Potential of Tsuga spp. from Western North America and Asia as Replacements for Eastern Hemlock (Tsuga canadensis)

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Figure 1.
Layout of plots at Lasdon Park and Arboretum, Katonah, New York, U.S. Distance from top of figure to bottom represents approximately 500 m (1650 ft).
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Figure 2.
Vigor ratings for the seven test species of Tsuga during fall and spring averaged over the 4 years of the study. Heights of the bars indicate average vigor ration on a 0 to 5 scale, higher numbers corresponding to higher vigor ratings. can = T. canadensis; car = T. caroliniana; het = T. heterophylla; mer = T. mertensiana; chi = T. chinensis; div = T. diversifolia; sie = T. sieboldii.
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Figure 3.
Photograph of Tsuga chinensis.

Table 1.

Average monthly temperature extremes and precipitation for Scarsdale, NY, approximately 20 mi from the research plots in Katonah, NY.^{^z}

Month	Minimum temperature		Maximum temperature		Precipitation
Month	°C	°F	°C	°F	mm	in
January	−6.8	19.8	3.1	37.6	87.9	3.5
February	−5.5	22.1	4.9	40.8	73	2.9
March	−1.4	29.5	10.1	50.2	106.6	4.2
April	3.6	38.5	16.5	61.7	101	4
May	8.7	47.7	22.7	72.9	101.1	4
June	13.7	56.7	27.2	81	91.2	3.6
July	16.9	62.4	29.8	85.6	101	4
August	16.3	61.3	28.7	83.7	119.5	4.7
September	12.1	53.8	24.5	76.1	111.6	4.4
October	6	42.8	18.6	65.5	88	3.5
November	1.8	35.2	12.3	54.1	103.9	4.1
December	−3.6	25.5	5.6	42.1	98.6	3.9

Table 2.

Height, survivorship, and vigor of test hemlock species after 4 years.^{^z}

Species	n	Survivorship^{^y}	Vigor^{^x}	Tree height (cm)
Species	n	Survivorship^{^y}	Vigor^{^x}	Initial	After 4 years
T. canadensis	36	83.3 ± 8.6 ab	4.2 ± 0.1 a	124.9 ± 3.4	325.5 ± 12.4
T. caroliniana	18	33.3 ± 12.2 c	3.7 ± 0.3 ab	23.5 ± 1.2	34.0 ± 4.6
T. heterophylla	11	75.0 ± 17.1 ab	3.4 ± 0.2 bc	62.0 ± 4.7	204.4 ± 44.2
T. mertensiana	18	44.4 ± 16.5 bc	3.0 ± 0.5 c	33.9 ± 0.8	30.7 ± 5.6
T. chinensis	18	94.4 ± 5.5 a	4.2 ± 0.1 a	89.8 ± 3.2	239.6 ± 9.9
T. diversifolia	18	38.9 ± 10.2 c	4.1 ± 0.2 a	16.1 ± 0.7	31.7 ± 6.6
T. sieboldii	18	44.4 ± 18.6 bc	3.6 ± 0.3 ab	16.7 ± 0.9	32.8 ± 6.8

↵^zValues are means ± SE of treatment mean.
↵^yValues followed by the same letter are not statistically different as determined by split-plot analysis of variance followed by least significant difference test.
↵^xVigor was measured during spring of Year 5. Values followed by the same letter are not statistically different as determined by split-plot analysis of variance followed by least significant difference test.

Table 3.

Percent increase in height of test species during the 4 years of the project.^{^z}

↵^zNote the species × fertilizer interaction. Values are means ± SE of treatment mean.
↵^yAsterisk (*) indicates significant difference between fertilizer treatments for individual species at P = 0.05.