One of my fondest memories of visiting Arizona was visiting a small oasis on the border of Mexico in Organ Pipe National Park. It was a brilliant gem in a dry and burning desert, a shallow spring-fed lake with cat-tails and coots. There was a stream that led all the way back to the spring source, and given enough time I am sure I would have found it. But the thing that impressed me the most about the oasis was the seven cottonwood trees.
These trees had been planted at the oasis over a century ago by settlers who were moving through the area. Cottonwoods do not normally grow in the desert because of their need for water, being a succulent. These seven giants drank from the oasis and provided shade to the mesquites nested around them. Their leaves quaked in the wind gently as the desert breeze moved through them, echoing the silence and serenity of the spot.
However, these trees have a problem. All seven are female. They have no male trees to fertilize them and create seeds. This means that when they die off, there will be no more cottonwoods at the oasis.
And now the ethical dilemma. Would you make sure that the trees were germinated or made babies or would you let nature take its course? The cottonwoods were not native to the area, being placed there by man. They are not natural to the environment, but encapsulate what the oasis means. To leave the trees to their own devices would ensure that you kept the oasis in its natural and untampered condition. But if the trees were to die off, there would be no cottonwoods for future generations to enjoy. Putting aside laws and regulations regarding such things, what would you, as a Park Ranger, do?
This is not, strictly speaking, correct. Cottonwoods will grow throughout the desert wherever there is water–a stream, a river, a spring, an oasis, or a really high water table.
Just because there didn’t happen to be cottonwoods growing at that particular oasis when the settlers got there, and so they went ahead and planted some, doesn’t necessarily mean that cottonwoods had never grown there before, or that, left to their own devices, cottonwoods wouldn’t have managed to seed themselves.
I am not saying that we should remove the trees, the real question is whether you would let them die out or plant new ones. Let’s keep this discussion about the trees please.
Btw december, it’s a little drive right along the border to get to it. The oasis is called Quitobaquito.
One vote here for “let nature take its course”. If the trees die, so be it. If new cottonwood seedlings come in from somewhere else, so be it. If you start micromanaging flora that wouldn’t normally be there, then you’ve got a “botanical garden”, not a “National Monument”.
If you focus on preserving a stand of cottonwood trees that wasn’t originally there, then what you’re actually preserving is just the historical fact that settlers once went through the area and planted cottonwood trees.
To me, the cottonwood looks way out of place in the picture. Although it may be able to live here, it doesn’t look right to me. All the other brush is scruffy and small–desert brush–and those saguaro cactus…well, cottonwood trees just don’t blend in well with saguaro cactus, IMO.
Thanks for those nice links, DDG. I agree with you. Leave it alone. The best part of the desert is the desert vegetation, like the organ pipe cactus (duh). We can see trees lots of places.
**suc·cu·lent** adj.
1. Full of juice or sap; juicy.
2. *Botany.* Having thick, fleshy, water-storing leaves or stems.
3. Highly interesting or enjoyable; delectable: a succulent bit of gossip.
n. Botany
A succulent plant, such as a sedum or cactus.
Succulents such as cacti are well adapted to desert conditions. Cottonwoods do grow well under dry conditions, but they are not succulents.
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IMHO, someone should bring in some pollen, and let nature take its course.
But…bringing in pollen isn’t “letting nature take its course”. Letting “nature takes its course” means leaving the situation alone, means letting the cottonwoods of Quitobaquito die out in the next 50 years or so, as there isn’t a breeding population. (Assuming that the cottonwoods that the settlers planted were the familiar eastern cottonwoods, which have a life span of about 80 to 100 years, their time is about up.)
It’s a little odd that after 100 years not a single pollen grain has blown in on the wind and produced a male tree. Surely these aren’t the westernmost stand of cottonwoods in the country ? Even if they are, that’s a lot of air and a lot of time for them not to have produced seed. Bringing in pollen would settle the question of whether or not the trees have the potential to form a viable breeding population. If no seeds form, the stand dies out. If the trees are viable, the stand will continue. That’s what I meant by allowing nature to take its course.
The trees have already disrupted the ecology of the oasis. There’s no way to go back to the pristine conditions of the 1800’s. If we allow the stand to die out that’ll disturb the current ecology. If we plant a bunch of male cottonwoods, they’ll be around for 150 years regardless of whether the population is viable, and during that time, the life at the spring will evolve further from it’s old “natural” state. If the trees all die 150 years from now, the disruption will be greater than if we allow them to die over the next few decades. If we bring in some pollen, the current ecosystem may become self-perpetuating. If it doesn’t, the trees will die and the system will move back towards it’s previous self perpetuating condition. IMHO a self-perpetuating ecosystem produces the most desirable outcome.