message: Nature Reserve gives -1 production
diff: <Description>TXT_KEY_IMPROVEMENT_NATURE_RESERVE</Description>
  <Civilopedia>TXT_KEY_IMPROVEMENT_NATURE_RESERVE_PEDIA</Civilopedia>
  <ArtDefineTag>ART_DEF_IMPROVEMENT_NATURE_RESERVE</ArtDefineTag>
  - <YieldChanges/>
  + <YieldChanges>
  + <iYield>0</iYield>
  + <iYield>-1</iYield>
  + </YieldChanges>
  <RiverSideYieldChange>
  <iYield>0</iYield>
  <iYield>0</iYield>
  