Climatic controls on the global distribution, abundance, and species richness of mangrove forests

Mangrove forests are highly productive tidal saline wetland ecosystems found along sheltered tropical and subtropical coasts. Ecologists have long assumed that climatic drivers (i.e., temperature and rainfall regimes) govern the global distribution, structure, and function of mangrove forests. However, data constraints have hindered the quantification of direct climate-mangrove linkages in many parts of the world. Recently, the quality and availability of global-scale climate and mangrove data have been improving. Here, we used these data to better understand the influence of air temperature and rainfall regimes upon the distribution, abundance, and species richness of mangrove forests. Although our analyses identify global-scale relationships and thresholds, we show that the influence of climatic drivers is best characterized via regional range-limit-specific analyses. We quantified climatic controls across targeted gradients in temperature and/or rainfall within 14 mangrove distributional range limits. Climatic thresholds for mangrove presence, abundance, and species richness differed among the 14 studied range limits. We identified minimum temperature-based thresholds for range limits in eastern North America, eastern Australia, New Zealand, eastern Asia, eastern South America, and southeast Africa. We identified rainfall-based thresholds for range limits in western North America, western Gulf of Mexico, western South America, western Australia, Middle East, northwest Africa, east central Africa, and west-central Africa. Our results show that in certain range limits (e.g., eastern North America, western Gulf of Mexico, eastern Asia), winter air temperature extremes play an especially important role. We conclude that rainfall and temperature regimes are both important in western North America, western Gulf of Mexico, and western Australia. With climate change, alterations in temperature and rainfall regimes will affect the global distribution, abundance, and diversity of mangrove forests. In general, warmer winter temperatures are expected to allow mangroves to expand poleward at the expense of salt marshes. However, dispersal and habitat availability constraints may hinder expansion near certain range limits. Along arid and semiarid coasts, decreases or increases in rainfall are expected to lead to mangrove contraction or expansion, respectively. Collectively, our analyses quantify climate-mangrove linkages and improve our understanding of the expected global- and regional-scale effects of climate change upon mangrove forests

The Freshman, vol. 4, no. 6

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. Germany\u27s withdrawal from the League of Nations is discussed in this edition\u27s editorial column. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post

The Freshman, vol. 4, no. 4

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. Behavioral issues exhibited by members of the freshman class during the annual President\u27s Reception are covered in this edition. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post

The Freshman, vol. 4, no. 2

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. Coverage in this issue includes discussion of the annual battle between the freshman and sophomore classes. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post

The Freshman, vol. 4, no. 5

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. Included in this issue is a discussion of School Spirit. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post

The Freshman, vol. 4, no. 3

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post

The Freshman, vol. 4, no. 8 [issue misnumbered]

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post

Linear and nonlinear effects of temperature and precipitation on ecosystem properties in tidal saline wetlands

Climate greatly influences the structure and functioning of tidal saline wetland ecosystems. However, there is a need to better quantify the effects of climatic drivers on ecosystem properties, particularly near climate-sensitive ecological transition zones. Here, we used climate- and literature-derived ecological data from tidal saline wetlands to test hypotheses regarding the influence of climatic drivers (i.e., temperature and precipitation regimes) on the following six ecosystem properties: canopy height, biomass, productivity, decomposition, soil carbon density, and soil carbon accumulation. Our analyses quantify and elucidate linear and nonlinear effects of climatic drivers. We quantified positive linear relationships between temperature and above-ground productivity and strong positive nonlinear (sigmoidal) relationships between (1) temperature and above-ground biomass and canopy height and (2) precipitation and canopy height. Near temperature-controlled mangrove range limits, small changes in temperature are expected to trigger comparatively large changes in biomass and canopy height, as mangrove forests grow, expand, and, in some cases, replace salt marshes. However, within these same transition zones, temperature- induced changes in productivity are expected to be comparatively small. Interestingly, despite the significant above-ground height, biomass, and productivity relationships across the tropical–temperate mangrove–marsh transition zone, the relationships between temperature and soil carbon density or soil carbon accumulation were not significant. Our literature review identifies several ecosystem properties and many regions of the world for which there are insufficient data to fully evaluate the influence of climatic drivers, and the identified data gaps can be used by scientists to guide future research. Our analyses indicate that near precipitation-controlled transition zones, small changes in precipitation are expected to trigger comparatively large changes in canopy height. However, there are scant data to evaluate the influence of precipitation on other ecosystem properties. There is a need for more decomposition data across climatic gradients, and to advance understanding of the influence of changes in precipitation and freshwater availability, additional ecological data are needed from tidal saline wetlands in arid climates. Collectively, our results can help scientists and managers better anticipate the linear and nonlinear ecological consequences of climate change for coastal wetlands

The Freshman, vol. 4, no. 12

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. Social news leading into the holiday season is the focus of this edition. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post

The Freshman, vol. 4, no. 18

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. Peer pressure related to annual Rush activities hold the spotlight in this edition. The Class of 1937 run of The Freshman featured original cover art by sketch artist Jack Frost (John Edward Frost, 1915-1997), who was born in Eastport, Maine. He attended the University of Maine for only a single academic year before moving to Massachusetts to work for the Boston Herald. Frost later became a columnist and illustrator for the Boston Post