of 13
dlings in semiarid Mediterranean regions, which are characterized
ural regimes which influence stock quality, as well as silvicultural
www.elsevier.com/locate/foreco
Forest Ecology and Management 215 (2005) 339351* Corresponding author. Tel.: +34 957 218655; fax: +34 957 218563.
E-mail address: [email protected] (J.A. Oliet).
0378-1127/$ see front matter # 2005 Elsevier B.V. All rights reserved.doi:10.1016/j.foreco.2005.05.024nursery mineral nutrition and application of individual tree shelters on 9-year seedling performance of the leguminous species,
Acacia salicina Lindl., planted on a degraded site in southeastern Spain. Survival was significantly greater throughout the
duration of the study for seedlings fertilized at high rates, while initial benefits to field growth associated with nursery
fertilization diminished after 4 years. A significant relationship was established between P supplied in the nursery and both
seedling survival and root dry weight after the first growing season (R2 = 0.68 and 0.77, respectively), though no relationship was
detected for N. The capacity of this species to fix N through root nodulation apparently dictates that P fertility is relatively more
important to initial establishment on low fertility sites characteristic of this region. Survival of protected seedlings became
significantly greater than that of non-protected seedlings following an extended drought after the sixth year. Stem diameter was
significantly greater for non-protected seedlings as of the fourth year but height was greater for protected seedlings throughout
the study, reflecting differential carbon allocation within the sheltered environment. Our results suggest that mineral nutrient
status of nursery stock (especially high P content) and tree shelters may positively affect long-term plantation establishment of
A. salicina seedlings in semiarid Mediterranean climates.
# 2005 Elsevier B.V. All rights reserved.
Keywords: Acacia salicina Lindl.; Forest seedling nutrition; Ecological restoration; Legumes; Phosphorus; Tree shelterstreatments applied at outplanting may affect the capacity of seedlings to establish successfully. We examined the influence ofTransplant stress limits establishment of newly planted see
by very low precipitation and poor fertility soils. Nursery cultNursery fertilization and tree shelters affect long-term
field response of Acacia salicina Lindl. planted in
Mediterranean semiarid conditions
Juan A. Oliet a,*, Rosa Planelles b, Francisco Artero b, Douglass F. Jacobs c
a E.T.S. Ingenieros Agronomos y de Montes de la Universidad de Cordoba, Avda. Menendez Pidal s/n, 14071 Cordoba, Spainb Departamento de Medio Ambiente, Instituto Nacional de Investigacion Agraria y Alimentaria,
Carretera de La Coruna, km 7,5, 28040 Madrid, Spainc Department of Forestry and Natural Resources, Hardwood Tree Improvement and Regeneration Center,
Purdue University, West Lafayette, IN 47907-2061, USA
Received 16 December 2004; received in revised form 11 April 2005; accepted 10 May 2005
Abstract
and M1. Introduction
Transplant shock is described as an interruption in
the normal physiology of a seedling after outplanting
caused mainly by water stress provoked by temporary
impairment of seedling root function or poor rootsoil
contact (Folk et al., 1996; Kavanagh and Zaerr, 1997;
Grossnickle, 2000). Transplant shock is one of the
most frequent causes of reforestation failure, and can
be very intense in semiarid conditions with limited soil
water availability. Morphological and physiological
attributes of nursery stock largely impact the capacity
of seedlings to resist post-transplant water stress.
Aspects such as biomass distribution between shoot
and roots (which affects the balance between water
uptake and evaporative demand), osmotic adjustment
and other water stress tolerance components, resis-
tance to cold, root growth capacity and carbohydrate
status each affect capacity of seedlings to establish on
the site (Puttonen, 1997).
