Understanding logback.xml file

HI,
I am using the following file in my java maven project :

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>
                %d{yyyy-MM-dd HH:mm:ss} %-5level %logger{36} - %msg%n
            </pattern>
        </encoder>    </appender>
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>yatra.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- daily rollover -->
            <fileNamePattern>logFile.%d{yyyy-MM-dd}.log</fileNamePattern>

            <!-- keep 30 days' worth of history capped at 3GB total size -->
            <maxHistory>30</maxHistory>
            <totalSizeCap>1GB</totalSizeCap>

        </rollingPolicy>

        <append>true</append>
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss} %-5level %logger{36} - %msg%n
            </pattern>
        </encoder>

    </appender>
    <logger name="chatAdapter" level="debug" additivity="false">
        <appender-ref ref="STDOUT" />
    </logger>
    <logger name="SMRunner" level="debug" additivity="false">
        <appender-ref ref="STDOUT" />
    </logger>
    <logger name="stateMachine" level="debug" additivity="false">
        <appender-ref ref="STDOUT" />
    </logger>

    <root level="error">
        <appender-ref ref="STDOUT"/>
    </root>
</configuration>

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This file resides in my top directory and inside it i have different modules like chatAdapter, stateMachine etc.

I have two questions :
1) Whats the meaning of defining root tag here ? Is it doing anything
2) As all of chatAdapter, stateMachine etc.. have the same logging conditions... Can i somehow avoid writing all of them and specify a common one for all the modules and yet have only one logback.xml file in the  project ?

Thanks