Quality evaluation of Nothofagus pumilio seeds linked to forest management and climatic events

RODRÍGUEZ-SOUILLA, JULIAN; CHAVES, JIMENA E.; LENCINAS, MARÍA VANESSA; CELLINI, JUAN MANUEL; ROIG, FIDEL A.; PERI, PABLO L.; MARTINEZ PASTUR, GUILLERMO

Ecological Processes

Springer

Año: 2024 vol. 13

Background Forest ecosystems undergo significant transformations due to harvesting and climate fluctuations,emphasizing the critical role of seeding in natural regeneration and long-term structural preservation. Climate changefurther amplifies these dynamics, affecting phenology across species and regions. In Tierra del Fuego (Argentina),Nothofagus pumilio (lenga) forests represent the most important timber resource, and it is managed through differentsilvicultural strategies. This species demonstrates notable post-disturbance regeneration, yet seed fall exhibits significantvariability, leading to variations in seed quality (e.g., viability). This study aims to assess fluctuations in N. pumilioseed quality, determine how it varies concerning forest management strategies, annual productivity, and the cooccurrenceof climatic phenomena including El Niño-Southern Oscillation (ENSO) and the Southern Annular Mode(SAM).Results Viable seeds represented 18.4% of the total, notably higher in unharvested than in managed areas. Conversely,empty seeds were more prevalent in harvested areas (> 75%). Seed quality exhibited significant differencesacross silvicultural treatments, except for insect-predated seeds, which had similar proportions across all areas,though dispersed retention showed higher predation. When considering years with varying production levels,high-production years favoured full and viable seeds, particularly in unharvested forests and aggregated retention,while low-production years saw reduced viability across all treatments. Quadratic models revealed that viabilityincreased with seed production, where unharvested forests achieved the highest values. Climate variability influencedseed proportions, where ENSO+/SAM+ promoting more full and viable seeds, while ENSO–/SAM+ favoured nonpredatedseeds, especially in unharvested stands.Conclusions Seed quality varies among treatments and years with different levels of seeding. Variations in seed quality,linked to climatic events, influence seed viability. Seed quality plays a critical role in forest regeneration, ensuringa seedling bank for harvested stands to face climate variability. These findings are relevant for forest managementand ecosystem services, considering the increasing climate variability and extreme events. Understanding these influencesis crucial for Nothofagus pumilio forests’ sustainability and global forest adaptation strategies.