Fertilization in the nursery is one of the most
important cultural practices for plant quality in
reforestation, especially for seedlings produced in
containers in which the limited volume seriously
hinders growth (Landis, 1989). Fertilization affects
shoot and root growth of plants, improves post-
transplant rooting and growth capacity, and increases
resistance to water stress, low temperature and disease
(van den Driessche, 1980, 1991a, 1992; Haase and
Rose, 1997; Shaw et al., 1998; Malik and Timmer,
1998; Grossnickle, 2000; Floistad and Kohmann,
2004). These properties are of vital importance for
successful early establishment under unfavorable
conditions (Puttonen, 1997; Birchler et al., 1998),
and can be influenced substantially by alternative
fertilization regimes. Moreover, remobilization of
internal nutrient reserves enables outplanted seedlings
to be partly independent of external nutrient availability
(Cherbuy et al., 2001). Thus, mineral nutrient reserves
can play an important role after planting, when nutrient
uptake is limited by poor rootsoil contact (Timmer and
Aidelbaum, 1996; Malik and Timmer, 1998), and a
decrease in tissue mineral nutrient concentrations
occurs (Close and Beadle, 2004). Nutrient loading by
applying increasing doses of fertilizer can be effective
in building up internal reserves that will be used after
planting (Quoreshi and Timmer, 2000; Salifu and
J.A. Oliet et al. / Forest Ecology340Timmer, 2003). Many studies have confirmed theinfluence of mineral nutrition on seedling quality for
reforestation, though most of these focus on conifers
from wet, temperate forests, with emphasis on N
additions (van den Driessche, 1988; Larsen et al., 1988;
Green and Mitchell, 1992; Green et al., 1994; Folk et al.,
1996; Timmer and Aidelbaum, 1996; Tan and Hogan,
1997; Irwin et al., 1998; Quoreshi and Timmer, 2000;
Jose et al., 2003). Relatively little is known, therefore,
regarding the relationship between nursery fertilization
with N or additional macronutrients on capacity of
seedlings of species from other ecoregions to resist
transplanting stress.
Another tool to help minimize transplant shock is
the use of individual tree shelters to protect outplanted
seedlings. Although shelters help to prevent damage
resulting from animal browse (Potter, 1991), tree
shelters also act as a small greenhouse providing a
modified microclimate that may affect both survival
and growth after planting (Potter, 1991; Bergez and
Dupraz, 1997, 2000; Dupraz and Bergez, 1999; Jacobs
and Steinbeck, 2001). Although many studies with
tree shelters have been conducted in temperate
regions, few experiments have been reported in dry
regions characterized by low transpiration rates and
higher temperatures. In these regions, plant response
to tree shelters appears to be species-specific, with
many species exhibiting improved survival and growth
when protected with shelters (Marques et al., 2001;
Oliet et al., 2003).
Many studies regarding seedling outplanting
response focus only on results incurred during the
first field season. However, some authors emphasize
the importance of tracking development for longer
timescales (Racey and Gerum, 1983; Burdett, 1990;
McDonald, 1991; Rose and Atkinson, 1992; Simpson
et al., 1994; Cain and Barnett, 1996; Jacobs et al.,
2004). This may sometimes alter the conclusions of a
single season study, due to interactions between
experimental treatments and time. In particular, the
effects of tree shelters or the combination of nursery
mineral nutrition and tree shelters may be prolonged
for several seasons after planting (Jacobs, 2004; Oliet
et al., 2000, respectively). However, few studies
consider more than first year response, especially
when examining effects associated with nursery
fertilization treatments (Puertolas et al., 2003).
Acacia salicina Lindl. is a N-fixing leguminous
anagement 215 (2005) 339351shrub or tree which is native to the arid zone of South
14.9K. Rates: 1.5, 3.25 and 5.0 g l1 substrate.
On 3 March 1993, A. salicina seedlings were planted0 0
nd Management 215 (2005) 339351 341
Table 1
N, P and K amounts per plant supplied by fertilizer treatments (rates
of each formulation per liter of substrate)
Formulation 9-13-18 16-8-9
Rate (g l1) 1.5 3.25 5.0 3.25 5.0 7.0
N (mg/seedling) 38.6 83.7 128.7 148.7 228.8 320.3
P (mg/seedling) 24.3 52.7 81.0 32.3 49.8 69.8
K (mg/seedling) 64.1 138.9 213.7 69.5 106.7 149.6
Annual rainfall recorded on the planting site during the study period
Year Precipitation (mm)
1993 205
1994 187
1995 122
1996 193
1997 204
1998 42
1999 176
2000 2292. 16-8-9 + 3Mg: 16N (6.6% NH4-N and 9.4% NO3-
N)-3.5P-7.5K. Rates: 3.25, 5.0 and 7.0 g l1
substrate.
Each formulation had an equivalent stated nutrient
release period: 1214 months at 21 8C. Micromax1
(Scotts Co.), a solid mixture of microelements, was
added at 0.15 g l1 for all treatments. Fertilizertreatments were designed to supply an increasing
amount of N per plant, from 38.6 mg (1.5 g l1 9-13-18) to 320.3 mg (7 g l1 16-8-9) while creatingdifferent N-P-K-balances (Table 1). Treatments in the
nursery were arranged as a completely randomized
design. Height and basal stem diameter were measured
on 30 randomly selected 9-month old seedlings perA. salicina seedlings were produced from May
1992 to planting time in the Boticario Centre (28240W,368520N, elevation 60 m), Almeria, Spain. Plants weregrown in 230 ml individual cell containers filled with a
4:1 (v/v) sphagnum peat mossvermiculite growing
medium in which fertilizer treatments were mixed.
