Richard T. Haard, Ph. D.
Plant Propagation Manager
Fourth Corner Nurseries

It is now widely accepted that populations of the same plant species growing in Idaho, the Cascades and the coastal lowlands of Western Washington have made genetic adaptations to the unique climates of each location. Our nursery is growing several species from multiple seed sources side by side and we know there are dramatic, genetically programmed differences between these strains regarding timing of germination and leaf drop, cold or rain tolerance, and disease susceptibility. We feel strongly that local sources should be used to provide the plants needed for restoration and landscaping here in Western Washington. This goal is becoming increasingly difficult to achieve because of urbanization and the effects of introduced invasive vegetation such as blackberries and reed canary grass. These major factors are responsible for a serious and continuing decline in populations of native plants, making seed and cutting collection from appropriate locations challenging. The diminishing remnants of native habitat are crucial for wildlife and our natural heritage, but are now facing a new threat - overharvest of propagation material.

Our local genetic stocks of native plants need to be protected and increased. I think careful stewardship of our collecting places is important. Our local native plants on public and private lands are important sources of seed and cutting wood for nursery propagation, or facines in bank stabilization, for revegetation stakes and for seed in hydro seeding mixes. In this writing, I would like to point out that even our collecting activities impact native plant populations. Collectors should be aware of the potential for damage to source plants.

Farm-raised native plant materials have advantages and applications. Collected materials, however, should always be available. In fact, I believe that natural groves of cutting wood and seed-bearing native shrubs can be manicured and sustainably harvested by a landsperson. Plants that are used for direct-stick cuttings or stakes in our area are:

• Cottonwood, Populus balsamifera ssp. trichocarpa
• Willow species, Salix spp.
• Red Twig Dogwood, Cornus sericea
• Black Twinberry, Lonicera involucrata
• Snowberry, Symphoricarpos albus (and others)

The Effects of Cutting and Seed Harvest

Some plants, in some seasons and habitats, can be gravely affected by heavy pruning. This evidence of pruning damage is typical and easily noticed the following year if the new shoot growth dies back or does not thrive. This condition is common and can be brought about by pruning during moist winter conditions. It is caused by a combination of bacterial and fungal pathogens. What I have observed in red twig dogwood and other plants is an apparent bacterial infection, followed by secondary fungal invasion.

Pruning to encourage attractive young growth, flowering and reasonable size is routinely used as a maintenance tool in the landscape garden. Our horticultural varieties of red twig dogwood can take severe pruning so that they produce the attractive red stems for garden plantings.

Be careful with our native strains of red twig dogwood, for when heavily cut back they may become diseased, decline or die. This is especially important because in recent years we have begun to use large quantities of collected red twig dogwood stake material in facines and cuttings for restoration plantings. A typical riparian restoration planting may require 1000 or more 3-foot cuttings. These cuttings are directly stuck into the soil, develop roots and grow into normal plants, but at the possible sacrifice of the parent plants.

In the winter of 1998, we noticed a loss of vigor or death of regrowth within 2 years in all of the sites where we have cut red osier plants back for cutting wood. These plants were all growing in rich moist and shady bottomlands. Recovery at our wild collecting sites in Whatcom and Skagit counties is rare and often the decline of the plants is followed by invasion by reed canary grass and blackberries.

The photo to the left is a planting of red twig at our nursery. The 3-year-old plants were first harvested for cuttings in winter 1996-97. In 1998 we went back again for cuttings but there were many dead branches, and dying plants with a systemic rot that looked like bacterial wilt. To a lesser degree we have noticed similar problems in Scouler Willow (Salix scouleriana). Timing of cutting collections and the susceptibility to disease of our local strains may be the critical factors. We have stopped using cutting wood for production of red twig dogwood plants and now depend entirely on seedlings. I strongly recommend that natural cutting beds be monitored for adverse effects.

Not every plant community is adversely impacted by cutting collection. Thinning in heavy cottonwood seedling stands makes good sense not only because there is a good supply of cutting wood for a few years, but collecting will have a somewhat beneficial effect on the resultant plant community, since cottonwood seedlings would thin themselves out naturally. Seed collectors should also know that sometimes their gathering activities could set back the donor plants. Native crabapple (Malus fusca), is a shrubby wetland tree that has clusters of fruits very tightly held on to fruiting spurs. These miniature apples persist on the trees well after the leaves drop. They are starchy and inedible until softened by the first hard freezes of fall. When this happens the birds move in to feed on the seeds and the sweet flesh.

When collecting these fruits it is impossible to avoid breaking off the fruit spur that is destined to produce next year's fruit. I have observed that these trees rarely produce fruit where picked for 3 or 4 years. The Pacific Ninebark (Physocarpus capitatus) is similarly affected by seedpod harvest, skipping flowering for at least one year with some branches never recovering. The solution to this problem is pruning.

In this time of heavy urbanization and weed pressure on our native plant populations, everyone in the ecological restoration community should be a careful steward of the plant communities from which we take our propagation material. Careful harvest and monitoring of the effects of harvest over several years is essential for maintaining healthy natural habitats even as we restore degraded habitats.