The Experts below are selected from a list of 10593 Experts worldwide ranked by ideXlab platform
Ruth E Sherman - One of the best experts on this subject based on the ideXlab platform.
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vegetation zonation in a neotropical montane forest environment disturbance and Ecotones
Biotropica, 2011Co-Authors: Patrick H Martin, Timothy J Fahey, Ruth E ShermanAbstract:Gradual changes in vegetationstructure and composition are expected to result from continuous environmental change with increasing elevation on mountains. Hence, the occurrence of abrupt or discrete Ecotones in vegetation patterns is intriguing and may suggest key controls on community assembly in montane forests. We review tropical montane forest (TMF) zonation patterns focusing on a case study from the Cordillera Central, Hispaniola where a striking discontinuity in forest composition occurs consistently at � 2000m elevation, with cloud forest below and monodominant pine forest above. We propose that a discontinuity in climatic factors (temperature, humidity) associated with the trade-wind inversion (TWI) is the primary cause of this and other Ecotones in TMFs that occur at a generally consistent elevation. Low humidity, fires and occasional frost above the TWI favor pine over cloud forest species. Fires in the high-elevation pine forest have repeatedly burned down to the Ecotone boundary and extinguished in the cloud forest owing to its low flammability, reinforced by high humidity, cloud immersion and epiphytic bryophyte cover. Small-scale fire patterns along the Ecotone are influenced by topography and where forest structure is impacted by hurricanes and landslides. Analogous patterns are observed worldwide in other TMFs where the TWI is important, high-elevation fires are frequent, and the flora contains frost-tolerant species (often of temperate lineage). The response of this and other TMFs to anthropogenic climate change is highly uncertain owing to potentially countervailing effects of different climatic phenomena, including warming temperatures and decreased frost; changes in the TWI, high-elevation drought or cloudiness; and increased frequency or
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tropical montane forest Ecotones climate gradients natural disturbance and vegetation zonation in the cordillera central dominican republic
Journal of Biogeography, 2007Co-Authors: Patrick H Martin, Ruth E Sherman, Timothy J FaheyAbstract:Aim We examined relationships between climate–disturbance gradients and patterns of vegetation zonation and Ecotones on a subtropical mountain range. Location The study was conducted on the windward slopes of the Cordillera Central, Dominican Republic, where cloud forest appears to shift in a narrow Ecotone to monodominant forest of Pinus occidentalis. Methods Climate, disturbance and vegetation data were collected over the elevation range 1100–3100 m and in 50 paired plots along the Ecotone. Aerial photographs were georeferenced to a high-resolution digital elevation model in order to enable the analysis of landscape-scale patterns of the Ecotone. Results A Shipley–Keddy test detected discrete compositional Ecotones at 2200 and 2500 m; the distributions of tree species at lower elevations were continuous. The elevation of the Ecotone determined with aerial photographs was fairly consistent, namely ± 164 m (SD) over its 124-km length, but it exhibited significant landscape variation, occurring at a lower elevation in a partially leeward, western zone. The Ecotone also occurred significantly lower on ridges than it did in drainage gullies. Ecotone forest structure and composition differed markedly between paired plots. In pine paired plots, the canopy height was 1.7 times higher and the basal area of non-pine species was 6 times lower than in the cloud forest directly below. Fire evidence was ubiquitous in the pine forest but rare in the abutting cloud forest. Mesoclimate changed discontinuously around the elevation of the Ecotone: humidity and cloud formation decreased markedly, and frost frequency increased exponentially. Main conclusions The discreteness of the Ecotone was produced primarily by fire. The elevational consistency of the Ecotone, however, resulted from the overarching influence of mesoclimate on the elevational patterns of fire occurrence. Declining temperature and precipitation combine with the trade-wind inversion to create a narrow zone where high-elevation fires extinguish, enabling fire-sensitive and fire-tolerant taxa to abut. Once established, mesotopography and contrasting vegetation physiognomy probably reinforce this boundary through feedbacks on microenvironment and fire likelihood. The prominence of the pine in this study – and of temperate and fire-tolerant taxa in subtropical montane forests in general – highlights the importance of climate-disturbance–biogeography interactions in Ecotone formation, particularly where fire mediates a dynamic between climate and vegetation.