Fertilizer treatments consisted of three rates of two
different controlled-release Osmocote1 (Scotts Co.,
Marysville, OH, USA) formulations plus a non-
fertilized treatment for comparison. The formulations
used were:
1. 9-13-18: 9N (6.1% NH4-N and 2.9% NO3-N)-5.7P-2. Mtreaterials and methodsneanAustralia, but has been introduced to other regions as a
multipurpose species (Le Houerou, 1986; Rehman
et al., 1999). It successfully establishes on degraded
areas (Grigg and Mulligan, 1999). In Spain, A. salicina
has been introduced in some Mediterranean areas to
examine its capacity to serve as a source of fodder for
livestock (Correal et al., 1988), as well as for use as an
ornamental and to rehabilitate disturbed areas
(Tilstone et al., 1998). The objective of this study
was to evaluate the individual and combined effects of
both nursery fertilization and tree shelter protection at
planting on mid to long timescale response of A.
salicina in a degraded land of a semiarid Mediterra-
region of Spain.
J.A. Oliet et al. / Forest Ecology aatment sampled directly from the nursery containers.on a degraded plain (2820 W, 36851 N, elevation 30 m)of Almeria, Spain. According to FAO taxonomy, the
soil belongs to cambic arenosol group formed on
calcareous parent material (Perez, 1989), with a first
sandy horizon (95% sand) 30 cm depth upon a sandy
loamy horizon (66% sand, 29% loam). Carbon (0.5%)
and fertility of the profile are very low (0.05% total N,
0.75 ppm POlsen and 0.13 mg g1 K) and pH is high
(pHH2O 8:5) (Perez, 1989). Annual rainfall and meantemperature of the area are 200.2 mm and 18.5 8C,respectively, with frequent strong southwest winds,
according to Spanish National Institute of Meteorology
reports (data averaged from 1969 to 2001). Precipita-
tion during the study period was collected and measured
by a pluviograph installed on the planting site (Table 2).
Annual rainfall from 1993 to 2001 averaged 160.5 mm,
with an average of 30 mm from May to September (data
not shown). The experimental site was fenced to restrict
access to rodents and herbivores. Cross ploughing to a
depth of 80 cm was accomplished prior to planting.
Seedlings were planted in manually opened pits
(0.3 m 0.3 m 0.3 m) at 1.5 m 1.5 m spacing.The 7 (nursery fertilization) 2 (with or without treeshelters at planting) factorial treatments were arranged
as a randomized complete block design with four
replications. Tree shelters (standard unventilated,
Table 22001 99
translucent, circular, twin-walled polypropylene tubes
0.6 m tall 0.11 m wide, Tubex Co., South Wales,UK) were installed at planting. The experimental unit
consisted of a row of 16 seedlings, each block
containing 14 rows. Manual weeding was conducted
annually. Seedling height and groundline stem diameter
(GSD) from all living plants were measured in June and
complete block design with four blocks. Analysis of
survival and growth was made by two-way ANOVA
(main factors consisting of fertilization in the nursery
and tree shelter at planting), with the treatment mean
for each block comprising the experimental unit (each
row of 16 plants). Any significant formulation rateinteraction was noted in the text. For plantation
differences between means were identified using
J.A. Oliet et al. / Forest Ecology and Management 215 (2005) 339351342
lings aOctober 1993, 1994, November 1995, January 1997,
February 1999, December 2000 and January 2002.
Height and diameter data were transformed into
slenderness quotient (height:GSD) and stem volume
index (SV), using the following formula: stem
volume = (1/3) p (1/4)(GSD)2 height. Volumeindex (VI) was calculated on a per hectare basis by
combining survival and mean SV per experimental unit.
Slenderness quotient is an important morphological
indicator of seedling quality (Thompson, 1985) which
was used to help evaluate shoot development, in
particular among protected and non-protected plants.
Stem volume index provided a more accurate indicator
of shoot biomass than height or GSD independently
(van den Driessche, 1988; South and Mitchell, 1999).
Volume index, computed by correcting stem volume
per treatment with survival on a per hectare basis,
emphasizes the variation among treatments in capacity
to occupy the site. In September 1993, a sample of three
plants per treatment replication among non-protected
seedlings was randomly selected, GSD and height were
measured, and seedlings were destructively harvested
(12 plants per fertilization level, 84 plants in total).
