Release from sheep‐grazing appears to put some heart back into upland vegetation: A comparison of nutritional properties of plant species in long‐term grazing experiments

Abstract

Rewilding or wilding is a popularised means for enhancing the conservation value of marginal land. In the British uplands, it will involve a reduction, or complete removal, of livestock grazing (sheep), based on the belief that grazing has reduced plant species diversity, the ‘Wet Desert’ hypothesis. The hope is that if livestock is removed, diversity will recover. If true, we hypothesise that the species extirpated/reduced by grazing and then recover on its removal would more nutritious compared to those that persisted. We test this hypothesis at Moor House National Nature Reserve (North‐Pennines), where seven sets of paired plots were established between 1953 and 1967 to compare ungrazed/sheep‐grazed vegetation. Within these plot‐pairs, we compared leaf properties of seven focal species that occurred only, or were present in much greater abundance, in the absence of grazing to those of 10 common species that were common in both grazed and ungrazed vegetation. Each sample was analysed for macro‐nutrients, micro‐nutrients, digestibility, palatability and decomposability. We ranked the species with respect to 22 variables based on effect size derived from Generalised Linear Modelling (GLM) and compared species using a Principal Components Analysis. We also assessed changes in abundance of the focal species through time using GLMs. Our results support the ‘Wet Desert’ hypothesis, that is, that long‐term sheep grazing has selectively removed/reduced species like our focal ones and on recovery, they were more nutritious (macro‐nutrients, some micro‐nutrients) palatable, digestible and decomposable than common species. Measured changes in abundance of the focal species suggest that their recovery will take 10–20 years in blanket bog and 60 years in high‐altitude grasslands. Collectively, these results suggest that sheep grazing has brought about biotic homogenization, and its removal in (re)wilding schemes will reverse this process eventually! The ‘white woolly maggots’ have eaten at least part of the heart out of the highlands/uplands, and it will take some time for recovery.

The importance of small natural features in forests—How the overgrowth of forest gaps affects indigenous flower supply and flower‐visiting insects and seed sets of six Campanula species

“…Historical forms of land use in forests such as forest grazing or coppice are complex (in terms of target species, type of grazing animal, and intensity and duration of grazing) and labor‐intensive and therefore not easy to implement (Bärnthol, 2003 ; Liegl & Dolek, 2008 ; Poschlod, 2017 ; Rackham, 2003 ; Rupp & Michiels, 2020 ; Zahn et al, 2014 ). However, grazing animals and coppicing would remove nutrients which contributes to the openness of the forest (Bärnthol, 2003 ; Berendse, 1985 ; Marrs et al., 2020 ). The new development of pristine forests is often set as a conservation goal, which is easier to manage but seemingly contradicts forest gap management.…”

Rainfall variability and socio-economic constraints on livestock production in the Ngorongoro Conservation Area, Tanzania

“…Sheep are an increasingly dominant livestock species in NCA, which might further degrade the rangeland vegetation due to their feeding ecology [64]. Grazing by sheep selectively removes nutritious plants and continually reduces species diversity and abundance of most vascular plants and grasses, leading to an increase in herbs, sedges and shrubs [65,66]. Yet, the long-term impact of small stock grazing on this landscape is still uncertain, and appropriate grazing management will be required.…”

Conservation of endangered and rare plants requires strategies additional to deer‐proof fencing for conservation of sub‐alpine plant diversity

“…Plant palatability is a major determinant of species’ susceptibility to deer browsing (Tanentzap et al, 2009; Marrs et al, 2020): palatable species are more susceptible to elimination than unpalatable species (Royo et al, 2010). In the Kirigamine grasslands, several unpalatable species (e.g., Rhododendron molle subsp.…”

“…Plant characteristics determine the tolerance of and resilience to ungulate browsing effects associated with plant palatability (Augustine & McNaughton, 1998; Marrs et al, 2020). For example, herbaceous forbs tend to be more palatable for ungulates than graminoid species (Horsley et al, 2003; Rooney, 2009).…”