Establishment of Chamaecyparis thyoides on an extremely low-nutrient sandy site on the Atlantic Coastal Plain, U.S.A

  • Published source details Haas M.J. & Kuser J.E. (2003) Establishment of Chamaecyparis thyoides on an extremely low-nutrient sandy site on the Atlantic Coastal Plain, U.S.A. Restoration Ecology, 11, 231-238.


Atlantic white cedar Chamaecyparis thyoides is a shade-intolerant conifer native to the Atlantic coastal region of North America. It is the only obligate wetland tree native to the northern U.S. Atlantic Coastal Plain, occurring patchily along freshwater courses and wetlands, typically on moist acidic soils. White cedar stands support a unique flora and fauna, some of which are endangered. Slow-release fertilizers have been successfully used in the introduction of deciduous trees such as cottonwood Populus fremontii, sandbar willow Salix exigua and screwbean mesquite Prosopis glandulosa onto sandy sites with underlying moisture. This study investigated the effects of sustained-release fertilizer and two mulch treatments on planted white cedar survival and growth at an extremely low nutrient site, a sand mine in north-east USA.

Study site: The study was conducted at a sand mine near the town of Cassville, New Jersey, USA, which lies within the natural range of Atlantic white cedar Chamaecyparis thyoides. The site comprised a well-drained sand flat with a freshwater-filled open pit mine 2 km in diameter and up to 30 m deep. The soil (almost pure silicon dioxide sand over 15 m deep) was deficient in P (<12 ppm), K (<20 ppm), Mg (<22 ppm) and Ca (<307 ppm). Soil organic matter content was effectively 0, soil pH was 4.4. Terrestrial vegetation cover was around 4% and consisted mostly of sedges Cyperaceae spp.

Planting material: White cedar cuttings were collected in October and November 1994 from mature trees in New Jersey. These were treated with rooting hormone and planted in potting soil in conical plastic planting tubes (21 cm long × 4 cm diameter). Mature closed cones were also collected in October 1994 and opened by drying for 3 days at room temperature so that seeds could be removed. Seeds were stratified and placed on moist Sphagnum. Sprouted seeds were potted in soil-filled tubes and grown on. After 7 months, cuttings and seedlings were fertilized weekly with a 1/600 (v:v) aqueous solution of Peter's (Marysville, OH, U.S.A.) 20:20:20 at a rate of 15 mL/tree.

Experimental design and planting: Two parallel blocks (each 50.1 × 15 m), separated by 10 m, were established parallel to the lake shore. Depths to underlying water ranged from 18 cm near the lake to 100 cm farthest upslope. Each block contained six randomized treatment plots (15 × 5.6 m) separated by 3.3 m unplanted strips. The treatments were:

1) Osmocote (O.M. Scott, U.S.A.) timed-release fertilizer (12-month release duration) mixed into the sand to 15 cm depth with a garden tiller. N:P:K = 17:7:12; application rate: 4,880 kg/ha.

2) Fresh (undecomposed) coarsely shredded "Clayton" mulch (produced primarily from A.rubrum typical fragment size 1 cm³) applied to 5 cm thick and tilled in.

3) Decomposed, finely ground "Jackson" mulch (derived from local municipal waste), application rate and incorporation by tilling as for Clayton mulch.

4) A combination of Osmocote and Clayton mulch, applied as above.

5) A combination of Osmocote and Jackson mulch, applied as above.

6) Tilled only.

Plots were divided into eight subplots, parallel to the lake shore, each planted with three white cedars, 288 trees planted in total. The eight groups of trees differed from one another with regard propagule type (cutting or seedling), age of the parent tree and geographic location of the parents. Trees were planted in mid-May 1996. Vegetation, primarily crabgrass Digitaria sp. and foxtail Setaria sp. growing in the plots was cut with a handheld mower and left onsite.

Growth, biomass & nutrient content: Tree height was recorded at planting and at the end of the first two growing seasons and basal diameters measured. After the second season, the total above ground tissue of four trees in each 24-tree treatment plot was collected, oven dried and weighed. Concentrations of nitrogen (N), phosphorus (P), and potassium (K) were measured.

