Forests Of Southern Chile Research Articles

NITROGEN RETENTION ACROSS A GRADIENT OF15N ADDITIONS TO AN UNPOLLUTED TEMPERATE FOREST SOIL IN CHILE

Accelerated nitrogen (N) inputs can drive nonlinear changes in N cycling, retention, and loss in forest ecosystems. Nitrogen processing in soils is critical to understanding these changes, since soils typically are the largest N sink in forests. To elucidate soil mechanisms that underlie shifts in N cycling across a wide gradient of N supply, we added 15NH415NO3 at nine treatment levels ranging in geometric sequence from 0.2 kg to 640 kg N·ha−1·yr−1 to an unpolluted old-growth temperate forest in southern Chile. We recovered roughly half of 15N tracers in 0–25 cm of soil, primarily in the surface 10 cm. Low to moderate rates of N supply failed to stimulate N leaching, which suggests that most unrecovered 15N was transferred from soils to unmeasured sinks above ground. However, soil solution losses of nitrate increased sharply at inputs >160 kg N·ha−1·yr−1, corresponding to a threshold of elevated soil N availability and declining 15N retention in soil. Soil organic matter (<5.6 mm) dominated tracer retention at low rates of N input, but coarse roots and particulate organic matter became increasingly important at higher N supply. Coarse roots and particulate organic matter together accounted for 38% of recovered 15N in soils at the highest N inputs and may explain a substantial fraction of the “missing N” often reported in studies of fates of N inputs to forests. Contrary to expectations, N additions did not stimulate gross N cycling, potential nitrification, or ammonium oxidizer populations. Our results indicate that the nonlinearity in N retention and loss resulted directly from excessive N supply relative to sinks, independent of plant–soil–microbial feedbacks. However, N additions did induce a sharp decrease in microbial biomass C:N that is predicted by N saturation theory, and which could increase long-term N storage in soil organic matter by lowering the critical C:N ratio for net N mineralization. All measured sinks accumulated 15N tracers across the full gradient of N supply, suggesting that short-term nonlinearity in N retention resulted from saturation of uptake kinetics, not uptake capacity, in plant, soil, and microbial pools.

Organic matter and wetting capacity distribution in aggregates of Chilean soils

The wetting capacity of Hapludands and Palehumults under grassland and forest in southern Chile was assessed by measuring contact angles of solid, water and air interfaces. Microaggregates obtained from natural aggregates of two sizes (4–6.3 and 10–12 mm) were spread onto microscope slides and drops of saturated aqueous KCl solution were placed on the surface of the aggregates. The wetting angles of the drops were measured with a microscope with a horizontal viewing direction and an ocular containing a goniometer. The wetting capacity was determined on layers peeled progressively from the walls of aggregates toward their centres, and the organic matter content of the different aggregate layers was determined. The water stability of the aggregates was measured by dry and wet sieving. Hapludands always showed greater hydrophobicity than Palehumults. The wetting resistance of the soil matrix samples was less than that of the single layers of aggregates. The wetting resistance of aggregates generally increased from the exterior to their centre. The increase was strongest in the topsoil under grassland. Smaller aggregates under both grassland and forest showed a greater hydrophobicity than larger ones. Organic matter content increased towards the aggregate interiors, especially in the fine aggregates. Aggregates with greater water repellence were more stable to dry and wet sieving, especially under forest. Therefore, intensive management decreases wetting resistance and makes the soil less stable.

Growth patterns of secondary Nothofagus obliqua– N. alpina forests in southern Chile

