ASCII/UTF8 terrestrial carbon cycle diagram

I have been thinking about the carbon cycle. I decided to try and make a simple terrestrial carbon cycle diagram using only ASCII art. It’s completely useless, but was quite fun to make. There’s two versions, one which uses some UTF8 characters, and another which only uses ASCII characters.

               ┌─────────────────────────┐
               │NPP = GPP - Ar           │
               │NEP = NPP - Hr           │
               │NBP = NEP - harvest, fire│
               └─────────────────────────┘
┌───┐ ┌───┐       ┌───┐         Harvest
│GPP│ │Ar │       │Hr │         +Fires
└─┬─┘ └─▲─┘       ▲─▲─▲         ' '▲'  '
  │     │         │ │ │        ' ' │ ' '
 _▼_____│_        │ │ │        ^^^^│^^^^
 \       /        │ │ │        \^  ^  ^/
  \ NPP────────┐ ┌┘ │ └┐        \^ ^ ^/
   \   /       │ │  │  │         \^^^/
    │ │        │ │  │  │          │^│
    │ │        │ │  │  │          │^│
    │ │        ▼ │  │  │         ^│^│^
════╬═╬════════""""═╬═######══════╩═╩═══
  ┌─┤ ├─┐     Litter│  Wood
  ┼ │ │ ┼           │
 ╱│╲   ╱│╲────────▶SOC─────────────────▶DOC

               +-------------------------+
               |NPP = GPP - Ar           |
               |NEP = NPP - Hr           |
               |NBP = NEP - harvest, fire|
               +-------------------------+
+---+ +---+       +---+         Harvest
|GPP| |Ar |       |Hr |         +Fires
+---+ +---+       +---+         ' '^'  '
  |     ^         ^ ^ ^        ' ' | ' '
 _v_____|_        | | |        ~~~~|~~~~
 \       /        | | |        \'  '  '/
  \ NPP--------+  | | |         \' ' '/
   \   /       |  | | |          \'''/
    | |        |  | | |           |'|
    | |        |  | | |           |'|
    | |        v  | | |          '|'|'
----| |--------""""-|-######------+-+---
  --| |--     Litter|  Wood
  | | | |           |
 /|\   /|\-------->SOC----------------->DOC