POTENTIAL IMPACTS OF GLOBAL WARMING ON AUTUMN COLORATION IN MAPLE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0215221
• Project Start Date: Oct 1, 2008
• Project End Date: Aug 30, 2011
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF VERMONT
(N/A)
BURLINGTON,VT 05405

Performing Department
Plant Biology

Non Technical Summary
Sugar maple is a species of both economic and cultural importance to the state of Vermont, and the display of brilliant red hues created by anthocyanin pigments in maple leaves during autumn leaf senescence is a particularly prized trait. Because of the strong relationship between environmental conditions (primarily temperature and light) and leaf senescence, the increased temperatures and longer growing seasons associated with global warming have the potential to disrupt the normal physiological processes of autumn color development in maple and to potentially decrease the intensity of fall coloration. Although there has been a great deal of speculation about possible impacts of global warming on fall foliage development, there has been little scientific study of the phenomenon. This project will involve conducting a variety of experiments in which the temperature of maple leaves and seedlings is manipulated, and subsequent autumn color development and the physiological effects on leaf function are measured. The results from these experiments will allow us to determine the relationship between temperature and autumn color development and the physiological triggers for autumn anthocyanin synthesis. This information will increase our fundamental knowledge of the process of autumn coloration and provide a scientific basis for projecting the potential impact of future warm autumns on leaf coloration.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
206	0620	1060	50%
206	2499	1060	50%

Knowledge Area
206 - Basic Plant Biology;

Subject Of Investigation
0620 - Broadleaf forests of the North; 2499 - Plant research, general;

Field Of Science
1060 - Biology (whole systems);

Keywords

global warming

climate change

autumn coloration

sugar maple

red maple

leaf senescence

anthocyanins

photooxidative stress

Goals / Objectives
The overall purpose of this project is to study the effects of temperature on development of autumn colors in maple. We will conduct two classes of experiments that will span over three years. The first series will be designed to evaluate the role of temperature in triggering the synthesis of anthocyanins in leaves. A second series of experiments will be conducted to elucidate the physiological processes that trigger the synthesis of anthocyanins. The specific goals of these experiments are to: 1. determine if cold nighttime temperatures trigger anthocyanin synthesis and promote autumn leaf coloration 2. assess the influence of combined low day and night temperatures on autumn color development 3. determine if cold temperatures trigger anthocyanin synthesis due to reduced phloem export from leaves 4. determine if cold temperatures trigger anthocyanin synthesis due to elevated photooxidative stress in leaves 5. examine the underlying physiological mechanism triggering anthocyanin synthesis, specifically, the relationship between anthocyanin synthesis and the imbalance in photosynthetic processes which occurs in autumn leaves Expected outputs: Results from this set of experiments will increase our fundamental knowledge of the relationship between temperature and the development of autumn leaf coloration and the fundamental physiological triggers of autumnal anthocyanin synthesis. These results will provide a scientific basis for projecting the potential impact of future warm autumns on leaf coloration, an area of intense interest to the future economic viability of Vermont and the New England region.

Project Methods
This project will involve conducting a series of experiments on red and sugar maple seedlings. In general, the experiments will involve exposing seedlings to various temperature treatments and monitoring subsequent color development and leaf physiological parameters. Leaf color development will be quantified nondestructively with both anthocyanin and chlorophyll content meters (ACM, CCM), which are hand-held spectrophotometric devices that measure light transmitted through leaves and yield a pigment content index value. We will also digitally photograph leaves adjacent to a red/green/blue color standard. Using the color standard, digital photographs can be normalized to adjust brightness and color to a uniform standard. A color algorithm can be developed and applied to the images to yield a numerical value for "redness". The first set of experiments will investigate the basic influence of temperature on autumn color development. Starting mid-September, whole red and sugar maple seedlings will be exposed to low temperature (4 degrees C) during the night by placing them in a cold room for 12 h. They will be moved out of the cold room during the day, and placed under ambient light conditions at 20C. Treatment will occur for 5-7 consecutive days. A control group will be subjected to constant temperature (20C) during the day and night. A second experiment will expose seedlings to low temperatures during the day and night for 5-7 consecutive days. Following the conclusion of the cold treatments, plants will be subjected to relatively constant temperature for the remainder of the autumn senescence period. Color development will be monitored prior to treatment initiation and every 2-3 days after treatments conclude until leaf abscission occurs. Leaf color development will be measured with ACM, CCM and digital photography. Data will be processed by calculating mean maximum anthocyanin content index (ACI) values for seedlings for each treatment. Data will be analyzed statistically, typically standard error around the mean, and will be subjected to further statistical tests as needed. The second set of experiments will explore the physiological triggers of autumn coloration. Starting mid-September, the petioles or portions of the lamina of selected maple leaves will be chilled using Peltier plates to 4C during the night for 5-7 evenings. Subsequent development of coloration will be monitored and measured in these leaves as well as for a control group. Anthocyanin synthesis and data analysis will be done as described above. The final set of experiments will investigate the underlying mechanisms that trigger autumnal leaf coloration. A LiCor 6400 gas-exchange system and an OptiSciences pulse-modulated fluorometer will be used to measure several leaf photosynthetic parameters in leaves selected from experiments above and in special experiments designed in the final phases of the project. These parameters, including rates of electron transport, CO2 fixation and nonphotosynthetic energy dissipation, will allow us to examine the relationship between anthocyanin synthesis and the imbalance in photosynthetic processes which occurs in autumn leaves.

