Publications (19)41.29 Total impact
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Article: Genetic structure of coastal and inland populations of Spergularia media (L.) C. Presl (Caryophyllaceae) in Central Europe
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ABSTRACT: In Central Europe, salt-influenced habitats are restricted mainly to the coastlines of the North Sea and the Baltic Sea. The few natural inland salt sites suffer from size reduction and loss in biodiversity, while anthropogenic salt sites around potash mining dumps experienced recent and massive de novo colonization by numerous halophytes. Our study aimed to elucidate the general patterns of gene flow among coastal and inland salt habitats. We used amplified fragment length polymorphisms to assess the genetic diversity and genetic structure of 18 European populations of the halophyte Spergularia media (Caryophyllaceae), sampled from inland and coastal salt sites of Germany, the Netherlands, Denmark, Austria, France and Italy. Estimates of genetic diversity on the population level were generally low, especially within inland salt habitats. Analyses of molecular variance showed comparatively strong differentiation among populations. Multivariate ordination (principal coordinate analysis) and a NeighborNet analysis revealed four distinct groups of populations that showed good correspondence to their geographic origins. A Bayesian analysis performed with the program Structure as well as high pairwise Φ ST values supported the results of the phenetic analyses. The observed patterns of diversity and differentiation among inland populations of S. media are best explained by the isolated nature of suitable salt habitats, with concomitant reduction of gene flow to and among these sites. Our data support the hypothesis that the colonization of anthropogenic salt sites by S. media originated from natural inland habitats. KeywordsAFLP markers-Halophytes-Inland salt sites-Potash mining dumps-Genetic structure- Spergularia mediaConservation Genetics 04/2012; 11(6):2169-2177. · 1.61 Impact Factor -
Article: Variation of seed mass and its effects on germination in Polylepis australis: implications for seed collection
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ABSTRACT: South American Polylepis mountain forests are recognised as being one of the most endangered forest ecosystems in the world. Reforestation measures have been strongly recommended but may be hampered due to the very low seed germination reported for several Polylepis species. In order to facilitate reforestation we analysed the influence of seed mass on germination probability for Polylepis australis seeds in the Córdoba mountains (central Argentina). We collected seeds from 43 trees distributed throughout five woodland fragments located within two regions differing in size, topographical position, and altitude (1,900m a.s.l. and 2,200m a.s.l.). Seeds of Polylepis australis exhibited a great variation in terms of mass and percent seed germination among individual trees and among geographical regions. The results of logistic regression showed that germination probability was highly correlated with seed mass. However, the explained deviance significantly increased by including the region, the woodland fragment and especially the individual tree in addition to seed mass in the regression models. We conclude that selecting seeds on the basis of mass is an appropriate way to enhance germination prospects for reforestation projects. However, no absolute mass values are applicable in this context as the highest germination probabilities were reached at varying seed mass values depending on geographical region, woodland fragment or individual tree. We suggest collecting the relatively heaviest available seeds, even though the absolute seed mass may be low.New Forests 04/2012; 33(2):171-181. · 1.18 Impact Factor -
Article: Do we need livestock grazing to promote Polylepis australis tree recruitment in the Central Argentinean Mountains?