Valentin Golosov - One of the best experts on this subject based on the ideXlab platform.
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assessment of soil erosion rate trends in two agricultural regions of european russia for the last 60 years
Journal of Soils and Sediments, 2018Co-Authors: Valentin Golosov, Alexander J Koiter, M A Ivanov, K A Maltsev, A V Gusarov, A G Sharifullin, Irina RadchenkoAbstract:Forest–steppe and the southern forest Ecotones of European Russia (ER) are the most productive agricultural areas in Russia. Both climate and land use changes have occurred within the ER during last 30 years. These changes can lead to changes in the timing, magnitude, and spatial distribution of soil erosion rates on cultivated lands. The objective of this research was to assess the trends in soil erosion rates since the 1960s for two agricultural regions of ER. Rates of soil erosion were estimated for two time windows (1963–1986 and 1986–2015) within the two agricultural regions. Both regions are characterized by a high proportion of cropland (> 60%), and within each region, one river basin and one 1st–3rd-order agricultural catchment were selected for a detailed assessment of soil erosion rates. Erosion models and visual interpretation of satellite images were used for the evaluation of the erosion rates for the river basins. Sediment budget assessments, 137Cs dating, geomorphologic mapping, and erosion models were used for the evaluation of the sediment redistribution for the two time windows in agricultural catchments. At the river basin scale, the mean annual erosion rate did not change in the western part of forest–steppe Ecotone; however, there was a weak negative trend in the mean annual erosion rate for the eastern part of the southern forest Ecotone. A large negative trend in the erosion rate was found for both small agricultural catchments. In all cases, the reduction in the erosion rates was mainly associated with a decrease of surface runoff during snowmelt, as a result of an increase in both the air and soil temperatures during winter season. The soil loss reduction during snowmelt was counteracted by an equal increase in rainfall erosion due to increase of rainfall intensity in western part of forest–steppe Ecotone. Reduction of surface runoff during spring snowmelt was the main reason the erosion rates declined on cultivated lands within the forest–steppe and southern forest Ecotones of ER. Evaluation of ephemeral gully erosion rate was not incorporated into State Hydrological Institute erosion model used for the evaluation of the soil losses during snowmelt. This has led to an underestimation of the total soil losses for the 1963–1986 time window for all study sites.
Timothy J Fahey - One of the best experts on this subject based on the ideXlab platform.
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vegetation zonation in a neotropical montane forest environment disturbance and Ecotones
Biotropica, 2011Co-Authors: Patrick H Martin, Timothy J Fahey, Ruth E ShermanAbstract:Gradual changes in vegetationstructure and composition are expected to result from continuous environmental change with increasing elevation on mountains. Hence, the occurrence of abrupt or discrete Ecotones in vegetation patterns is intriguing and may suggest key controls on community assembly in montane forests. We review tropical montane forest (TMF) zonation patterns focusing on a case study from the Cordillera Central, Hispaniola where a striking discontinuity in forest composition occurs consistently at � 2000m elevation, with cloud forest below and monodominant pine forest above. We propose that a discontinuity in climatic factors (temperature, humidity) associated with the trade-wind inversion (TWI) is the primary cause of this and other Ecotones in TMFs that occur at a generally consistent elevation. Low humidity, fires and occasional frost above the TWI favor pine over cloud forest species. Fires in the high-elevation pine forest have repeatedly burned down to the Ecotone boundary and extinguished in the cloud forest owing to its low flammability, reinforced by high humidity, cloud immersion and epiphytic bryophyte cover. Small-scale fire patterns along the Ecotone are influenced by topography and where forest structure is impacted by hurricanes and landslides. Analogous patterns are observed worldwide in other TMFs where the TWI is important, high-elevation fires are frequent, and the flora contains frost-tolerant species (often of temperate lineage). The response of this and other TMFs to anthropogenic climate change is highly uncertain owing to potentially countervailing effects of different climatic phenomena, including warming temperatures and decreased frost; changes in the TWI, high-elevation drought or cloudiness; and increased frequency or
