ExportTerrainTrees

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;

public static class ExportTerrainTrees
{
	[MenuItem("Utilities/Export Terrain Trees")]
	static void ExportTrees()
	{
		Terrain terrain = Selection.activeGameObject.GetComponent<Terrain>();
		if(terrain)
		{
			GameObject[] prefabInstances = new GameObject[terrain.terrainData.treePrototypes.Length];
			for (int i = 0; i < terrain.terrainData.treePrototypes.Length; i++)
				prefabInstances[i] = terrain.terrainData.treePrototypes[i].prefab;

			foreach (TreeInstance tree in terrain.terrainData.treeInstances)
			{
				GameObject spawnedTree = GameObject.Instantiate(prefabInstances[tree.prototypeIndex],
					Vector3.Scale(tree.position, terrain.terrainData.size) + terrain.GetPosition(),
					Quaternion.Euler(0f, tree.rotation, 0f));

				Vector3 pos = spawnedTree.transform.position;
				Quaternion rot = spawnedTree.transform.rotation;

				spawnedTree = PrefabUtility.ConnectGameObjectToPrefab(spawnedTree, prefabInstances[tree.prototypeIndex]);
				spawnedTree.transform.position = pos;
				spawnedTree.transform.rotation = rot;
			}
		}
	}

	[MenuItem("Sausage Soccer/Export Terrain Trees", true)]
	static bool ExportTreesValidate()
	{
		if(Selection.activeGameObject)
			return Selection.activeGameObject.GetComponent<Terrain>();

		return false;
	}
}