Search

Copyright of Boletín de la Sociedad Argentina de Botánica is the property of Sociedad Argentina de Botanica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background and aims: Mountains hold a large portion of global biodiversity and provide important benefits to humans. With the aim of providing a key tool for the sustainable management of Córdoba mountain ecosystems, we present an exhaustive list of vascular plants and their altitudinal ranges. M&M: We compiled 669 complete floristic surveys and 1178 partial surveys performed from 2005 to 2020. Results: We record 1069 plant species: 147 non-native, 143 endemic to Argentina, 25 endemic to Córdoba and San Luis and 19 endemic to Córdoba. Most species had their median elevation below 1000 masl. Species turnover up to 1250 masl is slow, but from this elevation onwards it begins to accelerate, and continues in a similar way up to the highest end of the gradient. Out of all recorded species, 46 % are recognized as medicinal, of which, 79 are non-natives, 36 are endemic to Argentina, two are endemic to Córdoba and San Luis and two are exclusive of Córdoba. Conclusions: The list includes 60% of the species cited for Córdoba province and 65.5% of the medicinal flora recorded for this province. The upper end of the mountains, which represents less than 10% of the area, concentrates the highest proportion and diversity of endemic species in central Argentina. Our results show the importance of these mountains for the conservation and sustainable management of Córdoba biodiversity, and represent a baseline for future studies. [ABSTRACT FROM AUTHOR]

Questions Most vegetation descriptions tacitly assume that floristic composition and physiognomy are tightly linked. However, the two vegetation properties may not respond in a similar way to environmental and disturbance gradients, leading to uninformed management planning and difficulties when attempting to restore degraded ecosystems. In this context, we addressed two main questions: (1) how close are relations between floristic and physiognomic types as defined by numerical vegetation classification in mountain ecosystems; and (2) how are floristic and physiognomic types distributed along the elevation gradient? Location Central mountains of Argentina, between 500 and 1700 m a.s.l. Methods We selected 437 sites where we performed complete floristic and physiognomic relevés. We classified eight physiognomic and eight floristic types. We tested the relationship between the two classifications through a chi square analysis. We tested the association between elevation and each physiognomic and floristic type with random permutations. Results In general, floristic types were significantly and positively associated with more than one physiognomic type and vice versa. Physiognomic and floristic types responded differently to the elevation gradient. Floristic types were restricted to different sections of the gradient, although having large overlap among them. In contrast, seven out of the eight physiognomic types did not show elevation restriction, being distributed along the complete elevation gradient. The open low woodland with shrubs was the only restricted physiognomy, significantly absent from the upper part of the gradient. Conclusions We highlight the importance of considering the two vegetation properties independently when characterizing vegetation patterns in heterogeneous systems, since they show decoupled responses to environmental gradients. We note that the assumption of a direct link between floristic composition and physiognomy may induce bias into the understanding of vegetation patterns and processes. Hence, we encourage managers and restoration practitioners to consider the complete range of possible physiognomic types under each floristic type. [ABSTRACT FROM AUTHOR]

• Biomass accumulation of P. australis was measured for 10 years under livestock use. • Effective stocking densities lower than 0.12 AU ha−1 (animal units per ha) allows forest vertical biomass accumulation. • Effective stocking densities higher than 0.21 AU ha−1 are incompatible with forest conservation. • A land sharing strategy with low livestock production is possible. • Polylepis forests across the Andes could benefit from similar management strategies. Developing a land sharing strategy requires a thorough understanding of what is the maximum productivity that can be achieved without altering key ecosystem processes. In the central Argentina highlands, Polylepis australis dominates the few remaining patches of forests and its evergreen trees are highly selected by domestic livestock. Grazing exclusion and low herbivory pressure allow P. australis forest expansion and soil conservation, while high herbivory pressure promotes forest retraction and environment degradation. However, the extent to which stocking densities should be reduced to allow forest expansion and stand maturation is still unknown. We aimed at answering this question by studying 15 stands located in paddocks with different management, from grazing enclosures to heavily stocked. In 2003 we selected 12 trees less than 2 m tall at each stand. Almost annually along 10 years, for each tree we registered survival, and if alive, we measured the height and two perpendicular diameters of the canopy. We built indicators of vertical and horizontal biomass accumulation rate along the study period and calculated an average effective stocking density (i.e., animal units per ha of non-rocky surface, AU ha−1) for each stand. We found a piece-wise relationship with two pieces between the accumulation rate of each biomass component and average stocking density. Biomass accumulation was maximum under grazing exclusion (i.e. zero stocking density). Between zero and 0.21 AU ha−1 we detected a strongly negative relationship among stocking density and biomass accumulation. Effective stocking densities lower than 0.12 and 0.06 AU ha−1 promoted a widespread vertical and horizontal biomass accumulation, respectively. Stands with stocking densities higher than 0.21 AU ha−1, had null horizontal and vertical biomass accumulation and higher tree mortality. We suggest that effective stocking densities lower than 0.12 AU ha−1 allow a land sharing strategy in central Argentina highlands, ensuring the conservation of a traditional economic activity and the restoration of Polylepis australis forests. Additionally, in areas where Polylepis australis is absent we suggest active restoration without herbivory pressure. Finally, we suggest that these management recommendations may be studied and promoted throughout the extension of Polylepis spp. forests in South America. [ABSTRACT FROM AUTHOR]