I have a love hate relationship with mesquite. When kept to manageable levels, it is a valuable part of the ecosystem and provides food and shelter for a number of critters. It has wood that makes great bar-b-que, if handled properly*. But it is also a sign of very poor land management, and once it takes over, it ruins pasture and lowers the local water table.
I’m always pleased to see large piles of grubbed up mesquite, because that means that someone is investing in the land, improving it, and will take care of the property as it needs to be cared for. You can’t “just” spray mesquite, or take a chainsaw to it if the spread has gotten too bad. No, you have to use a D-8 Cat bulldozer or bigger with a grubbing-plow attachment on the blade mount and rip it out, getting as much of the roots as possible. Then, if you have the money and time, you add a dose of Bush-B-Gone to the stump. Sort of the botanical version of “nuke it from orbit.” Once the dead brush is dry, you get the proper burn permit, let your local VFD know the date(s) and burn what you have not sold.
Otherwise, mesquite spreads. It does so at the expense of grass, wildflowers, springs, streams, and pretty much anything short of kudzu and cockroaches. It is excellent at surviving, and actually poisons the ground around it’s self to prevent competition. Cows and other things eat the seed pods, then leave the now fertilized seeds well away from the parent plant. To see a pasture filling with mesquite or yucca means that some one is not taking care of the land, either with controlled burns, or grubbing, or proper grazing management.
Once you get a critical mesquite mass, nothing short of mechanical intervention or a very bad fire will stop it. Mesquite burns exceedingly hot once it gets going, and mature plants are somewhat flame resistant, but not fireproof. A mesquite tree, like you find in central Texas, can withstand a low or creeping fire. The brushy version like we have out here burns a little more easily. When it does, Katy bar the door. Yes, it is good for the land in the long run, but it is rough on the critters, plants, and people in the here-and-now.
Mesquite also sends roots down as well as out. It can reach the water table in many cases, and sucks up lots of water. This can dry up springs and seeps, depriving critters and birds of water. Over time, enough mesquite will dry up streams.
Yes, mesquite is a native plant. It does full a useful role in the ecosystem, when it is present in moderation and checked either by fire or by human action. But like other native plants, when it is no longer checked by fire or pests, it causes species and habitat loss.
We do need to keep it around, however, Otherwise no one up here would know when to plant tomatoes. You never, ever plant tomatoes until the mesquite blooms. Then you’re safe from hard freezes. Before then? You have no one to blame but your foolishly optimistic self when you wake up to seedling-cicles.
*If you smoke meat using mesquite, keep it at the far end of your firebox, so the smoke can cool a little before it reaches the meat. That is, unless you really like a crunchy, thick black carbon crust on your ribs et al.