Forest and taiga type biomes spawn with large treeless areas when ore vein spawn sizes are set to excessive values

The bug

Forest and taiga type biomes spawn with large treeless areas when ore vein spawn sizes are set to excessive values.

How to reproduce

1. Create a new customized world and edit the Andesite and Diorite spawn sizes to 100 in the Presets screen. I tested on the seed -802523552 in versions 1.9.4 and 1.12.1.
   Used preset:

   {"coordinateScale":171.103,"heightScale":684.412,"lowerLimitScale":512.0,"upperLimitScale":512.0,"depthNoiseScaleX":200.0,"depthNoiseScaleZ":200.0,"depthNoiseScaleExponent":0.5,"mainNoiseScaleX":80.0,"mainNoiseScaleY":480.0,"mainNoiseScaleZ":80.0,"baseSize":8.0,"stretchY":12.0,"biomeDepthWeight":0.0,"biomeDepthOffset":0.0,"biomeScaleWeight":0.0,"biomeScaleOffset":1.0,"seaLevel":79,"useCaves":true,"useDungeons":true,"dungeonChance":21,"useStrongholds":true,"useVillages":true,"useMineShafts":true,"useTemples":true,"useMonuments":true,"useMansions":true,"useRavines":true,"useWaterLakes":true,"waterLakeChance":4,"useLavaLakes":true,"lavaLakeChance":80,"useLavaOceans":false,"fixedBiome":-1,"biomeSize":6,"riverSize":30,"dirtSize":33,"dirtCount":0,"dirtMinHeight":0,"dirtMaxHeight":256,"gravelSize":33,"gravelCount":0,"gravelMinHeight":0,"gravelMaxHeight":256,"graniteSize":50,"graniteCount":2,"graniteMinHeight":0,"graniteMaxHeight":32,"dioriteSize":125,"dioriteCount":1,"dioriteMinHeight":32,"dioriteMaxHeight":96,"andesiteSize":50,"andesiteCount":4,"andesiteMinHeight":96,"andesiteMaxHeight":192,"coalSize":17,"coalCount":20,"coalMinHeight":48,"coalMaxHeight":192,"ironSize":9,"ironCount":20,"ironMinHeight":41,"ironMaxHeight":96,"goldSize":9,"goldCount":2,"goldMinHeight":41,"goldMaxHeight":48,"redstoneSize":8,"redstoneCount":8,"redstoneMinHeight":0,"redstoneMaxHeight":25,"diamondSize":8,"diamondCount":1,"diamondMinHeight":0,"diamondMaxHeight":16,"lapisSize":7,"lapisCount":1,"lapisCenterHeight":25,"lapisSpread":16}
   

2. Fly around the forest and observe there are fewer trees than there should be