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ABSTRACT: South American Polylepis mountain forests are endangered due to centuries of logging, fire clearance, and intensive livestock grazing. Polylepis australis (Rosaceae) dominates the tree canopy in the Central Argentinean Mountains, where livestock have been excluded or reduced to very low densities over wide areas. Lowered plant and bird diversity in these abandoned grazing areas suggest that some livestock grazing may be beneficial for conservation purposes. Our study aimed to determine whether this may also be true for forest regeneration. In 300 plots of 1m2 distributed in sub-regions of high to moderate grazing pressure as well as grazing exclusion, we recorded the presence of P. australis seedlings and grazing indicators. Topographical parameters as well as vegetation and soil characteristics were also assessed. Seedling frequencies were highest in the region with moderate grazing, intermediate with grazing exclusion, and the lowest with high grazing pressures. Logistic regression models revealed that seedling occurrence was highest close to seeder trees, with intermediate litter coverage and at intermediate altitudes above sea level. Since grazing ultimately affects seeder tree occurrence through browsing and reduces litter cover and predominates in higher areas, we conclude that grazing is an important driving factor for P. australis regeneration. We confirm previous studies determining high grazing pressure to be detrimental for P. australis regeneration, but also provide data suggesting that its complete exclusion may not be recommendable either. Management should aim to alternate between a moderate grazing intensity to promote seedling recruitment, with subsequent exclusion to accelerate the growth of the established seedlings.Ecological Research 04/2012; 24(5):1075-1081. · 1.57 Impact Factor -
Article: Do Polylepis australis trees tolerate herbivory? Seasonal patterns of shoot growth and its consumption by livestock
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ABSTRACT: Browsing is one of the main factors determining survival, growth rate, woodland structure, and distribution of the high mountain tree Polylepis australis. This species has a substantial regrowth capacity, which may function as a mechanism to tolerate herbivory, but it is unknown to what extent it may compensate for the impact of herbivory. In 15 low-density tree stands subject to exclusion, moderate, and heavy livestock pressure, we selected 12 P. australis individuals <2m tall, tagged four new shoots per tree and measured shoot length every month during a year. At the stand and at the tree level, we analyzed monthly dynamics of growth and browsing, and the annual output in terms of total browsing and total gross and net growth (not discounting and discounting consumption, respectively). In addition, we assessed the influence of stand, tree and microsite characteristics on growth and browsing patterns. Polylepis australis fully compensated for herbivory in terms of shoot gross growth at moderate, but not at heavy livestock pressure. In terms of net growth, this species did not fully compensate for herbivory at any stocking rate. We found a strong coupling between browsing and growth along the year, suggesting that regrowth attracts browsing, and browsing promotes regrowth. At the stand level, annual gross growth was not affected by habitat characteristics, while at the tree level, annual gross growth decreased on more rocky microsites for browsed but not for unbrowsed trees. We concluded that stocking densities should be limited to allow for a reasonable annual net growth, as its nitrogen rich leaves are a valuable food resource and P. australis forests provide important ecosystem services. KeywordsBrowsing-Compensation-Consumption-Growth-Livestock- Polylepis australis -TolerancePlant Ecology 04/2012; 207(2):307-319. · 1.83 Impact Factor -
Article: Germination performance of native and non-native Ulmus pumila populations
NeoBiota. 01/2012; 15:53-68. -
Article: Range-wide genetic structure and diversity of the endemic tree line species Polylepis australis (Rosaceae) in Argentina.
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ABSTRACT: • Premise of the study: Knowledge on the range-wide distribution of genetic structure and diversity is required to facilitate the understanding of historical tree migration and for predicting responses to current climate change. With respect to post-glacial migration patterns known from the northern hemisphere, we tested the prediction that the southernmost populations of a subtropical tree line species have lower within-population genetic diversity and higher genetic differentiation than the central and northernmost populations. • Methods: We used AFLP to assess the genetic structure of 18 populations of the wind-pollinated Polylepis australis (Rosaceae) sampled over its entire distributional range in three Argentinean high mountain regions. Genetic diversity was calculated as a percentage of polymorphic bands (P) and Nei's expected heterozygosity (He); genetic differentiation was assessed using AMOVA, Φ(ST) - statistics, and Bayesian cluster analysis. • Key results: Contrary to our expectations, the northernmost Polylepis australis stands had lower within-population genetic diversity and higher genetic differentiation than the central and southernmost stands. Populations grouped into two major clusters, the first containing the southern populations and four central populations and the second containing the northern and one central population. • Conclusions: Patterns of Polylepis australis genetic structure and diversity differ from historical migration scenarios observed for the northern hemisphere. The decline in genetic diversity toward the north may point to an equatorward migration following past climatic changes. Populations within the south and central part appear to be connected by effective long-distance pollination while gene flow in the northern part is probably hampered by geographic isolation.American Journal of Botany 11/2011; 98(11):1825-33. · 2.66 Impact Factor -
Article: Increased genetic differentiation but no reduced genetic diversity in peripheral vs. central populations of a steppe grass.
