Good answers already, I am just going to post the code for reference
<objective type="Goto" id="trader" value="5" phase="1">
<property name="biome_filter_type" value="OnlyBiome" />
<property name="biome_filter" value="pine_forest" />
<!-- <property name="biome_filter_type" value="ExcludeBiome" /> -->
<!-- <property name="biome_filter" value="wasteland" /> -->
<property name="nav_object" value="go_to_trader" />
</objective>
<objective type="InteractWithNPC">
<property name="phase" value="2"/>
<property name="nav_object" value="return_to_trader" />
<property name="use_closest" value="true" />
</objective>
So the quest will only look for traders that are in the Pine Forest Biome. The commented out sections can be reutilized so it looks for any nearby trader that is not in the wasteland biome.
If you are using a custom map or spawning away from the pine forests, you might want to create a quick modlet to change out the filters.
Code:
<config>
<set xpath="/quests/quest[@id='quest_whiteRiverCitizen1']/objective[@type='Goto']/property[@name='biome_filter_type']/@value">ExcludeBiome</set>
<set xpath="/quests/quest[@id='quest_whiteRiverCitizen1']/objective[@type='Goto']/property[@name='biome_filter']/@value">wasteland</set>
</config>