Definitely needs more air and spacing. As a comparison grab a book and open up to a random page. You will see smaller paragraphs with a decent amount of detail (books also use a trick of indenting paragraphs in order to indicate it is the same scene and keep the page number to a minimum)

You are also repeating words, it doesn't always flow, and it sounds recipe like in it's structure.

[quote][color=cccccc]Austin ran till he tripped over a vine which caused his leg to be stuck in the vines. He could see the monster coming closer, so he grabbed his knife before cutting the vines from his leg. Once they were cut, he hid behind a tree.[/color][/quote]
An example of this done differently and with more emotion could be this:

[quote][color=cccccc]As Austin ran he felt the thick scrub latch onto his foot, pulling him down to the ground. His heart pounded as he knew he had minutes, seconds even, to escape this organic bear trap before he was discovered by the monster. He had to cut himself free and use the knife attatched to his belt, the very knife that he fumbled within his clammy hands.

Frantically Austin slashed and hacked, he sliced through the vines with a sense of earnest knowing that his life depended on it. He was free! Austin could feel the green tendrils release him, falling away and retreating back into the very earth they sprouted from.

With the beast coming closer, Austin could hear the heavy panting become louder and louder. He made a desperate dash, using a tree as a barrier between the two, hiding in the shadows of the very fauna that betrayed him moments earlier. There he waited, pressing his body against the rough bark, feeling the wood prick into his skin. The subtle pain of splinters was nothing compared to the nightmare he was experiencing.[/color][/quote]

Admiditly I have managed to lengthen the post by a large margin compared to the few sentences that you wrote, but for a scene like that you need to portray the emotion a lot more and cause your reader to feel scared, worried even about your characters.

Something I do sometimes is imagine how I would cope in a situation like that and try to her the heart rate going a bit. I can then take note of what my body is doing, how it's reacting and what I would do in that situation.

Also, when you write something like when he tripped, noticed how I switched it up and turned the vines into a secondary character. He still tripped, but it creates the illusion that even nature is playing against him.