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ABSTRACT: Intraspecific genetic variation is essential for the performance and evolution of species. Populations at a species' geographic range periphery receive considerable attention in biogeography and conservation because they are smaller and spatially more isolated than central populations, a pattern expected to lead to higher genetic differentiation and lower within-population genetic diversity. We tested these predictions in central and peripheral populations of the Eurasian steppe grass Stipa capillata. We analyzed AFLP fingerprint patterns in 319 individuals from 20 large and abundant populations in the core, in Kazakhstan, and 23 small and isolated populations at the periphery, in Central Europe. We calculated different genetic diversity estimates and assessed genetic differentiation among populations by examining F(ST) values, a neighbor-net network, and an AMOVA. As expected, genetic differentiation among populations was significantly larger at the range periphery (F(ST) = 0.415) than in the range core (F(ST) = 0.164). In contrast to predictions, however, we found similarly low genetic diversity within central (proportion of polymorphic bands = 21.9%) and peripheral (20%) populations. Higher genetic differentiation in the small and spatially isolated peripheral populations is likely driven by genetic drift and reduced gene flow due to a complex landscape structure and the abandonment of traditional management regimes. With regard to unchanged genetic diversity, it appears that life-history traits like longevity or sufficiently large population sizes could allow S. capillata to escape deleterious effects at the range edge.American Journal of Botany 06/2011; 98(7):1173-9. · 2.66 Impact Factor -
Article: Historic and recent fragmentation coupled with altitude affect the genetic population structure of one of the world's highest tropical tree line species
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ABSTRACT: Aim To assess the effects of altitude and historic and recent forest fragmentation on the genetic diversity and structure of the wind-pollinated tropical tree line species Polylepis incana.Location One of the highest mountain forest regions of the world, located in the Eastern Cordillera of the Ecuadorian Andes.Methods We compared genetic diversity and structure of adult trees with those of seedlings (n= 118 in both cases) in nine forest stands spanning an altitudinal gradient from 3500 to 4100 m a.s.l. using amplified fragment length polymorphisms (AFLPs). Genetic diversity was calculated as percentage of polymorphic bands (P) and Nei's expected heterozygosity (He); genetic differentiation was assessed using analysis of molecular variance, ΦST statistics and Bayesian cluster analysis.Results Estimates of genetic diversity at the population level were significantly lower in seedlings than in adults. Genetic diversity (He-value) was, in both cases, negatively correlated to altitude and positively correlated to population size in the seedlings. Genetic differentiation of the seedlings was approximately as high (φST= 0.298) as that of the adults (φST= 0.307), and geographical differentiation was clearly reflected in both AFLP profiles, with mountain ridges acting as barriers to gene flow.Main conclusions Our study provides evidence of a historic upslope migration of P. incana in central Ecuador. In addition, it highlights the detrimental effects of unexpectedly strong genetic isolation, both recent and historical, particularly for our wind-pollinated species where the distance between forest stands was less than 25 km. We therefore additionally propose that in habitats with pronounced high-mountain landscape structures, gene flow may be hampered to such an extent that species have a more pronounced sensitivity to habitat fragmentation, even among populations of wind-pollinated trees.Global Ecology and Biogeography. 06/2011; 21(4):455 - 464. -
Article: Landscape Structural Complexity of High Mountain Polylepis australis Forests: A New Aspect of Restoration Goals
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ABSTRACT: Forest restoration efforts should aim at creating landscapes with a balanced array of forest stands at varying successional stages, thus providing habitat for a wealth of species and multiple ecosystem services. In most high-mountain ecosystems of South America, long-term livestock rearing activities that include fires, browsing, and trampling have delayed or stopped forest succession resulting in simplified landscapes. To determine appropriate restoration goals for Polylepis australis mountain forests of Central Argentina, we established 146 plots of 900 m2 plots throughout five river basins with different historic livestock stocking rates. In each plot, we measured tree heights, canopy cover, estimated age of oldest tree, volume of standing and fallen dead wood, fern cover, and abundance of shade tolerant Maytenus boaria trees. K-means cluster analysis using tree heights and canopy cover as classificatory variables yielded four biologically meaningful clusters. Clusters 1, 2, 3, and 4 comprising 68, 10, 13, and 9% of the plots, respectively, showed increasing amounts of standing and fallen dead wood, fern cover, and abundance of shade tolerant M. boaria trees. Plots in clusters 1 and 2 were proportionally more abundant in basins with high human impact and at the altitudinal extremes of P. australis distribution, whereas plots in clusters 3 and 4 were relatively more abundant in well-preserved basins and at the optimum of their altitudinal distribution. We interpret clusters 1, 2, 3, and 4 as degraded, regenerating, young, and mature forests, respectively. Restoration goals should focus on attaining an even distribution of forest types similar to that found in our best-preserved basins.Restoration Ecology 04/2011; 19(3):390 - 398. · 1.68 Impact Factor -
Article: Prevailing negative soil biota effect and no evidence for local adaptation in a widespread Eurasian grass.
