What are the remedies for land trespassing?

If the trespassser refuses to leave (usually in a situtation where they believe that they own the land, but do not), you can sue to have them ejected.

Trespass is one of the few torts which is considered to be "actionable per se", meaning that the law deems you to have suffered an injury the instant the invasion of your property occurs, whether or not the property is actually damaged. This is based on the common-law principle that one's land is absolutely inviolable.

Accordingly, if a person enters your property without your permission, and causes absolutely no physical damage, you can still sue them, because you suffered a legal wrong the instant they trespassed. However, you are likely to recover only "nominal" damages, meaning the court will recognize that your legal rights have been violated, but since you suffered no physical or economic harm, order the defendant to pay you a very small sum (awards of $1 are not uncommon in these cases).

Of course, if the trespasser actually causes physical damage to your property, you can sue to recover for those damages.