After cautious excavation, root systems were extracted,
taking care to retain roots >1 mm diameter. Shootswere separated from roots and dry mass of each fraction
was determined by oven drying at 65 8C for 24 h andweighing. Following this sampling, a significant shoot
dry weight over SV power regression model was fitted
(R2 = 0.894, P < 0.001, n = 84).Data from the planting experiment were analyzed
using analysis of variance (ANOVA) for a randomized
Table 3
Height and basal stem diameter of containerized Acacia salicina seed
of each formulation per liter of substrate)
Formulation 9-13-18
Rate (g l1) 0 1.5 3.25
Height (cm) 19.3c 34.3b 40.2ab
Diameter (mm) 2.3d 3.1c 3.6bcWithin a row, means with different letters (a, b and c) indicate significanFishers protected least significant differences
(L.S.D.) test (Steel and Torrie, 1989). To assess the
relationships between certain variables, Pearson
correlation coefficients were calculated, and linear
regression models were fitted to quantify relationships
among certain variables. Effects were considered
significant when P < 0.05. SPSS Version 11.00 (2001)was used for all statistical tests.
3. Results
3.1. Seedling morphology
Height ranged from 19.3 cm (non-fertilized) to
49.7 cm (fertilized with 7 g l1 of 16-8-9) (Table 3),although plant height response to rate within a
formulation was not significant. Among fertilized
treatments, all but 1.5 g l1 of 9-13-18 were in thesame statistical height group. Basal stem diameter
fter 9 months as affected by fertilizer treatments in the nursery (rates
16-8-9
5 3.25 5 7
42.2ab 44.5ab 45.7ab 49.7a
3.9ab 4.1ab 4.1ab 4.4asurvival percentages, comparison data were arcsine
transformed (Steel and Torrie, 1989), though data are
reported as original means with standard errors. Data
from the destructive sampling of planted seedlings
were subjected to one-way ANOVA (with fertilization
in the nursery as the main factor) with the three plants
excavated in each block for each treatment comprising
the experimental unit. Seedling morphology before
planting was assessed using one-way ANOVA for a
completely randomized design. For each analysis,
when ANOVA was significant, statistically significantt differences (n = 30).
ranged from 2.3 mm (non-fertilized) to 4.4 mm
(fertilized with 7 g l1 of 16-8-9). Within the 9-13-18 formulation a significant shift appeared when rate
increased from 1.5 to 5 g l1 (Table 3), but nosignificant basal stem diameter response occurred
from 3.25 to 7 g l1 within 16-8-9. Linear correlationsbetween both height and basal stem diameter and N
and P supplied were positive and significant
(P = 0.015 for N, P = 0.031 for P and P = 0.009 for
N, P = 0.033 for P, respectively, n = 7).
3.2. Outplanted biomass after first summer
Whole plant, shoot and root biomass after the first
summer for non-protected seedlings were significantly
affected by fertilization in the nursery (ANOVA
40.6 and 24.1%, respectively, while the reduction in
survival for the remainder of treatments was lower
(Table 4). In 1994 and 1995 the decrease in survival was
similar among treatments, ranging from 11.2% in non-
fertilized plants to 2% in plants fertilized with 5 g l1 of16-8-9. However, in 19961998 mortality was more
severe and several shifts in significance of differences
between treatments appeared: while A. salicina
fertilized in the nursery with 3.25 g l1 of 16-8-9experienced a survival decrease of 19.7%, 5 g l1 of 9-13-18 provoked a 6% reduction in survival (Table 4).
During 19992001 no significant changes in survival
occurred. Following the first summer, 5 g l1 of 9-13-18 showed the best performance, followed by plants
fertilized with 5 g l1 of 16-8-9. At the end of the periodconsidered (January 2002), survival among fertilized
J.A. Oliet et al. / Forest Ecology and MP = 0.011, 0.016 and 0.006, respectively). Plants
fertilized with 9-13-18 experienced a significant
increase in root dry weight with rate (Fig. 1), while
this was not observed among 16-8-9 fertilized A.
salicina seedlings. Maximum root biomass was
attained with 5 g l1 of 9-13-18. Within a formulation,shoot dry weight was not significantly affected by rate,
although a positive trend was observed (Fig. 1).
Maximum shoot biomass was reached with 7 g l1 of16-8-9. A significant positive linear regression model
was fitted for P supplied in the nursery and mean root
biomass after planting (Fig. 2), while no significant
relationship was found for N supplied. Mean shoot
biomass was positively correlated to both N and P
Fig. 1. Mean (+S.E.) biomass (dry weight, DW) of Acacia salicina
after the first field growing season as affected by nursery fertilizer
treatments (rates of each formulation, 9-13-18 and 16-8-9, per liter
of substrate). For each fraction (shoot or root), columns marked withdifferent letters indicate significant differences (n = 12).supplied (R2 = 0.780, P = 0.008 and R2 = 0.814,
P = 0.005, respectively, n = 7).