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ABSTRACT: Soil biota effects are increasingly accepted as an important driver of the abundance and distribution of plants. While biogeographical studies on alien invasive plant species have indicated coevolution with soil biota in their native distribution range, it is unknown whether adaptation to soil biota varies among populations within the native distribution range. The question of local adaptation between plants and their soil biota has important implications for conservation of biodiversity and may justify the use of seed material from local provenances in restoration campaigns. We studied soil biota effects in ten populations of the steppe grass Stipa capillata from two distinct regions, Europe and Asia. We tested for local adaptation at two different scales, both within (ca. 10-80 km) and between (ca. 3300 km) regions, using a reciprocal inoculation experiment in the greenhouse for nine months. Generally, negative soil biota effects were consistent. However, we did not find evidence for local adaptation: both within and between regions, growth of plants in their 'home soil' was not significantly larger relative to that in soil from other, more distant, populations. Our study suggests that negative soil biota effects can prevail in different parts of a plant species' range. Absence of local adaptation points to the possibility of similar rhizosphere biota composition across populations and regions, sufficient gene flow to prevent coevolution, selection in favor of plasticity, or functional redundancy among different soil biota. From the point of view of plant--soil biota interactions, our findings indicate that the current practice of using seeds exclusively from local provenances in ecosystem restoration campaigns may not be justified.PLoS ONE 01/2011; 6(3):e17580. · 4.09 Impact Factor -
Article: Similar performance in central and range‐edge populations of a Eurasian steppe grass under different climate and soil pH regimes
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ABSTRACT: The abundant centre hypothesis predicts that changing environmental conditions are detrimental to a species’ abundance and performance towards the periphery of its range. We tested these predictions for the perennial grass Stipa capillata, a species that is commonly found in steppes of Asia but is rare at its north-western range edge, in central Europe. We compared 21 populations in dry grassland fragments in central Europe and 20 populations in steppe habitats of Kazakhstan. We studied 15 plant performance traits both in situ and under laboratory and common greenhouse conditions, including local density, plant size and biomass production, seed size, weight and viability. To assess environmental conditions, we assembled data on topography, soil properties and climatic parameters. Using variance components analysis and multivariate methods we analyzed whether plant performance and environmental attributes differed more, as predicted, between the core and peripheral regions or whether they differed more among their subregions or populations. Additionally, we tested whether performance was affected by the same set of environmental predictors in each region. Contrary to our expectations, plant performance traits were virtually unchanged between the range periphery and centre. As expected, macroclimatic conditions showed a significant difference between the two regions (annual mean temperature, annual precipitation). The only other measured environmental variable that differed significantly between the two regions was soil pH, which was lower in core-range populations. Our findings thus do not support the notion of reduced performance at the range edge. Instead, our data lend support to earlier theories of relative habitat constancy, suggesting that peripheral populations can shift to other habitats through plasticity or adaptation.Ecography 11/2010; 34(3):498 - 506. · 4.19 Impact Factor -
Article: Soil conservation in Polylepis mountain forests of Central Argentina: Is livestock reducing our natural capital?
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ABSTRACT: Mountain forests and their soils provide ecological services such as maintenance of biodiversity, provision of clean water, carbon capture and forage for livestock rearing, which is one of the principal economic activities in mountain areas. However, surprisingly little is known about livestock impact in South American mountain forest soils. With the aim of understanding how livestock and topography influence patterns of forest cover, soil compaction, soil loss and soil chemical properties, we analysed these parameters in 100 Polylepis australis woodland plots situated in the humid subtropical mountains of Central Argentina. We used distance from the nearest ranch as an objective index of historical livestock impact and measured standard topographic variables. Our main results reveal that distance from ranch in all cases partly explains tree canopy cover, soil loss, soil compaction and soil chemical properties; suggesting a strong negative effect of livestock. Intermediate altitudes had more tree canopy cover, while landscape roughness – a measure of the variability in slope inclination and aspect – was negatively associated to soil impedance and acidity, and positively associated to soil organic matter content. Finally, flatter areas were more acid. We conclude that livestock has had a substantial influence on forest soil degradation in the Mountains of Central Argentina and possibly other similar South American mountains. Soil degradation should be incorporated into decision making when considering long-term forest sustainability, or when taking into account retaining livestock for biodiversity conservation reasons. Where soil loss and degradation are ongoing, we recommend drastic reductions in livestock density.Austral Ecology 10/2009; 35(4):435 - 443. · 1.82 Impact Factor -
Article: Microsatellite markers for Spergularia media (L.) C. Presl. (Caryophyllaceae) and their cross-species transferability.
