The term "wight" in general simply refers to "a sentient being". But moreso today the term is applied to mean "a spiritual being, neither God nor human". So as you can imagine, the term "land wight" is referring to spiritual beings of the land. I'm indebted to Jenny Blain (Sheffield Hallam University, author of Nine Worlds of Seid-Magic (Routledge, 2002) for introducing me to the word wight . She tells me that wight can be a synonym of beings or persons, but, more usefully, that it refers to sentient beings for which we don't have other words. Derived from an old English word (with cognates in Old Norse), wiht , the word seems much more useful that the word spirit.( http://www.animism.org.uk/wights.htm)
They are said to come in a variety of shapes, sizes, attitudes, personalities. They tend to live in certain aspects of a landscape- a tree, rock, stump. Wights are often seen to be less than actually deities, but more close to a kinship with us as people. It is for this reason that many practices in Heathenry encourage the building of relationships with these wights. But one must know when working with wights that they are very similar in disposition to us, in that they have the capacity to be good bad and everywhere in-between. Wights are individualized spirits and cannot be lumped together under and specific stereotype.
They serve a multitude of purposes, some magickal and some not. For instance, in many northern workings (and this can be seen in heathenry as well) the wights are called upon for protection and defense. Magick, such as the nidstang or cursing pole, often serves the purpose of altering the wights in some manner. In cursing, the goal would be to disrupt the wights and anger them to the point of causing them to take action. They tend to become uneasy and upset at a variety of things: loud noises, disturbances, blood shed, etc. Stories, for instance, of machinery breaking down on land with angered wights are common. Landnamabok tells the story that in older times, dragon head ornaments were taken off ships before they reached land to keep from frightening or upsetting the land wights.
However, with things like this one must be careful.It is possible that you will effect more than you intended. It can alter the land around the workings, and this would technically be driving away the land wights. The idea of the nidhing pole is to anger the spirits near the intended person and cause them to take their anger out upon them. Sometimes the intended purpose IS to drive out the wights, and this is called "alfreka" or "driving away the elves": this is to make a land spiritually dead through your cursing or workings. This is not something to be taken lightly, at all, and is seen as heinous to do.
It is not common for anyone to actually see a wight- but it is said that those who practice northern traditions and have the "sight" (related to seidhr and trance work) have been able to see them before. (If you read through the eddas and sagas, there is mention and tale of people who have seen the wights, and what occurs).The wights affect quite a bit- so they are treated with courtesy and respect. It is said to be unwise to offend a wight at all. Often in heathenry offerings are made to the wights and seen as just as important as an offering to any deity. This is for a variety of reasons. Since it believed that these wights and spirits live in nature, when we take from nature we are propitiating the Wights. We are taught to only take what you need, nothing more, and to give back when you can. This idea of reciprocal exchange is very important. If you should take a tree, for instance, it would only be fitting that you plant one in its stead.
Landtaking and Landleaving are rites done in Northern rituals for the wights specifically. These serve the purpose of befriending and working towards a relationship with the wights of the land you are entering or leaving, rather than upsetting them. When a house is built and inhabited, the nearest wights of that place, assuming that they accept the new human inhabitants, have little choice but to see and explore the house that was built. They peer into the realities of human life, and watch. They feel the effects of the human settlement on themselves and on their existence.( Alfarrin). It is believed that when we move to a new place, we bring our ancestral wights with us- and they affect the native wights and spirits of the land. These rites and rituals play a part in joining the two, and offering a respect to the land you are coming to/from. During these rites sacred fire is often carried around the borders of the land, and certain spots are deemed sacred space for the wights- offerings are to be made here, work is to be done here, etc. These are beacons of a sort for the surrounding wights of the land. the wights "bond" with the house and the people who live there, becoming house wights. In Germanic countries, they were called Husinga or (individually) a Husing, a tomt, tompt, or tomtekarl.(Alfarrin).
I personally leave offerings for the landwights and include them in a large amount of my workings. I spend a great deal of my time doing my work outside in the woods, and thus like to include them. I talk to the trees, stones, plants- and am respectful. I've heard this may have similarities to other practices and I was simply curious if anyone had input.
Sources, and extra information:
Elves, Wights, and Trolls by Kveldulf Gundarsson