Exercise in futility

This thread is overrun by specious arguments. Chill, flabotany.

I got tired of reading all the "back and forth" debate but I wanted to say that I am 74 yrs old and have seen kudzu ever since I was a little kid in Augusta, GA. It was excellent at stopping the red clay from washing down hills onto the roads (killing people because red mud is "Slippery when Wet". I never saw it overtake vast areas or kill wonderful native plants or .....

The loss of native species through unsuccessful competition is sad isn't it. That's what evolution is all about. (sorry if some of you don't believe in evolution). I think one of the most invasive species around me are all these "native" white tail deer that eat peoples' plants and crash into peoples' cars at night. Wish we had wolves to control the deer but I wouldn't say that if they killed my much loved dog, would I?

I think what I believe is that it's a real complex situation and if you want to be upset, go ahead, but I probably won't believe you are correct.

flabotany - I dare you to plant running bamboo, wait five years and still make this same claim:

There is a major flaw in the argument that invasives increase diversity. I am a biologist, and have the joy of teaching undergraduate ecology. One of the first things they learn is that the species diversity of an area takes into account two different factors-- species richness and species evenness. Species richness is the absolute number of species in an area; this is what might increase when invasive species become part of the ecosystem. Species evenness refers to the relative abundance of each species. Let's say you have habitat A, which contains 5 different species, all of which are abundant in the system, and habitat B, which has 5 species as well, but only one species is abundant and the rest are all rare. A biologist would say that while species richness is exactly the same for the two habitats, habitat A has the greater species diversity. The problem with invasives is that while they might increase the absolute number of species in an area, they tend to reduce evenness-- which often causes the system to reach a point where-- from a biologist's perspective-- species diversity is REDUCED.

I've heard the argument many times before that humans are part of the system too, and if plants/animals/etc. get moved around by us it doesn't really matter. Also, people cite that competition is natural, and evolution will eventually determine the winners and losers. The problem is that invasives that are initially brought to an area by humans are given a leg up-- they have suddenly been transplanted to an area where they are no longer held in check by their own predators, the diseases they might have been susceptible to in their home environments, or the competitors that the initially evolved with. Evolution can be fast at times (I have a colleague who has demonstrated extremely rapid evolution in aphids-- much to my dismay), but for the most part, it is a very, very slow process. Plants and animals can't always just adapt to the new situation (the most common fallacy in people's understanding of evolution is that individuals evolve. They don't. Populations do, over time, as changes in the frequency of certain genes occur throughout the population over time). Because invasives have the opportunity to reproduce at will, without being checked by the same processes that would check all the other species in the area, they have an unfair advantage, that I would argue is not particularly natural.

Next, about invasives not driving anything else extinct: I beg to differ. The invasive brown tree snake has been credited with driving 11 bird species in Guam to extinction. Likewise, Hawaiian birds are being decimated by mosquitoes which carry avian malaria & pox, feral cats, and mongooses, all of which were brought over accidentally or intentionally by humans. Some species are down to fewer than 10 remaining individuals, and are not expected to recover. Island species are particularly at risk from invasive species because they have evolved in isolation for so long. Ever wonder why so many island birds are flightless and nest on the ground? There were no rats or mongooses or snakes or cats on the islands! It takes a long, long time for evolution to result in birds that have useless wings. Maybe the island birds that became flightless over time will eventually achieve flight again, but will they do it before being wiped out by invasive predators that themselves have no predators on the islands? Unlikely.

In other systems, invasives are changing the dynamics of the system in a way that natives aren't particularly capable of dealing with. Again, evolution may happen over time, but it might not occur at a fast enough to keep pace with ecosystem change. An example-- invasive grasses in southern California are changing the fire regime. The native plants of the coastal sage scrub ecosystem evolved in a system where small patchy fires occurred about once every 30 years. The fires were relatively small and patchy because the habitat was primarily shrubs that had bare ground between them, which was not conducive to the spread of fire. Now, the areas between shrubs are filled with grasses. Fires are much larger and more frequent. The native shrubs are adapted to infrequent fires (they can crown sprout after low intensity fires), but not to frequent, high intensity fires. It's a positive feedback loop-- the grasses invade, result in more fire, killing shrubs and allowing more grasses to grow, thereby increasing the fire risk even more. Furthermore, until they burn, the grasses create ever growing layers of litter (the decaying plant material kind). Plants that evolved in conjunction with these grasses can germinate underneath these layers of litter-- the SoCal plants, which evolved in a system where the ground was bare, cannot germinate under all this litter. So, have the native coastal sage scrub plants been driven extinct? No, not yet. But they have certainly drastically declined in abundance. The hills near my home were previously coastal sage scrub, but are now primarily exotic grasslands, with exotic mustard thrown in too. I could count on one hand the number of California poppy plants or lupines that I find blooming on those hills each year; people who have lived in the area for 20 years or more can talk about when those hills used to be awash in purple and orange each spring. And again-- going back to the diversity thing . . . we have our students work on small experimental plots in these hills. All they do is rake away the litter left by the invasive grasses. Average species richness for the raked plots? 8 species. Average richness for the litter plots? 1 species.

