I thought it would be interesting to start a thread on beneficial invasives; considering 99% of what we hear about introduced plants and animals is negative, it might be cool to hear about some success stories.
To my knowledge, dung beetles in many countries are mostly beneficial, acting as a control for domesticated animal dung and controlling fly populations, although my knowledge on them is limited and I’d be keen to learn more. Rainbow lorikeets,Monarch Butterflies and Argiope trifasciata arent beneficial exactly, but as far as I know don’t do heaps of damage and are pretty incredible to see!
Dingos could count too, they have been proven to decrease fox numbers in areas where they live.
The first thing that comes to my mind is attempts at biocontrol of harmful invasive species by releasing their natural predators. For example, in my area there has been some success with releasing beetles that target hemlock woolly adelgid. Other examples of this approach have backfired spectacularly though (e.g. cane toads in Australia).
i’m a plant guy and i don’t think introduced plants are really ever beneficial ecologically (they can certainly be beneficial to humans in various ways) but i do think they vary a LOT in their impacts and some are neutral ecologically. For instance… i do a lot of wetland ecological surveys in Vermont and have detected that Glossy Buckthorn, an invasive species, acts very differently than other invasive shrubs. It does displace speckled alder, which shares similar ecological niche, but it doesn’t appear to have any negative effects on understory native vegetation. The herbaceous understory tends to be as diverse and ecologically appropriate under glossy buckthorn as it is under alder. For its relative common buckthorn, this is not the case and the native sedges and such don’t persist under it, same for the invasive honeysuckles, barberry, and multiflora rose (the worst of all). So when people do invasive species management i suggest they don’t focus on glossy buckthorn if those other species are present.
Also dandelions. Thrive in human habitats such as lawns. I guess i could see dandelions as mildly beneficial because they don’t impact intact ecosystems at all that i have observed, but they displace grass in lawns and offer some food for pollinators.
I guess the closest thing I can mention here (without brining up European Honeybee “controversy”) is the Great Mullein. They’re a pretty standard large, tall flowering plant I see occasionally, often nearby riverbanks, beaches, etc. I never see them in choking groups or collapsing other plants, and if they are inedible to native wildlife, I haven’t heard of it yet.
I kinda feel “beneficial” aliens can be seen as such if they help regenerate native ecosystems in the region they are found in.
Examples for me include the African Tulip Tree (Spathodea campanulata) acting as a ‘nursery’ tree to regenerate forests in Puerto Rico, or Nootka lupine (Lupinus nootkatensis) helping regenerate soils to allow native trees to germinate and sprout in Iceland, or organisms that have been released as highly host-specific biocontrols, such as the Longleaf Wattle Gall Wasp Trichilogaster acaciaelongifoliae and cochineal bugs for invasive Opuntia cacti.
Of course, in many cases ‘invasive’ species are simply opportunistic species that have come in after human disturbance and impacts, such as farmland, the edges around urban areas, polluted environments, etc. Water Hyacinth (Pontederia crassipes), for example, loves water bodies with high nutrient loads; therefore, areas with high runoff of fertiliser and sewage create better conditions for this water weed to take advantage of, while those same human impacts may make it less suitable for native species.
What makes for an ‘invasive’ species also is dependent on human subjective assessment. A non-native species that is moderately successful in spreading may be deemed ‘invasive’, while a vigorous native plant that forms monospecific stands which crowds out all other species may be seen as benign simply because it happens to be native, and therefore ignored.
Many native and alien species have by now formed complex interactions which complicates nonative species management. An endangered subspecies of the willow flycatcher (Empidonax traillii), for example, depends largely on non-native tamarisk for nesting sites.
Glossy Buckthorn replacing Speckled Alder is a big deal in some ways. Lots of Lepidoptera use alder as a host plant, but almost none use Glossy Buckthorn. Since songbirds require massive amounts of caterpillars to nest, Glossy Buckthorn significantly decreases usability for the habitat for nesting birds.
yeah i don’t think it is a good thing i just think it’s lower priority than other invasives such as common reed that obliterate literally everything else in the wetland.
i thought it was considered a major invasive there. Also is Iceland meant to have trees? I thought most of it was naturally bare, but maybe it’s like Great Britain where it used to be dense forest but is now not due to deforestation?
Iceland used to be densely forested before humans colonized it.
Pastoralism was the main form of sustenance for the settlers so most of the natural forests of Iceland were decimated to create pastures.
Even to this day the widespread presence of sheep is a major obstacle in reforestation efforts.
I was just thinking about this today. When I lived in Washington State, I noticed that in summer, bumble bees would come out of the nearby woods to feast on common cat’s ear (Hypochaeris radicata) in the lawn. Once the huckleberries had finished flowering, no other bumble bee food source was available in anything like that abundance.
The unglaciated land is estimated to have been 25-40% forested prior to human settlement. Deforestation and overgrazing led to pretty extreme soil loss, what with the high winds and rainfall that are characterisitic of the Icelandic climate.
Lupine was planted extensively beginning in the mid-20th Century as a soil stabilizer. It has reduced erosion but it is considered invasive and is the focus of control measures promoted by groups worried about its impact on iconic Icelandic habitats. There’s a fair bit available online about the argument over whether L. nootkatensis is good or bad. Here’s one example.
This seems to indicate it used to have substantial birch forest, but was not densely forested as most of it was willow scrub, tundra, glacier etc. Not like Britain which basically used to look like Vermont where I live now - dense hardwood forest - and now has almost no trees. For sure regrowing birch and willow in Iceland would be beneficial but it isn’t meant to be a densely forested landscape overall and i’m skeptical that a carbon fixing invasive species would be beneficial. That being said, i am not an Icelandic ecologist so if you are, i defer to you.