Peter Petraitis - Academia.edu (original) (raw)
Uploads
Papers by Peter Petraitis
Mean annual air temperature in the Lake Hövsgöl region of northern Mongolia has increased by 1.8 ... more Mean annual air temperature in the Lake Hövsgöl region of northern Mongolia has increased by 1.8 °C over the last 40 years, greater than global average temperature increases. A decrease of soil moisture due to changes in precipitation regime is also predicted over the northern region of Mongolia. Warmer temperatures generally result in higher soil CO2 efflux, but responses of soil efflux to climate change may differ among ecosystems due to response variations in soil temperature and moisture regime. The objectives of our study were to examine the environmental responses (soil temperature and moisture) to experimental warming, and to test responses of soil CO2 efflux to experimental warming, in three different ecozones. The experimental site is located in Dalbay Valley, on the eastern shore of Lake Hövsgöl in northern Mongolia (51.0234° N 100.7600° E; 1670 m elevation). Replicate plots with ITEX-style open-top passive warming chambers (OTC) and non-warmed control areas were installed in three ecosystems: (1) semi-arid grassland on the south-facing slope not underlain by permafrost, (2) riparian zone, and (3) larch forest on the north-facing slope underlain by permafrost. Aboveground air temperature and belowground soil temperature and moisture (10 and 20 cm) were monitored using sensors and dataloggers. Soil CO2 efflux was measured periodically using a portable infra-red gas analyzer with an attached soil respiration chamber. The warming chambers were installed and data collected during the 2009 and 2010 growing seasons. Passive warming chambers increased nighttime air temperatures; more so in grassland compared to the forest. Increases in daytime air temperatures were observed in the grassland, but were not significant in the riparian and forest areas. Soil temperatures in warmed plots were consistently higher in all three ecozones at 10 cm depth but not at 20 cm depth. Warming chambers had a slight drying effect in the grassland, but no consistent effect in forest and riparian areas. Measured soil CO2 efflux rates were highest in riparian area, and lowest in the grassland. Initial results of soil efflux measurements suggest that the effect of warming treatment significantly depends on the ecosystem type: soil efflux rates differed between warming treatments in forest plots, but not in riparian and grassland plots.
Ecology, 1999
The possibility that different species assemblages may represent persistent alternative community... more The possibility that different species assemblages may represent persistent alternative community states remains largely unexplored by experimental ecologists because of a variety of conceptual and experimental problems. We discuss some of the conceptual roadblocks to ...
The Quarterly Review of Biology
The Quarterly Review of Biology
Journal of Experimental Marine Biology and Ecology
ABSTRACT
Journal of Experimental Marine Biology and Ecology
ISBN 0 521 00976 8 (paperback), GBP 29.95; ISBN 0 521 00976 8 (hardback), GBP 75.00
Seasonality is a characteristic of nearly all ecosystems and, thus, organisms have evolved a bewi... more Seasonality is a characteristic of nearly all ecosystems and, thus, organisms have evolved a bewildering array of adaptations to sense and cope with the environmental variation imposed by seasonal changes. Seasonality is ultimately driven by the declination of the earth, which in turn determines the annual variation in day length and amount of solar radiation arriving at the surface (which is not only visible light and is measured in kW/m 2). Annual cycles of oceanographic and atmospheric conditions—what we normally associate with the change in seasons—are powered by the input of energy from solar radiation. These seasonal patterns can affect organisms and, thus, populations and communities in two fundamentally different ways. First, organisms can sense and respond to these annual cycles. This includes sensing changes not only in photoperiod, which are directly linked to declination, but also in conditions such as water and air temperatures and wave surge, which are driven by variat...
The recent study in the Lake Hövsgöl region of northern Mongolia has shown that mean annual air t... more The recent study in the Lake Hövsgöl region of northern Mongolia has shown that mean annual air temperature has increased by 1.8 °C over the last 40 years, greater than global average temperature increases. The observed climate change will have a significant impact on the ecosystem of this region, and thus simulating the warming and its impacts on the ecosystem are essential. Passive open-top chambers (OTC) have been proposed as a method to simulate temperature change and used in ITEX (International Tundra Experiment) sites (Marion et al., 1997; GCB 3(S1)20-32). The OTCs cause air temperature to increase by 1.2-2.0 °C, mostly during the day by decreasing convective cooling. However, actual climate warming will be caused mainly through increased long-wave radiation. An alternative design is an open-side chamber (OSC) which is supposed to increase long-wave radiation and thus to increase air temperature (Germino and Demshar, 2008; ESA Annual Meeting). The objective of this study was t...