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tropical montane forest Ecotones climate gradients natural disturbance and vegetation zonation in the cordillera central dominican republic
Journal of Biogeography, 2007Co-Authors: Patrick H Martin, Ruth E Sherman, Timothy J FaheyAbstract:Aim We examined relationships between climate–disturbance gradients and patterns of vegetation zonation and Ecotones on a subtropical mountain range. Location The study was conducted on the windward slopes of the Cordillera Central, Dominican Republic, where cloud forest appears to shift in a narrow Ecotone to monodominant forest of Pinus occidentalis. Methods Climate, disturbance and vegetation data were collected over the elevation range 1100–3100 m and in 50 paired plots along the Ecotone. Aerial photographs were georeferenced to a high-resolution digital elevation model in order to enable the analysis of landscape-scale patterns of the Ecotone. Results A Shipley–Keddy test detected discrete compositional Ecotones at 2200 and 2500 m; the distributions of tree species at lower elevations were continuous. The elevation of the Ecotone determined with aerial photographs was fairly consistent, namely ± 164 m (SD) over its 124-km length, but it exhibited significant landscape variation, occurring at a lower elevation in a partially leeward, western zone. The Ecotone also occurred significantly lower on ridges than it did in drainage gullies. Ecotone forest structure and composition differed markedly between paired plots. In pine paired plots, the canopy height was 1.7 times higher and the basal area of non-pine species was 6 times lower than in the cloud forest directly below. Fire evidence was ubiquitous in the pine forest but rare in the abutting cloud forest. Mesoclimate changed discontinuously around the elevation of the Ecotone: humidity and cloud formation decreased markedly, and frost frequency increased exponentially. Main conclusions The discreteness of the Ecotone was produced primarily by fire. The elevational consistency of the Ecotone, however, resulted from the overarching influence of mesoclimate on the elevational patterns of fire occurrence. Declining temperature and precipitation combine with the trade-wind inversion to create a narrow zone where high-elevation fires extinguish, enabling fire-sensitive and fire-tolerant taxa to abut. Once established, mesotopography and contrasting vegetation physiognomy probably reinforce this boundary through feedbacks on microenvironment and fire likelihood. The prominence of the pine in this study – and of temperate and fire-tolerant taxa in subtropical montane forests in general – highlights the importance of climate-disturbance–biogeography interactions in Ecotone formation, particularly where fire mediates a dynamic between climate and vegetation.
Patrick H Martin - One of the best experts on this subject based on the ideXlab platform.
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vegetation zonation in a neotropical montane forest environment disturbance and Ecotones
Biotropica, 2011Co-Authors: Patrick H Martin, Timothy J Fahey, Ruth E ShermanAbstract:Gradual changes in vegetationstructure and composition are expected to result from continuous environmental change with increasing elevation on mountains. Hence, the occurrence of abrupt or discrete Ecotones in vegetation patterns is intriguing and may suggest key controls on community assembly in montane forests. We review tropical montane forest (TMF) zonation patterns focusing on a case study from the Cordillera Central, Hispaniola where a striking discontinuity in forest composition occurs consistently at � 2000m elevation, with cloud forest below and monodominant pine forest above. We propose that a discontinuity in climatic factors (temperature, humidity) associated with the trade-wind inversion (TWI) is the primary cause of this and other Ecotones in TMFs that occur at a generally consistent elevation. Low humidity, fires and occasional frost above the TWI favor pine over cloud forest species. Fires in the high-elevation pine forest have repeatedly burned down to the Ecotone boundary and extinguished in the cloud forest owing to its low flammability, reinforced by high humidity, cloud immersion and epiphytic bryophyte cover. Small-scale fire patterns along the Ecotone are influenced by topography and where forest structure is impacted by hurricanes and landslides. Analogous patterns are observed worldwide in other TMFs where the TWI is important, high-elevation fires are frequent, and the flora contains frost-tolerant species (often of temperate lineage). The response of this and other TMFs to anthropogenic climate change is highly uncertain owing to potentially countervailing effects of different climatic phenomena, including warming temperatures and decreased frost; changes in the TWI, high-elevation drought or cloudiness; and increased frequency or
