For the object to cut the thorny bushes you need [SPOILER] L2 Exploration PLUS a Master Scientist[/SPOILER]. For the scarecrow you need [SPOILER] L2 Engineering for the dam) PLUS an Adept Farmer[/SPOILER]. To clear the vines you need [SPOILER] L3 Culture [/SPOILER].
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To err is human; to arr is pirate.