Background/Question/Methods Taiga forest and steppe grassland form distinct alternating bands in ... more Background/Question/Methods Taiga forest and steppe grassland form distinct alternating bands in the valleys of northern Mongolia. Taiga forest, which consists almost exclusively of Siberian larch (Larix sibirica), occurs on north-facing slopes and steppe grassland occurs on south-facing slopes. The ecotone between forest and grassland on the ridge between north and south facing slopes is sharp, and this pattern is extensive throughout northern Mongolia, yet no data on the ridge-top ecotones in this region exist. We characterized this ecotone using transects in summer 2009. Data were collected along 24 transects that ran north-south near the peak of the south-facing slope in Dalbay Valley along the east coast of Lake Hövsgöl in northern Mongolia [51°01'36.54"N, 100°45'54.23"E]. Each transect began at singleton trees clearly outside the forest and extended up to 100 m into the forest. Diameter at breast height (DBH), distance to nearest neighbor, and nearest neighbo...
Background/Question/Methods To characterize the ecotones between taiga forest and steppe grasslan... more Background/Question/Methods To characterize the ecotones between taiga forest and steppe grassland in the Dalbay Valley along the east coast of Lake Hövsgöl in northern Mongolia, we collected data along 24 transects that ran roughly north-south near the peak of the south-facing slope and 25 transects on the north-facing slope. Throughout this region, steppe grassland occurs on the south-facing slope while taiga forest consisting almost exclusively of Siberian larch (Larix sibirica) occurs at the peak of the slope and continues down the north-facing slope into the next valley before switching back to steppe or riparian vegetation. This pattern reoccurs in the other valleys in this region. A better understanding of the switch from steppe to taiga is also currently relevant because this region is undergoing environmental changes due to global climate change that may affect the position and character of these ecotones. Each transect began in the grassland and ended in the forest. Breast...
Background/Question/Methods Ecotones, the transitional zones between ecosystems, are sensitive to... more Background/Question/Methods Ecotones, the transitional zones between ecosystems, are sensitive to climate and land-use changes, both occurring rapidly in northern Mongolia. However, the pattern of species’ distributions and abundances that define ecotones in this region are not well understood, impeding their protection and management. The region’s landscape is a patchwork of steppe, occuring on the south-facing slopes and base of the valleys, and taiga forest (almost entirely Siberian larch, Larix sibirica), covering most of the north-facing slopes. We set out to measure changes in larch and understory plants through ecotones between forest and steppe in the Dalbay valley of Mongolia’s Hövsgöl National Park. For understory plants, we recorded presence/absence in 1m by 1m plots every 5m along ten, 75m transects in 2012. For larch, we sampled trees on 100m long transects, 24 through the south-facing ecotone in 2009 and 25 through the north-facing ecotone in 2011. All transects starte...
Background/Question/Methods Maintaining species interactions is critical to preserving important ... more Background/Question/Methods Maintaining species interactions is critical to preserving important ecological services. Land use change can alter biodiversity directly and trophic interactions indirectly. Commonly, the changes involve modifications to active land management, such as increases in agricultural intensity or urbanization. However, the important consequences of ceasing, rather than increasing, management are often overlooked. Historically grazed systems may face grazing cessation due to societal changes and could trigger important consequences for trophic interactions. We asked how the grazing cessation affects flower and pollinator community composition and their network of interactions. We studied the effects of excluding grazers, primarily yaks, on forb and pollinator communities in northern Mongolia. The mountain steppe in this region has been subject to nomadic pastoralism for hundreds of years. Our study was conducted throughout the summer flowering season. In our sp...
The capability of ecosystems to deliver services, such as agricultural production, in the future ... more The capability of ecosystems to deliver services, such as agricultural production, in the future is largely dependent upon human land use. Land use change resulting in habitat loss negatively alters ecosystem services. In particular, services mobile organisms provide, such as insects and wild pollination, are negatively impacted. Negative effects on wild pollination threaten the maintenance of local plant diversity and result in a productivity decline of insect pollinated crops. We studied how the cessation of ungulate grazing in a traditionally grazed system would affect the community composition and abundance of forbs and insect flower visitors. In the Mongolian steppe, between June and August, we observed and collected insect flower visitors in grazed and ungrazed paired plots. We also recorded total flower abundance per species. Using ordination and permutation tests, we found that forb community composition differed significantly between paired plots. Overall flower abundance w...
