Stand development stages and recruitment patterns influence fine-scale spatial genetic structure in two Patagonian Nothofagus species

Abstract

Key message Nothofagus alpina (Poepp. et Endl.) Oerst. and Nothofagus obliqua (Mirb.) Oerst forests have strong fine-scale spatial genetic structures. The intensity of genetic structure patterns differed according to species, stand development stages, life stages, and spatial arrangement of regeneration groups. This data becomes useful for forest management as it provides an understanding of how populations evolve as well as of the consequences of disturbances and enables the establishment of sampling strategies. Context The understanding of fine-scale spatial genetic structure in natural populations is useful for forest management. Although Nothofagus alpina (Poepp. et Endl.) Oerst. and N. obliqua (Mirb.) are important species of the Patagonian forest, little is known about the genetic structure of their populations. Aims The main objectives were to investigate the differences in fine-scale spatial genetic structure among mature tree populations of both species considering two stands at different development stages. Genetic structure was also evaluated among life stages and spatial distribution groups of regeneration within the old-growth stand. Methods Genetic structure was examined by microsatellite DNA analysis of regeneration and mature tree populations of both species (around 1300 individuals). Gene dispersal distance was additionally estimated. Results In both stands and species, strong fine-scale spatial genetic structure and short dispersal distance were found. This pattern was stronger in the early successional forest, in N. obliqua populations, in earlier life stages, and in scattered regeneration. Conclusion Stand development stages and recruitment patterns influence the fine-scale spatial genetic structure of both Nothofagus species. However, the genetic structure also differs between species.

The More the Merrier or the Fewer the Better Fare? Effects of Stand Density on Tree Growth and Climatic Response in a Scots Pine Plantation

“…This means that mortality during this period is independent of planting density. However, over forty years, the gradual closure of crowns and root systems as trees increase in size is leading to the emergence and gradual increase of competition for limited resources [69][70][71][72], primarily sunlight and water. The nonlinear increase in size with age causes the observed negative exponent in the dynamics of stand density.…”

Contrasted spatial, demographic and genetic structures of a light-demanding African timber species, Cylicodiscus gabunensis Harms – Implications for a sustainable management of its populations

“…It typically depends on various biotic and abiotic factors such as pollination, dispersal, seed predation and germination success (Connell, 1971;Janzen, 1970;Wright, 2002). Moreover, regeneration success of lightdemanding species also depends on natural and anthropogenic disturbances (Morin-Rivat et al, 2017;Sola et al, 2022;Tappeiner et al, 1997). By disrupting ecosystem structure and changing resource availability, and especially access to light, disturbances create the conditions for a new succession of species (Yamamoto, 2000).…”

“…Regeneration success of light-demanding species also depends on intrinsic factors such as the mating system and the extent of seed and pollen dispersal (Hardy et al, 2019), processes affecting in turn the demographic, spatial and genetic structures of tree populations (Luambua et al, 2021;Sola et al, 2022). Most tropical tree species are allogamous but self-compatible and occur at low population density (Duminil et al, 2016a;Duminil et al, 2016b;Hardy et al, 2019).…”

“…Comprehensive understanding of demographic and genetic factors and their influence on population dynamics is crucial to evaluate the impacts of present human disturbances such as selective logging on the natural regeneration of commercial species (Degen et al, 2006;Dupuy & Chazdon, 2008;Sola et al, 2022). To better understand how mating systems, gene flow and disturbances shape the regeneration success of long-lived light-demanding species and how these processes affect demography, spatial distribution and spatial genetic structure (SGS) of tree populations, we compared three distinct populations of C. gabunensis located in various environmental contexts.…”