometimes used for desert tortoises living in the Mojave Desert of southern Nevada, eastern California and northwestern Arizona (and a tiny portion of Utah).  The tortoise is listed as threatened by the U. S. Fish and Wildlife Service.  They are found in a variety of desert habitats, but must have soil suitable for digging burrows, where they spend the vast majority of their time.  Most will live within the same square mile for their entire 50 – 100 year lifespan.

In additional to habitat loss due to construction activities, the tortoises are threatened by vehicles (on- and off-highway), disease, vandalism, illegal collection for human pets, and predation by ravens.  The raven problem is human-related, and I do not agree with vilifying the birds as some conservationists do.  Military development and utility-scale renewable energy projects also have a serious impact on tortoise habitat.  Here’s an example of desert tortoise habitat.

As with the BFC, construction projects are preferably located outside tortoise habitat.  But sometimes it can’t be avoided.  Trained biologists will accompany construction crews and any tortoises found will be moved, usually nearby.  For a road, pipeline or powerline, this is probably not terribly detrimental to the tortoises.  But when a large project covers many acres or square miles (e.g. military base, airport, or solar farm), the number of tortoises being translocated will have an impact similar to what I demonstrated for the cacti.

Tortoises are territorial.  Translocating a tortoise to a territory already occupied by another tortoise is stressful for both, and one will sometimes die as a result.  Most often it will be the newcomer.  Just handling a tortoise can be a threat to its survival.  Translocated animals (of any species) are always at a higher risk for predation, as well.  Anyone who has worked on desert tortoise projects can tell you about the numerous carcasses to be found in translocation areas.

Granted, there are now areas where tortoises have become extirpated, and tortoises will not face competition from an existing population.  But why did the extirpation occur?  Are those threats still existent?

What is the Best Course of Action?

We really know how to have a negative impact on other species.  What we usually don’t do well is fixing the problems we’ve created.  Frequently, we take a bad situation and make it worse.  There are always unintended consequences, collateral damage, if you will.  We simply do a poor job of envisioning outcomes over the long term.

I do appreciate the efforts of all the people who are trying to mitigate our harmful actions.  But the best course is to avoid it in the first place.  Once the damage is done, the best course is sometimes – do nothing.

Take your finger off the button; step back from the control panel; don’t just DO something – Stand There!  Let nature reassert herself in whatever way she deems appropriate.  She can see much further than we ever will.

Sources:

Bureau of Land Management (BLM) Special Status Plant Species (SSPS) – Brack’s Cactus and Aztec Gilia. https://www.blm.gov/policy/im-nmf01210-2017-003

New Mexico Rare Plants. Sclerocactus cloverae ssp. brackii (Brack hardwall cactus). http://nmrareplants.unm.edu/rarelist_single.php?SpeciesID=162

U. S. Fish and Wildlife Service. 2011. Revised Recovery Plan for the Mojave Population of the Desert Tortoise (Gopherus agassizii). https://ecos.fws.gov/docs/recovery_plan/RRP%20for%20the%20Mojave%20Desert%20Tortoise%20-%20May%202011_1.pdf