The environmental factors that influence the diameter-growth of the Nothofagus obliqua and Nothofagus alpina were investigated in secondary forests in southern Chile. A total of 17 edaphic, topographic and climatic variables were studied. The annual periodic diameter increment (API) in 15 and 20 year-old trees was measured using dendrochronological techniques. A multiple correspondence factorial analysis (MCFA) indicated that longitude, minimum precipitation, summer humidity index, frost-free period, maximum drought period, and percentage of silt and sand in the soil were driving variables influencing diameter-growth. The first three factors accounted for 70% of the total variation. Higher diameter-growth rates were associated with intermediate annual rainfall, a short dry period, and sandy soil. Lower rates were associated with an intermediate frost-free period, a low summer humidity index, a long dry period and silty soil. A spatial pattern of the driving variables was found in the study area. The first two factors showed a longitudinal division separating the sites located in the Central Depression, Coastal Range and Andean Range. Using the results generated by MCFA, an ascendant hierarchic classification analysis (AHCA) was conducted to classify the study area into five sites of homogeneous productivity. The highest diameter-growth (>7.1 mm per year) sites were located in the pre-Andes of Valdivia Province, followed by sites in the northern pre-Andes of Cautin Province and the Andean Range of both provinces. Intermediate growth rates corresponded to the coastal site. The lowest diameter-growth (<5.3 mm per year) was located in the Central Depression in both provinces. The use of multivariate methods and the adequate selection of environmental variables enabled us to identify the diameter-growth driving variables, as well as to classify the study area into five productivity categories.

Growth patterns of secondary Nothofagus obliqua?N. alpina forests in southern Chile

The environmental factors that influence the diameter-growth of the Nothofagus obliqua and Nothofagus alpina were investigated in secondary forests in southern Chile. A total of 17 edaphic, topographic and climatic variables were studied. The annual periodic diameter increment (API) in 15 and 20 year-old trees was measured using dendrochronological techniques. A multiple correspondence factorial analysis (MCFA) indicated that longitude, minimum precipitation, summer humidity index, frost-free period, maximum drought period, and percentage of silt and sand in the soil were driving variables influencing diameter-growth. The first three factors accounted for 70% of the total variation. Higher diameter-growth rates were associated with intermediate annual rainfall, a short dry period, and sandy soil. Lower rates were associated with an intermediate frost-free period, a low summer humidity index, a long dry period and silty soil. A spatial pattern of the driving variables was found in the study area. The first two factors showed a longitudinal division separating the sites located in the Central Depression, Coastal Range and Andean Range. Using the results generated by MCFA, an ascendant hierarchic classification analysis (AHCA) was conducted to classify the study area into five sites of homogeneous productivity. The highest diameter-growth (>7.1 mm per year) sites were located in the pre-Andes of Valdivia Province, followed by sites in the northern pre-Andes of Cautin Province and the Andean Range of both provinces. Intermediate growth rates corresponded to the coastal site. The lowest diameter-growth (<5.3 mm per year) was located in the Central Depression in both provinces. The use of multivariate methods and the adequate selection of environmental variables enabled us to identify the diameter-growth driving variables, as well as to classify the study area into five productivity categories.

Litterfall dynamics and nitrogen use efficiency in two evergreen temperate rainforests of southern Chile

Abstract In unpolluted regions, where inorganic nitrogen (N) inputs from the atmosphere are minimal, such as remote locations in southern South America, litterfall dynamics and N use efficiency of tree species should be coupled to the internal N cycle of forest ecosystems. This hypothesis was examined in two evergreen temperate forests in southern Chile (42°30′S), a mixed broad‐leaved forest (MBF) and a conifer forest (CF). Although these forests grow under the same climate and on the same parental material, they differ greatly in floristic structure and canopy dynamics (slower in the CF). In both forests, biomass, N flux, and C/N ratios of fine litterfall were measured monthly from May 1995 to March 1999. There was a continuous litter flux over the annual cycle in both forests, with a peak during autumn in the CF. In the MBF, litterfall decreased during spring. In both forests, the C/N ratios of litterfall varied over the annual cycle with a maximum in autumn. Annual litterfall biomass flux (Mean ± SD = 3.3 ± 0.5 vs 2.0 ± 0.5 Mg ha−1) and N return (34.8 ± 16 vs 9.1 ± 2.8 kg N ha−1) were higher in the MBF than in the CF. At the ecosystem level, litterfall C/N was lower in the MBF (mean C/N ratio = 60.1 ± 15, n = 3 years) suggesting decreased N use efficiency compared with CF (mean C/N ratio = 103 ± 19.6, n = 3 years). At the species level, subordinated (subcanopy) tree species in the MBF had significantly lower C/N ratios (&lt;50) of litterfall than the dominant trees in the CF and MBF (&gt;85). The litterfall C/N ratio and percentage N retranslocated were significantly correlated and were lower in the MBF. The higher net N mineralization in soils of the MBF is related to a lower N use efficiency at the ecosystem and species level.