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tropical montane forest Ecotones climate gradients natural disturbance and vegetation zonation in the cordillera central dominican republic
Journal of Biogeography, 2007Co-Authors: Patrick H Martin, Ruth E Sherman, Timothy J FaheyAbstract:Aim We examined relationships between climate–disturbance gradients and patterns of vegetation zonation and Ecotones on a subtropical mountain range. Location The study was conducted on the windward slopes of the Cordillera Central, Dominican Republic, where cloud forest appears to shift in a narrow Ecotone to monodominant forest of Pinus occidentalis. Methods Climate, disturbance and vegetation data were collected over the elevation range 1100–3100 m and in 50 paired plots along the Ecotone. Aerial photographs were georeferenced to a high-resolution digital elevation model in order to enable the analysis of landscape-scale patterns of the Ecotone. Results A Shipley–Keddy test detected discrete compositional Ecotones at 2200 and 2500 m; the distributions of tree species at lower elevations were continuous. The elevation of the Ecotone determined with aerial photographs was fairly consistent, namely ± 164 m (SD) over its 124-km length, but it exhibited significant landscape variation, occurring at a lower elevation in a partially leeward, western zone. The Ecotone also occurred significantly lower on ridges than it did in drainage gullies. Ecotone forest structure and composition differed markedly between paired plots. In pine paired plots, the canopy height was 1.7 times higher and the basal area of non-pine species was 6 times lower than in the cloud forest directly below. Fire evidence was ubiquitous in the pine forest but rare in the abutting cloud forest. Mesoclimate changed discontinuously around the elevation of the Ecotone: humidity and cloud formation decreased markedly, and frost frequency increased exponentially. Main conclusions The discreteness of the Ecotone was produced primarily by fire. The elevational consistency of the Ecotone, however, resulted from the overarching influence of mesoclimate on the elevational patterns of fire occurrence. Declining temperature and precipitation combine with the trade-wind inversion to create a narrow zone where high-elevation fires extinguish, enabling fire-sensitive and fire-tolerant taxa to abut. Once established, mesotopography and contrasting vegetation physiognomy probably reinforce this boundary through feedbacks on microenvironment and fire likelihood. The prominence of the pine in this study – and of temperate and fire-tolerant taxa in subtropical montane forests in general – highlights the importance of climate-disturbance–biogeography interactions in Ecotone formation, particularly where fire mediates a dynamic between climate and vegetation.
Anthony W Damato - One of the best experts on this subject based on the ideXlab platform.
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montane forest Ecotones moved downslope in northeastern usa in spite of warming between 1984 and 2011
Global Change Biology, 2015Co-Authors: Jane R Foster, Anthony W DamatoAbstract:Ecotones are transition zones that form, in forests, where distinct forest types meet across a climatic gradient. In mountains, Ecotones are compressed and act as potential harbingers of species shifts that accompany climate change. As the climate warms in New England, USA, high-elevation boreal forests are expected to recede upslope, with northern hardwood species moving up behind. Yet recent empirical studies present conflicting findings on this dynamic, reporting both rapid upward ecotonal shifts and concurrent increases in boreal species within the region. These discrepancies may result from the limited spatial extent of observations. We developed a method to model and map the montane forest Ecotone using Landsat imagery to observe change at scales not possible for plot-based studies, covering mountain peaks over 39 000 km(2) . Our results show that Ecotones shifted downward or stayed stable on most mountains between 1991 and 2010, but also shifted upward in some cases (13-15% slopes). On average, upper Ecotone boundaries moved down -1.5 m yr(-1) in the Green Mountains, VT, and -1.3 m yr(-1) in the White Mountains, NH. These changes agree with remeasured forest inventory data from Hubbard Brook Experimental Forest, NH, and suggest that processes of boreal forest recovery from prior red spruce decline, or human land use and disturbance, may swamp out any signal of climate-mediated migration in this ecosystem. This approach represents a powerful framework for evaluating similar ecotonal dynamics in other mountainous regions of the globe.