3.3. Planting response: survival
A significant interaction between both factors
(nursery fertilization and tree shelter) was present in
June 1993 (P = 0.027), but was not detected for the
remainder of the study period. After the first summer
(October 1993), A. salicina seedling survival decreased
in all fertilization treatments, and differences were
significant through January 2002 (P < 0.001 for alldates). Survival in October 1993 of non-fertilized plants
and plants fertilized with 1.5 g l1 of 9-13-18 decreased
anagement 215 (2005) 339351 343
Fig. 2. Linear regression models fitted for the relationships between
Acacia salicina root dry biomass (Root DW) and survival after the
first field growing season (September and October 1993, respec-
tively) and P supplied in the nursery.treatments ranged from 49.9% (1.5 g l1 of 9-13-18) to
80.5% (5 g l1 of 16-8-9), with survival of remainingtreatments ranging from only 63.4 to 67.3% (Table 4).
Tree shelters did not significantly affect post-
planting survival of A. salicina until 1999. However,
following this year, survival of non-protected plants
was reduced to 54.9%, while survival of protected
seedlings exhibited a less pronounced reduction,
reaching 64.0% in February 1999 (Fig. 3). As
survival occurred during 1999, 2000 and 2001 and
the significant difference in survival among protected
and non-protected plants was maintained.
3.4. Planting response: growth
Similar to the response for survival, a significant
interaction between both factors (nursery fertilization
J.A. Oliet et al. / Forest Ecology and Management 215 (2005) 339351344
Table 4
Survival (%) of Acacia salicina (S.E., n = 8) during 9 years as affected by nursery fertilizer treatments (rates of each formulation per liter ofsubstrate)
Formulation 9-13-18 16-8-9
Rate (g l1) 0 1.5 3.25 5 3.25 5 7
June 1993# 83.6 3.1 95.3 2.6 96.9 1.7 98.4 1.0 100.0 0.0 94.5 2.5 93.8 2.0October1993 43.0 5.9c 71.2 5.5b 86.4 4.5a 92.1 2.6a 90.7 1.7a 86.5 4.0a 86.8 2.6aOctober 1994 31.8 5.5c 62.4 6.7b 79.3 4.4a 87.4 3.5a 84.7 2.0a 84.6 4.8a 81.6 2.3aNovember 1995 31.8 5.5c 62.4 6.7b 78.3 4.4a 87.4 3.5a 83.9 2.0a 84.6 4.8a 81.6 2.3aJanuary 1997 27.1 4.6d 59.1 6.6c 68.6 4.7c 86.7 3.6a 72.7 4.0bc 81.7 4.1ab 74.3 4.1bcFebruary 1999 19.0 4.6d 49.9 8.0c 65.3 5.6bc 81.4 4.0a 64.2 5.1bc 70.2 2.3ab 66.2 6.8bDecember 2000 18.2 4.5d 49.9 8.0c 64.4 6.3bc 80.5 4.7a 63.4 5.2bc 68.3 2.3ab 65.4 6.5bcJanuary 2002 18.2 4.5d 49.9 8.0c 64.4 6.3bc 80.5 4.7a 63.4 5.2bc 67.3 2.4ab 64.6 6.8bcWithin a row, means with different letters (a, b and c) indicate significant differences.
# A nursery fertilization tree shelter at planting interaction occurred precluding statistical analysis of main effects.mentioned previously, no substantial changes inFig. 3. Mean (S.E., n = 28) survival, height, groundline stem diameter aduration as affected by tree shelters at planting. (*) and (***) indicate Pand tree shelter at planting) appeared in June 1993nd slenderness quotient of Acacia salicina during the 9-year study
< 0.05 and P < 0.001, respectively.
nd M
study
ifican
red pr
ducted(P = 0.001) for height, though it disappeared for the
remainder of the study period. From October 1993 to
the end of 1995, height response was significantly
affected by nursery fertilization (P < 0.01), with plantsfertilized with maximum rates of both formulations
achieving highest values (Table 5). However, from 1996
to the end of the study period, no further significant
effect on height occurred. Maximum differences in
mean height among fertilizer treatments ranged from
34.3 cm in June 1993 to 22.1 cm in January 2002
(Table 5). Groundline stem diameter (GSD) was
significantly affected by fertilization in the nursery
during the entire study period, though P-values
decreased over time (P < 0.001 from June 1993 toJanuary 1997, P < 0.05 for February 1999 to January
J.A. Oliet et al. / Forest Ecology a
Table 5
Height (cm) of Acacia salicina (S.E., n = 8) during the 9-yearformulation per liter of substrate)
Formulation 9-13-18
Rate (g l1) 0 1.5 3.25
June 1993# 13.9 2.0 33.0 4.3 39.6 4.2October 1993 23.4 4.6c 42.0 8.9b 49.1 8.9abOctober 1994 38.0 6.6b 56.0 9.9a 62.8 7.8aNovember 1995 43.2 6.7b 57.6 9.3a 63.1 7.1aJanuary 1997 61.6 10.4 64.7 11.6 77.7 9.1February 1999 70.9 10.4 69.9 11.2 84.5 8.4December 2000 79.0 10.9 73.7 9.4 91.1 7.8January 2002 88.3 12.9 84.8 9.1 103.9 8.3Within a row, means with different letters (a, b and c) indicate sign
# A nursery fertilization tree shelter at planting interaction occureffect was not significant the multiple comparison test was not con2002). Correspondingly, the number of statistically
different groups according to multiple comparison tests
decreased from 5 to 2 between 1993 and 2002 (Table 6).
