• Energy Research

Hedgerows are semi-natural wooded habitats and an important element in agricultural landscapes across Western and North-Western Europe. They reduce erosion, function as carbon sinks and thus provide essential ecosystem services. Moreover, they form a structurally diverse ecosystem for numerous taxa and connect otherwise fragmented forest habitats. This study compiled data from the hedgerow-rich oceanic regions of Europe, covering a gradient from Southern Sweden to Northern France, to analyse the influence of management, landscape context and climate variables on the number of herbaceous forest specialists in hedgerows. The species frequencies in hedgerows were related to their functional traits to identify plant characteristics that are beneficial for species dispersal and persistence in hedgerows. Our results show that numerous forest plant species, but not all, can thrive in hedgerows. Those are likely thermophilic, tolerant against regular disturbance and able to disperse efficiently. Hedgerows in regions that are warm or that are impacted by heat and drought events contain fewer forest species. Intensive adjacent land-use had a negative impact on forest species richness, while the surrounding forest cover was not significantly important. In congruence with previous regional studies, wider hedgerows contain more forest species, which is most likely caused by a more effective buffering of the microclimate. Thus, hedgerow width gains in importance in times of climate change and increasing extreme weather events. It is a key factor for habitat quality also on a European scale that needs to be considered for future management strategies.

Hedgerows are semi-natural wooded habitats and an important element in agricultural landscapes across Western and North-Western Europe. They reduce erosion, function as carbon sinks and thus provide essential ecosystem services. Moreover, they form a structurally diverse ecosystem for numerous taxa and connect otherwise fragmented forest habitats. This study compiled data from the hedgerow-rich oceanic regions of Europe, covering a gradient from Southern Sweden to Northern France, to analyse the influence of management, landscape context and climate variables on the number of herbaceous forest specialists in hedgerows. The species frequencies in hedgerows were related to their functional traits to identify plant characteristics that are beneficial for species dispersal and persistence in hedgerows. Our results show that numerous forest plant species, but not all, can thrive in hedgerows. Those are likely thermophilic, tolerant against regular disturbance and able to disperse efficiently. Hedgerows in regions that are warm or that are impacted by heat and drought events contain fewer forest species. Intensive adjacent land-use had a negative impact on forest species richness, while the surrounding forest cover was not significantly important. In congruence with previous regional studies, wider hedgerows contain more forest species, which is most likely caused by a more effective buffering of the microclimate. Thus, hedgerow width gains in importance in times of climate change and increasing extreme weather events. It is a key factor for habitat quality also on a European scale that needs to be considered for future management strategies.

Litter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1–3.5% and of the more stable substrates by 3.8–10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4–2.2% and that of low-quality litter by 0.9–1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate.

Litter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1–3.5% and of the more stable substrates by 3.8–10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4–2.2% and that of low-quality litter by 0.9–1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate.