National University of Comahue

Invasive species often interact in novel ways affecting native ecosystems, but the role of herbivore-mediated plant responses to damage in such interactions remains understudied. We conducted a common garden experiment in northern Patagonia to assess the tolerance and resistance of native and non-native tree saplings—broadleaved and coniferous—to simulated browsing by introduced ungulates. Eight dominant tree species were subjected to mechanical clipping and sheep saliva application to mimic herbivory. We evaluated performance metrics, biomass allocation, leaf traits, induced chemical defenses, and subsequent leaf damage by insects (only in broadleaved species). Overall, plant responses to damage varied depending on whether the trees were native or non-native. In general, non-native broadleaved species exhibited strong compensatory regrowth, while native broadleaved species showed limited height recovery. However, broadleaved species showed less insect damage after simulated browsing, especially native ones, suggesting the induction of some defensive traits not evaluated here. In turn, non-native conifers showed reduced aboveground biomass but increased branch production and induced chemical defenses, including elevated levels of resin and monoterpenes, particularly γ-carene. In comparison, native conifers showed a conservative growth response and limited plasticity. Saliva application triggered specific defensive responses only in non-native species, suggesting evolved recognition of herbivore cues. These findings highlight distinct functional strategies: non-natives combined architectural plasticity with inducible defenses, while natives relied more on constitutive traits. Our results show that introduced ungulates may indirectly facilitate non-native tree invasion by differentially affecting native species recovery and defense, with implications for forest dynamics under ongoing invasion and co-invasion scenarios.

Decomposition in temporary wetlands occurs under two alternating conditions: terrestrial (dry) and aquatic phases. We explored the environmental drivers of litter decomposition in Patagonian temporary wetlands from forest and steppe biomes with different hydroperiods. Litter from two dominant species, Carex aematorhyncha and Juncus procerus decomposed in litterbags during approx. 470 days, through aquatic and dry conditions. Both species decomposed faster in the forest wetlands but not at the longest but at intermediate hydroperiod, and C. aematorhyncha decomposed faster than J. procerus. Hydrological condition (dry or aquatic) strongly influenced both litter decomposition and nutrient dynamics (nitrogen and phosphorus). During the aquatic phase, higher decomposition was found in wetlands with higher temperature and dissolved phosphorus concentration, whereas during the dry phase both litter decomposition and nutrient accumulation were associated with longer hydroperiods, higher temperature, and higher soil moisture. Our findings imply that hydroperiod length is a crucial pathway determining decomposition rates and nutrient accumulation in litter. Under current climate change scenarios, declining precipitation in Patagonia will lead to shorten hydroperiods, potentially increasing organic matter accumulation in temporary wetlands and altering detritivore food webs.

Pesticide use is a core strategy to control agricultural pests. Although international treaties and health recommendations call for banning hazardous pesticides, globally harmonized pesticide governance remains elusive. In Latin America (LATAM), the main net food exporter worldwide, agricultural pesticide use has increased by approximately 500% since 1990, compared with only approximately 3% in Europe. To assess the environmental and health rigour of LATAM's pesticide legislation, we reviewed active ingredients (AIs) approved for ten major crops, and AIs banned at national level, in eight LATAM countries, assessed their hazardousness according to international standards, and legal status in the European Union (EU) and explored sources of variation in the number of AIs approved in LATAM. We identified 523 AIs approved and 236 banned in LATAM; approximately 50% of the approved and approximately 85% of the banned AIs in LATAM were either not approved or prohibited in the EU. Higher crop production and, to a lesser extent, export value were linked to more AIs approved in LATAM. These findings imply weaker regulatory frameworks for hazardous pesticides in LATAM, reflecting more permissive environmental policies compared with the EU. This reinforces the urgency of addressing asymmetries in pesticide governance and rethinking the prevailing agricultural paradigm.

Landscape complexity shapes insect spatiotemporal population dynamics and trophic interactions. In this context, understanding seasonal and environmental patterns of potential resident natural enemies of novel polyphagous herbivores, such as the globally invasive fruit fly pest Drosophila suzukii, is fundamental for developing effective landscape-scale pest management strategies. Here, we investigated for the first time in the Andean Patagonian region of Argentina the spatiotemporal dynamics and parasitism of three resident parasitoids-Leptopilina heterotoma, Pachycrepoideus vindemiae, and Spalangia endius-with the potential to attack D. suzukii across heterogeneous landscape including fruit crops and surrounding natural habitats. All three parasitoid species were recorded across all environments, although their seasonal dynamics differed. L. heterotoma peaked in spring, P. vindemiae in summer, while S. endius showed a non-significant tendency toward higher activity in autumn. We further provide the first field-based evidence in the region that S. endius successfully attacks and completes development in D. suzukii, and that D. suzukii exploits wild fruit species as alternative hosts. These findings highlight the need for further research on the pupal parasitoid S. endius to assess its potential as a suitable candidate for the development of biological control strategies.

Ectomycorrhizal (EcM) fungi are key forest symbionts, yet the extent to which environmental factors and host identity interact to shape EcM communities remains unclear. We examined EcM fungi biodiversity changes associated with three co-occurring Nothofagus species across two sites along a precipitation gradient in northern Patagonia. Specifically, we hypothesized that (i) environmental context modulates host-specific effects on EcM fungal biodiversity, and (ii) the distribution of exploration types, as key functional traits, is primarily structured by precipitation-driven abiotic conditions (e.g., soil moisture and related edaphic factors). Fine roots of Nothofagus alpina, N. obliqua, and N. dombeyi were sampled in mixed forests at two sites with different precipitation levels (humid vs. mesic). EcM colonization was determined and EcM fungi identified by morphotyping and Sanger sequencing (ITS). We compared EcM colonization, taxonomic α- and β-diversity, and functional diversity based on the characterization of EcM exploration types across sites and hosts, and assessed soil properties (moisture, pH, electrical conductivity, and nutrient content). Site was the principal driver of EcM abundance and of both taxonomic and functional diversity. While EcM colonization and taxonomic α-diversity responded exclusively to site, taxonomic β-diversity revealed a site-dependent host effect; communities differed among Nothofagus species only at the mesic site. Functional diversity was determined solely by site. Site, representing environmental context, especially determined by precipitation level, generally overrides host effects on EcM communities, with host identity influencing β-diversity only under specific conditions. Our findings provide new insight into EcM ecology in temperate Patagonian forests and underscore the value of integrating functional and taxonomic perspectives to understand plant-fungal interactions across environmental gradients, particularly under ongoing climate change. This information is critical for informing climate-adaptive forest management.