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Miguel Martinezramos - One of the best experts on this subject based on the ideXlab platform.
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recovery of amphibian and reptile assemblages during old field succession of tropical rain Forests
Biotropica, 2015Co-Authors: Omar Hernandezordonez, Nicolas J Urbinacardona, Miguel MartinezramosAbstract:Conversion of tropical Forests to agriculture affects vertebrate assemblages, but we do not know how fast or to what extent these assemblages recover after field abandonment. We addressed this question by examining amphibians and reptiles in secondary Forests in southeastern Mexico. We used chronosequence data (12 secondary Forests fallow for 1–23 yr and 3 Old-Growth Forest sites) to analyze successional trajectories and estimate recovery times of assemblage attributes for amphibians and reptiles. We conducted 6 surveys at each site over 14 mo (1200 person-hours) and recorded 1552 individuals, including 25 species of amphibians and 36 of reptiles, representing 96 and 74 percent of the expected regional number of species, respectively. Abundance, species richness, and species diversity of amphibians increased rapidly with successional age, approaching Old-Growth Forest values in < 30 yr. Species richness and species diversity of reptiles reached Old-Growth Forest values in < 20 yr. By contrast, the abundance of reptiles and the assemblage composition of amphibians and reptiles recovered more slowly. Along the chronosequence, we observed more species replacement in reptile assemblages than in amphibian assemblages. Several species in the Old-Growth Forest were absent from secondary Forests. Dispersal limitation and harsh conditions prevailing in open sites and early successional environments appear to preclude colonization by Old-Growth Forest species. Furthermore, short fallow periods and isolation of Forest remnants lead to the formation of new assemblages dominated by species favored by human disturbances. Resumen La conversion de los bosques tropicales en campos agropecuarios afecta a los ensambles de vertebrados, pero no sabemos en que medida y con que rapidez estos ensambles se recuperan despues del abandono de los campos. Exploramos este aspecto para el caso de los anfibios y reptiles en el sureste de Mexico. Basados en datos de una cronosecuencia (12 bosques secundarios con edades de 1-23 anos de desarrollo y tres sitios de bosques maduro), analizamos trayectorias sucesionales para estimar los tiempos de recuperacion de diferentes atributos de los ensambles de anfibios y reptiles. En cada sitio, se llevaron a cabo seis muestreos a lo largo de 14 meses (1200 horas persona en total). Globalmente, se registraron 1552 individuos, 25 especies de anfibios y 36 de reptiles, lo que represento el 96% y el 74% del numero esperado de especies regionales, respectivamente. La abundancia, la riqueza de especies y la diversidad de especies de anfibios se incrementaron rapidamente con la edad sucesional, acercandose a los valores del bosque maduro en menos de tres decadas. La riqueza de especies y la diversidad de especies de reptiles alcanzaron valores del bosque maduro en menos de 20 anos. Por el contrario, la recuperacion de la abundancia de reptiles fue mucho mas lenta como fue tambien el caso de la composicion del ensamble de anfibios y reptiles. A lo largo de la cronosecuencia, hubo una mayor sustitucion de especies en los ensamblajes de reptiles que en los de anfibios. Varias especies que se encontraron en el bosque maduro estuvieron ausentes en los bosques secundarios. Discutimos que la limitacion de la dispersion y las duras condiciones que prevalecen en los sitios abiertos y en los ambientes sucesionales tempranos impiden a las especies que habitan en el bosque maduro la colonizacion de esos habitats. Ademas, los periodos de barbecho corto y el aislamiento de los remanentes de bosques llevan a la formacion de nuevos ensambles dominados por especies favorecidas por las perturbaciones humanas.
