Tree life histories in a montane subtropical forest: species differ independently by shade‐tolerance, turnover rate and substrate preference

Abstract

Summary 1.To investigate life-history differentiation and an objective functional classification of tree species we analysed the demography of 29 species in subtropical montane forests in north-western Argentina. 2. We computed 13 growth, demographic, abundance and distribution variables based on: (i) two 5-year re-measurements of stems ≥ 10 cm diameter at breast height (d.b.h.) in 8 ha of old growth forest and 4 ha of secondary forest; (ii) assessments of tree crown illumination; and (iii) sapling counts under shade and on landslides. 3. We assessed the potential confounding effects of stem size and crown illumination on absolute stem diameter growth rate for the 24 most abundant species. As diameter increased, one species showed significant increases in growth rate and five showed significant reductions. Seventeen species grew significantly faster with increased exposure to light and we controlled for this confounding effect in the computation of diameter growth rates for subsequent analyses. 4. A principal component analysis resulted in three meaningful and interpretable axes of demographic variation across species. The first axis (interpreted as shade tolerance) indicates that trees of species with inherently high growth rates tend to have wellexposed crowns at 10-30 cm d.b.h., have high density of trees in secondary forest and are less tolerant of shade. 5. The second axis (turnover) shows that in old-growth forest short-lived species, with high mortality rates, size-class distributions with a steep negative slope and low dominance, persist due to high rates of recruitment (to ≥ 10 cm d.b.h.). 6. The third axis indicates that species that colonize landslides have lower tree recruitment rates and greater growth variability in secondary forest, reflecting spatio/ temporal differences in species' recruitment linked to differences in their substrate requirements for regeneration. 7. Maximum height and diameter are correlated with the first and second axes, indicating that higher rates of both growth and survival permit some species to attain large size. 8. All three demographic axes depict separate trade-offs that confer competitive advantage to each 'demographic type' under contrasting ecological conditions (of light availability, disturbance frequency and disturbance intensity), thus underpinning species' coexistence in dynamic forest landscapes.

FOREST MANAGEMENT FOR THE CONSERVATION OF Araucaria angustifolia IN SOUTHERN BRAZIL

“…Information on the growth of trees is essential to predict their production and elaborate forest management plans, since their growth can vary within the same species; this variability is attributed to combined factors that may have temporal and spatial variation (EASDALE et al, 2007).…”

Dynamics of the association between a long-lived understory myrmecophyte and its specific associated ants

“…Beside its myrmecophytism, H. physophora also shares several biological traits with many plant species from the understory that enables its survival in this environment, such as shade tolerance and slow growth, mortality, and recruitment rates (Easdale et al 2007;Gourlet-Fleury et al 2005;Nascimento et al 2005;Vieira et al 2005). Moreover, like for any plant species in the understory, the impact and consequences of the physical damage caused by debris falling from the canopy are of importance.…”

Efectos de la invasión del ligustro, Ligustrum lucidum, en la dinámica hídrica de las Yungas del noroeste Argentino

“…El sotobosque del bosque nativo, que es mucho más diverso y denso que el del bosque invadido (Ayup et al 2014) tendría un porcentaje de especies que aprovechan esta mayor disponibilidad de luz para crecer durante esta época y aportar significativamente al incremento de los valores de NDVI registrado. Mientras que los bosques de ligustro, al no perder las hojas en ninguna estación, aprovecharían la luz a lo largo de todo el año, explicando también las mayores tasas de crecimiento encontradas con respecto a los árboles nativos (Easdale et al 2007) e imposibilitando el uso de este recurso al sotobosque mucho menos diverso de estos bosques. Esta situación acotaría las diferencias en los valores de NDVI observadas a lo largo del año entre los dos tipos de bosques.…”

“…Estos bosques presentan mayor área basal y biomasa acumulada que sus coetáneos nativos, como consecuencia de poseer la mayor tasa de crecimiento observada para árboles de las Yungas (Easdale et al 2007), pero presentan menor biodiversidad animal y vegetal (Ayup et al 2014). El ligustro presenta un desfasaje fenológico con respecto a las especies nativas (Grau y Aragón 2000), altísima producción de frutos durante el invierno, eficiente dispersión de semillas por aves, buena capacidad de reproducción vegetativa y germinación y supervivencia en un amplio rango de hábitats (Aragón y Groom 2003).…”

“…Paralelamente, estudios fisioló-gicos demuestran que en especies arbóreas subtropicales existe una correlación positiva entre la tasa de crecimiento, la fotosíntesis y el consumo de agua (Campanello 2004). Este hecho, sumado a las altas tasas de crecimiento del ligustro (Lichstein et al 2004, Easdale et al 2007, sugiere que los bosques de esta especie estarían efectuando un mayor consumo de agua que los bosques nativos.…”