Seedling survival and growth of Podocarpus glomeratus (Podocarpaceae) along different altitudes and microsites in grassland ecosystems from the central Andes of Bolivia after four years

La altitud y el micrositio son factores clave para el establecimiento de las plantas en ecosistemas de montaña. En este estudio evaluamos cómo la sobrevivencia y el crecimiento de plántulas de Podocarpus glomeratus, una conífera nativa vulnerable a la extinción, varía a través de ambos factores. Plantamos 150 plántulas de la especie, repartidas en 15 parcelas a lo largo de un gradiente altitudinal con cinco altitudes (2700, 3000, 3300, 3600 y 3900 m s.n.m) y tres repeticiones por altitud (parcelas anidadas) en ecosistemas de pastizales de la comunidad de Pajchanti (Cochabamba, Bolivia). La sobrevivencia, crecimiento y los componentes del micrositio alrededor de cada plántula (porcentaje de cobertura de pastos, arbustos, piedras, musgos, hierbas y porcentaje de pendiente) se evaluaron tres veces durante cuatro años. La influencia de la altitud sobre la sobrevivencia final o el crecimiento acumulado de cada plántula fueron analizados con modelos lineales generalizados mixtos (MLGM) y pruebas de Tukey (incluyendo a las parcelas repetidas como factor aleatorio). Asimismo, la influencia de cada uno de los componentes del micrositio sobre la sobrevivencia o el crecimiento de cada plántula fueron analizados por separado para cada altitud, también con MLGM, para que los efectos de esas variables no se confundan debido a su correlación. La sobrevivencia de las plántulas fue mayor en la altitud intermedia y menor en ambos extremos altitudinales. Sin embargo, el crecimiento fue mayor en el rango de la altitud inferior y la intermedia (2700 a 3300 m s.n.m) y menor en altitudes mayores. Los componentes del micrositio no influyeron en la sobrevivencia. Sin embargo, la cobertura de arbustos incrementó el crecimiento en la altitud inferior, la cobertura de piedras redujo el crecimiento en la altitud intermedia, y mayor porcentaje de pendiente y cobertura de piedras incrementaron el crecimiento a 3590 m s.n.m. La reforestación de P. glomeratus en ecosistemas de pastizales debería realizarse entre 2700 y 3300 m s.n.m. Sin embargo, las piedras, arbustos y pendiente, dependiendo su porcentaje de cobertura en el micrositio e interacciones con la altitud, incrementan o reducen el establecimiento de las plántulas, por lo que deben manejarse en futuras reforestaciones.Altitude and microsite are key factors for the establishment of seedlings in mountain ecosystems. In this study, we evaluated how seedling survival and growth of Podocarpus glomeratus, a native tree vulnerable to extinction, varied across different altitudes and microsites. As part of a four-year reforestation program, 150 seedlings were planted in 15 experimental plots along an altitudinal gradient of five levels (2747, 3005, 3300, 3590 and 3850 m a.s.l.) and three repetitions by altitude (nested plots) in a grassland ecosystems from the community of Pajchanti (Cochabamba, Bolivia). Plant survival, growth and microsite around each seedling, such as slope and ground cover (rock outcrops, grasses, shrubs, mosses and herbs) were measured three times during the reforestation program. Generalized linear mixed models (GLMM) and Tukey tests were used in order to evaluate the influence of altitude on seedling survival and growth (including nested plots as random factor). The influence of each component biotic or abiotic in the microsites on the survival and growth was analyzed also with GLMM, for each altitude separately. Thus, we avoided confusing effect of altitude and microsite. Seedlings survival was significantly greater at the intermediate altitude and lower at both altitudinal extremes, but seedlings growth was greater at the lower altitude range (from 2700 to 3300 m a.s.l.), while smaller at higher altitudes. Seedlings survival was not influenced by abiotic or biotic components of the microsite. However, high shrub cover was related to higher seedlings growth at the lowest altitude. High rock outcrops cover had a negative effect on growth in the intermediate altitude, while more rock outcrops and higher slope percentage had positive effect on the growth at a higher altitude (3590 m a.s.l.). Reforestation of P. glomeratus in grassland ecosystems should be carried out at 2700 to 3300 m a.s.l. Nonetheless, shrubs, rock outcrops and slope of the microsite influenced the establishment of the seedlings, depending on cover percentage and interactions with the altitude. These microsite components must be managed in future reforestations

Efecto de la tala de Podocarpus glomeratus (Podocarpaceae) sobre la estructura de un bosque de neblina en los Andes (Cochabamba, Bolivia)