OK, that was a long rant. I could keep going and going, but I need to go fix some breakfast ;-) This thread started with a post from Florida-- feel free to ask me about my time in Florida, working with the endangered Red-cockaded Woodpecker. I could tell you all about how the stands of invasive melaleuca are affecting it.

I look forward to some of the learned responses from the other posters to this thread. I wouldn't presume to respond to Dr. Fritchie.

A few interesting dates in North American natural history:
65 mya. DINOSAURS (then extinction)
65 mya. Survivors: TURTLES, SALAMANDERS, ALLIGATORS
60 mya. Rocky mountains; Bearpaw Seaway drains; North America is born
55 mya. HORSES and CAMELS (evolve in NA)
55 mya. RHINOCEROS (immigrates from Asia)
40 mya. DOG FAMILY (evolves in NA)
40 mya. CAT FAMILY (immigrates from Asia)
35 mya. TREE FROGS, TOADS, LIZARDS (floats from South America)
35 mya. RAVEN (immigrates from Australia) [BATS; other birds]
35 mya. SNAKES (immigrate from Asia)
30 mya. SQUIRRELS (co-evolve with Nut Trees in NA)
20 mya. GRASSES (co-evolve with big mammals; later lawnmowers)
17 mya. ELEPHANTS (immigrate from Africa via Asia)
15 mya. BEAR FAMILY (immigrates from Asia)
15 mya. CHEETAH (evolves in North America, immigrates to Asia)
5 mya. DEER and MOUNTAIN SHEEP (immigrate from Asia)
5 mya. RHINOCEROS goes extinct in NA
5 mya. HUMAN ANCESTORS evolve in Africa
3 mya. POSSUM, ARMADILLO, PORCUPINE, GROUND SLOTHS (immigrate fr S.A.)
3 mya. SQUIRREL, RABBIT, RACCOON, MICE/RAT, PECCARY (PIG), DEER, CAT, DOG, BEAR, LLAMA (colonize South America across Isthmus of Panama)
3 mya. CAMELS and HORSES (colonize Asia and Africa fr. NA, [Zebra])
2 mya. ICE AGES: POLAR BEAR (evolves in Arctic)
400,000 ya BISON (buffalo immigrate from Asia)
15,000 ya PEOPLE (immigrate from Asia)
13,000 ya EXTINCTION OF PLANT-EATERS: GROUND SLOTHS, GLYPTODONTS, ELEPHANTS, HORSES, CAMELS
13,000 ya EXTINCTION OF MEAT-EATERS: DIRE WOLF, SABERTOOTH CAT, GIANT BEAR
500 ya HORSES return (brought back by Spanish)

Well, this is a very interesting discussion. Much to think about from all points of view. I don't know if the hoarhound that I have
been engaged in battle with is a native to Arizona or not. I do know that the area beneath the oak trees where it was flourishing is showing a lot more diversity in plants than it was when covered with hoarhound. And my cats and I can walk through there without getting full of hoarhound seeds. In the greater plan of the universe I'm sure my puny efforts don't even count. And I'm ok with that. Thanks to all of you for an informative and interesting discussion.

It's not native to AZ (or anywhere else in the US). I have no idea if it's considered invasive in your area or not, but it's definitely an introduced species not a native one.

What flabotany conveniently leaves out is all the geologic, hydrologic, and climatic changes that occurred alongside the faunal natural history milestones recounted - because that likely upsets the applecart constructed.

Little things like meteorite impacts, earthquakes, volcanic eruptions, glaciers advancing and receding, etc. play more than a small role in the incidence (or not) of many of the plant and animal life populations listed.

Conveniently and completely avoided are all the points laid out by fritchie21. Well played.

