Is there any kind of standard for representing date ranges?

ISO 8601 does have a standard for representing date ranges. To represent the start and end date using this format you would write:

2013-01-01/2013-06-31

Note how the forward slash is used as the interval designator to separate the start and end dates.

See here for more information.

Just to add to Ben Smith's answer above, the standard also mentions using a double hypen (--) as the interval designator in certain contexts, instead of the forward slash (/). For example, in file or directory names where using a forward slash is forbidden in some operating systems (e.g. Windows).

So the above examples would be

2013-01-01--2013-06-31

or

2013-01-01--06-31

in abbreviated form