Seed germination in temperate rain forest species of southern Chile: chilling and gap-dependency germination

Canopy gap and chilling requirements for seed germination were assessed in 61 and 44 species, respectively, in the temperate rain forest of southern Chile. Germination assays within canopy gap and understorey were carried out under natural conditions. Germination tests in cold stratified and non-stratified seeds were performed under laboratory conditions. Seeds were collected of common trees, shrubs, vines and perennial herbs of forests in southern Chile. Final percent germination was significantly enhanced under canopy gap conditions in 19 species, and significantly reduced in 11 species. Germination proved indifferent under gap vs. understorey conditions in half the species tested. Cold stratification affected germination in 11 species: significantly increasing final germination of four species, and significantly decreasing final percent germination of seven species. A Principal Components Analysis (PCA) was applied with the purpose of identifying groups of species with similar germination strategies. Four attributes were included in the PCA: final germination percentage in canopy gap, germination rate in the laboratory, and gap-and chilling-dependency indices (EGAP and STRAT, respectively). The first axis separated species mainly on EGAP variation while the second axis separated them mainly according to STRAT variation; the two axes together explaining 73% of the among-species variation. A small group of trees and vines germinating best in the understorey and neutral to chilling could clearly be distinguished from the remaining species analyzed. Multifactorial ANOVAs were used for evaluating the combined effect of successional status, seed mass, dispersal period, life form, phylogenetic categories, and dispersal syndrome on EGAP and STRAT variation. The EGAP value of secondary successional species proved significantly greater than that of primary successional species and species with endozoochorous seed dispersal were significantly less dependent on chilling (according to STRAT values) compared to species with mainly wind-dispersed seeds. The possible implications of these results for seedling establishment are discussed.

Regeneration and stand dynamics of Fitzroya cupressoides (Cupressaceae) forests of southern Chile’s Central Depression

Several populations of Fitzroya cupressoides (Mol.) Johnst. (Cupressaceae, common name “alerce”), a threatened, long-lived conifer endemic to southern Chile and parts of Argentina, have recently been found in Chile’s Central Depression, where the species was thought to have been extirpated. The objective of this study was to determine, on eight sites in the Depression, Fitzroya’s regeneration behavior in relation to disturbance, its substrate and cover requirements for establishment, and whether regeneration is by seed or vegetative means. This objective required inspection of tree age-class distributions, analyses of microsite conditions and spatial distributions of Fitzroya individuals, and genetic analysis of Fitzroya trees using random amplified polymorphic DNA (RAPD) analysis. Age-class distributions indicated a “catastrophic” regeneration mode, in which seedling establishment follows stand-devastating disturbance, such as fire. Regeneration was both by seed and vegetative means (root sucker sprouting and layering), although overall, vegetative reproduction was more prevalent (63% of all regeneration). Regeneration from seed occurred primarily under open canopies (<40% cover) and on substrates of humus, moss beds, and coarse woody debris. Spatial analyses revealed clumping at various scales for Fitzroya seedlings, saplings, and trees. Several obvious clumps of trees were assumed to be sucker sprouts from cut stumps; however, RAPD analyses indicated they were of seed origin. Such clumping is likely due to the patchy co-occurrence of appropriate substrates and canopy covers. Despite substantial environmental differences between the Central Depression and the portions of the Coastal and Andean Cordilleras where Fitzroya is found, populations in all three regions show striking similarities in their regeneration and stand dynamics. Fitzroya’s longevity and at times abundant regeneration provide the biological basis for its persistence in Chile’s Central Depression.

