(svn r19644) -Fix [FS#3728]: don't allow building cacti outside of the desert or rain forest trees outside of the rain forest area. This to prevent people from thinking planting rain forest trees makes the rain forest bigger and thus adds more place to build a lumber mill.

src/lang/english.txt

@@ -3529,6 +3529,7 @@ STR_ERROR_CAN_T_BUILD_AQUEDUCT_HERE                             :{WHITE}Can't bu
 
 # Tree related errors
 STR_ERROR_TREE_ALREADY_HERE                                     :{WHITE}... tree already here
+STR_ERROR_TREE_WRONG_TERRAIN_FOR_TREE_TYPE                      :{WHITE}... wrong terrain for tree type
 STR_ERROR_CAN_T_PLANT_TREE_HERE                                 :{WHITE}Can't plant tree here...
 
 # Bridge related errors

src/tree_cmd.cpp

@@ -375,12 +375,25 @@ CommandCost CmdPlantTree(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 					continue;
 				}
 			/* FALL THROUGH */
-			case MP_CLEAR:
+			case MP_CLEAR: {
 				if (IsBridgeAbove(tile)) {
 					msg = STR_ERROR_SITE_UNSUITABLE;
 					continue;
 				}
 
+				TreeType treetype = (TreeType)tree_to_plant;
+				/* Be a bit picky about which trees go where. */
+				if (_settings_game.game_creation.landscape == LT_TROPIC && treetype != TREE_INVALID && (
+						/* No cacti outside the desert */
+						(treetype == TREE_CACTUS && GetTropicZone(tile) != TROPICZONE_DESERT) ||
+						/* No rain forest trees outside the rain forest, except in the editor mode where it makes those tiles rain forest tile */
+						(IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS) && GetTropicZone(tile) != TROPICZONE_RAINFOREST && _game_mode != GM_EDITOR) ||
+						/* And no subtropical trees in the desert/rain forest */
+						(IsInsideMM(treetype, TREE_SUB_TROPICAL, TREE_TOYLAND) && GetTropicZone(tile) != TROPICZONE_NORMAL))) {
+					msg = STR_ERROR_TREE_WRONG_TERRAIN_FOR_TREE_TYPE;
+					continue;
+				}
+
 				if (IsTileType(tile, MP_CLEAR)) {
 					/* Remove fields or rocks. Note that the ground will get barrened */
 					switch (GetRawClearGround(tile)) {
@@ -402,7 +415,6 @@ CommandCost CmdPlantTree(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 				}
 
 				if (flags & DC_EXEC) {
-					TreeType treetype = (TreeType)tree_to_plant;
 					if (treetype == TREE_INVALID) {
 						treetype = GetRandomTreeType(tile, GB(Random(), 24, 8));
 						if (treetype == TREE_INVALID) treetype = TREE_CACTUS;
@@ -413,11 +425,12 @@ CommandCost CmdPlantTree(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 					MarkTileDirtyByTile(tile);
 
 					/* When planting rainforest-trees, set tropiczone to rainforest in editor. */
-					if (_game_mode == GM_EDITOR && IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS))
+					if (_game_mode == GM_EDITOR && IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS)) {
 						SetTropicZone(tile, TROPICZONE_RAINFOREST);
+					}
 				}
 				cost.AddCost(_price[PR_BUILD_TREES]);
-				break;
+			} break;
 
 			default:
 				msg = STR_ERROR_SITE_UNSUITABLE;