Nine years following planting, significant differences
were only present between non-fertilized or low
fertilized (1.5 g l1 substrate of 9-13-18) A. salicinaseedlings and the remainder of nursery fertilization
treatments, with maximum differences of 10.9 mm
between the smallest (non-fertilized, GSD = 20.8 mm)
and largest (fertilized with 5 g l1 of 16-8-9,GSD = 31.7 mm) plants. Slenderness quotient
decreased in all treatments with time after planting
(Table 6), though differences among treatments still
persisted in 2002 (P < 0.05). Interactions betweennursery fertilization and tree shelter protection on
slenderness quotient occurred at the 1993, 1995 and
1997 measurements (data not shown). Stem volumeindex differences as affected by nursery fertilization
were significant during the first 3 years after planting
(P < 0.01 in 1993 and P < 0.05 in 1994 and 1995) butdifferences were no longer significant in January 1997,
4 years after planting. High variability was present
within each treatment at the end of the study period
(Table 6). Volume index on a per hectare basis 9 years
after planting was significantly affected by nursery
fertilization (P < 0.05), with maximum difference of2.31 m3 ha1 between non-fertilized plants and thosefertilized with 7 g l1 of 16-8-9, followed by a2.17 m3 ha1 difference between the former treatmentand the lowest rate of 9-13-18 (1.5 g l1, Table 6).
Height was significantly affected by tree shelter
application from June 1993 (three months after
anagement 215 (2005) 339351 345
period as affected by nursery fertilizer treatments (rates of each
16-8-9
5 3.25 5 7
44.7 5.5 44.7 3.7 44.7 3.5 48.2 3.348.5 8.3ab 48.9 9.0ab 43.2 6.4ab 50.8 8.7a63.8 7.5a 61.6 9.9a 54.7 7.7a 62.3 10.1a65.1 6.5a 63.1 9.2a 60.8 7.5 a 63.2 9.4 a75.8 9.4 74.9 10.5 72.7 9.6 75.4 9.784.4 10.3 83.0 9.0 83.3 9.6 85.1 10.390.7 10.7 95.8 6.7 95.3 11.7 94.2 10.599.7 11.5 95.3 7.4 110.4 12.5 106.1 11.1t differences.
ecluding statistical analysis of main effects. Note: when a treatment
.planting) to the end of the study period (P < 0.001for all dates). In October 1993, a decrease in mean
height was observed in non-protected plants (Fig. 3),
while height of protected plants increased. From this
time to the end of the study period, differences in
height between protected and non-protected plants
remained relatively consistent, ranging from 45.3 cm
in January 1997 to 35.0 cm in January 2002 (Fig. 3). In
contrast, GSD was not affected by tree shelter
protection until the third year after planting (Novem-
ber, 1995), when GSD was significantly greater for
non-protected seedlings (Fig. 3). Statistically signifi-
cant differences continued (P < 0.05 for all dates)through January 2002. Maximum slenderness quotient
difference among protected and non-protected plants
was 7.1 cm mm1 after the first summer (October1993), though it was progressively reduced to
and M
efore
planti
substr
5
5
7
2
June 1993# 6.4 0.9 9.1 1.1 9.3 1.0 87
4
3
1
5
b 2
ifican
red pr
ducted2.8 cm mm1 coinciding with the final measurement
October 1993# 7.8 1.5 8.3 1.7 7.9 1.4January 2002 4.6 0.7c 4.5 0.6bc 3.9 0.5a
Stem volume (cm3)
June 1993 0.2 0.0e 1.2 0.2d 2.2 0.2cOctober 1993 0.8 0.3d 4.7 1.6cd 7.6 1.9abcJanuary 2002 227.5 108.7 136.8 32.5 470.9 79.2
Volume index (m3 ha1)January 2002 0.22 0.10b 0.35 0.11b 1.42 0.32a
Within a row, means with different letters (a, b and c) indicate sign# A nursery fertilization tree shelter at planting interaction occur
effect was not significant the multiple comparison test was not conJ.A. Oliet et al. / Forest Ecology346
Table 6
Groundline stem diameter, slenderness quotient, stem volume index b
years after planting (January 2002) and volume index 9 years after
nursery fertilizer treatments (rates of each formulation per liter of
Formulation 9-13-18
Rate (g l1) 0 1.5 3.25
Stem diameter (mm)
June 1993 2.2 0.1e 3.6 0.1d 4.3 0.1cOctober 1993 3.1 0.3e 5.1 0.4d 6.3 0.4bcJanuary 2002 20.8 2.6b 21.1 1.5b 29.1 1.8a
Slenderness (cm: mm)(Fig. 3). As mentioned above, an interaction between
nursery fertilization and tree shelter protection was
detected for slenderness quotient in 1993, 1995 and
1997; when no interaction appeared, ANOVA was
significant for the tree shelter main factor (P < 0.001).Stem volume of plants in tree shelters was only
statistically different (P < 0.01) during the first yearfollowing planting, with protected seedlings having
greater volumes (data not shown). Likewise, volume
index on a per hectare basis 9 years after planting was
not affected by shelter treatments (data not shown).
