Never let yourself be psychologically influenced by people who think that deforestation should inspire them, who cut down trees in their garden. I believe an environmentalist- veggie/vegan should really include gardening into her practiced understanding of their ethical lifestyle.
You spend more money on cooling the house than heating it ... but not just for the financial side to it you should have trees grow all around your garden to protect the immediate climate surrounding your house. Someone who does not know how to respect and be thankful for that tree round her house, can't really be a good example in conveying a clear message against deforestations - of any kind really - that eat up the environment, and thus the climate.
An environmental protection that bases on a mere calculation misses the point why damaging the "natural world" is something immoral in the first place. Well why is that immoral? Because it hurts? Because it hurts if we overdo it? No, but because it's wrong in the first place. What's wrong is to deduce a principle from an initial mistake; instead of trying to solve the problems caused by the core mistakes.
Gardening plays a role for people in all societies, everywhere, at any given time; only what type of gardening: garden parties, trimming the hedges into styles, the oasis as a garden, eden? I assume that even agriculture is an enormously outsized residue of what once was something which today would amount to our current day permaculture (in regards to what it would have looked like at least). Right after the "gatherer" stage there must have been the gardening stage, at which the "gatherer" had permanently settled within the berry shrubs, mabye eglantines (sweetbrier) and grain bearing grasses. Both, the harvest of foods that constitute a staple diet and medical herbs and spices took their outset from the garden.