<groundcover name="Trees" source="hiclipart.com (non-commercial use only)">
    <spacing>20</spacing>
    <biomes>
        <biome classes="forest grassland" fill="1" size_variation="0.4">        
            <asset url="tree_ginkgo.png"/>
            <asset url="tree_maple.png"/>
            <asset url="tree_pine.png"/>
            <asset url="tree_poplar.png"/>
            <asset url="tree_sycamore.png"/>
            <asset url="tree_sycamore_2.png"/>
            <asset url="tree_transpiration.png"/>
            <asset url="tree_white_poplar.png"/>
        </biome>
    </biomes>
</groundcover>

