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The aim of this study is 1°) to quantify environmental changes in herbivory due to Orthoptera on two perennial grasses and 2°) to assess the processes involved in the control of herbivory. Herbivory varies strongly according to shade, drought and mowing, and is positively related to vapour pressure deficit and temperature. Besides the hypothesis of a trophic control of herbivory, our results are consistent with a microclimatic control of herbivory by Orthoptera. The coexistence of different hypothesis of herbivory control may depend on the studied system and specifically on the type of herbivore involved. [Copyright &y& Elsevier]

Recruitment is a key process for forest sustainability, especially in warm margin of distribution area. The influence of climate (temperate or warm), of soil water availability, and of allelopathic interactions from different forest species have been tested on the germination of Fagus sylvatica in controlled climatic conditions. Germination rates of non-dormant Fagus seeds were improved by relatively warm temperatures (20°C), but reversibly stopped under heat constraint (27°C). The relative growth rate of Fagus seedlings was better under temperate climatic conditions. Foliar extracts of Hedera helix showed the highest allelopathic effect on Fagus recruitment, especially in temperate conditions. Our results suggest a limitation of Fagus recruitment in warm margin of its distribution area, and a modulation of recruitment success according to the identity of plant neighbourhood., (Copyright © 2018. Published by Elsevier Masson SAS.)

The aim of this study is 1 degree) to quantify environmental changes in herbivory due to Orthoptera on two perennial grasses and 2 degrees) to assess the processes involved in the control of herbivory. Herbivory varies strongly according to shade, drought and mowing, and is positively related to vapour pressure deficit and temperature. Besides the hypothesis of a trophic control of herbivory, our results are consistent with a microclimatic control of herbivory by Orthoptera. The coexistence of different hypothesis of herbivory control may depend on the studied system and specifically on the type of herbivore involved.