We examined the effect of logged mature trees on the structure, composition and natural regeneration of cloud forest. We installed 40 plots of 707 m2 measuring individuals >10 cm Dbh (Diameter at breast height), sub-parcels of 5 m2 for the regeneration <10cm Dbh and of 1 m2 for the seed-bank. We evaluated density and cover understory of all the trees. We did a cluster analysis for generating categories of cover canopy and also it makes principals components analysis (PCA) for determining the association of canopy cover with the density of different seedings species. The logging of mature trees modified the covering (p=<0,001) generating cano- pies different (few to strongly intervened). The canopy gaps improved the density of species shade-intolerant (Myrsine pseudocrenata, Vallea stipularis, Nectandra sp., Trichilia hirta, Miconia theaezans), some species shade-tolerant decreases their density sampling when decrease the covering canopy (Weinmannia microphylla, Condalia weberbaueri, Blepharocalix salicifolius and Styloceras columnare). The management of the forest has that maintain the understory cover of individuals >60 cm Dbh, to create areas protect in old forest and to promote practical of facilitating the growing of important trees.En el presente trabajo fueron analizados los efectos de la tala sobre la estructura, composición y la regeneración natural de un bosque andino de neblina. Se instalaron 40 parcelas de 707 m2 para medir individuos >10 cm DAP y sub-parcelas de 5 m2 para evaluar la regeneración de individuos <10 cm DAP y de 1 m2 para evaluar el banco de semillas. Se evaluó la densidad y cobertura de todos los árboles. Se realizó un análisis cluster para establecer las categorías de cobertura de dosel y un análisis de componentes principales para determinar su asociación con la densidad de diferentes especies de plántulas. La tala ha modificado la cobertura (p= <0,001) generando doseles de poco a fuertemente intervenidos. Los claros de dosel favorecen a las heliófitas (Myrsine pseudocrenata, Vallea stipularis, Nectandra sp., Trichilia hirta, Miconia theaezans), algunas esciófitas que requieren luz en clases avanzadas (Podocarpus glomeratus y Myrcianthes osteomeloides) y otros arbustos (Solanaceae, Verbenaceae y otras). Por otra parte, algunas esciófitas reducen su densidad en doseles inter- venidos (Weinmannia microphylla, Condalia weberbaueri, Blepharocalix salicifolius y Styloceras columnare). El manejo del bosque debe mantener la cobertura de individuos > 60 cm DAP, la creación de reservas en bosques maduros y prácticas de facilitación para el crecimiento de especies de árboles claves

Biomass and dominance of conservative species drive above-ground biomass productivity in a mediterranean-type forest of Chile

Abstract Background Forest productivity has a pivotal role in human well-being. Vegetation quantity, niche complementarity, mass-ratio, and soil resources are alternative/complementary ecological mechanisms driving productivity. One challenge in current forest management depends on identifying and manipulating these mechanisms to enhance productivity. This study assessed the extent to which these mechanisms control above-ground biomass productivity (AGBP) of a Chilean mediterranean-type matorral. AGBP measured as tree above-ground biomass changes over a 7-years period, was estimated for twelve 25 m × 25 m plots across a wide range of matorral compositions and structures. Variables related to canopy structure, species and functional diversity, species and functional dominance, soil texture, soil water and soil nitrogen content were measured as surrogates of the four mechanisms proposed. Linear regression models were used to test the hypotheses. A multimodel inference based on the Akaike’s information criterion was used to select the best models explaining AGBP and for identifying the relative importance of each mechanism. Results Vegetation quantity (tree density) and mass-ratio (relative biomass of Cryptocarya alba, a conservative species) were the strongest drivers increasing AGBP, while niche complementarity (richness species) and soil resources (sand, %) had a smaller effect either decreasing or increasing AGBP, respectively. This study provides the first assessment of alternative mechanisms driving AGBP in mediterranean forests of Chile. There is strong evidence suggesting that the vegetation quantity and mass-ratio mechanisms are key drivers of AGBP, such as in other tropical and temperate forests. However, in contrast with other studies from mediterranean-type forests, our results show a negative effect of species diversity and a small effect of soil resources on AGBP. Conclusion AGBP in the Chilean matorral depends mainly on the vegetation quantity and mass-ratio mechanisms. The findings of this study have implications for matorral restoration and management for the production of timber and non-timber products and carbon sequestration

Efecto de la tala de Podocarpus glomeratus (Podocarpaceae) sobre la estructura de un bosque de neblina en los Andes (Cochabamba, Bolivia)

