Before I came to New Zealand from the US, I had thought that the footage from the Lord of the Rings of rolling green hills and idyllic countryside represented how lush and natural New Zealand was. I discovered when I came here that those rolling green hills are mostly invasive, exotic grasses and that before humans were here in NZ, the land was covered mostly in forest. Now the sheep and cows that graze these exotic grasses are part of an intensified agricultural system that relies on fertilizers and irrigation to keep the grasses so green and lush.
Conversion of forest lands to pasture land is not limited to New Zealand; in the Andes mountain region in Ecuador, conversion to agricultural land is the leading cause of loss of the unique high montane forests. These high-altitude ecosystems support a high level of biodiversity as well as ecosystem services, those services from nature that benefit people.
However, this situation is not all doom and gloom. In a recent study published in 2014 in the journal Agroforestry Systems, Lincoln University postgrad Chloe MacLaren, together with her supervisors Hannah Buckley and Roddy Hale, looked at how remnant forest or woody vegetation patches in pastoral land near these forests can mitigate biodiversity and ecosystem service loss. Imagine a mountain forest in the clouds (just like the Misty Mountains in Lord of the Rings) with pasture land on the slopes and a mix of pasture and woody plants and shrubs in between the pastures and forests.
The study examined those areas of forest, a mix of forest and pasture, and pasture land measuring plant species abundance, number of juvenile timber trees, and the soil properties of organic matter content and moisture. These four properties served as indicators of ecosystem service provision; in other words, how well these grazed Misty Mountains would benefit people. Plant species abundance represents general biodiversity, number of juvenile trees represents the future timber production for income and traditional cultural practices, and the soil properties of organic content and moisture represent carbon storage, soil nutrients, and soil hydrology. Each of these areas of forest and/or pastureland, with the exception of the centre of the forest, had a range of grazing intensities by livestock, so the researchers could investigate how varying levels of agricultural intensity affected their study.
Beyond being a really awesome region to study (I’m picturing doing field work in the clouds), this research found a number of thought-provoking results that could influence future pasture designs. In the mature forest areas, there was the highest number of species, as well as number of juvenile timber trees. Moving from the mature forest areas to less forested areas to pasture land with few woody plant species, there was a lower number of woody plant species and juvenile timber trees as well as a trend in lower organic matter and moisture in the soil, which suggests that grazing and change in land use can significantly alter biodiversity and ecosystem service provision.
Let’s imagine then that the Misty Mountains form Lord of the Rings were grazed- what do these results mean for ecosystem services? With a lower number of woody plant species, there would have been fewer varieties of trees (less good places to hide from trolls) and not as many sources of food from the lower biodiversity (resulting in really hungry trolls). With a lower number of juvenile trees, there would be less income generated from the forest. Lower organic matter content and soil moisture would result in the soil being less healthy and less able to support growing trees and plants and less able to handle floods and regulate water, all harming forest production and biodiversity. All of these consequences of grazed pastureland in the Misty Mountains would apply to real-world mountain forests, only without the trolls.
Having more mature forests protected and more woody vegetation in pasture land promotes biodiversity and supports more ecosystem services. So why does this matter? As an ecologist, I think that biodiversity is amazing. More species = More fun! With more species, there are more interactions to study, more unique ways that species use and contribute to their natural environment. Maintaining biodiversity has human benefits too, being tied in with tourism and cultural identity. Additionally, both biodiversity and the ecosystem services provided by biodiversity benefit industries such as agriculture. A study in 2012 by Nicholls & Altieri found that having more plant species around agricultural fields benefits bees and insects, thereby enhancing pollination of those agricultural fields.
Bringing this discussion back to NZ, I wonder if we can bring to life the ideas in Chloe MacLaren’s study in our dairy and sheep pastures. I have not found any papers or articles that replicate the idea of encouraging more forest patches to grow in pastures, but I hope this idea will take off here. The ecosystem services examined in the study by Chloe MacLaren and her supervisors, specifically soil nutrient content and soil hydrology, would have economic benefits to farmers by increasing the pasture grass growth and thus the livestock yields. Wouldn’t it be awesome then if there were patches of native beech forest in and surrounding pasture land? In some areas, the rolling green hills could be replaced by gentle beech forests full of birdsong. With the tantalizing economic benefits and additional benefits from biodiversity, these forests could become the new image of New Zealand, and the mountains would become just like the Misty Mountains in the Lord of the Rings.
For more information:
MacLaren, C., Buckley, H., & Hale, R. (2014). Conservation of forest biodiversity and ecosystem properties in a pastoral landscape of the Ecuadorian Andes. Agroforestry Systems, 88: 369-381.
The author Rowan Sprague is a postgraduate student at Lincoln University. She wrote this article as part of her assessment for ECOL 608 Research Methods in Ecology.