The decline of Pinus thunbergii and P. densiflora trees in coastal forests from the mega-tsunami following the Great East Japan Earthquake

Figures & data

Table 1. Description of the study plots and outline of the pine tree populations

Location	Plot	Latitude/1ongitude	Area (m^2)	Initial number of the trees monitored	Pine tree population				Starting time of monitoring	Interruption of continuous monitoring
					Species ^a	Density (/ha)	Height of canopy trees (m)	Mean DBH ± SD (cm)
Watari
	Af	38°01'17”N/140°54'59”E	1,200	121	Pt	1,008	7–11	12.3 ± 3.8 ^b	June2011	Partially cut before July2012
	Ab1	38°01'17”N/140°54'55”E	1,600	147	Pt, Pd	919	11–15	14.2 ± 7.5	June2011	Totally cut before July2012
	Ab2	38°01'15”N/140°24'56”E	1,650	99	Pt, Pd	600	11–15	19.8 ± 5.5	July2012	–
Yamamoto
	B	37°57'58”N/140°54'42”E	1,000	96	Pt, Pd	960	17–22	20.2 ± 9.3	June2011	–
Higashi-matsushima
	C	38°22'21”N/141°09'56”E	800	95	Pt	1.188	11–16	19.8 ± 7.4	June2011	Partially cut before September2011 and October2012
	D	38°23'05”N/141°10'56”E	2,500	91	Pd	364	13–16	26.6 ± 5.6	June2011	Partially cut before July2012 and mostly cut before October2012
Yamada
	E	39°26'19”N/141°58'35”E	4,680	207	Pt	442	15–20	28.5 ± 10.1 ^b	June2011	Mostly cut before June2012
Hachinohe					Pt
	Ff	40°34'59”N/141°28'23”E	125	136	Pt	10,880	5–6	6.6 ± 2.9	June2011	–
	Fb1	40°35'07”N/141°28'14”E	1,450	89	Pt	613	14–18	16.6 ± 4.5	June2011	–
	Fb2	40°35'07”N/141°28'17”E	500	80	Pt	1,600	14–18	16.8 ± 3.9	November2011	–

^aPt; Pinus thunbergii, Pd; P. densiflora

^bDBHs for three and 43 trees that lost their trunk due to the tsunami was estimated from the diameter at the trunk base.

Figure 1. Location of the study sites and overview cross-section of each study plot

Table 2. Pine tree mortality with reference to the status of the trees and their species in the plots set in the first census time after the tsunami disaster

Plot	Status of the trees after tsunami	P.thunbergii trees			P.densiflora trees
		N	Mean DBH ± SD (cm)	Mortality (% dead trees)	N	Mean DBH ± SD (cm)	Mortality (% dead trees)
Af	Broken at trunk	31	13.4 ± 4.0	100.0	0	–	–
	Felled/leaning	49	12.6 ± 3.6	100.0	0	–	–
	Standing	15	11.4 ± 5.0	93.3	0	–	–
Ab1	Broken at trunk	4	7.8 ± 5.2	100.0	0	–	–
	Felled/leaning	56	9.3 ± 3.4	89.3	2	15.6	100.0
	Standing	79	17.6 ± 7.7	20.3	6	20.1 ± 5.7	16.7
B	Broken at trunk	5	9.1 ± 1.5	100.0	0	–	–
	Felled/leaning	3	7.4 ± 1.4	100.0	6	9.5 ± 1.3	100.0
	Standing	57	20.7 ± 8.3	28.1	25	25.6 ± 8.5	56.0
C	Broken at trunk	10	11.9 ± 5.9	100.0	0	–	–
	Felled/leaning	1	24.7	0.0	0	–	–
	Standing	56	23.1 ± 6.3	25.0	0	–	–
D	Broken at trunk	0	–	–	0	–	–
	Felled/leaning	0	–	–	0	‒	‒
	Standing	0	–	–	91	26.6 ± 5.6	76.9
E	Broken at trunk	26	20.4 ± 5.8	100.0	0	–	–
	Felled/leaning	27	25.2 ± 7.7	88.9	0	–	–
	Standing	154	31.6 ± 9.1	30.5	0	–	–
Ff	Broken at trunk	0	–	–	0	–	–
	Felled/leaning	0	–	–	0	–	–
	Standing	136	6.6 ± 2.9	70.6	0	–	–
Fb1	Broken at trunk	0	–	–	0	–	–
	Felled/leaning	0	–	–	0	–	–
	Standing	89	16.6 ± 4.5	97.8	0	–	–

Tree mortality was estimated from the final census data taken in autumn 2012 in plots Af, B, C, Ff and Fb1, and from those in autumn 2011 in plots Ab1 D, E, as the plots were demolished or underwent removal of a substantial number of trees due to post-quake reconstruction activities before the end of the monitoring period in 2012. Data for the trees removed in the course of the continuous monitoring were discarded in calculating tree mortalities.