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dispersal mode shade tolerance and phytogeographical affinity of tree species during secondary succession in tropical montane cloud Forest
Plant Ecology, 2012Co-Authors: Miguel Angel Munizcastro, Guadalupe Williamslinera, Miguel MartinezramosAbstract:Secondary succession following land abandonment, represented by a chronosequence of 15 old fields (0–80 years old) and two Old-Growth Forests, was studied in the tropical montane cloud Forest region of Veracruz, Mexico. The objective was to determine successional trajectories in Forest structure and species richness of trees ≥5 cm DBH, in terms of differences in seed dispersal mode, shade tolerance, and phytogeographical affinity. Data were analyzed using AIC model selection and logistic regressions. Mean and maximum canopy height reached values similar to Old-Growth Forest at 35 and 80 years, respectively. Species richness and diversity values were reached earlier (15 and 25 years, respectively) while basal area and stem density tended to reach Old-Growth Forest values within 80 years. Along the chronosequence, the proportion of species and individuals of wind-dispersed trees declined, that of bird dispersed small seeded trees remained constant, while that of gravity and animal dispersed large seeded trees increased; shade-intolerant species and individuals declined, while intermediate and shade-tolerant trees increased. Shade-tolerant canopy trees were rare during succession, even in the Old-Growth Forest. Tropical tree species were more frequent than temperate ones throughout the chronosequence, but temperate tree individuals became canopy dominants at intermediate and Old-Growth Forest stages.
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the soil seed bank in abandoned tropical pastures source of regeneration or invasion
Revista Mexicana De Biodiversidad, 2011Co-Authors: Leonel Lopeztoledo, Miguel MartinezramosAbstract:We assessed the availability of both pioneer and non-native species in the soil seed bank of Old-Growth Forest and recently abandoned pasture, to evaluate whether the soil seed bank in these pastures represents a source of regeneration of species from adjacent Old-Growth Forest or of invasion by non-native species. Our study was conducted at Selva Lacandona, Chiapas, Mexico. Soil samples were randomly collected from 6 sites in Old-Growth Forest, and 6 sites in abandoned pastures. Seedlings from soil samples were identified and classified into pioneer, non-native (weeds/ graminoids), and other Forest species. Pioneer species seeds were virtually absent in pastures, but represented ~30% of seeds in the Forest. Non-native species comprised ~99% of the soil seed bank in pastures. In the Forest, soil seed bank density of weeds and graminoids decreased with increasing distance (up to 4 km) from agricultural fields, and comprised up to 25% (Mean ± 1SE= 16 ± 7) of the seed bank. Our results show a near total elimination of pioneer species from the soil seed bank in pastures, and considerable invasion of the borders of the Montes Azules reserve by seeds of non-native species. Thus, in the region studied, the soil seed bank in abandoned pastures represents a source of invasion by non-native species into Old-Growth Forest rather than a potential source of Forest regeneration.
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the soil seed bank in abandoned tropical pastures source of regeneration or invasion el banco de semillas en pastizales tropicales abandonados fuente de regeneracion o de invasion
2011Co-Authors: Leonel Lopeztoledo, Miguel MartinezramosAbstract:We assessed the availability of both pioneer and non-native species in the soil seed bank of Old-Growth Forest and recently abandoned pasture, to evaluate whether the soil seed bank in these pastures represents a source of regeneration of species from adjacent Old-Growth Forest or of invasion by non-native species. Our study was conducted at Selva Lacandona, Chiapas, Mexico. Soil samples were randomly collected from 6 sites in Old-Growth Forest, and 6 sites in abandoned pastures. Seedlings from soil samples were identified and classified into pioneer, non-native (weeds/ graminoids), and other Forest species. Pioneer species seeds were virtually absent in pastures, but represented ~30% of seeds in the Forest. Non-native species comprised ~99% of the soil seed bank in pastures. In the Forest, soil seed bank density of weeds and graminoids decreased with increasing distance (up to 4 km) from agricultural fields, and comprised up to 25% (Mean ± 1SE= 16 ± 7) of the seed bank. Our results show a near total elimination of pioneer species from the soil seed bank in pastures, and considerable invasion of the borders of the Montes Azules reserve by seeds of non-native species. Thus, in the region studied, the soil seed bank in abandoned pastures represents a source of invasion by non-native species into Old-Growth Forest rather than a potential source of Forest regeneration.
Dirk Holscher - One of the best experts on this subject based on the ideXlab platform.
