The study published in ‘Nature – Ecology & Evolution’ suggest that native species residing at higher altitudes are under threat from the non-native invasive species as they are now making their habitats within the habitats occupied by natives
New Delhi, Feb 1
A latest study published in ‘Nature – Ecology and Evolution’ says that alien species are rapidly spreading in the mountains of the world including the Himalayan range and are making their habitats at higher altitudes.
The mountainous regions of the world are considered biodiversity hotspots and the Himalayan mountains house rich biodiversity of endemic and rare plant species. The study suggests that the native species are under threat from the alien invasive species that are slowly taking over.
The research carried out over a period of 10 years in 20 mountainous regions spreading across continents except Antarctica, by a group of researchers from the Mountain Invasion Research Network (MIREN). In the Himalayas, the area covered under research are the Himalayan mountains of Kashmir region in India. MIREN was founded in 2005 to understand the effects of global change on species’ distribution and biodiversity in mountainous areas.
“Starting in 2007, we conducted repeated surveys of non-native plant distributions along mountain roads in 11 regions from 5 continents. We show that over a 5- to the 10-year period, the number of non-native species increased on average by approximately 16% per decade across regions,” the research says. “The direction and magnitude of upper range limit shifts depended on elevation across all regions… We found greater than-expected upward shifts at lower/mid-elevations in at least seven regions. After accounting for elevation dependence, significant average upward shifts were detected in a further three regions (revealing evidence for upward shifts in 10 of 11 regions). Together, our results show that mountain environments are becoming increasingly exposed to biological invasions, emphasizing the need to monitor and prevent potential biosecurity issues emerging in high-elevation ecosystems”.
The mountainous regions contain semi-natural habitats experiencing little human interference and are home to many animal and plant species, some of them endemic and highly specialized. Mountains have also been largely spared by invasions of these alien plant species or neophytes.
But the new study suggests that the pressure of non-native species on mountain ecosystems and their unique vegetation is intensifying worldwide.
“We have found that the non-native invasive species are making the mountains as their new habitats,” says Irfan Rashid a steering committee member of MIREN and one of the researchers of the study. “We have found that these invasive species were not visible on higher altitudes where the endemic species are already under threat because of climate change. The invasive species can engineer such a change in the area that would make life difficult for the native species”.
Irfan says the effect on the Himalayan mountains would be drastic. “The mountainous regions generally are rich in biodiversity but the Himalayan mountains are more so. In the Himalayas, Kashmir is a part of the biodiversity hotspot. Himalayas have rare endemic species which you can’t find anywhere else. In fact, there are lot many species that are yet to be scientifically explored,” says Irfan. “With the invasion of non-native species, especially in the higher altitudes, these endemic species are under threat. There is the impact of climate change on these endemic species but we don’t have empirical data on climate change’s impact on native biodiversity available for the Himalayas like in the West. But the impact of invasive species is now clear”
While in lowlands, non-native plants are often introduced by humans, their rise to higher altitudes is a matter of concern for researchers. The research has found that the exotic species have easily propagated along mountainous regions along roads although their presence is less in the intact mountain habitats away from roads.
The researchers established the MIREN road survey protocol in 2007 to document the distribution of non-native species in mountains and test hypotheses about the drivers of these patterns. The survey was implemented in over 20 mountain regions on all continents except Antarctica.
The research study is based on almost 15,000 observations of 616 non-native plant species from 651 study plots and are collected worldwide using the same procedure. The researchers record the alien species in T-shaped study plots, i.e., a 50-meter-long strip (164 feet) along mountain roads and a perpendicular strip of 100 meters (324 feet). The study areas are distributed at regular intervals along multiple mountain roads in each region.
“The results pertain to the period from 2012 to 2017,” says Rashid. “It is a continuous process and the results rom 2017 to 2022 would be published separately”.
The vegetation surveys took place in southern and central Chile, two regions of Australia, Tenerife, Switzerland, two regions of the western United States, Hawaii, Kashmir, and Norway.
The first time such data were collected was in 2007 in six of the regions, and in 2012 in the rest of the regions. Vegetation surveys are repeated every five to ten years. The researchers participate in this project voluntarily, mostly funding the research from their own resources. It was only recently that MIREN received some funding for their RangeX project.
Irfan says to fully understand the alien invasion in the Himalayas, the scope of study needs to be widened to cover the entire Hindu Kush Himalayas including the regions of Afghanistan, Bangladesh, Bhutan, China, Myanmar, Nepal, and Pakistan, and the central and eastern parts of the Indian Himalayan Region.
The Biological invasion is not only responsible for a substantial decline in biodiversity but has a huge economic cost as well. A study published earlier in the journal Nature suggested that the total reported costs of biological invasion has reached a minimum of US $ 1.288 trillion from 1970 to 2017. The annual mean cost comes to US $26.8 billion.
A similar research in India suggests that India has lost US $127.3 billion in last six decades because of the invasive non-native species.
“It is important to manage these invasive species before it is too late and all the stakeholders have to take their responsibility in managing this nuisance,” Irfan says.