Land surface greening suggests vigorous woody regrowth throughout European semi‐natural vegetation

Abstract

The satellite record has revealed substantial land surface “greening” in the northern hemisphere over recent decades. Process‐based Earth system models (ESMs) attribute enhanced vegetation productivity (greening) to CO2 fertilisation. However, the models poorly reproduce observed spatial patterns of greening, suggesting that they ignore crucial processes. Here, we explore whether fine‐scale land cover dynamics, as modified by ecological and land‐use processes, can explain the discrepancy between models and satellite‐based estimates of greening. We used 500 m satellite‐derived Leaf Area Index (LAI) to quantify greening. We focus on semi‐natural vegetation in Europe, and distinguish between conservation areas and unprotected land. Within these ecological and land‐use categories, we then explored the relationships between vegetation change and major climatic gradients. Despite the relatively short time‐series (15 years), we found a strong overall increase in LAI (i.e., greening) across all European semi‐natural vegetation types. The spatial pattern of vegetation change identifies land‐use change, particularly land abandonment, as a major initiator of vegetation change both in‐ and outside of protected areas. The strongest LAI increases were observed in mild climates, consistent with more vigorous woody regrowth after cessation of intensive management in these environments. Surprisingly, rates of vegetation change within protected areas did not differ significantly from unprotected semi‐natural vegetation. Overall, the detected LAI increases are consistent with previous, coarser‐scale, studies. The evidence indicates that woody regrowth following land abandonment is an important driver of land surface greening throughout Europe. The results offer an explanation for the large discrepancies between ESM‐derived and satellite‐derived greening estimates and thus generate new avenues for improving the ESMs on which we rely for crucial climate forecasts.

Fostering natural forest regeneration on former agricultural land through economic and policy interventions

“…The greatest increases in tree cover were in Eastern Europe (35%), including European Russia and Carpathian montane forests (Song et al 2018). In Eastern Europe, tree cover gain was attributed to natural forest regeneration on abandoned agricultural land following the collapse of the former Soviet Union (Potapov et al 2015, Rudel et al 2016, Buitenwerf et al 2018. Political changes in Eastern Europe and land-use subsidies in the European Union to set aside marginal agricultural areas in regions with steep slopes to limit food production and avoid surpluses (Common Agricultural Policy reforms) led to abandonment of farmland from 1998 to 2008 (Lasanta et al 2017).…”

Roadside diversity in relation to age and surrounding source habitat: evidence for long time lags in valuable green infrastructure

“…For the past 150 years, there has been a sharp and ongoing decline in the area of semi‐natural grassland habitat across Europe, following the conversion or abandonment of ancient pastures and meadows (Auffret, Kimberley, Plue, & Waldén, 2018; Buitenwerf, Sandel, Normand, Mimet, & Svenning, 2018; Hooftman & Bullock, 2012). This loss, together with the high value of grassland habitat in terms of biodiversity and ecosystem services (Bengtsson et al., 2019; Billeter et al., 2008; Wilson, Peet, Dengler, & Pärtel, 2012), means that it is important to understand the role of alternative, marginal habitats in the landscape that are also able to support grassland communities.…”

Forest age improves understanding of the global carbon sink

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