Mean annual air temperature in the Lake Hövsgöl region of northern Mongolia has increased by 1.8 ... more Mean annual air temperature in the Lake Hövsgöl region of northern Mongolia has increased by 1.8 °C over the last 40 years, greater than global average temperature increases. A decrease of soil moisture due to changes in precipitation regime is also predicted over the northern region of Mongolia. Warmer temperatures generally result in higher soil CO2 efflux, but responses of soil efflux to climate change may differ among ecosystems due to response variations in soil temperature and moisture regime. The objectives of our study were to examine the environmental responses (soil temperature and moisture) to experimental warming, and to test responses of soil CO2 efflux to experimental warming, in three different ecozones. The experimental site is located in Dalbay Valley, on the eastern shore of Lake Hövsgöl in northern Mongolia (51.0234° N 100.7600° E; 1670 m elevation). Replicate plots with ITEX-style open-top passive warming chambers (OTC) and non-warmed control areas were installed in three ecosystems: (1) semi-arid grassland on the south-facing slope not underlain by permafrost, (2) riparian zone, and (3) larch forest on the north-facing slope underlain by permafrost. Aboveground air temperature and belowground soil temperature and moisture (10 and 20 cm) were monitored using sensors and dataloggers. Soil CO2 efflux was measured periodically using a portable infra-red gas analyzer with an attached soil respiration chamber. The warming chambers were installed and data collected during the 2009 and 2010 growing seasons. Passive warming chambers increased nighttime air temperatures; more so in grassland compared to the forest. Increases in daytime air temperatures were observed in the grassland, but were not significant in the riparian and forest areas. Soil temperatures in warmed plots were consistently higher in all three ecozones at 10 cm depth but not at 20 cm depth. Warming chambers had a slight drying effect in the grassland, but no consistent effect in forest and riparian areas. Measured soil CO2 efflux rates were highest in riparian area, and lowest in the grassland. Initial results of soil efflux measurements suggest that the effect of warming treatment significantly depends on the ecosystem type: soil efflux rates differed between warming treatments in forest plots, but not in riparian and grassland plots.
Ecology, 1999
The possibility that different species assemblages may represent persistent alternative community... more The possibility that different species assemblages may represent persistent alternative community states remains largely unexplored by experimental ecologists because of a variety of conceptual and experimental problems. We discuss some of the conceptual roadblocks to ...
The Quarterly Review of Biology
The Quarterly Review of Biology
Journal of Experimental Marine Biology and Ecology
ABSTRACT
Journal of Experimental Marine Biology and Ecology
ISBN 0 521 00976 8 (paperback), GBP 29.95; ISBN 0 521 00976 8 (hardback), GBP 75.00
Seasonality is a characteristic of nearly all ecosystems and, thus, organisms have evolved a bewi... more Seasonality is a characteristic of nearly all ecosystems and, thus, organisms have evolved a bewildering array of adaptations to sense and cope with the environmental variation imposed by seasonal changes. Seasonality is ultimately driven by the declination of the earth, which in turn determines the annual variation in day length and amount of solar radiation arriving at the surface (which is not only visible light and is measured in kW/m 2). Annual cycles of oceanographic and atmospheric conditions—what we normally associate with the change in seasons—are powered by the input of energy from solar radiation. These seasonal patterns can affect organisms and, thus, populations and communities in two fundamentally different ways. First, organisms can sense and respond to these annual cycles. This includes sensing changes not only in photoperiod, which are directly linked to declination, but also in conditions such as water and air temperatures and wave surge, which are driven by variat...
The recent study in the Lake Hövsgöl region of northern Mongolia has shown that mean annual air t... more The recent study in the Lake Hövsgöl region of northern Mongolia has shown that mean annual air temperature has increased by 1.8 °C over the last 40 years, greater than global average temperature increases. The observed climate change will have a significant impact on the ecosystem of this region, and thus simulating the warming and its impacts on the ecosystem are essential. Passive open-top chambers (OTC) have been proposed as a method to simulate temperature change and used in ITEX (International Tundra Experiment) sites (Marion et al., 1997; GCB 3(S1)20-32). The OTCs cause air temperature to increase by 1.2-2.0 °C, mostly during the day by decreasing convective cooling. However, actual climate warming will be caused mainly through increased long-wave radiation. An alternative design is an open-side chamber (OSC) which is supposed to increase long-wave radiation and thus to increase air temperature (Germino and Demshar, 2008; ESA Annual Meeting). The objective of this study was t...