Of the 288 white cedars planted, 249 (86%) survived. Most mortality was near the lake edge and was attributed to periodic increases in water level. Three trees (excluded from analysis) had slight browsing damage, probably due to rabbits Sylvilagus spp.
At planting, average heights of cedars (eight parent/propagule groups planted) varied from 14.2 to 22.2 cm, height distributions within each group were normal.

Effects of treatment on seedling height: Whilst survival was high without soil amendment (96%) growth was poor, with an average relative growth of 1.2 (i.e. only slightly more than doubling in height in 2 years). Undecomposed mulch had little effect or even slightly retarded growth compared with controls. In contrast, the other treatments produced trees more than 1 m tall after two seasons, with relative growth as high as 5. Decomposed mulch roughly doubled growth compared with controls, presumably because nutrient availability from this mulch was high. Joint treatment with decomposed mulch and Osmocote did not increase growth over Osmocote alone. However, the combination of undecomposed mulch with Osmocote did enhance growth and produced the greatest growth overall.

Planting position relative to the lake edge significantly impacted growth. The 2-year average growth of all cedars in the plots closest to the water was 2.8 (n = 112), those in the plots slightly farther away 2.5 (n = 134). Though statistically significant, this effect of position on growth was less than that of fertilizer and mulch. The slightly better growth nearer the lake was perhaps due to greater availability of subsurface moisture.

Relative growth according to parent tree type, fell into two groups with average relative growths of 2.1–3.0 and 2.5–3.3, suggesting that individual parent trees may produce progeny that grow faster than others. These effects on growth were however much less than those of fertilizer treatments. No consistent relationship was evident between growth and either planting position or cedar origin (age of parent, geographic origin) or propagation method (cutting or a seedling).

Effects of treatment on stem cross-section: Soil treatment exerted a significant effect on stem cross-section, but position and tree type did not. The degree of area increase stimulated by the treatments roughly mirrored that for height, with the smallest increases in controls and those treated with undecomposed mulch, and the greatest produced by combinations of Osmocote and mulch.

Effects of treatment on biomass: Fertilizer and fertilizer–mulch treated plots exhibited substantial biomass increases compared with untreated or mulch-only plots with dry weights as much as 21 times greater than controls. The relative effects of treatments on dry weights were generally the same as on height and cross-sectional area. It was lowest in the undecomposed mulch treatment, but the combination of this mulch with fertilizer gave the highest production (> 20 times greater than controls). Biomass levels in other soil treatments fell between these two extremes.

Effects of treatment on nutrient content: In general, trees receiving no treatment or only undecomposed mulch were deficient in N (1.0–2.2%) and P (0.06%) compared with other treatments (N:1.8–2.2%, P:0.19–0.23%). Decomposed mulch (with 2-3 times higher N/P content than undecomposed mulch) alone significantly increased P and N content. The combined Osmocote and mulch treatment plants generally had the highest nutrient contents. Those in soil with Osmocote + undecomposed mulch had generally higher nutrient content than Osmocote + decomposed mulch. All treatment groups had K levels similar to those of untreated controls.

Conclusions: After two growing seasons, white cedar seedling survival was very high in untreated controls (86%) and was not significantly increased by soil treatment. Stem height and cross-sectional area doubled in unamended plots over two growing seasons. Fresh mulch alone caused no additional growth increase, but decomposed mulch caused a slight increase. Sustained-release fertilizer caused significant increases in seedling height (3-fold) and dry weight (6-fold). Fertilizer and mulch combined resulted in significantly greater growth than other treatments (heights 4-5-fold, trunk cross-sectional areas 4-fold, and dry weights 11- to 21-fold). Combined with fertilizer, undecomposed mulch stimulated greater increases in height and dry weight than decomposed mulch. In this study, the growth of white cedar seedlings on the low-nutrient sandy soils was improved most by a combined soil amendment of sustained-release fertilizer and organic mulch.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at:

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 19

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust