Vitality, Variation, and Causes of Decline of Trees in Oslo Center (Norway)

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Figure 1.
General impression of tree vitality in Oslo center 1990 by percentage distribution.
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Figure 2.
Foliar contents of chloride and sodium (percent of dry weight) in A. hippocastanum among different injury groups. Mean value of samples from two months in 1991, and four months in 1993

Table 1.

Recording parameters for the study of trees in Oslo center.

Parameter	Score	Description
general impression	0	dead
	5	moderate vigor
	9	excellent vigor
leaf necrosis	0	no leaf injury
leaf necrosis	9	severe injury on all leaves
attack by insects and/or mites	0	no attack
attack by insects and/or mites	9	whole crown affected
dieback of twigs and branches	0	no dieback
dieback of twigs and branches	9	whole crown dead
stem injury	0	no visible injury
stem injury	9	extensive and Dotentiallv lethal iniurv

Table 2.

Mean scores for species frequently used as park and street trees in Oslo, 1989-1993.

Species	General impression		Leaf necrosis		Pest attack		Dieback of twigs and branches
Species	Street	Park	Street	Park	Street	Park	Street	Park
A. platanoides	4.9c	6.4ab	2.0b	0.2b	0.5d	2.0b	2.4a	0.2a
A. pseudoplatanus	4.7c	6.7ab	2.7a	0.1b	1.1c	1.3b	2.4a	0.0a
A. hippocastanum	5.8b	7.2a	3.3a	0.3ab	0.1e	1.0b	0.4c	0.0a
B. pendula	5.7b	5.9b	0.5c	0.6a	0.3d	0.0c	1.0b	0.1a
T. platyphyllos	6.5a	6.5ab	0.1c	0.1b	3.9a	3.8a	1.1b	0.0a
T. x vulgaris	6.5a	6.3b	0.1c	0.0b	3.1b	2.9a	1.1b	0.2a
*Mean (weighted)*	*5.8*	*6.5*	*1.7*	*0.2*	*1.3*	*1.9*	*1.1*	*0.1*

- Scale 0-9
- Values followed by the same letter within a column are not significantly different at p=0.05

Table 3.

Variation in street tree leaf edge necrosis during survey period 1989-1993.

Species	1989		1990		1991		1992		1993
Species	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
A. platanoides	2.1b	1.6	2.3b	1.6	2.5b	2.1	1.5c	1.9	1.4b	1.6
A. pseudoplatanus	2.8a	1.9	3.5a	2.4	3.4a	2.7	2.3b	1.8	1.7b	1.7
A. hippocastanum	3.1a	2.1	3.3a	3.2	3.Oab	2.6	3.9a	2.8	2.8a	2.8
B. pendula	0.3c	0.6	0.8c	1.7	0.3c	0.8	0.0d	0.0	0.0c	0.0
T. platyphyllos	0.3c	0.5	0.1c	0.5	0.1c	0.3	0.0d	0.2	0.0c	0.0
T. x vulgaris	0.2c	0.4	0.3c	0.7	0.0c	0.0	0.0d	0.2	0.0c	0.0
Mean (weighted)	1.7	2.0	1.9	2.6	1.6	2.4	1.9	2.6	0.6	1.2

- Scale 0-9
- Values followed by the same letter within a column are not significantly different at p=0.05
- SD-standard deviation

Table 4.

Street tree attack by insects and mites from 1989 to 1993.

Species	1989		1990		1991		1992		1993
Species	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
A. platanoides	1.4c	1.6	0.9d	1.0	0.1b	0.3	0.3c	0.8	0.0d	0.0
A. pseudoplatanus	2.1b	0.9	2.5c	1.0	0.0b	0.0	0.1c	0.3	1.0c	1.0
A. hippocastanum	0.2d	0.7	0.0e	0.0	0.0b	0.0	0.0c	0.0	0.0d	0.0
B. pendula	0.2d	0.7	0.6d	1.4	0.1b	0.4	0.0c	0.0	0.0d	0.0
T. platyphyllos	4.3a	1.4	6.8a	1.7	2.2a	1.6	2.5a	1.7	4.1a	2.0
T. x vulgaris	4.0a	1.3	4.6b	2.4	2.1a	1.0	1.7b	1.1	2.9b	1.7
Mean (weighted)	1.8	2.0	2.2	2.8	0.7	1.2	0.8	1.3	2.2	2.2

- Scale 0-9
- Values followed by the same letter within a column are not significantly different at p=0.05
- SD-standard deviation

Table 5.

Contents of foliar elements in leaves from A. platanoides, A. hippocastanum, and Tilia spp. in the street and park environment (1991).

- Values followed by the same letter within a column are not significantly different at p=0.05.