Linking field performance to initial morphological traits of thuja seedlings in a semiarid Mediterranean area

Haddadi, Rachid El; Mekkaoui, Abdelali El; Douira, Allal

Linking field performance to initial morphological traits of thuja seedlings in a semiarid Mediterranean area

Forestry Studies

Volume 81 (2024): Issue 1 (December 2024)

By:

Rachid El Haddadi, Abdelali El Mekkaoui and Allal Douira

Open Access

|Oct 2025

Figures & Tables

Thuja seedlings from the nursery to the field: (i) at lifting time in the nursery (December 10, 2019), (ii) after extraction from the container showing: [a] shoots, [b] collar, [c] root plug, (iii) after outplanting in the field (July 15, 2020).

Average monthly rainfall (mm) during the entire planting season (October 1st, 2019 to October 30th, 2020) collected in the meteorological station of Oued Beht, Khémisset. Note how the plantation window (December 12th, 2019) was decided after the occurrence of more than 100 mm cumulative rainfall.

Variation of daily rainfall (mm) and temperatures (Tmax and Tmin (°C)) from April 1st to October 30th, 2020. It is noteworthy that the dry period (from mid-May to mid-October 2020) coincided with the hottest season; data collected in the meteorological station of Oued Beht, Khemisset.

Figure 4.

Profile of a forest bench showing how seedlings were planted on the bench ridges.

Survival rates of Tetraclinis articulata seedlings during the dry period of 2020 showing a remarkable drop between July 15 and August 15, 2020.

The survival rate of thuja seedlings within initial morphological classes among the 51 observed plots (A: Small, B: Medium, C: Large, D: Extra-large seedlings). Different letters among treatments denote significant differences (p < 0.05) according to Fisher LSD test (n = 204).

Gravimetric soil moisture content Hg (%) pattern within soil depth (10, 30, 50, 70 and 90 cm) during drought season (May to October 2020).

Soil moisture content Hg (%) variation as affected by soil depth (cm) at the end of the drought season (September 15, 2020). Different letters among treatments denote significant differences (p < 0.05) according to Fisher LSD test (n = 100).

Relationship between initial collar diameter and rooting depth of thuja seedlings after 11 months of outplanting in the field.

Relationship between initial shoot height and rooting depth of thuja seedlings after 11 months of outplanting in the field.

Relationship between initial sturdiness index and rooting depth of thuja seedlings after 11 months of outplanting in the field.

General morphological traits of thuja seedlings at lifting time in the nursery (n = 1734)_

Attributes	Min	Max	Mean
Shoot height (cm)	4.01	53.01	20.58 ±8.25
Collar diameter (mm)	1.07	9.11	3.37 ±0.78
Sturdiness index	2.26	10.69	5.92 ± 1.48

Logistic regression model parameters of the survival and rooting depth (cm) (n = 62) of thuja seedlings_ SE: standard error; OR: odds ratio; CI: confidence interval; Rd: rooting depth (cm)_

Source	β	μ	SE	Wald’s χ²	Pr > χ²	OR	95% CI for OR
Source	β	μ	SE	Wald’s χ²	Pr > χ²	OR	Lower	Upper
Constant	-5.428		1.542	12.394	<0.0001
Rd (cm)	0.094	57.74	0.026	13.284	<0.0001	1.1	1.045	1.156

Logistic regression model parameters of the survival and initial morphological traits of thuja seedlings: shoot height H0 (cm), collar diameter D0 (mm) and sturdiness index SI0 (cm mm−1) (n = 1734)_ SE: standard error; OR: odds ratio; CI: confidence interval_

Source	β	μ	SE	Wald’s χ²	Pr > χ²	OR	95% CI for OR
Source	β	μ	SE	Wald’s χ²	Pr > χ²	OR	Lower	Upper
Constant	-0.158		0.113	1.946	0.163
H₀ (cm)	0.008		0.005	2.371	0.124	1.008	0.998	1.018
Constant	-1.693		0.197	73.789	<0.0001
D₀ (mm)	0.522	3.24	0.059	78.966	<0.0001	1.685	1.502	1.891
Constant	0.475		0.179	6.991	0.008
SI₀ (cm mm¹)	-0.080	5.93	0.029	7.528	0.006	0.924	0.873	0.978