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ABSTRACT: We developed 11 polymorphic microsatellite markers for Spergularia media (Caryophyllaceae), a perennial halophyte of coastal salt meadows and continental areas of western Eurasia. The number of alleles per locus observed in a single population of 20 individuals from the German North Sea coast ranged from 3 to 20. Observed and expected heterozygosities ranged from 0.200 to 0.850 and from 0.278 to 0.936 respectively. Observed heterozygosities were lower than expected heterozygosities at all loci, presumably as a consequence of inbreeding. All markers cross-amplified in the closely related S. salina. Of these, nine were polymorphic in the heterologous species. Only two primer pairs generated PCR products in S. diandra.Molecular Ecology Resources 09/2009; 9(5):1424-6. · 3.06 Impact Factor -
Article: Microsatellite markers for the tetraploid halophyte Suaeda maritima (L.) Dumort. (Chenopodiaceae) and cross-species amplification in related taxa.
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ABSTRACT: We developed 12 polymorphic microsatellite markers for the tetraploid halophyte Suaeda maritima (Chenopodiaceae). Population genetic parameters were estimated for three populations from different habitats (coastal and inland), using the program Tetrasat. Between two and 15 alleles per locus were observed. Mean expected heterozygosities (H(E) ) and Shannon-Wiener Diversity Indices (H') per locus and population ranged from zero to 0.852, and from zero to 2.990, respectively. The two inland populations were less diverse than the coastal one at most of the loci. All markers cross-amplified in the closely related Suaeda salsa, and all but one were transferable to Suaeda spicata and Suaeda salinaria.Molecular Ecology Resources 07/2009; 9(4):1247-9. · 3.06 Impact Factor -
Article: The performance of Polylepis australis trees along their entire altitudinal range: implications of climate change for their conservation
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ABSTRACT: Altitudinal gradients are expected to heavily influence the general performance of mountain tree species. For this study we evaluated vitality, radial growth and reproductive efficiency in Polylepis australis (Rosaceae) throughout its complete altitudinal range in central Argentina. We selected seven forest fragments ranging from 900 to 2700 m a.s.l. In the field, we subjectively assigned vitality and seed productivity indexes to 12 P. australis trees per fragment. In addition, we cored and assessed for radial growth 10–18 trees per altitudinal level. In the laboratory, we individually weighed seeds from four or five trees from each altitudinal level and divided into two seed mass classes (light and heavy). We then tested for germination and monitored their seedlings for survival. Seedlings of three trees per altitudinal level were harvested after 40 days and assessed for dry mass. Seedlings of one to two trees per altitudinal level were monitored for survival until both leaves and roots had died. Our main results showed two types of responses to altitude: a unimodal relationship with an optimum at intermediate altitudes of around 1800 m a.s.l. for tree vitality, radial growth, seed productivity and seed mass; and an increase with altitude for in-vitro seed germination and seedling survival. A rise in temperature due to climate change could restrict P. australis to the upper most altitudes, where conservation of these forests will be a priority.Diversity and Distributions 01/2008; 14(4):630 - 636. · 4.83 Impact Factor -
Article: Cover and growth habit of Polylepis woodlands and shrublands in the mountains of central Argentina: human or environmental influence?
