The idea is a good one, in theory: You buy one plastic Christmas tree for life, and never again will an evergreen be chopped down in your name. And yet plastic trees – especially in the low-price segment – only have a lifespan of a few years before they start to look old and are thrown away. While they don’t shed needles and aren’t a problem for people with allergies, plastic pines do appear to be losing their image as the more environmentally friendly choice. Recent research in the UK has shown that Gen Z respondents and Millennials are more likely to select a real fir tree than their older G…