"TO" can be used as
(3)to + V (與原形動詞一起構成不定詞)
when it is used as "介係詞", it will follow with an object(受詞) , if it is a verb, this verb will be in "v-ing" form.
In your questioned sentence, "to" is a preposition, so uses"safeguarding" not "safeguard".
Now, the question is how do you know it is a preposition, not used to form "不定詞" ?
To explain it with grammar is virtually impossible, so let me explain it with logic:
When someone "commit" to safeguard something, will such an action be a CONTINUOUS action or just an one-second commitment ? I am sure, you will answer with "continuous action". If so, then it is better to use "V-ing" to indicate such an action, right?
Other Example: Look forward to + V-ing. why?
It has the same reason, when you look forward to something, your mind shall be a continuous effort, not just one-second effort. Therefore, it is better to use "V-ing".
Hopefully, this logic explanation can help you better than using grammar !!!
2012-03-16 14:22:34 補充：
"To explain it with grammar is virtually impossible", I mean how grammar rules can tell you the "to" is preposition in the sentence, how to DECIDE? All it says is "WHEN it is a preposition, you use V-ing".
2012-03-16 14:24:44 補充：
For a person who knows English well, he or she can easily DECIDE, but for a beginner, how do you decide? Therefore, I offer you a logical way to decide. Practice it, you will get it !
2012-03-16 22:07:42 補充：
If I have a way to tell you about "甚麼時候是介系詞甚麼時候是不定詞呢", then I don't need to tell you about using LOGIC to determine to use "Ving" or "to V". After all, English is used in a LOGICAL way.
2012-03-16 22:10:04 補充：
Grammar is just to assist you in using English correctly when you are NOT used to use English. Once you are used to English, you will NOT need grammar, your instinct will tell you what is right and wrong way to use English.
2012-03-16 22:27:30 補充：
I was bothered by this kind of questions a lot. My explanation is how I reason with myself. Hopefully, it will help you too.