Long-term woodland restoration on lowland farmland through passive rewilding

Abstract

Natural succession of vegetation on abandoned farmland provides opportunities for passive rewilding to re-establish native woodlands, but in Western Europe the patterns and outcomes of vegetation colonisation are poorly known. We combine time series of field surveys and remote sensing (lidar and photogrammetry) to study woodland development on two farmland fields in England over 24 and 59 years respectively: the New Wilderness (2.1 ha) abandoned in 1996, and the Old Wilderness (3.9 ha) abandoned in 1961, both adjacent to ancient woodland. Woody vegetation colonisation of the New Wilderness was rapid, with 86% vegetation cover averaging 2.9 m tall after 23 years post-abandonment. The Old Wilderness had 100% woody cover averaging 13.1 m tall after 53 years, with an overstorey tree-canopy (≥ 8 m tall) covering 91%. By this stage, the structural characteristics of the Old Wilderness were approaching those of neighbouring ancient woodlands. The woody species composition of both Wildernesses differed from ancient woodland, being dominated by animal-dispersed pedunculate oak Quercus robur and berry-bearing shrubs. Tree colonisation was spatially clustered, with wind-dispersed common ash Fraxinus excelsior mostly occurring near seed sources in adjacent woodland and hedgerows, and clusters of oaks probably resulting from acorn hoarding by birds and rodents. After 24 years the density of live trees in the New Wilderness was 132/ha (57% oak), with 390/ha (52% oak) in the Old Wilderness after 59 years; deadwood accounted for 8% of tree stems in the former and 14% in the latter. Passive rewilding of these ‘Wilderness’ sites shows that closed-canopy woodland readily re-established on abandoned farmland close to existing woodland, it was resilient to the presence of herbivores and variable weather, and approached the height structure of older woods within approximately 50 years. This study provides valuable long-term reference data in temperate Europe, helping to inform predictions of the potential outcomes of widespread abandonment of agricultural land in this region.

Optimizing opportunities for oak woodland expansion into upland pastures

“…Our study finds that natural colonized oak sapling densities on selected UK upland pasture slopes were sufficient (mean of 1246 saplings per ha −1 ) to satisfy UK woodland creation grant requirements (1100 stems per ha −1 ) within 20 m of the woodland edge (Defra, 2018b). Vectors like jays and squirrels can transport acorns at high densities (400 ha −1 ) and over long distances (1.5 km) (Bossema, 1979; Worrell et al., 2014), notably so in lowland settings (Broughton et al., 2021). However, in this UK upland setting, native oak establishment was largely confined to within 20 m of the nearest adult congeneric, and principally located on west‐facing pasture slopes with well‐drained soils (Table 1).…”

Is it possible to attain the same soil organic matter content in arable agricultural soils as under natural vegetation?

“…There are written records of arable cropping on these fields from the 1840s, with the Broadbalk Wheat Experiment starting in 1843. Sections of Broadbalk and Geescroft fields were left unharvested from 1882 and 1886, respectively, and have reverted to deciduous woodland, a process now termed passive rewilding (Broughton et al, 2021); see Poulton et al (2003) for details. We suggest that the SOC stocks in these sites, following some 120 years of woodland reversion, may be a reasonable indication of the SOC before initial clearance.…”

Prediction of soil seed bank of piedmont and alluvial environments of Dera Ghazi Khan, Punjab, Pakistan

“…Dry and xerophytic environment of Piedmont zone increases the abortive seed number that caused reduction in viable seed bank (Zordoky, 2016). This distribution might be a result of accumulation of wind-blown seeds in sparsely disseminated micro-depressions in the soil surface, with seeds comparatively rare elsewhere (Broughton et al, 2021;Liu et al, 2020). Moreover, the low soil seed bank in Piedmont areas reflect the fact that in dry arid habitat various environmental stresses like, periodic aridity, high temperature, and physical and soil erosion caused lowering the density of seed bank (Clark et al, 2016).…”