Gut instinct based on no knowledge:
With some plants, over time, with good ferts, and if you were manually propagating them when possible, probably but not practically. I honestly have no experience in high tech planting and I have no idea what plants those are, so this is just my 2 cents from the peanut gallery. That said, it looks really cool.
Brian
CO2 and ferts (IMO) is the only way, I have 2 tanks that are heavily planted (well, only one that is heavily planted now). With high lights, CO2 and ferts, the plants grew twice as fast and twice as nice. .To get the coverage you want, you will have to go that same route.
There are ways around having CO2 with other "less than" plants/moss but if that scape you love, be prepared to work (adding co2) at it, it's an art project, long term! Not something I'm willing to do...yet anyway...try it, it's awesome!
With exactly those plants? I don't know, I can't tell what they all are. Can you achieve a similar look without CO2? Absolutely. I have had tanks with CO2, tanks without, and tanks where I dose liquid carbon. Personally, I prefer dosing with liquid carbon at this point. It is easier to make a mistake (or have someone else make one... as in the time a relative who was kindly watching my house/fish tank while I was on vacation dumped like 150ml of KN03 into my tank as opposed to the regular dose of 5ml) and recover than a "high tech" tank IMO. That being said; one day I would like to setup another high tech tank with fully automated dosing and switches for water changes.... that'll be a fun project for another day/another house.
Most carpeting plants do better with Co2. A handful can go without, Monte Carlo, some of the compact mosses. In fact, most of the look can be achieved from low light, low maint. Plants. Thing is, it will take a lot more time. All depends on your patience.
Your not gonna achieve growth like that without pressurised Co2, good Fertilization (both micro and macro) and some decent lighting (IMO this should be the limiting factor). Liquid carbon and diy Co2 aren't getting you results near to that.