4. Discussion
4.1. Nursery fertilization and survival at planting
Overall survival of A. salicina after 9 years was
relatively high, considering the rainfall shortage
during the whole period, which included years with
precipitation as low as 42 mm (1998, Table 2). In a
planting trial undertaken near our study site from
1988 to 1991 to compare response of different multi-
purpose tree species, A. salicina exhibited the bestperformance among species in terms of survival and
anagement 215 (2005) 339351
(June 1993) and after (October 1993) the first growing season and 9
ng (January 2002) of Acacia salicina (S.E., n = 8) as affected byate)
16-8-9
3.25 5 7
.2 0.2b 5.1 0.1b 5.0 0.1b 5.5 0.1a
.2 0.4ab 6.8 0.8abc 5.9 0.2cd 7.6 0.7a8.5 3.4a 27.0 2.2ab 31.7 3.0a 29.6 4.0a
.5 0.9 8.7 0.7 8.9 0.7 8.7 0.6
.0 1.2 7.4 1.3 7.3 1.1 7.4 1.3
.0 0.5ab 3.9 0.4a 4.1 0.5ab 4.2 0.6abc
.6 0.6b 3.5 0.4b 3.3 0.3b 4.4 0.3a0.2 2.0ab 9.2 3.5abc 5.1 0.8bcd 10.8 2.9a64.4 187.8 320.5 73.2 728.1 222.4 858.0 371.0
.04 0.66a 0.96 0.26ab 2.10 0.60a 2.52 1.22at differences.
ecluding statistical analysis of main effects. Note: when a treatment
.growth (Tilstone et al., 1998).
The maximum rate (5 g l1 substrate) of 9-13-18(the richest P fertilizer) promoted the highest survival
following the first year after planting. When examin-
ing the relationships between survival or root dry
weight and P supplied in the nursery, significant
regression models were fitted (Fig. 2), while no
significant models were found for N. The role of P in
the enhancement of root growth after planting may
help explain this finding. Many authors have
suggested a positive effect of P on root development
(Timmer and Armstrong, 1987; Salisbury and Ross,
1994), and several studies have confirmed this
relationship. For instance, while dry weight of
Pseudotsuga menziesii (Mirb.) Franco nursery seed-
lings was affected by both N and P supplied in a
nursery fertilization experiment, root growth capacity
after planting was mostly influenced by P (Bigg and
Schalau, 1990). Likewise, Dominguez et al. (2000)
reported that Pinus pinea L. seedlings grew more roots
in the nursery and attained higher post-transplant root
growth capacity values when fertilized at the highest
rate of P. In a study with Picea glauca Piceaengelmanii, new root biomass from seedlings grown in
nd Mthe presence of P after 12 weeks was almost two times
greater than that of seedlings grown without P (Folk
and Grossnickle, 2000). Enhanced root system
morphology associated with P additions might help
improve survival on harsh sites. For instance, Planelles
(2004) found a significant improvement in survival of
outplanted Ceratonia siliqua L. in response to P
supplied in the nursery under low fertility Mediterra-
nean semiarid field conditions. The response we
observed may be accentuated by the scarcity of P in
the soil (see Section 2), though a study of Pinus
halepensis Mill. seedlings in the same location and
with the same nursery fertilization treatments showed
a significant and positive response of survival to N
supplied, but not to P (Oliet et al., 1997). This suggests
a species-specific response of outplanted seedlings to
mineral nutrition in the nursery. Thus, capacity of
leguminous species, like A. salicina, to fix atmo-
spheric N may reduce dependence on internal N to
help support establishment after planting. Nodulation
of another leguminous shrub, Retama sphaerocarpa L.
