Drought-induced decline of productivity in the dominant grassland species Lolium perenne L. depends on soil type and prevailing climatic conditions

Abstract

Severe constraints on grasslands productivity, ecosystem functions, goods and services are expected to result from projected warming and drought scenarios under climate change. Negative effects on vegetation can be mediated via soil fertility and water holding capacity, though specific mechanisms are fairly complex to generalise. In field drought experiments, it can be difficult to disentangle a drought effect per se from potential confounding effects related to vegetation or soil type, both varying along with climate. Furthermore, there is the need to distinguish the long-term responses of vegetation and soil to gradual climate shift from responses to extreme and stochastic climatic events. Here we address these limitations by means of a factorial experiment using a single dominant grassland species (the perennial ryegrass Lolium perenne L.) grown as a phytometer on two soils types with contrasted physicochemical characteristics, placed at two elevation sites along a climatic gradient, and exposed to early or late-season drought during the plant growing season. Warmer site conditions and reduced precipitation along the elevational gradient affected biogeochemistry and plant productivity more than the drought treatments alone, despite the similar magnitude in volumetric soil moisture reduction. Soil type, as defined here by its organic matter content (SOM), modulated the drought response in relation to local site climatic conditions and, through changes in microbial biomass and activity, determined the seasonal above and belowground productivity of L. perenne. More specifically, our combined uni-and multivariate analyses demonstrate that microbes in a loamy soil with low SOM are strongly responsive to change in climate, as indicated by a simultaneous increase in their C,N,P pools at high elevation with cooler temperatures and wetter soils. Contrastingly, microbes in a clay-loam soil with high SOM are mainly sensitive to temperature, as indicated by a strong increase in microbial biomass under warmer temperatures at low elevation and a

Responses of plant leaf economic and hydraulic traits mediate the effects of early- and late-season drought on grassland productivity

“…These authors also showed that heat waves in summer were indirectly increasing the negative effect of drought on biomass production decrease. At both of our study sites, air temperatures were higher, and induced higher vapour-pressure deficit (VPD), during the late-season drought compared to the early-season drought (VPD = 0.78 vs. 0.47 KPa at Site 1 and VPD = 0.59 vs. 0.27 KPa at Site 2; see Buttler et al . 2019).…”

“…plant growing season, 6 months, see Fig. 1) was 441 ± 36 mm at Site 1 and 682 ± 46 mm at Site 2, and mean daily average temperatures were 16 ± 0.3 °C at Site 1 and 13.5 ± 0.3 °C at Site 2 (see also Buttler et al 2019). Despite receiving different amount of precipitation during the plant growing season, both sites experience similar rainfall frequency with about 11 rainy days per months with precipitation equally spread over the season (see Buttler et al 2019).…”

“…1). Detailed precipitation data during (2 months) and after the peak (2 months) of plant growing season, as well as until the end of the growing season (2 months), are available in Buttler et al (2019). Watering was done manually, every 2–3 days in control plots to simulate the rainfall frequency of the region (i.e.…”

The Performance of Mesotrophic Arrhenatheretum Grassland under Different Cutting Frequency Regimes for Biomass Production in Southwest Germany

“…Therefore, it remains unclear whether a three-cut regime would still outperform the four-cut regime in the long term. This is especially relevant because an increased frequency of extreme weather events such as droughts and heavy rain is projected for European grassland areas [61][62][63][64][65] and therefore their management needs to become less intensive with regard to cutting frequencies.…”

Modelling the Interactions of Soils, Climate, and Management for Grass Production in England and Wales

“…Based on modelled predictions, grassland productivity could be enhanced under future climate, i.e., rising temperatures and potentially longer cropping seasons [7]. However, reduced soil water availability in summer may also limit the growing season [8], reducing forage productivity and increasing the variability of yield [9]. In the short-term in England and Wales, Rounsevell et al [10] predicted that climate change was unlikely to have a negative impact on grasslands, although, across Europe, the impact of climate change is likely to vary significantly between regions [11,12].…”