50 glades of grey: Farming the cloud forests

Ecuador landscape
Ecuadorean cloud forest. Mature forest in distance, glades in foreground. Notice the branches used as fence posts.

My favourite author is Tanith Lee. Perhaps I should say that she was my favourite as she recently passed away. I came across two slim novellas in a bookshop in Balclutha in early 1984 and devoured Companions on the Road and The Winter Players on the 2nd and 3rd March 1984 (yes even as a 16 year old I recorded data!). I knew that I had found an author that I could read for life (and that is the case as she published over 90 books, often in small, hard to fine presses, as well as hundreds of short stories). Lee was a master of the short story but could produce multi-volume series with the best of them. She ranged from youth fiction to extremely adult stories and covered the bases from high fantasy, dark fantasy, science fiction, horror to historical fiction. Her writing can best be described as quirky and gothic, with strong female characters, and a curious sense of greyness about the characters and the stories. Lee very rarely wrote simple stories about simple characters. There were seldom good guys and bad guys, or even clear goals for the not-so-good-guys. Many of her characters had questionable motives and did questionable things but often did the ‘right’ thing in the end (if not for the ‘right’ reasons). Alan Garner (who I first read in 1979!) is the author who I have found that comes closest to Lee. As a teenager this murkiness of story was a revelation (especially having been raised on Tolkein, Lewis and Eddings). As a proto-scientist this was extremely important stage in my development. The greyness of the stories emphasised that there are seldom simple answers to questions, that ‘it depends’ is a reasonable place to get to, that there may be multiple ways in which to approach a situation.

Ecuador forest
Cloud forest scrub.

One area where greyness is common place in biology is understanding human effects on the environment. For example, high Andean cloud forests are fast disappearing as they are removed due to transforming these areas for agriculture. Mature cloud forest offers a range of benefits (nature tourism, resources like timber, food and medicine, and regulating local water storage and movement) that local farmers try to preserve by leaving/planting forest species around boundaries as well as allowing regeneration of woody species within their pastures. Does creating these glades actually help to preserve local diversity and ecosystem function? Afterall, recovering native plants are subject to grazing from cattle as well as competing with introduced grasses as may not play much of a role at all. Chloe MacLaren, a masters student from Lincoln University, with her supervisors Hannah Buckley and Roddy Hale, had the opportunity to study this idea in the Papallacta Valley, Ecuador, high in the Andes. The valley is at about 3500 metres above sea level and still has patches of native forest, areas of agriculture and areas where the ‘wild-life friendly’ glades are present. Much of the native cloud forest is now restricted to steep hillsides.

Ecuador cows
Cattle with altitude!

Chloe details in a paper in Agroforest Systems how she set up 50+ 10 x 10 m quadrats spread throughout the valley from 3355 to 3752 m.a.s.l. and in different levels of agricultural impact. Within each quadrat she recorded the identity and abundance of woody plants over 30 cm in height, vegetation type, canopy cover and cattle impact. In many sites she also took soil samples to look at organic matter and moisture contents which would give her an idea about how moisture and carbon were faring.

Overall, Chloe found 65 plant species that were organised into groups, of which the main clusters were: mature forest, high altitude disturbed vegetation, low altitude disturbed vegetation, regenerating pasture and shrubby pasture. At most, only half of the species were shared between any two groups and each group had their own indicator species. Grazing disturbance and higher light levels seemed to be the most important drivers of the change in membership of these groups, of which species grew in each cluster. Surprisingly, organic matter and moisture content of the soils were not found to be significantly different even between mature forest and shrubby pasture.

So do glades work? Well it depends on what you want them to do. There are certainly some native plant species that benefit from growing in amongst the grazing cattle and the high light levels. The glade approach is definitely way better than complete clearance of forest even if the mix of plants found in mature cloud forest are usually not those found in the presence of cattle. Fencing off cloud forest areas is the certainly the best way of preserving these ecosystems. However, the glades do provide a useful service, not least because they can provide logs from large woody species that can be used as fence posts, and protect large trees within the mature forest from this fate. The glades also help conserve plants that grow on edges and tolerate high light levels. So glades are useful enough without being the full solution. A typically grey kind of science answer. A Tanith Lee kind of answer.

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