Correlations between different initial morphological traits of thuja seedlings_

Regression model	n	p-value	R²
H₀= -9.507 + 8.896*D₀	1734	p < 0.0001	0.72
H₀ = -8.323 + 4.875*SI₀	1734	p < 0.0001	0.76
SI₀ = 2.608 + 0.978*D₀	1734	p < 0.0001	0.26

Initial morphological classes of thuja seedlings at outplanting time using the K-means method_ IMC: Initial morphological class_

IMC	Seedling size	Centroid			Class weight	lntra-class variance
IMC	Seedling size	H₀ (cm)	D₀ (mm)	SI₀ (cm mm⁻¹)	Class weight	lntra-class variance
A	Small	10.8	2.52	4.35	513	6.333
B	Medium	18.25	3.31	5.57	460	5.100
C	Large	24.93	3.76	6.7	435	4.641
D	Extra-large	32.75	4.26	7.74	326	12.477
Total					1734

Comparison of shoot height and collar diameter relative growth rates and sturdiness index variation within the initial morphological classes of thuja seedlings using the Kruskal-Wallis test with a 5% significance level_ The means are separated by the Dunn procedure_ Values followed by different letters within the same column are significantly different_ IMC: Initial morphological class_

IMC	Obs.	RGR(H) (cm/cm/month)	RGR(D) (mm/mm/month)	Sturdiness index variation
IMC	Obs.	RGR(H) (cm/cm/month)	RGR(D) (mm/mm/month)	Sl₀	Sl₁	SI₁/SI₀
A	200	0.033 ± 0.017 c	0.029 ± 0.017 a	4.250 a	4.449 a	1.061 ± 0.171 c
B	200	0.028 ± 0.018 b	0.028 ± 0.018 a	5.472 b	5.442 b	1 ± 0.147 b
C	200	0.023 ± 0.013 ab	0.030 ± 0.014 a	6.696 c	6.649 c	0.938 ± 0.127 a
D	200	0.02 ± 0.014 a	0.031 ± 0.017 a	7.393 d	6.215 d	0.911 ± 0.118 a

DOI: https://doi.org/10.2478/fsmu-2024-0014 | Journal eISSN: 1736-8723 | Journal ISSN: 1406-9954

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Language: English

Page range: 62 - 78

Published on: Oct 30, 2025

Published by: Estonian University of Life Sciences

In partnership with: Paradigm Publishing Services

Publication frequency: 2 issues per year

Keywords:

Tetraclinis articulata,

seedling quality,

seedling survival and growth,

drought,

Related subjects:

Ecology,

© 2025 Rachid El Haddadi, Abdelali El Mekkaoui, Allal Douira, published by Estonian University of Life Sciences
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Previous article Volume 81 (2024): Issue 1 (December 2024)

Linking field performance to initial morphological traits of thuja seedlings in a semiarid Mediterranean area

Figures & Tables

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General morphological traits of thuja seedlings at lifting time in the nursery (n = 1734)_

Logistic regression model parameters of the survival and rooting depth (cm) (n = 62) of thuja seedlings_ SE: standard error; OR: odds ratio; CI: confidence interval; Rd: rooting depth (cm)_

Logistic regression model parameters of the survival and initial morphological traits of thuja seedlings: shoot height H0 (cm), collar diameter D0 (mm) and sturdiness index SI0 (cm mm−1) (n = 1734)_ SE: standard error; OR: odds ratio; CI: confidence interval_

Correlations between different initial morphological traits of thuja seedlings_

Initial morphological classes of thuja seedlings at outplanting time using the K-means method_ IMC: Initial morphological class_

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