There's an article titled "Everything weighs something", but this isn't true, one thing we can take with us in the bush that doesnt weigh anything at all is knowledge.
When shopping for new gear we often consider how many $ per ounce saved to judge the efficiency of the purchase, but have you ever considered time as a factor?
With "leave no trace" trekking and todays focus on gear a lot of useful bushcraft skills that can replace gear are ignored. They weigh nothing, but their penalty is time.
A lot of people carry some combination of stove/pot stand/windscreen. I carry none of these, instead I cook on the camp fire and make an adjustable pot hanger for my billy can.
Time: 5 minutes. Weight saved, dunno, never owned a stove lol.
When cooking fish, instead of using a grill or a pan you can just put them on a stick over the fire, or what I like to is lay a bed of damp sphagnum moss over a hot coals, put my fish on that, then put another layer of moss on. That way I can keep fishing without having to tend to my meal while it cooks.
When I go hike in the Canadian Shield I don't bother bringing toilet paper. Sphagnum moss works even better, it's moist and slightly antiseptic. It gets my butt cleaner and is more hygienic.
Time: 2 seconds to bend over and pick some up. Weight saved: ~2 oz.
Tinder. In my neck of the woods birch bark is abundant, and while there are many other excellent alternatives it's my first choice. It's easier to light than pine needles, much easier to gather than fatwood, and unlike dry grass or old mans beard it's weather proof. You can dunk it under water, shake it off then light it.
Time: None, I just grab a lose piece off a tree on my way into camp. Weight saved: negligible.
Wild foods can potentially save you quite a bit of weight. I'm not a fan of relying on it, but I love to supplement my grub with forage. Aside from the seasonal delicacies there's often staples. I'm quite partial to the roots of cattails (aka bull rushes, reedmace), the green shoots are supposed to be quite good too. Instead of bringing tea bags I simply enjoy the indigenous "labrador tea".
A bed can be fashioned out of spruce bows & moss. I've had to do this one time when I was ill prepared for the night time temperatures on a late October hike. I don't recommend it though, aside from the amount of time it takes it requires a lot of green branches.
Of course there are countless other natural alternatives, but these ones I've found are the best trade off.
What bushcraft techniques do you guys employ in your travels?
