Exploring the effects of pasture trees on plant community patterns

Abstract

Questions We aim to answer three questions: (a) what are the effects of canopy shading of different tree species on seed germination of eight understorey grassland species? (b) how is plant species’ occurrence in understorey communities affected by differences in canopy cover and does that depend on tree species composition? and (c) are there mechanistic links between the effects of trees on species’ germination and their occurrence in the understorey plant community? Location Semi‐natural wooded pastures in the biosphere reserve Östra Vätterbranterna, southern Sweden. Methods In this study, we examined the germination of eight grassland plant species in a seed sowing experiment under natural conditions in the field. Seeds were sown beneath and outside the canopy of two tree species within 48 plots split up by four wooded pasture sites. We combined observed germination responses with a plant community survey to assess the effects of canopy cover in relation to tree species composition on plant community responses. We analysed these data in relation to species’ seed mass and vegetative shade tolerance. Results Shade‐tolerant species germinated better beneath compared to outside tree canopies, without any clear advantage of large‐seeded over small‐seeded species. As expected, species’ shade tolerance was also positively related to canopy cover within the understorey plant community. Importantly, we found strong tree species‐specific effects of canopy shading on the species’ germination response, but not on their presence within the plant community. However, optimal canopy cover conditions for germination and for the mature plants differed across grassland species and depended on tree species. Conclusions Our results show that different tree species play key ecosystem engineering roles in shaping wooded grassland plant community composition at the germination stage. Management practices favouring specific tree species may therefore be highly relevant for targeted biodiversity conservation of wooded semi‐natural grasslands.

Woody encroachment in grassland elicits complex changes in the functional structure of above‐ and belowground biota

“…Woody plant encroachment influences grassland plant community composition (Kahmen and Poschlod 2008, Eldridge et al 2011, Ratajczak et al 2012, Jakobsson et al 2019). There is also evidence that woody plant encroachment causes changes in the composition of fungal (Yannarell et al 2014, Schwob et al 2017, Neuenkamp et al 2018, Grau et al 2019), nematode (Biederman and Boutton 2009), and collembolan (Kwok and Eldridge 2016) communities.…”

Agri-environment schemes are associated with greater terrestrial invertebrate abundance and richness in upland grasslands

“…Although there have been studies assessing AES impacts in grasslands more generally (e.g. Caruso et al 2015;Berg et al 2019;Jakobsson et al 2019), there are a paucity of data spanning the diversity of whole invertebrate taxonomic groups (e.g. Smith et al, 2008), and still fewer studies have assessed the impact of AESs on marginal farmland; specifically, few invertebrate multi-taxa studies have been conducted in intensively grazed improved grasslands (where the benefits of AESs are questionable) and compared to more species-rich, semi-improved grasslands in upland regions (> 150 m above sea level).…”

Efeito das espécies de árvores do dossel na dinâmica de populações de regenerantes

“…Distintas espécies de dossel e emergentes podem criar diferentes condições ambientais sob suas copas, e afetar diferencialmente a sobrevivência e crescimento de plântulas e juvenis de espécies arbóreas com diferentes graus de adaptação e tolerância à condição abaixo de cada uma delas (GANDOLFI, 2000;GUEVARA et al, 2004;VIVAR e CHAZDON, 2005;PIOTTO, 2007;BARBIER, GOSSELIN e BALANDIER, 2008;GARCÍA-ORTH e MARTÍNEZ-RAMOS, 2011;MEJÍA-DOMÍNGUEZ et al, 2011;SOUZA, GANDOLFI e RODRIGUES 2014e 2015AGRA et al, 2015;LEY-LÓPEZ et al, 2016;RAWLIK et al, 2018;LI e LIBER, 2018;JAKOBSSON et al, 2019). Assim, as espécies de estratos superiores determinariam, ainda que parcialmente, a composição e a estrutura (quantidade e tamanho dos indivíduos por espécie) da comunidade regenerante nesses locais (p.ex., PETERS et al, 2004;VIEIRA e GANDOLFI, 2006;MEJÍA-DOMÍNGUEZ et al, 2011;SOUZA, GANDOLFI e RODRIGUES, 2014, ALCANTARA et al, 2018JUÁREZ-GARCÍA et al, 2019;LAMEIRA et al, 2019).…”