Parent tree distance-dependent recruitment limitation of native and exotic invasive seedlings in urban forests

Abstract

Urban forests are more vulnerable to exotic species invasions than natural forests and are often a pathway for exotic invasions into natural areas. Investigating the mechanisms responsible for species coexistence in urban ecosystems is important to prevent forest invasions and conserve native biodiversity. In this experiment, we studied seedling recruitment for two exotic invasive (Acer platanoides and Rhamnus cathartica) and two native tree species (Acer saccharum and Betula papyrifera) in two urban forests. We measured the effects of distance from a mature tree on the growth of conspecific seedlings and their belowground interactions (mutualisms and pathogens). We expected that native seedlings growing in close proximity to a mature conspecific tree would more likely be damaged by co-specific pathogens than those growing further away. In contrast, considering that exotic invaders have not coevolved with the local soil pathogens, distance from the adult conspecific tree would not affect their seedlings. We collected undisturbed soil cores at five incremental distances from each adult tree and grew conspecific seeds in these cores. After three months of growth, we measured plant biomass, mycorrhizal root colonization and root lesions. We found that biomass increased with distance from the mature conspecific tree only for A. platanoides and no distance dependent signal was detected for other response variables. Our results show that distance from a conspecific mature tree may not determine exotic species invasibility in an urban forest and that, instead, this may contribute to promote native and invasive species coexistence in urban forest systems.

Differential impacts of soil microbes on native and co‐occurring invasive tree species

“…, Martínez‐García et al. ), we find it important to recognize either frequency or strength of such mechanisms. Research on enemy release in invasive species to date has led to inconsistent findings either supporting the hypothesis (Wolfe , Mitchell and Power , Reinhart et al.…”

Application of plant–soil feedbacks in the selection of crop rotation sequences

“…However, the direction of this relationship was positive, which is contrary to the assumption that root lesions are a symptom of disease or herbivory. Although root lesion frequency has been used in this context (Dukes et al, 2019 ; Maron et al, 2014 ; Martínez‐García et al, 2015 ; Schnitzer et al, 2011 ), the data are inconsistent. Some pathogens may not cause root lesions, resulting in underestimation of disease effects (Dukes et al, 2019 ).…”

Impacts of soil conditions and light availability on natural regeneration of Norway spruce Picea abies (L.) H. Karst. in low-elevation mountain forests

“…Young regeneration is especially vulnerable to limiting abiotic factors, for instance frost or drought (Niinemets and Valladares 2006;Eckstein et al 2011;Jagodziński et al 2017), as well as to herbivory (de Chantal and Granström 2007;Iszkuło et al 2014;Bodziarczyk et al 2017), leading to low survival rates. Another important factor is competition with understory herbaceous species (Lorimer et al 1994;Emborg 1998;Chmura and Sierka 2007), as well as competition within the regeneration layer, both intra-and interspecific (Janzen 1970;Robakowski and Bielinis 2011;Kawaletz et al 2014;Martínez-García et al 2015). For that reason, assessment of natural regeneration is crucial both for understanding dynamics of forest species composition and for developing forest management strategies.…”