actually that wouldn't work. at least not in true space. changes of state aren't dependent on temperature, but rather on an object's vapor pressure. (vapor pressure is created by the random atoms that are constantly leaving solids and liquids, which also create an object's smell) as an example, reducing the pressure around a beaker of water will allow it to boil at room temperature. the atmospheric pressure is what allows liquids and solids to exist. because there's no pressure in true space, the tree would turn into vapor, not into a liquid. (the same thing would happen to an astronaut if he didn't wear his pressurized space suit) to liquify the tree, there would still have to be some pressure present in the tree's environment. as to how much pressure, i have no idea. also, as for the question about the tree burning.....i have no idea as to whether or not flash point is affected by pressure