Current Distribution of Ecosystem Functional Types in Temperate South America

We described, classified, and mapped the functional heterogeneity of temperate South America using the seasonal dynamics of the Normalized Difference Vegetation Index (NDVI) from NOAA/AVHRR satellites for a 10-year period. From the seasonal curves of NDVI, we calculated (a) the annual integral (NDVI-1), used as an estimate of the fraction of photosynthetic active radiation absorbed by the canopy and hence of primary production, (b) the relative annual range of NDVI (RREL), and (c) the date of maximum NDVI (MMAX), both of which were used to capture the seasonality of primary production. NDVI-1 decreased gradually from the northeastern part of the study region (southern Brazil and Uruguay) toward the southwest (Patagonia). High precipitation areas dominated by rangelands had higher NDVI-1 and lower RREL values than neighboring areas dominated by crops. The relative annual range of NDVI was maximum for the northern portion of the Argentine pampas (high cover of summer crops) and the subantarctic forests in southern Chile (high cover of deciduous tree species). More than 25% of the area showed an NDVI peak in November. Around 40% of the area presented the maximum NDVI during summer. The pampas showed areas with sharp differences in the timing of the NDVI peak associated with different agricultural systems. In the southern pampas, NDVI peaked early (October–November); whereas in the northeastern pampas, NDVI peaked in late summer (February). We classified temperate South America into 19 ecosystem functional types (EFT). The methodology used to define EFTs has advantages over traditional approaches for land classification that are based on structural features. First, the NDVI traits used have a clear biological meaning. Second, remote-sensing data are available worldwide. Third, the continuous record of satellite data allows for a dynamic characterization of ecosystems and land-cover changes.

Santessoniella Rosettiformis, A New Species From South America With Notes On 5. Pulchella (Pannariaceae)

The new species Santessoniella rosettiformis Henssen is described from a temperate Nothofagus forest in southern Chile and compared with the superficially similar S. pulchella P. M. Jørg. In both species, the thallus is corticate on all surfaces, the characteristic feature separating Santessoniella from Parmeliella. In the blue iodine reaction of the hymenium and the presence of smooth spores, S. rosettiformis corresponds to the closely related S. chilensis (Hue) Henssen whereas S. pulchella with warty spores and reddish brown hymenium in iodine is related to S. polychidioides (Zahlbr.) Henssen, the type species of the genus. A key to the species of Santessoniella is provided; the delimitation of the genus is discussed.

SANTESSONIELLA ROSETTIFORMIS, A NEW SPECIES FROM SOUTH AMERICA WITH NOTES ON S. PULCHELLA (PANNARIACEAE)

The new species Santessoniella rosettiformis Henssen is described from a temperateNothofagus forest in southern Chile and compared with the superficially similar S. pulchella P. M. Jørg. In both species, the thallus is corticate on all surfaces, the characteristic feature separating Santessoniella fromParmeliella . In the blue iodine reaction of the hymenium and the presence of smooth spores, S. rosettiformis corresponds to the closely related S. chilensis (Hue) Henssen whereas S. pulchella with warty spores and reddish brown hymenium in iodine is related to S. polychidioides (Zahlbr.) Henssen, the type species of the genus. A key to the species of Santessoniella is provided; the delimitation of the genus is discussed.

Composition and Structure of Remnant Fitzroya cupressoides Forests of Southern Chile's Central Depression

ulations exist as small forests (core areas ' 3 ha), where Fitzroya forms nearly pure stands. We established permanent plots in each of these five stands, determining tree ages and recording species composition. Multivariate analyses performed on both understory and tree species composition separated one stand from the remaining four, the differences being a function of stand ages and disturbance histories. Given their small size and isolation (from each other and from Fitzroya populations of the Coastal and Andean Cordilleras), these stands represent an extreme example of habitat fragmentation. A combination of conservation efforts is being undertaken to ensure their persistence in the Central Depression.

High-resolution paleoecological analysis of recent disturbance in a southern Chilean Nothofagus forest

A 1600 year paleoecological record of environmental change is developed from a small lake in the Nothofagus forest of southern Chile (45.5°S, 72°W). High resolution fossil pollen, charcoal, sedimentological, and chrysophycean stomatocyst analyses are used to investigate the impacts of natural and anthropogenic disturbances on terrestrial and lacustrine environments. Chronological control is based on a combination of 210Pb and 14C dating. Temporal resolution during the past 150–200 yr is ca. 8 yr/sample. The macroscopic charcoal record correlates very closely with historical and dendroecological records of 20th century anthropogenic burning in this region. The chrysophyte stratigraphy indicates that this burning had immediate impacts on the lake itself, while the pollen record provides evidence for a succession of vegetation changes lagging slightly behind the disturbance. These palynological changes are very similar to the pollen signal of European disturbance in northeastern North America. Pre-European shifts in chrysophyte assemblages may be due to the influence of earthquake activity on the lake, though there is no corroborative evidence in the pollen or charcoal records. This study demonstrates that high resolution paleoecological methods can be used to help bridge the temporal gap between traditional ecological and paleoecological studies of environmental change in the temperate forests of southern South America.

