Climate change sharpens weed and pest threat

Richard Rennie NEWS Pests

AT the forefront of the global megatrends coming to bear on New Zealand’s foodproducing future is climate change as it starts to impact how and where crops and proteins can be grown.

A report by the Better Border Biosecurity (B3) sector group, which consists of the best minds in border protection and invasive species, also underscores how weeds and diseases are likely to spread further, accompanied by new “alien” pests and diseases enabled by the changing climate.

But the report also highlights the upside of climate change and how it may enable viable new crops, including sorghum, peanuts and chickpeas.

Dairying and forestry are tapped to do better under climate change’s impact, while beef and sheep are less favoured.

The study aims to better understand and inform the primary sector on how it can handle the changes, both to prepare for them and to take advantage of the opportunities they may present for a food-producing country at the edge of the South Pacific.

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Chris Hipkins, has not had time to get fully up to speed.

There are also concerns within the government at the impact of an emissions charge on already high food prices.

Another issue is the variable accuracy of the 11 emission calculators currently available. There is some speculation that the government may

“Biological invasions are already a big concern for NZ with its unique insular ecosystems and being home to one of the highest proportions of threatened indigenous species in the world. Our economy is also very dependent upon our primary sector,” project leader Dr Nicolas Meurisse said.

Climate change is by far the biggest megatrend identified by the report’s authors, with changes in trade routes, international conflict and extreme weather all ultimately leading back to the predictable rising of CO2 levels.

The context of climate change in NZ has lowered rainfall across Northland and the eastern regions of both islands, with production declining in those regions. In contrast, western areas are set to benefit from lower frosts and more water availability.

The report’s authors project that, based on existing emissions pricing, dairying could increase 9.6% by 2050 while sheep and beef decline by 13% and horticulture remains relatively unchanged.

However, the authors qualify this, citing market conditions and irrigation that will have a significant effect on actual outcomes.

The report notes that the incidence of non-native species introduce a tax, such as that on fertiliser, to fund the development of a more robust and accurate calculator. living beyond their native ranges has substantially increased in recent decades, with little sign of slowing, while agriculture and ornamental plant industries have pushed expansion faster.

O’Connor declined to answer questions on these claims.

DairyNZ chair Jim van der Poel said while HWEN looks unlikely to be in place by 2025, legislation needs to be passed preventing farming emissions from being folded into the emissions trading scheme (ETS).

The hundreds of non-native pest species already in NZ are also only likely to increase further over coming decades, and there is a need to understand which are likely to arrive, establish and become harmful.

“Natural environments, such as native forests, may be especially vulnerable to invading biosecurity threats. These could be adversely impacted by the combined effects of biological invasions, climate warming and other human-related pressures,” Meurisse said.

Dr Trevor James, NZ’s leading weed expert, said while he had not yet read the report, he has mixed feelings about how much climate change contributes to the spread of invasive species, and how much is from weeds’ adaptive ability to move beyond their usual habitat.

“When I think about kikuyu grass, no one thought it would ever move beyond Northland, where it was introduced, but it has got down to Waikato despite there being quite strong frosts, and I have personally seen it in the top of the South Island.”

Far from being a climate change

“There is legislation drafted at the moment that will have us in the ETS in 2025 and we have to get that changed,” Van der Poel said.

That legislation – the Climate Change Response (Emissions Trading Reform) Amendment Bill – puts agriculture into the ETS at farm level for livestock emissions and processor level for fertiliser emissions in 2025.

“We had an agreement in place denier, James said invasive species often have a habit of turning up in areas where they are least expected.

CRAFTY: AgResearch senior scientist Dr Trevor James says with or without climate change, weeds have proven themselves to be highly adaptable when it comes to spreading beyond their usual habitats.

He cited work on the dock weed from Europe and comparisons to where it grows in NZ.

“When they mapped its home zones in Europe, then compared to NZ, they found it did not really match up, it was growing here in areas that were not in its home zone. Sometimes some real curve balls are thrown up by weed species. NZ is a land with many microclimates.”

He suspects insects may be more likely to respond directly to climate change, such as increased before Christmas and the industry has met all of its deadlines and now we’re waiting for the government to say whether they still support that or that they have a different view,” he said.

Beef + Lamb NZ chief executive Sam McIvor concurred.

“The government has acknowledged that agriculture shouldn’t be in the ETS, and our sector has done its part, so it’s up to the government now.” levels of black beetle in areas that have warmed over the years. He believes the greatest future weed threat to NZ is from plants that are already here.

There was a reserve of 25,00035,000 plants in NZ not yet established outside gardens. But James said many experts are anticipating this reservoir of plants will likely be the source for NZ’s next surge in invasive species.

“They could be triggered by climate change, or even a slight change in conditions. We have a programme underway to assess which of these thousands of plants pose the greatest risk.”

Our position is that because of that uncertainty and complex detail still to be worked through, it is not appropriate to start pricing emissions by 2025.