Background/Question/Methods Taiga forest and steppe grassland form distinct alternating bands in ... more Background/Question/Methods Taiga forest and steppe grassland form distinct alternating bands in the valleys of northern Mongolia. Taiga forest, which consists almost exclusively of Siberian larch (Larix sibirica), occurs on north-facing slopes and steppe grassland occurs on south-facing slopes. The ecotone between forest and grassland on the ridge between north and south facing slopes is sharp, and this pattern is extensive throughout northern Mongolia, yet no data on the ridge-top ecotones in this region exist. We characterized this ecotone using transects in summer 2009. Data were collected along 24 transects that ran north-south near the peak of the south-facing slope in Dalbay Valley along the east coast of Lake Hövsgöl in northern Mongolia [51°01'36.54"N, 100°45'54.23"E]. Each transect began at singleton trees clearly outside the forest and extended up to 100 m into the forest. Diameter at breast height (DBH), distance to nearest neighbor, and nearest neighbo...
Background/Question/Methods To characterize the ecotones between taiga forest and steppe grasslan... more Background/Question/Methods To characterize the ecotones between taiga forest and steppe grassland in the Dalbay Valley along the east coast of Lake Hövsgöl in northern Mongolia, we collected data along 24 transects that ran roughly north-south near the peak of the south-facing slope and 25 transects on the north-facing slope. Throughout this region, steppe grassland occurs on the south-facing slope while taiga forest consisting almost exclusively of Siberian larch (Larix sibirica) occurs at the peak of the slope and continues down the north-facing slope into the next valley before switching back to steppe or riparian vegetation. This pattern reoccurs in the other valleys in this region. A better understanding of the switch from steppe to taiga is also currently relevant because this region is undergoing environmental changes due to global climate change that may affect the position and character of these ecotones. Each transect began in the grassland and ended in the forest. Breast...
Background/Question/Methods Ecotones, the transitional zones between ecosystems, are sensitive to... more Background/Question/Methods Ecotones, the transitional zones between ecosystems, are sensitive to climate and land-use changes, both occurring rapidly in northern Mongolia. However, the pattern of species’ distributions and abundances that define ecotones in this region are not well understood, impeding their protection and management. The region’s landscape is a patchwork of steppe, occuring on the south-facing slopes and base of the valleys, and taiga forest (almost entirely Siberian larch, Larix sibirica), covering most of the north-facing slopes. We set out to measure changes in larch and understory plants through ecotones between forest and steppe in the Dalbay valley of Mongolia’s Hövsgöl National Park. For understory plants, we recorded presence/absence in 1m by 1m plots every 5m along ten, 75m transects in 2012. For larch, we sampled trees on 100m long transects, 24 through the south-facing ecotone in 2009 and 25 through the north-facing ecotone in 2011. All transects starte...
Background/Question/Methods Maintaining species interactions is critical to preserving important ... more Background/Question/Methods Maintaining species interactions is critical to preserving important ecological services. Land use change can alter biodiversity directly and trophic interactions indirectly. Commonly, the changes involve modifications to active land management, such as increases in agricultural intensity or urbanization. However, the important consequences of ceasing, rather than increasing, management are often overlooked. Historically grazed systems may face grazing cessation due to societal changes and could trigger important consequences for trophic interactions. We asked how the grazing cessation affects flower and pollinator community composition and their network of interactions. We studied the effects of excluding grazers, primarily yaks, on forb and pollinator communities in northern Mongolia. The mountain steppe in this region has been subject to nomadic pastoralism for hundreds of years. Our study was conducted throughout the summer flowering season. In our sp...
The capability of ecosystems to deliver services, such as agricultural production, in the future ... more The capability of ecosystems to deliver services, such as agricultural production, in the future is largely dependent upon human land use. Land use change resulting in habitat loss negatively alters ecosystem services. In particular, services mobile organisms provide, such as insects and wild pollination, are negatively impacted. Negative effects on wild pollination threaten the maintenance of local plant diversity and result in a productivity decline of insect pollinated crops. We studied how the cessation of ungulate grazing in a traditionally grazed system would affect the community composition and abundance of forbs and insect flower visitors. In the Mongolian steppe, between June and August, we observed and collected insect flower visitors in grazed and ungrazed paired plots. We also recorded total flower abundance per species. Using ordination and permutation tests, we found that forb community composition differed significantly between paired plots. Overall flower abundance w...