In farming we are increasingly familiar with the phrase ‘you can’t manage what you can’t measure’. While 60% of New Zealand’s land area is made up of production landscapes, there has been a poor understanding about the amount of native vegetation that these areas contain. Research by Pannell et al. (2021) sought to be the first research to assess national-scale native vegetation cover for multiple types of native vegetation on different land uses. Their paper, titled ‘The significance of sheep and beef farms to conservation of native vegetation in New Zealand’, provides a range of insights into the importance of different land uses in New Zealand for the conservation of native vegetation.
Why is this research important?
Pannell et al. (2021) state that ‘relying solely on public conservation lands for habitat provision will be inadequate for achieving national conservation goals’. Public conservation land only accounts for 31% of New Zealand’s total land use, compared to production landscapes which make up 60%. As much of New Zealand’s land use is through modified agricultural systems, there is a real need to understand the role that these landscapes have in maintaining New Zealand’s rich biodiversity of native plants and animals.
Despite their modification, agricultural landscapes still retain biodiversity, and biodiversity also provides benefits to agricultural landscapes such as ecosystem services, social benefits, and retaining cultural and heritage values. In addition to the biodiversity that remains, there has also been an increasing interest in the food and fibre sector to increase riparian and restoration plantings on farm for environmental and social benefits. This is not without challenge though, as the ability to conserve and restore native vegetation on farm is constrained by factors such as balancing farm productivity and profit, lack of financial incentives and rewards for conservation and restoration, challenges of pest and weed management, just to name a few.
Pannell et al. (2021) identify that knowing where biodiversity occurs in our farming landscapes is the first step that is needed in order to be able to work towards maintaining and improving it. In order to plan for the management and restoration of native biodiversity, it is essential that we can quantify the amount, distribution, and condition of the remaining native vegetation in New Zealand.
Why are sheep and beef farms particularly important?
Sheep and beef farms make up approximately 40% of New Zealand’s land use. While much of these landscapes have been cleared and exotic pasture species are the dominant vegetation cover, these farms often contain areas of native vegetation. Compared to more intensive systems like dairy farming, sheep and beef farms have steeper topography which protects many forest remnants.
How was this research done?
This study focused quantifying the distribution of native vegetation types on the North and South Island mainland. A national-scale land cover database was used to undertake a nationwide GIS assessment of native vegetation cover on different land uses. The different land uses identified were arable, public conservation, dairy, forestry, horticulture, sheep and beef, urban, and ‘other’. This assessment allowed for the calculation of areas of native vegetation. In addition, as public conservation and sheep and beef farms are the two largest land uses, the mean distance between native forest patches in these areas was calculated, as well as the mean area of these forest patches.
So, what did the research find?
The assessment of native vegetation and land use was undertaken for overall native vegetation, as well as breaking it down into categories of woody vegetation, grasslands, and wetlands.
Native Vegetation
Native vegetation was defined as alpine grass/herbfield, tall tussock grassland, depleted tussock grassland, flaxland, fernland, mānuka and/or kānuka, broadleaved indigenous hardwood, sub-alpine shrubland, matagouri or grey scrub, and indigenous forest.
Pannell et al. (2021) found that approximately 11 million hectares of native vegetation remain in New Zealand. Of these 11 million hectares, just over 61% in found on Public Conservation Land, and close to 25% of this is found on sheep and beef farms. Overall, these two land uses combined account for 86% of New Zealand\’s remaining native vegetation.
It is really important to take away from this research that sheep and beef farms are very important custodians of native vegetation in New Zealand, and particularly in the context of production land uses. In comparison, land used for dairy farming accounted for 1.4% of native vegetation (165,000 hectares), with forestry accounting for 2.8% (317,000 hectares).
The way that native vegetation is distributed differs between public conservation land, and sheep and beef farms. For conservation land, native vegetation is largely located on the western part of the South Island and in various areas in the North Island (Green image on Figure 1). Native vegetation on public conservation land is also much denser. In comparison, sheep and beef farms show a greater distribution of native vegetation across the country. The areas of native vegetation on sheep and beef farms are distinctly different as they are highly fragmented and have a greatly reduced vegetation density compared to areas of vegetation on public conservation land (Yellow image on Figure 1).
