Systems of Holy Grounds and Holy Trees have existed in the past and they do exist in the present in different religions and cultures. It may be different how such places are used in the physical world. Often they are sites of prayer and contact to the spiritual world. Sometimes temples are built on such locations.
From a spiritual viewpoint, such Holy Grounds and - Trees can be seen as crossroads of more roads in spirit world coming together. In the physical world the network that connects several Holy Grounds is invisible, but in the spiritual world it can be clearly seen and experienced.
These spiritual networks are often made by angels and kept intact by human spirits who travel over the roads of the network. When a religious group has established such a network of Holy Grounds in a good way, many spirits of that religion will be able to visit places that otherwise would not be reachable. For someone praying on such a Holy Ground under a Holy Tree, that may mean that his or her questions are more quickly answered by spirit world and, in case the Holy Ground has really been dedicated to God, from God.
Roads in spirit world is a big topic by itself. Roads in spirit world may be connected to roads in the physical world, meaning that spirits can use the roads in the physical world to travel from A to B. This is only one way how roads in spirit world can be formed. Other roads, the ones connected to Holy Grounds, are not necessarily bound to physical roads. These spiritual roads may cross other spiritual roads as if these different roads would exist in different dimensions.
In the order of restoration of God's Ideal, the 'Garden of Eden,' the establishment of Holy Grounds is a first stage. The Holy Grounds represent the centers of the Gardens of Eden. Later houses can be built, in a second stage. In a third stage, temples can be constructed.
The Holy Trees have a similarity to man. Trees are a kind of image representation of man. Trees connect to Heaven and Earth and spread their influence and elements horizontally. The elements that are given out are made out of Heaven and Earth, this is a spiritual or energetic reality. In the physical world this is the same. The tree takes in light and gases from 'heaven' and water and nutritional elements from the earth and combines these two in a chemical process that makes the tree grow and send out oxygen to its environment.
Tribes that existed long ago often had their religion centered on Holy Trees. Druids knew how to use the trees to enhance the druid's abilities in many different ways. Such trees and grounds would often be placed on energy lines of the earth.
Because the Holy Trees clearly have a spiritual reality, if something goes wrong in spirit world, it mostly will be visible in the physical world. The tree gets ill or is blown over by a storm or is cut by people who don't understand the significance.