We examined the effect of logged mature trees on the structure, composition and natural regeneration of cloud forest. We installed 40 plots of 707 m2 measuring individuals >10 cm Dbh (Diameter at breast height), sub-parcels of 5 m2 for the regeneration <10cm Dbh and of 1 m2 for the seed-bank. We evaluated density and cover understory of all the trees. We did a cluster analysis for generating categories of cover canopy and also it makes principals components analysis (PCA) for determining the association of canopy cover with the density of different seedings species. The logging of mature trees modified the covering (p=<0,001) generating cano- pies different (few to strongly intervened). The canopy gaps improved the density of species shade-intolerant (Myrsine pseudocrenata, Vallea stipularis, Nectandra sp., Trichilia hirta, Miconia theaezans), some species shade-tolerant decreases their density sampling when decrease the covering canopy (Weinmannia microphylla, Condalia weberbaueri, Blepharocalix salicifolius and Styloceras columnare). The management of the forest has that maintain the understory cover of individuals >60 cm Dbh, to create areas protect in old forest and to promote practical of facilitating the growing of important trees.En el presente trabajo fueron analizados los efectos de la tala sobre la estructura, composición y la regeneración natural de un bosque andino de neblina. Se instalaron 40 parcelas de 707 m2 para medir individuos >10 cm DAP y sub-parcelas de 5 m2 para evaluar la regeneración de individuos <10 cm DAP y de 1 m2 para evaluar el banco de semillas. Se evaluó la densidad y cobertura de todos los árboles. Se realizó un análisis cluster para establecer las categorías de cobertura de dosel y un análisis de componentes principales para determinar su asociación con la densidad de diferentes especies de plántulas. La tala ha modificado la cobertura (p= <0,001) generando doseles de poco a fuertemente intervenidos. Los claros de dosel favorecen a las heliófitas (Myrsine pseudocrenata, Vallea stipularis, Nectandra sp., Trichilia hirta, Miconia theaezans), algunas esciófitas que requieren luz en clases avanzadas (Podocarpus glomeratus y Myrcianthes osteomeloides) y otros arbustos (Solanaceae, Verbenaceae y otras). Por otra parte, algunas esciófitas reducen su densidad en doseles inter- venidos (Weinmannia microphylla, Condalia weberbaueri, Blepharocalix salicifolius y Styloceras columnare). El manejo del bosque debe mantener la cobertura de individuos > 60 cm DAP, la creación de reservas en bosques maduros y prácticas de facilitación para el crecimiento de especies de árboles claves

Trait similarity among dominant highly-competitive species rather than diversity increases productivity in semi-arid Mediterranean forests

Biodiversity plays a pivotal role in forest productivity and, through it, on the provision of ecosystem services. Consequently, understanding the mechanisms by which biodiversity drives productivity is a challenge for sustainable forest management. It has been proposed that functional dissimilarity can increase forest productivity, particularly in water-limited ecosystems (as Mediterranean forests), where water stress might increase complementarity resource use among species (hypothesis of niche complementarity). Alternatively, strongly water-limited forests may favor the dominance of woody species with slow-growth and conservative resource-use trait values, which in turn, might increase plant community productivity proportionally to their biomass (hypothesis of mass-ratio). The effects of such mechanisms on productivity is yet understudied in water-limited forests. We assessed the effect of both previously described mechanisms on productivity in a semi-arid Mediterranean-type climate matorral of Chile through a trait-based approach. We hypothesized that: (1) higher dissimilarity of functional trait values of crowns, roots and phenology among woody species increases community productivity. Alternatively, (2) higher dominance of woody species of conservative trait values increases forest productivity. We installed twenty-three 25 × 25 m plots in the matorral of the National Reserve of “Roblería de Los Cobres de Loncha” located in the Coastal Range. Forest productivity was estimated as above-ground biomass changes between 2010 and 2017. The mean species pairwise dissimilarity (MPD) and the community-weighted mean trait values (CWM) were calculated for each single trait as surrogates of the hypotheses of niche complementarity and mass-ratio, respectively. Environmental variables (e.g. altitude, slope, precipitation) were included as potential drivers influencing productivity. We performed a selection procedure of multiple linear regression models based on the Akaike Information Criterion. Our findings show that higher forest productivity was related with higher trait similarity of plant maximum height and onset of growth among species. Besides, productivity increased with CWM values that reflect greater dominance of species exhibiting acquisitive traits (i.e. greater maximum plant height, lower wood density and earlier onset of growth) rather than conservative traits. Moreover, forest productivity increased with increasing altitude, precipitation and decreasing temperatures from 300 to 900 m. Therefore, in contrast with our hypotheses, productivity increased by greater trait similarity among dominant highly-competitive species - which might be favored by mesic conditions at middle altitudes of the Coastal Range. The sustainable management of semi-arid Mediterranean forests with the main focus on productivity should promote higher dominance of highly-competitive species with similar functional trait values in mesic conditions, and conservative species with greater trait functional dissimilarity to increase drought resistance in stressful environments.Fil: Ayma-Romay, Ariel Isaías. Universidad de Chile; ChileFil: Bown, Horacio E.. Universidad de Chile; ChileFil: Pérez Harguindeguy, Natalia. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina. Universidad Nacional de Córdoba; Argentin

Corredores Biológicos Urbanos de Cochabamba

Proyecto multidisciplinario sobre corredores biológicos urbanos como espacios de integración socio-ambientales en el Municipio de Cochabamb