It was also found that the areas where native vegetation remains on sheep and beef farms is often climatically and environmentally different to that of public conservation land. These areas are often warmer, at lower elevations, and are in areas that have otherwise been heavily deforested in the past. This shows that native vegetation conservation is as equally important on private land, as it is on public conservation land, as they retain different types of biodiversity.
Native Woody Vegetation
Native woody vegetation was defined as mānuka and/or kānuka, broadleaved indigenous hardwood, and indigenous forest
Of the 11 million hectares of remaining native vegetation in New Zealand, 8 million hectares is classified as native woody vegetation.
Of this native woody vegetation, 17.1% is found on sheep and beef farms, accounting for approximately 1.4 million hectares. In contrast, public conservation land holds approximately 5.3 million hectares of the remaining native woody vegetation.
Again, it is clear that sheep and beef farms are key in the conservation of native vegetation, with 156,000 hectares of native woody vegetation to have been found in dairy farming systems, and 305,000 hectares in forestry land use. While the percentage of native woody vegetation that remains on dairy and forestry landscapes is much less than that of public conservation and sheep and beef farms, Pannell et al. (2021) stress that this is not an insignificant area of land. While the extent may be less than other land uses, it does not make the conservation of this vegetation any less important.
Like that of Figure 1, assessing native woody vegetation also shows distinct differences in distribution and density. Pannell et al. (2021) state that the ‘continued existence of large amounts of native woody vegetation on sheep and beef farms is likely due to farm management practices, historical legacy, and policy’. Sheep and beef farms are often less intensive systems, have steeper country and areas of gullies that are uncultivated, leading to the retention of native woody vegetation. This vegetation is also largely beneficial with various ecosystem services they provide such as erosion control, pollination and carbon sequestration.
Native Grasslands and Wetlands
Approximately 2.7 million hectares of native grasslands remain in New Zealand. 44.6 % of this occurs on sheep and beef farms (1.2 million hectares), compared to 52.1% (1.4 million hectares) on public conservation land. Together, these two land uses account for just under 97% of New Zealand’s remaining native grassland vegetation, showing the importance that these two land uses both have in the retention of these areas of vegetation.
Wetlands were defined as areas of herbaceous freshwater vegetation, herbaceous saline vegetation, lake or pond, and mangrove.
It was found that the total of remaining wetlands in New Zealand account for 556,000 hectares.
Interestingly, sheep and beef farms only accounted for 0.6 % of native wetlands (3000 hectares). These wetlands largely occured on unclassified land (land that falls outside of the classification scheme (roads, rivers, estuaries), however 13,000 hectares (2.4%) of these wetlands are found in dairy farming systems. While 3000 hectares of wetlands on sheep and beef farms is not at all insignificant and must be protected, this shows that dairy systems are also very important custodians of our native wetland vegetation in New Zealand.
In summary…
Production landscapes in New Zealand account for 60% of land use, with sheep and beef farms making up approximately 40%.
It was identified in this research that approximately 25% of New Zealand’s remaining native vegetation occurs on sheep and beef farms, accounting for approximately 2.8 million hectares of land. This is second only to that of public conservation land which accounts for approximately 62%, or 7.1 million hectares of land.
Native woody vegetation and native grasslands are the most dominant forms of native vegetation that remain on sheep and beef farms, compared to native wetlands being the most dominant form on dairy farms.
Vegetation on sheep and beef farms is distributed differently to that of public conservation land which shows the importance of conserving native vegetation on both land types in order to conserve vegetation in different climates and environments.
Overall, Pannell et al. (2021) concluded that ‘sheep and beef farms have the potential to contribute substantially to biodiversity conservation in New Zealand , both in terms of overall area of native vegetation, but also because vegetation on these farms occurs in areas that have otherwise been heavily cleared’.
Irrespective of farm type, any native vegetation is worth conserving. Whether it’s sheep and beef, dairy, or any other production based system, we are all able to play a part in ensuring native vegetation in New Zealand thrives into the future.