Progress 10/01/08 to 08/30/11

Outputs
OUTPUTS: The annual display of autumn coloration in Vermont is a highly prized, economically and culturally important event. Global warming will result in a longer growing season and the temperature of both the autumnal days and nights will increase. Because of the strong relationship between environmental conditions and leaf senescence, these changes in climate have the potential to disrupt the normal physiological processes involved in the development of autumn coloration, particularly the development of red-colored anthocyanin pigments. And although there has been a great deal of speculation about possible impacts of global warming on fall color development, there has been little scientific study of the phenomenon. Thus, the overall objective of this project was to investigate the effects of temperature on the development of autumn colors in maple. The results obtained will help us to make more informed statements about the effects of global warming on autumn coloration. Several experiments were conducted to investigate how temperature affects the onset of autumn coloration, and also to probe the physiological basis for any effects of temperature observed. The first experiment was focused on determining if cold temperatures promote the development of autumn coloration. In these experiments, red and sugar maple seedlings were subjected to various temperature treatments for one week prior to the onset of fall coloration, and their subsequent color development was monitored with nondestructive pigment content meters and digital photography. The subsequent set of experiments focused on determining the physiological mechanisms through which cold temperatures promote autumn coloration. In these experiments, leaf petioles or portions of leaves were cooled at night and during the day, and color development subsequently monitored throughout the fall. The results obtained will provide scientific data to help understand the potential effects of climate change on autumn coloration. The results of this work have been disseminated to the public through numerous interviews with a variety of media outlets, and a scientific manuscript describing the results is in preparation. PARTICIPANTS: AK van den Berg served as an investigator and completed the experiments for this work. TD Perkins and TC Vogelmann served as Co-Principal Investigators. TARGET AUDIENCES: The target audience includes scientists and the public at large. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
The results of the first set of experiments indicated that temperature does impact the development of fall coloration: colder temperatures promoted the onset of coloration, while warmer temperatures delayed the onset. In the second set of experiments designed to investigate the physiological mechanism through which cold temperatures impact leaf color development, chilling portions of the leaf lamina at night promoted anthocyanin development, while chilling the petiole had no effect. These results suggest that the physiological mechanism underlying the development of red anthocyanin pigments during autumn leaf senescence may involve inhibition of sugar transport out of cells, but not out of the leaf, during the night. Together, these results provide new knowledge of the process of autumn coloration and leaf senescence that help increase our understanding of how the warmer temperatures expected as a result of climate change can be expected to affect this process. The results suggest that the development of autumn coloration will likely be impacted by warmer autumn temperatures in the future. The annual display of autumn leaf coloration in Vermont is a highly prized, economically and culturally important event. It is an integral part of the state's public image and cultural heritage, and is an economic engine that drives the generation of millions of dollars in revenue for the state from tourism and related activities each fall. There is a growing urgency to understand how global warming will affect this process and how these effects might impact the economic well-being of the state. Results from these experiments have provided a more scientific basis for projecting the potential impact of future warm autumns on leaf coloration and allow us to make more informed statements about the effects of global warming on autumn coloration.