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rainfall partitioning along a tree diversity gradient in a deciduous old growth Forest in central germany
Ecohydrology, 2009Co-Authors: Inga Kramer, Dirk HolscherAbstract:This study investigated whether rainfall partitioning into throughfall, stemflow, and interception changes along a tree species diversity gradient. The 12 study plots in Old-Growth Forest stands in the Hainich National Park, Germany, were composed of up to 11 tree species. Fagus sylvatica (beech) formed the monospecific plots. Mixed Forest plots consisted of a variable admixture of other broad-leaved deciduous species such as Tilia spec., Fraxinus excelsior, Carpinus betulus, and Acer pseudoplatanus. Rainfall partitioning was influenced by several stand characteristics. Tree species diversity expressed as Shannon index was the variable that explained throughfall for different seasons most frequently. For example, in high-rainfall summer 2007, median throughfall per stand was between 66 and 77% of gross precipitation, whereas stemflow played a minor role (2–6% per stand). Throughfall correlated positively with Shannon index (rs = 0·74, p = 0·008), stemflow negatively (rs = − 0·87, p < 0·001), and interception showed no correlation along this beech to mixed Forest gradient. These relationships were similar in summer 2005 and autumn 2006, but no or weak changes of throughfall with tree diversity were observed during other study periods. Multiple linear regressions supported the assumption that combinations of several characteristics are important. Shannon index in combination with mean dbh explained much of the variability observed in throughfall among stands in two seasons (up to R2adj = 0·63, p < 0·01). Influential stand characteristics varied between seasons and years due to different rainfall conditions. Spatial variability of throughfall within a stand did not change consistently with any stand characteristic. Copyright © 2009 John Wiley & Sons, Ltd.
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nutrient fluxes in stemflow and throughfall in three successional stages of an upper montane rain Forest in costa rica
Journal of Tropical Ecology, 2003Co-Authors: Dirk Holscher, Lars Kohler, Ch Leuschner, Maarten KappelleAbstract:Nutrient fluxes in stemflow and throughfall were compared among three successional stages of an upper montane rain Forest and related to structural characteristics of the stands (stem density, leaf area, epiphyte abundance). An Old-Growth Forest stand, an early successional (10-y-old) Forest stand and a mid-successional (40-y-old) Forest stand were studied in the Cordillera Talamanca, Costa Rica. All three sites were dominated by Quercus copeyensis with a variable admixture of other tree species. There was no difference in the average stand leaf area index between the Old-Growth Forest and the early successional Forest. A significantly higher leaf area was found in the mid-successional Forest. There were large differences in litterfall from non-vascular epiphytes (mosses, liverworts and lichens) which reflected differences in epiphyte abundance, with highest values in the Old-Growth Forest. Total nutrient transfer via stemflow and throughfall from the canopy to the soil showed only minor differences among the stands. The stands differed widely in the ratio of nutrient transport via stemflow to the total nutrient flux by water below the canopy. The K flux with stemflow accounted for 5% of the total in the Old-Growth Forest but it accounted for 17% (early successional Forest) and 26% (mid-successional Forest) in the secondary Forests. It is concluded that differences in canopy structure and epiphyte abundance in Old-Growth and secondary Forests resulted in large differences in the partitioning of nutrient transport into stemflow and throughfall components although total nutrient transfers via water reaching the soil were similar.
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size and structure of fine root systems in old growth and secondary tropical montane Forests costa rica
Biotropica, 2003Co-Authors: Dietrich Hertel, Christoph Leuschner, Dirk HolscherAbstract:Abstract The fine root systems of three tropical montane Forests differing in age and history were investigated in the Cordillera Talamanca, Costa Rica. We analyzed abundance, vertical distribution, and morphology of fine roots in an early successional Forest (10–15 years old, ESF), a mid-successional Forest (40 years old, MSF), and a nearby undisturbed Old-Growth Forest (OGF), and related the root data to soil morphological and chemical parameters. The OGF stand contained a 19 cm deep organic layer on the Forest floor (i.e., 530 mol C/m2), which was two and five times thicker than that of the MSF (10 cm) and ESF stands (4 cm), respectively. There was a corresponding decrease in fine root biomass in this horizon from 1128 g dry matter/m2 in the Old-Growth Forest to 337 (MSF) and 31 g/m2 (ESF) in the secondary Forests, although the stands had similar leaf areas. The organic layer was a preferred substrate for fine root growth in the Old-Growth Forest as indicated by more than four times higher fine root de...
