Isabella Tree on Wilding

Episode Summary

Executive Summary: Isabella Tree describes how her family’s 3,500-acre Sussex farm, after years of unprofitable industrial farming on heavy clay soil, was converted into a rewilding project at Knepp. By removing intensive agriculture and introducing free-roaming herbivores as ecological proxies, the estate saw dramatic biodiversity recovery, but also required ongoing management, culling, and new revenue models such as meat sales and ecotourism.

Main Topics: From failed farming to rewilding: Tree explains that the land’s heavy clay made conventional farming chronically unprofitable, leading the family to seek a land use that worked with the soil rather than against it. Ecological awakening and the role of soil: A consultation about a dying oak tree revealed how plowing, chemicals, and root disturbance were harming the land’s living systems, shifting the owners’ thinking from stewardship to culpability and restoration. Dynamic landscapes, not closed-canopy forests: The conversation challenges the idea that untouched nature means dense forest, arguing instead for historically open, mixed landscapes shaped by large herbivores, scrub, glades, and disturbance. Using proxy megafauna to restore ecosystem processes: Because extinct wild species cannot be reintroduced directly, Knepp uses domesticated proxies such as longhorn cattle, Exmoor ponies, Tamworth pigs, fallow deer, and red deer to recreate grazing and browsing dynamics. Biodiversity resurgence and emergent order: Tree details the unexpected return of rare birds, bats, butterflies, and dung beetles, presenting Knepp as evidence that complex ecosystems can self-organize in ways no planner could fully predict. Management, culling, and ethical meat sales: Even rewilding requires intervention in a fenced landscape without predators. Tree defends culling and selling meat as a pragmatic, humane way to keep herds healthy and make the project financially viable. Policy, economics, and public attitudes: The discussion covers subsidies, ecosystem services, agri-environment funding, ecotourism, and the need to change public aesthetics and policy incentives to support wilder land use.

Key Arguments: Industrial farming on poor soils can be economically and ecologically destructive, especially when the land is unsuited to intensive production. Healthy ecosystems depend on soil life, disturbance, and animal interactions; plowing and chemicals can destroy the subsurface systems trees and biodiversity rely on. The English landscape was historically not a closed forest but a dynamic mosaic of wood pasture, scrub, grassland, and wetlands maintained by large herbivores. Rewilding works best by restoring ecological processes rather than trying to design every species outcome in advance. Many species returned because the project recreated the right conditions, illustrating emergent properties in complex natural systems. In a fenced, predator-free setting, some management and culling are necessary to prevent starvation and maintain ecological balance. Selling meat and offering ecotourism can turn rewilding from a subsidy-dependent experiment into a sustainable business model. Policy should reward ecosystem services such as carbon storage, flood mitigation, water purification, and biodiversity rather than subsidizing damaging land use. Public aesthetic preferences strongly shape land policy; people must learn to see wildness as beautiful rather than neglectful. Connectivity between rewilded areas, farms, and corridors is essential for scaling up biodiversity recovery and possibly reintroducing predators later.

Data Points: Estate size: 3,500 acres - Size of the Knepp Castle Estate in Sussex where rewilding took place. Distance from London: about 50 miles south of London - Location of Knepp relative to London. Time to realize farming was failing: 17 years - Tree says it took 17 years to understand the land could not support profitable conventional farming. Biodiversity loss in Britain: 60% since 1970 - Tree cites a catastrophic decline in UK biodiversity as motivation for rewilding. Historical turtle dove decline: from 125,000 pairs to less than 3,000 - Illustrates species recovery concerns and the significance of turtle doves returning to Knepp. Footpaths on the estate: about 20 miles - Public access through the semi-open rewilded landscape. Initial longhorn cattle introduced: about 20 - Early stocking level when reintroducing grazing animals. Current longhorn cattle herd: about 400 head - Scale across the project’s different rewilding sections. Initial ponies introduced: about 6 - Starting group of Exmoor ponies used as tarpan proxies. Current pony herd: about 30 - Approximate pony population after expansion. Initial pig introduction: 10 pigs - Early Tamworth pig introduction, described as two sows and eight piglets. Current pig females: about 6 - Approximate number of breeding female pigs remaining due to their high disturbance. Project meat output: 75 tons of meat per year - Culling produces saleable meat as an income stream. Annual income from meat: about £200,000 - Tree cites meat sales as a significant low-input revenue source. Annual grant support: Higher Level Stewardship funding - EU agri-environment money that helps support rewilding activities. Predator examples in Europe: 60 wolf packs in Germany - Used to show that predator coexistence is possible in modern Europe. European brown bears: 10 times as many as in America - Tree claims Europe has far more brown bears than the U.S. in total.

Pivotal Quotes: "It was becoming clear to Charlie and me that we had set out with the intention, that had we set out with the intention of creating the perfect habitat for purple emperors, which is a butterfly, we would never have achieved the numbers that have spontaneously emerged through rewilding." — Isabella Tree: Tree explains the importance of emergent properties and why ecological complexity cannot be fully engineered. "We were basically killing their life support systems." — Isabella Tree: Her realization that intensive farming and chemicals were harming the trees and soil ecosystems. "We’re all on a journey, in a sense." — Isabella Tree: Describing rewilding as a spectrum from intensive management to near-complete hands-off restoration.

Implications: The episode argues that rewilding can restore biodiversity, improve soils and water systems, and create viable rural businesses, but only if policy, public taste, and land management adapt to support dynamic, species-rich landscapes.