You can easily mod a new spell that clears trees.
<?xml version="1.0" encoding="iso-8859-1"?>
<Spells>
<DataChecksum NoParse="1">
<Ignore>DisplayName,Description,IconFG,IconBG,IconColor,SoundFX,ParticleEffect,EffectScale</Ignore>
<Translate>DisplayName,Description</Translate>
</DataChecksum>
<SpellDef InternalName="ClearForest">
<DisplayName>Clear Forest</DisplayName>
<Description>Clears aways pesky forest</Description>
<Image>BG_ReviveLand.png</Image>
<IconFG>Spellseed1.png</IconFG>
<IconBG>Spellseed1_BG.png</IconBG>
<IconColor>245,245,245</IconColor>
<SoundFX>Cast_ReviveLand</SoundFX>
<ManaCost>5.0</ManaCost>
<Range>3</Range>
<Cooldown>0</Cooldown>
<SpellLevel>5</SpellLevel>
<SpellType>Strategic</SpellType>
<SpellClass>Terraform</SpellClass>
<SpellTargetType>NeutralGround</SpellTargetType>
<ValidTerrainCategory>Forest</ValidTerrainCategory>
<SpellDefEffect>
<EffectName>Revive_Land</EffectName>
<LocalPosition>0,0,0</LocalPosition>
<EffectScale>0.25</EffectScale>
<EffectDelay>0.0</EffectDelay>
<SnapToTerrain>1</SnapToTerrain>
</SpellDefEffect>
<GameModifier InternalName="PlaceTerrain">
<ModType>Map</ModType>
<Attribute>PlaceTerrain</Attribute>
<TerrainType>Land</TerrainType>
<Value>0</Value>
</GameModifier>
</SpellDef>
<Spellbook InternalName="EarthSpellbook">
<SpellbookNode InternalName="Node12">
<NodeID>12</NodeID>
<SpellDef>ClearForest</SpellDef>
<StartingResearch>1</StartingResearch>
</SpellbookNode>
</Spellbook>
</Spells>