Publications

• No publications reported this period

Progress 10/01/09 to 09/30/10

Outputs
OUTPUTS: The annual display of autumn coloration in Vermont is a highly prized, economically and culturally important event. Global warming will result in a longer growing season and the temperature of both the autumnal days and nights will increase. Because of the strong relationship between environmental conditions and leaf senescence, these changes in climate have the potential to disrupt the normal physiological processes involved in the development of autumn coloration, particularly the development of red-colored anthocyanin pigments. And although there has been a great deal of speculation about possible impacts of global warming on fall color development, there has been little scientific study of the phenomenon. Thus, the overall objective of this project is to investigate the effects of temperature on the development of autumn colors in maple. The results obtained will help us to make more informed statements about the effects of global warming on autumn coloration. Several experiments are currently being conducted to investigate how temperature affects the onset of autumn coloration, and also to probe the physiological basis for any effects of temperature observed. The first experiment was focused on determining if cold temperatures promote the development of autumn coloration. In these experiments, red and sugar maple seedlings were subjected to various temperature treatments for one week prior to the onset of fall coloration, and their subsequent color development was monitored with nondestructive pigment content meters and digital photography. The results indicated that temperature does impact the development of fall coloration: colder temperatures promoted the onset of coloration, while warmer temperatures delayed the onset. Thus, the next set of experiments will focus on determining the physiological mechanisms through which cold temperatures promote autumn coloration. In these experiments, leaf petioles or portions of leaves will be cooled at night and during the day, and color development subsequently monitored throughout the fall. The results obtained will provide scientific data to help understand the potential effects of climate change on autumn coloration, and will help guide the design of subsequent experiments to be conducted for the project. PARTICIPANTS: AK van den Berg served as an investigator and completed the experiments for this work. TD Perkins and TC Vogelmann served as Co-Principal Investigators. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The experiments for this project are still ongoing, and thus no major results or findings have yet been obtained. The annual display of autumn leaf coloration in Vermont is a highly prized, economically and culturally important event. It is an integral part of the state's public image and cultural heritage, and is an economic engine that drives the generation of millions of dollars in revenue for the state from tourism and related activities each fall. There is a growing urgency to understand how global warming will affect this process and how these effects might impact the economic well-being of the state. Results from these experiments will provide a scientific basis for projecting the potential impact of future warm autumns on leaf coloration and will allow us to make more informed statements about the effects of global warming on autumn coloration.

Publications

• No publications reported this period

Progress 10/01/08 to 09/30/09

Outputs
OUTPUTS: The annual display of autumn coloration in Vermont is a highly prized, economically and culturally important event. Because of the strong relationship between environmental conditions and leaf senescence, changes in climate have the potential to disrupt the normal physiological processes involved in the development of autumn coloration, particularly the development of red-colored anthocyanin pigments. Although there has been a great deal of speculation about possible impacts of global warming on fall color development, there has been little scientific study of the phenomenon. In addition, though anecdotal accounts suggest color development is promoted by specific temperature conditions ("warm sunny days followed by cool, but not freezing, nights"), no physiological evidence currently exists to support this. Global warming will result in a longer growing season and the temperature of both the autumnal days and nights will increase, disrupting the normal chain of physiological events of maple leaf senescence and potentially decreasing the intensity of fall coloration. Thus, the overall objective of this project is to investigate the effects of temperature on the development of autumn colors in maple. The results obtained will help us to make more informed statements about the effects of global warming on autumn coloration. Several experiments are currently being conducted to investigate how temperature affects the onset of autumn coloration, and also to probe the physiological basis for any effects of temperature observed. The first experiment is currently being conducted in the autumn of 2009 and is focused on determining if cold temperatures promote the development of autumn coloration. In these experiments, red and sugar maple seedlings were subjected to four temperature treatments for one week prior to the onset of fall coloration: 1) colder than ambient temperatures during the night, 2) colder than ambient temperatures during the day and night, 3) warmer than ambient temperatures during the night, and 4) ambient temperatures (control). The development of autumn coloration was monitored in each seedling before and after treatment with nondestructive pigment content meters and with digital photography. Data collection is currently ongoing. When complete, data will be analyzed statistically to determine if significant differences exist between the temperature treatments in the timing and extent of autumn color development. The results obtained will help guide the design of subsequent experiments to be conducted for the project. PARTICIPANTS: TC Vogelmann served as the Principal Investigator and determined overall project direction. TD Perkins served as the day to day Project Manager. AK van den Berg served as an investigator and completed many of the experiments for this work. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The experiments for this project are still ongoing, and thus no major results or findings have yet been obtained. The annual display of autumn leaf coloration in Vermont is a highly prized, economically and culturally important event. It is an integral part of the state's public image and cultural heritage, and is an economic engine that drives the generation of millions of dollars in revenue for the state from tourism and related activities each fall. There is a growing urgency to understand how global warming will affect this process and how these effects might impact the economic well-being of the state. Results from these experiments will provide a scientific basis for projecting the potential impact of future warm autumns on leaf coloration and will allow us to make more informed statements about the effects of global warming on autumn coloration.

Publications

• No publications reported this period