Many years ago I saw a photo in National Geographic of the fence constructed across Australia to try to stop the spread of the jackrabbits introduced for sport. Taken from a low-flying plane, on one side of the fence was a verdant landscape with diverse flora. On the other side of the fence was bare soil as far as the eye could see, right up to the fence. Flabotany would have us believe that he considers the barren landscape as the more diverse one because of the addition of the jackrabbit, which absurd. He otherwise appears to be intelligent and lucid, so I propose we assume he is playing Devil's Advocate and simply trying to stir folks up. If we don't rise to the bait periodically, this thread would stay mercifully dormant. As they said back in the 60's: "What if they held a war and nobody came?"

Well, being stirred up occasionally helps me to look at things a bit more carefully, study a bit, consider several angles, and make up my mind about how I feel about whatever the subject may be. In other words, it makes me think. Anything that makes me think is a good thing. I think........

Humans and beavers are the only animals that change the land to suit there needs on purpose.

Genesis 1:1-----In the beginning God created the heavens and the earth. Luciee {;^)

Just found this thread. Very interesting. I took a lot biology in college and enjoyed it immensely. Ecology and mans' role in mucking up environments always was interesting and distressing to me. And it continues to be. We (people in general) continue to sabotage the most precious and valuable thing we have, the Earth.
fritchie, I very much enjoyed your input. Things are always more complex than lay people realize. The more you study the more you realize how little you know.
I am a long time supporter of The Nature Conservancy.
luciee, I hope your winking face after the bible quote means you don't take it seriously.
I don't have anything profound to say but I really enjoy everyones input here. Well almost everyone!

God said it, I believe it, that settles it. Luciee

Well, I just spent three thousand dollars to have two giant truckloads of hedera helix (English ivy) removed from my backyard. This invasive monster plant literally strangles trees to death, and has roots so thick that it is impossible to clear any area to plant anything else. Even if you use a chain saw to remove the roots, the ivy grows right back and kills anything else in the ground. In addition, the ivy serves as a cozy home for Norway rats. It chokes out the plants that are native to Southern California, where I live, and also chokes out any desirable garden plants that one might want to import into one's yard. In short, it chokes out everything. The rats, of course, outcompete other local mammals for food and living space. I can't see any advantage in leaving this situation alone to get worse and worse, with the idea that there is no such thing as an invasive species. Neither English ivy nor the Norway rat belong in Southern California, and there is nothing positive about either one of them.

Hooray for you Veeneck!!!

ditto on that frost weed. Hooray for veeneck and ivy pulling.
Here in Atlanta ivy and rats are abundant and a mess. I pull ivy in my yard regularily but with 3 neighboring yards mostly ivy its an ongoing battle. At least most of the ivy in my yard comes in from the edges so if I pull it up regularily it won't strangle my yard. And I am happy to report an increase in the local RedTail Hawks and owls have put a big dent in the rats. Coyotes help too.

I enjoyed flabotany and the others' conversations a lot.
It is interesting to me that the secondary effects of many imports are so hard to evaluate. When the Europeans (Spanish or others) brought some vegetation to FL, there is no telling what biological advantages or disadvantages were conferred upon some of the native plants and animals. Perhaps for some of the imports there were no advantages but for others there were major ones. After 500 years, the changes are hard to evaluate. In 200 years it will be difficult for our successors to evaluate the bad (maybe good) for which the maleluca, Australian pine, kudzu, et.al. have been responsible.

I think these are interesting thoughts, do you?

Paul

The obliteration of vast acreages of diverse flora in the South by kudzu along with the myriad fauna species supported by these displaced plant communities isn't too difficult to evaluate. Neither is the desertification of a major portion of the continent of Australia by the introduction of jackrabbits. The wholesale loss of species diversity to a single introduced species is not very charming in the real world. It is little different from paving an entire countryside and suggesting that it is beneficial to nature. Introduction of exotic species and other human activities have rendered a stunning percentage of the planet unable to sustain agriculture. If too little of the environment is degraded in this way even you and I won't eat. What will be the grand advantage to the many species, and nature in general, by their being eliminated by the pythons introduced into the Everglades? Flabotany enjoys playing devil's advocate. One has to either be unaware of, or ignore, thousands of years of documented human modification of the world to buy it.

in response to flabotony's review of north american history,ibelieve one species has been left out ,one of which after the influx of european
settlers, was displaced and almost virtually erradicated. I suppose one
would refer to this as biodiversity.