Invasive shrub threatens climate change adaptation

The Cactus Rosea is certainly an unwanted guest  The Cactus Rosea is certainly an unwanted guest

Jeffrey Gogo 

AN invading thorny shrub known as the Cactus Rosea (Opuntia Fulgida) has laid siege on Matabeleland South, killing dozens of livestock and making it difficult for 1 500 families to adapt to climate change.The plant has colonised 3 000 hectares of land in the province since it was first detected in 2010, making the land useless for agriculture or grazing, according to Mr Washington Zhakata, climate change director in the Ministry of Environment, Water and Climate.

In the worst affected districts of Gwanda and Beitbridge, the total area of pasture and arable land have dropped 0,1 percent or 2 355 hectares, he said of the shrub, which is also wreaking havoc in Insiza, Bulilima, Mangwe and Matobo,

Mr Zhakata is concerned the invading Cactus Rosea, which originates from South Africa, will derail efforts to help communities in an area already facing harsh weather and climates, adapt to climate change.

“This plant is affecting climate change adaptation in Zimbabwe, as it reduces the hectarage of land for agricultural activities in an area already heavily impacted by climate change,” he said, in an emailed statement.

“The draught power for tilling land is also affected as a number of livestock deaths have been recorded as a result of contact with the plant.”

Nowhere else in Zimbabwe could the dangerous impacts of climate change be playing out more than in Matabeleland South province.

The region is one of the driest in the country, with annual precipitation averaging 300mm or less.

Crop failure is not uncommon in a region that has seen rainfall decline 15 percent since the 1960s, and where future scenarios point towards increased dryness due to climate change, experts say.

Unwanted Guest

A foreign fast growing invading plant will be the last thing that a province like Matabeleland South needs at a time of climate change, when coping options are increasingly becoming limited.

But growing to a height of up to two metres, with tough pricking thorns that can harm both humans and animals with ease, the Cactus Rosea is certainly an unwanted guest.

Mr Steady Kangata, spokesperson for environment regulator, the Environmental Management Agency (EMA), said the shrub is deadly, attaching itself to the skin or mouth of animals and causing them to starve to death as they are unable to feed.

“It (Cactus Rosea) reproduces vegetatively and suppresses the germination and growth of all native flora under its canopy,” he said, in emailed responses to The Herald Business.

“Of concern is the destruction of grass and browsing species that sustain livestock and the domestic herd in the (Matabeleland South) province.”

The Environment Ministry’s Mr Zhakata went further to claim that “once it (the shrub) prickles into the skin, the pain is unbearable and the thorn is not easily removable. Persons have to undergo surgical operations to remove the thorns.”

The number of livestock killed since 2010 is not clear. In 2016, however, a total of 41 livestock, made up of 21 goats, 16 cattle and 4 donkeys were injured as a result of attacks by the plant, according to Mr Kangata of EMA.

Of these, 28 animals had eye injuries that led to total blindness. Most farmers were eventually forced to sell or slaughter the animals, he said. Livestock deaths from such injuries include 4 donkeys, 27 goats, 58 fowls and 6 goats.

“In extreme cases, invaded lands have become inhabitable and non-arable due to the presence of the weed. In some instances, households have abandoned their traditional cropping lands . . .” Kangata explained.

With back to back droughts experienced since the summer of 2011 /12, peaking with the El Nino-triggered drought of 2015 /16, both pastures and water have already been receding fast in Matabeleland, Zimbabwe’s biggest cattle producing region.

Thousands of cattle and other livestock died last year, and the years before, due to drought, authorities say.

Control Measures

A continued expansion in the area of land under the Cactus Rosea could mean a lot of deaths, and also massive headaches for Government authorities seeking to help communities cope with climate change.

The Environmental Management Agency, which is tasked under law to protect ecosystems and biodiversity, estimates that it will cost $2,4 million to eradicate the shrub and prevent it from spreading further.

But despite assurances from Treasury that the money will be released, nothing is flowing, forcing communities in Gwanda, one of the worst affected areas, to do so by themselves.

Mr Kangata pointed out that the most effective and practical way for Zimbabwe to control the shrub was by mechanical means — cutting the plant, burning it and then bury it underground to prevent recurrence. Biological means are still under investigation.

To do that, communities in Gwanda need protective gear and specialised equipment, which have been provided by EMA.

Results are unpleasing, however. Out of 1 465 hectares of land under attack in Gwanda, only 305 hectares were cleared last year due to a shortage of labour and money, Kangata said.

Overall, only a fifth of the 3 000 hectares under the Cactus Rosea invasion in Matabeleland South have been cleared to date.

“If the weed is not cleared it will spread, destroy and further reduce the livestock carrying capacity of six districts,” warned EMA’s Kangata.

With global trade on the increase, invasive alien species, including crop damaging pests such as fungi, have moved into new territories with speed, helped on by climate change, according to a 2013 report in the journal — “Nature Climate Change”.

In the last 50 years, hundreds of pests and pathogens have shifted their ranges towards the poles by an average 3 kilometres per year, with varying degrees of impact in the invaded territories.

Invasive alien species are currently the main driver of animal species extinctions globally, say scientists.

Concerned by the expansion in invasive species, the International Union for Conservation of Nature (IUCN) in November launched a new global initiative called the Honolulu Challenge, which calls on governments to commit to developing effective biosecurity measures, increasing the number and scale of invasive alien species eradications, boosting the resources for invasive alien species control and addressing priority pathways.

God is faithful.



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