Saskia Droge - One of the best experts on this subject based on the ideXlab platform.
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listening to a changing landscape acoustic indices reflect bird species richness and plot scale vegetation structure across different land use types in north eastern madagascar
Ecological Indicators, 2021Co-Authors: Saskia Droge, Dominic A Martin, Rouvah Andriafanomezantsoa, Zuzana Burivalova, Thio Rosin Fulgence, Kristina Osen, Eric Rakotomalala, Dominik Schwab, Annemarie WurzAbstract:Abstract New technologies like ecoacoustic surveys promise time and cost efficiency for biodiversity assessments, serve as a basis for effective conservation policies, and are particularly appealing for remote and highly diverse tropical areas. Acoustic indices facilitate the analysis of large acoustic datasets but no consensus on their performance has been reached yet. We evaluated the efficacy of four acoustic indices (Acoustic Complexity Index, Acoustic Diversity Index, Acoustic Evenness Index, Acoustic Entropy) for sound data analysis and biodiversity assessments inside a national park and the agricultural mosaic landscape of north-eastern Madagascar, a global biodiversity hotspot. We used self-built sound recorders to continuously record soundscapes on 80 plots across seven land-use types (Old-Growth Forest, Forest fragment, Forest–derived and fallow-derived vanilla agroForest, herbaceous and woody fallow, rice paddy) and compared index values between land–use types, assessed the correlation with bird species richness as measured by point counts, and related the acoustic indices to plot- and landscape-scale parameters. The Acoustic Diversity Index, Acoustic Evenness Index (inverse) and Acoustic Entropy were highest in Old-Growth Forest and lowest for rice paddies and fallow land. Index values for structurally similar land-use types did not differ significantly from each other. The correlation of the three acoustic indices with bird species richness was strongest during daytime ( R 2 ≥ 0.30 ) . Differences in the index values were best explained by land-use type and vegetation density. Our results showed that all investigated indices except the Acoustic Complexity Index were suitable biodiversity indicators for a tropical, agricultural landscape. Soundscape diversity was positively affected by plot-scale vegetation structure, emphasizing the importance of Forests and particularly Old-Growth Forest for conservation. We demonstrated that acoustic indices and sound recordings are a useful tool for assessing biodiversity in tropical agricultural mosaic landscapes. To realize the full potential of ecoacoustics in conservation, sampling guidelines and user-friendly analysis packages will be key to facilitate a wider implementation.
Annemarie Wurz - One of the best experts on this subject based on the ideXlab platform.
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listening to a changing landscape acoustic indices reflect bird species richness and plot scale vegetation structure across different land use types in north eastern madagascar
Ecological Indicators, 2021Co-Authors: Saskia Droge, Dominic A Martin, Rouvah Andriafanomezantsoa, Zuzana Burivalova, Thio Rosin Fulgence, Kristina Osen, Eric Rakotomalala, Dominik Schwab, Annemarie WurzAbstract:Abstract New technologies like ecoacoustic surveys promise time and cost efficiency for biodiversity assessments, serve as a basis for effective conservation policies, and are particularly appealing for remote and highly diverse tropical areas. Acoustic indices facilitate the analysis of large acoustic datasets but no consensus on their performance has been reached yet. We evaluated the efficacy of four acoustic indices (Acoustic Complexity Index, Acoustic Diversity Index, Acoustic Evenness Index, Acoustic Entropy) for sound data analysis and biodiversity assessments inside a national park and the agricultural mosaic landscape of north-eastern Madagascar, a global biodiversity hotspot. We used self-built sound recorders to continuously record soundscapes on 80 plots across seven land-use types (Old-Growth Forest, Forest fragment, Forest–derived and fallow-derived vanilla agroForest, herbaceous and woody fallow, rice paddy) and compared index values between land–use types, assessed the correlation with bird species richness as measured by point counts, and related the acoustic indices to plot- and landscape-scale parameters. The Acoustic Diversity Index, Acoustic Evenness Index (inverse) and Acoustic Entropy were highest in Old-Growth Forest and lowest for rice paddies and fallow land. Index values for structurally similar land-use types did not differ significantly from each other. The correlation of the three acoustic indices with bird species richness was strongest during daytime ( R 2 ≥ 0.30 ) . Differences in the index values were best explained by land-use type and vegetation density. Our results showed that all investigated indices except the Acoustic Complexity Index were suitable biodiversity indicators for a tropical, agricultural landscape. Soundscape diversity was positively affected by plot-scale vegetation structure, emphasizing the importance of Forests and particularly Old-Growth Forest for conservation. We demonstrated that acoustic indices and sound recordings are a useful tool for assessing biodiversity in tropical agricultural mosaic landscapes. To realize the full potential of ecoacoustics in conservation, sampling guidelines and user-friendly analysis packages will be key to facilitate a wider implementation.