Alsodes Australis, A New Species of Leptodactylid Frog from the Temperate Nothofagus Forest of Southern Chile and Argentina

A new species of frog, Alsodes australis, is described from the temperate Nothofagus forest of southern Chile and Argentina, based on adults and tadpoles. Up to now, no sympatric occurrence of another congeneric species is known from the type locality. The genus comprises three species groups. From a karyological point of view this species is included in the monticola group, whose species have 26 chromosomes.

Organic Matter Budgets for Streams: A Synthesis

Organic Matter Budgets for Streams: A Synthesis

Seed size, establishment sites and species coexistence in a Chilean rain forest

Abstract. Seedling densities on the forest floor and on elevated microsites (logs and stumps) were compared for eight woody species in a temperate rain forest in southern Chile. Degree of association with elevated microsites varied significantly between species, showed no systematic relationship with reported shade tolerance, but was significantly negatively correlated with seed mass. Large‐seeded Podocarpus nubigena established preferentially on undisturbed forest floor sites, whereas seedlings of small‐seeded species such as Nothofagus nitida and Laurelia philippiana were found mainly on fallen logs and stumps. The abundance of large seedlings and saplings of N. nitida on logs/stumps, and the growth forms of canopy trees, confirm that recruitment of this species occurs mainly on decaying wood. The relationship between seed size and microsite preferences may be caused by effects of seed size on (1) ability to establish in forest floor litter and (2) retention of seeds on logs.Seedling occupancy of logs and stumps varied with state of decay. Few seedlings of any species were present on logs in the early stages of decay. N. nitida established earlier than the other species, attaining maximum abundance on wood in the middle decay classes. Species richness and overall seedling abundance were highest on wood in advanced stages of decay.Seed size differences are suggested as a determinant of differential utilization of forest floor heterogeneity, and hence of plant species coexistence.

Dynamics of Fitzroya cupressoides Forests in Southern Chile

Dynamics of Fitzroya cupressoides Forests in Southern Chile

Emendation of yeasts isolated from decayed wood in the evergreen rainy Valdivian Forest of southern Chile

After a thourough revision carried out by the author on yeasts isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile, that were described previously as new species [1–10], very important errors were found that had slipped into them, due to an unfortunate and unexpected technical failure. Thence, the necessity of a full emendation. Ten of them were found to by synonymous with others. And ten have been maintained as new species and are presented here with amended Latin diagnoses.

Microhabitat and Reproductive Traits in Populations of the Frog, Batrachyla taeniata

A comparative study of reproductive processes and habitats of northern and southern pop- ulations of Batrachyla taeniata was carried out in Chile. Differences in reproductive traits are related to climatic variability, particularly amount of rainfall and water availability. The most important difference is in the reproductive mode, namely that clutch and egg sizes are modified without changes in size of females. Batrachyla taeniata (Girard, 1854) occurs between 32?50'S to 45?25'S in Chile. In this wide range there are populations living in the cold rain forest of southern Chile (36050'S to 45?25'S) and also in the dry warm

Rhodotorula nothofagi sp. nov., isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

Rhodotorula nothofagi sp. nov., isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

Two new amycelial Candida isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

Two novel representatives of the yeast genus Candida, isolated from advanced stages of degradation from fallen trunks of Nothofagus dombeyii (Mirb.) Blume and Laurelia sempervirens Weim., in the evergreen rainy Valdivian forest of southern Chile, are described and illustrated. The strains differ from all accepted Candida species to warrant their establishment as two new species: Candida petrohuensis and Candida rancensis.