Table 3. Detection of Bursaphelenchus xylophilus in declined or dead pine trees

Plot	Number of trees tested	Number of trees in which B.xylophilus was detected
Af	41	0
Ab1	38	0
Ab2	8	2
B	44	2
C	14	9
D	72	2

Table 4. Factors potentially contributing to the death in the trees remained standing after the tsunami disaster in each plot

Location	Plot	No. standing trees ^a	Mean DBH ± SD (cm)	Tree species		Classification by trunk injury ^b			% suppressed trees	% trees with sand deposition	% trees with root excavation	% trees with root submergence	Mortality at the final census time (% dead trees)
				P.thunbergii	P.densiflora	Heavy	Light	None
Watari
	Af	10	12.7 ± 5.3	10	0	0	0	10	20.0	100.0	0.0	0.0	90.0
	Ab1	85	17.8 ± 7.6	79	6	7	13	65	35.3	94.1	0.0	0.0	20.0
	Ab2	97	19.6 ± 5.4	92	5	0	0	97	22.7	0.0	0.0	0.0	7.2
Yamamoto
	B	80	21.9 ± 8.4	56	24	17	30	33	32.5	93.8	0.0	0.0	36.3
Higashi-matsushima
	C	54	23.5 ± 6.0	54	0	4	11	39	11.1	59.3	0.0	0.0	0.0
	D	89	26.5 ± 5.7	0	89	12	26	51	16.9	100.0	0.0	0.0	76.4
Yamada
	E	152	31.8 ± 9.1	152	0	12	48	92	16.4	10.5	4.6	8.6	29.6
Hachinohe
	Ff	136	6.1 ± 2.9	136	0	0	0	136	58.1	100.0	0.0	0.0	70.6
	Fb1	89	16.6 ± 4.5	89	0	0	0	89	38.2	100.0	0.0	0.0	97.8
	Fb2	80	16.9 ± 3.9	80	0	2	34	44	30.0	88.8	0.0	0.0	12.5

^aThe trees died of Bursaphelenchus xylophilus infection and those we could not determine the suppression status because of the broken trunk or branch in the crown were eliminated. Therefore, the counts are not identical to those in Table 2.

^bPine trees with one or more major injuries (i.e. longer than 10cm) or more than five minor injuries are categorized as “Severe”, with less than four minor injuries as “light”.

^cTree mortality was estimated from the autumn 2011 census data for plot Ab1, Dand E, because those plots were demolished before 2012.

Figure 2. Development of foliage discoloration of the pine trees in each study plot. Trees were classified as follows:

broken;

< 50% foliage discolored;

50–99% foliage discolored;

100% foliage discolored;

defoliated. Letters following the stand name on each graph indicate the stand type: Pt; Pinus thunbergii-dominated stand, Pd; P. densiflora-dominated stand, mixed: mixed stand of P. thunbergii and P. densiflora.

Table 5. The generalized linear models (GLMs) for explaining the mortalities found in the remaining standing pine trees in the tsunami-damaged stands

Plot	No. standing trees	Mortality ^a (% dead trees)	Full model (upper) and minimal model (lower) to explain tree mortality ^b	AIC
Ab1 + B	165	26.7	−1.35 + 2.03(Tree species) + 0.006(DBH) −1.50(Suppression) + 0.03(Trunk injury1)– 0.002(Trunk injury2) + 0.17(Sand deposition)	165.63
			−1.19 + 2.03(Tree Species) + 0.006(DBH)– 1.50(Suppression)	159.68
C+ D	143	47.6	0.84 + 20.75(Tree species)– 0.007(DBH) −1.12(Suppression)– 0.50(Trunk injury1)– 0.57(Trunk injury2) + 0.18(Sand deposition)	108.68
			−1.175 + 20.74(Tree species)	101.25
E	152	29.6	−2.45 + 0.001(DBH) −1.11(Suppression) + 0.92(Trunk injury1) + 1.39(Trunk injury2)– 0.46(Sand deposition)– 1.67(Root excavation)– 3.16(Root submergence)	153.39
			−2.65 + 0.001(DBH) −1.07(Suppression) + 0.92(Trunk injury1) + 1.44(Trunk injury2)– 1.62(Root excavation)– 3.11(Root submergence)	151.89
Ff	136	70.6	−2.65 + 0.03(DBH) −0.81(Suppression)	138.01
			−2.65 + 0.03(DBH) −0.81(Suppression)	138.01
Fb1	89	97.8	−6.01 + 0.01(DBH) −1.24(Suppression)	24.85
			−3.38	21.14

^aPine mortality was estimated from the autumn 2012 census data for plots Ff and Fb1, and those taken in autumn 2011 for plots Ab1 + B, C+ D and E, because the plots Ab1, D and E were demolished before 2012.

^bThe term for the factor “trunk injury” was divided into two terms showing the effect of “light” to “heavy” (term “trunk injury 1”) and that of “none” to “heavy” (term “trunk injury 2”) in the GLM.