Nigel E Stork - One of the best experts on this subject based on the ideXlab platform.
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recovery of decomposition rates and decomposer invertebrates during rain Forest restoration on disused pasture
Biotropica, 2020Co-Authors: Marisa J Stone, Luke P Shoo, Nigel E Stork, Fran Sheldon, Carla CatterallAbstract:Converting Forest to pasture can alter the roles of biota in ecosystem functioning, while vegetation restoration should arguably assist functional recovery. Since tests of this are scarce, this study quantifies both litter decomposition rates and their association with decomposer invertebrates, across 25 sites representing different phases of deForestation and subsequent reForestation of rain Forest. Open and closed (to exclude macro‐invertebrates) mesh bags containing Forest leaves were exposed in the field for up to eight months, and invertebrates were extracted from separate collections of ground surface litter. Sites spanned five vegetation categories (five sites in each): reference states of both old‐growth Forest and grazed pasture; unassisted woody regrowth aged 20–50 years on former pasture; and assisted regeneration aged 1–3 and 5–10 years after interventions were applied to similar regrowth. Decomposition rates in open bags were about 50% slower in pasture than old‐growth Forest, and abundances of macro‐ and meso‐decomposer invertebrates were 95% and 77% lower, respectively. However, in all restoration site‐types, decomposition rates had recovered to 83% of old‐growth values, and abundances of invertebrate decomposers were similar in old‐growth Forest. Decomposer community composition at a broad taxonomic level differed strongly between pasture and all other vegetation types. Exclusion of macro‐invertebrates decreased decomposition rates by only about 3.1%, but decomposition rates in open bags were significantly correlated (across sites) with abundances of both macro‐ and meso‐decomposers, most strongly so for meso‐decomposers. Drawing useful generalizations across studies is impeded by differing methodologies and because few include both agricultural and Forest reference sites.
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the potential for species conservation in tropical secondary Forests
Conservation Biology, 2009Co-Authors: Robin L Chazdon, Carlos A. Peres, Nigel E Stork, Ariel E Lugo, Daisy H Dent, Douglas Sheil, David Lamb, Scott E MillerAbstract:In the wake of widespread loss of Old-Growth Forests throughout the tropics, secondary Forests will likely play a growing role in the conservation of Forest biodiversity. We considered a complex hierarchy of factors that interact in space and time to determine the conservation potential of tropical secondary Forests. Beyond the characteristics of local Forest patches, spatial and temporal landscape dynamics influence the establishment, species composition, and persistence of secondary Forests. Prospects for conservation of Old-Growth species in secondary Forests are maximized in regions where the ratio of secondary to Old-Growth Forest area is relatively low, older secondary Forests have persisted, anthropogenic disturbance after abandonment is relatively low, seed-dispersing fauna are present, and Old-Growth Forests are close to abandoned sites. The conservation value of a secondary Forest is expected to increase over time, as species arriving from remaining Old-Growth Forest patches accumulate. Many studies are poorly replicated, which limits robust assessments of the number and abundance of Old-Growth species present in secondary Forests. Older secondary Forests are not often studied and few long-term studies are conducted in secondary Forests. Available data indicate that both Old-Growth and second-growth Forests are important to the persistence of Forest species in tropical, human-modified landscapes.
