The best horticultural practice when transplanting trees or shrubs, native or non-native, is to use existing soil as backfill for the planting hole.
Roots tend to stay in planting holes with amended soil rather than growing out of the hole to form an extensive and healthy root system. In fact they can encircle the planting hole, just as they do when they outgrow a container, further hindering root establishment.
Amending the soil in the planting hole can result in poor water mobility between the planting hole and the surrounding native soil. During winter when there is rain, water in the planting hole will not migrate out to the surrounding soil, resulting in excessive moisture around the roots and crown. In the summer, the plant quickly uses up the water in the planting hole, while at the same time the surrounding soil is drawing this water away from the hole. The plant will need frequent irrigation, and may rot from excessive heat and moisture.
Organic amendments decompose. If they comprise much of the soil in the planting hole, the plant can sink or pockets can form, further exacerbating drainage problems near the plant.
Rather than modifying your garden, select plants that are adapted to your conditions. Native plants clearly are well-adapted to their local setting. Gardens, though, represent a great disturbance to the natural environment. Select native plants that accept disturbance, while you work towards creating a more stable system. Forego soil amendments, fertilizers, irrigation, and physical disturbance to the soil. Not only will your native plants appreciate this, it is far easier on your back and wallet!