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ABSTRACT: Aim To determine whether the cover and growth habit of the main forest forming species (Polylepis australis BITT.) in a mountain range with low human population density is mainly affected by anthropogenic activities or by environmental influences.Location Central Argentina.Methods Using GIS and field surveys we established 146 plots of 30 × 30 m located in five river basins differing in human impact. We measured P. australis cover, growth habit of each individual (number of basal ramifications), index of long term human impact (percentage of rock exposed by soil erosion due to livestock and fires), evidence of logging, fire scars, local relief, percentage of rock outcrops and altitude above sea level. We analysed the influence of independent variables on P. australis cover and growth habit (average number of basal ramifications per plot) using correlations and General Linear Models.Results Polylepis australis cover was greater at intermediate altitudes above sea level and in areas with reduced long term human impact. Contrastingly local relief, percentage of rock outcrops and logging in the recent past did not have a major influence on P. australis abundance. Growth habit varied in complex patterns. Individuals with fewer ramifications were found in valley bottoms and more disturbed basins, while more ramifications were found at mid- and upper slopes and well preserved basins. In valley bottoms, ramifications decreased with increasing altitude whereas the opposite trend was observed for mid-slopes. Ramifications were positively related to fires in two river basins and in mid- and upper slopes but not in valley bottoms. Fire impact was always less in valley bottoms than at mid- and upper slopes.Main conclusions Human impact had a major role on P. australis cover, while growth habit was determined by complex combinations of potentially cumulative natural and anthropogenic factors. Even in sparsely populated mountains, both human impact and their interaction with natural environmental gradients influence plant communities and need to be understood for effective management.Journal of Biogeography 04/2006; 33(5):876 - 887. · 4.54 Impact Factor -
Article: Anthropogenic soil degradation affects seed viability in Polylepis australis mountain forests of central Argentina
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ABSTRACT: South American Polylepis mountain forests belong to the most endangered forest ecosystem in the world. Reforestation measures have been strongly recommended but may be hampered due to the very low seed germination rates reported for several Polylepis species. In order to determine the causes behind reduced seed germination we analysed seed viability of Polylepis australis trees in the mountains of central Argentina. We picked seeds from seven heterogeneous areas (4–5 well-separated trees per area totaling 29 trees) with high within and between variation in degradation status. At the landscape scale we measured altitude above sea level and forest fragmentation in a radius of 1000 m around seven areas. At the mesohabitat scale we measured vegetation types and amount of soil erosion in a square of m around each study tree. At the microhabitat scale we assessed site characteristics under the tree canopy. Additionally, we measured some individual characteristics of each tree. Average percentage of viable seeds was 23.0±15.7 S.D. and lack of an embryo was the main reason for seeds not being able to germinate. Landscape variables were not related to seed viability. At the mesohabitat scale, a multiple regression procedure showed that seed viability was positively associated with relatively undisturbed soils supporting tussock grasslands (38.7% of variance) and negatively associated with soil erosion (18.8% of the variance). Microhabitat variables and individual Polylepis characteristics were also related to seed viability, but explained less variability than mesohabitat characteristics. In order to improve seed viability, our data suggests that livestock pressure and burning practices should be reduced, as these are the main causes for erosion and other forms of soil destruction. For reforestation purposes, we recommend collecting seeds from undisturbed areas.Forest Ecology and Management. -
Article: Cover and growth habit of Polylepis woodlands and shrublands in the mountains of central Argentina: human or environmental influence?
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ABSTRACT: The upper timberline is a conspicuous natural vegetation limit in many upper montane settings, but the causes determining its elevation and structure are still poorly understood. Modern forest distributions and particular characteristics such as species distributions, growth habits and fitness, need to be seen in the context of historical human land use, natural disturbances and site conditions (Foster et al., 1999; Guyette & Spetich, 2003). However, in many inaccessible mountain ABSTRACT Aim To determine whether the cover and growth habit of the main forest forming species (Polylepis australis BITT.) in a mountain range with low human population density is mainly affected by anthropogenic activities or by environmental influences. -
Article: Polylepis australis’ regeneration niche in relation to seed dispersal, site characteristics and livestock density
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ABSTRACT: Establishment of Polylepis forests endemic to the mountains of South America may be affected by seed dispersal, site characteristics and livestock density. Polylepis australis (“tabaquillo”) grows in the high mountains of central Argentina, where we set up 76 square study plots of 900 m2. To determine dispersal distance, we distributed 6 seed traps per plot in and around 20 plots. To determine the best site characteristics and livestock stoking rates, at two river basins differing in historic stocking rates, we analyzed the presence of seedlings in 56 plots and recorded topography, vegetation types and indicators of livestock activity. We also measured microsite characteristics in a sample of 32 comparable pairs of 1 m2 quadrats, with and without seedlings. Maximum recorded dispersal distance of P. australis seeds was 6 m, and seedlings were found no more than 10 m from seed trees. The numbers of seedlings and seed trees were 3.5 and 4 times higher, respectively, in the basin with less livestock. At the 900 m2 plot scale, a Poisson regression indicated a positive relationship between seedling number and P. australis canopy cover. At the quadrat scale (1 m2), seedlings were found in quadrats with significantly lower evidence of soil erosion than comparison quadrats without seedlings. We conclude that the main limitations to recruitment are short seed dispersal distances, lack of seed trees and extreme soil erosion. Management should therefore aim at preserving seed trees and reducing livestock density to prevent erosion.Forest Ecology and Management 254(2):255-260. · 2.49 Impact Factor
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2006–2012
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Martin-Luther-Universität Halle-Wittenberg
Halle, Saxony-Anhalt, Germany
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