was enhanced when growing in low fertility condi-
tions and this promoted N uptake efficiency, while P
uptake was not affected by nodulation (Valladares
et al., 2002). Therefore, as N dependence decreases, P
dependence increases, particularly in low fertility soils
and for leguminous species, since legume nodules
responsible for N fixation have a high P requirement
(Vance, 2001). Likewise, outplanting performance of
some other conifer species is largely affected by P
reserves in needles produced in the nursery (van den
Driessche, 1991b; Folk and Grossnickle, 2000).
Nine years following planting, differences in first
year survival among fertilization treatments in the
nursery still persisted, and from the fourth year on
there were no relevant shifts in survival and
composition of statistical groups, indicating that
treatment responses had consolidated. Survival of
non-fertilized or low fertilized (1.5 g l1 9-13-18)plants was significantly lower for the entire study
period, reflecting superior performance of nutrient
loaded seedlings during both the period of initial
establishment and throughout early plantation devel-
opment. A positive field response from nutrient
loading may persist over time as a result of the initial
advantage of rapid root growth which may help to
enhance subsequent uptake of nutrients (McAlister
J.A. Oliet et al. / Forest Ecology aand Timmer, 1998).4.2. Nursery fertilization and growth after
planting
In contrast to survival response, the effect of
fertilization in the nursery on post-planting height
persisted only 34 years. Moreover, during these
years, plant height was strongly related to initial
seedling height in the nursery (rPearson = 0.992, 0.853,
0.764, 0.843 and 0.797 in June 1993, October 1993,
1994, November 1995 and January 1997, respectively,
P < 0.05 for all dates). Post-planting height is largelyassociated with initial seedling size in the nursery
(Roth and Newton, 1996; Villar-Salvador et al., 2000;
Puertolas et al., 2003). However, after 4 years, the field
height of initially smaller plants from non-fertilized or
low fertilized treatments did not differ significantly
from the height of the taller fertilized seedlings. Small
plants tend to have greater height growth rates
irrespective of nutrient status or other treatments
applied in the nursery, which acts to minimize initial
size differences of taller plants, particularly on harsh
planting sites (Tuttle et al., 1988). However, this effect
often does not become apparent until several years
after planting (Rose and Ketchum, 2003). For
instance, Oliet et al. (2000) reported no significant
height differences after three to four years for
outplanted P. halepensis seedlings among fertilizer
treatments (excepting non-fertilized plants) exposed
to the same nursery fertilizer treatments as in this
study. Furthermore, some authors have reported that a
nutrient concentration effect promoting field height
growth (irrespective of initial size), only persisted for
one year (Irwin et al., 1998; Puertolas et al., 2003). In
contrast, GSD and slenderness quotient differences
among nursery fertilization treatments in our study
still persisted 9 years after planting. No significant
differences in SV were present in 2002, indicating that
shoot biomass per plant was not affected by nursery
fertilizer treatments at a mid to long timescale.
However, when considering survival combined with
stem volume (i.e., volume index) in the analysis, the
highest fertilized rates of both formulations promoted
significantly higher per hectare volume.
4.3. Tree shelters and planting response
Tree shelters did not affect survival until the fifth to
anagement 215 (2005) 339351 347sixth year, when survival of non-protected plants was
and Mreduced compared to that of protected seedlings. This
phenomenon was first noted at the February 1999
measurement, after the intense drought of 1998. By
this time, shoot height exceeded that of the shelter
(mean height of protected trees >100 cm, Fig. 3) soshelter microclimate should not have had as strong an
effect on plant growth conditions compared to earlier
in the study, particularly since the majority of foliar
canopy had emerged from the shelter (data not
shown). However, shelters may have provided some
continuous benefit even at this point by minimizing
transpirational demand of protected foliage associated
with drying winds (Bergez and Dupraz, 1997). Several
other studies reported significant differences in first
year seedling survival as affected by tree shelters,
some suggesting a species-specific response to shelter
microclimatic conditions under Mediterranean envir-
onments (Costello et al., 1996; Marques et al., 2001;
Oliet et al., 2003). However, corresponding with our
results, some studies have also found changes in
survival response with time. For instance, survival of
Quercus rubra L. and Fraxinus pennsylvanica Marsh.
was not affected during the first year after planting, but
significant differences appeared in years 3 and 8,
respectively, with improved seedling survival for each
species when protected with shelters (Ponder, 2003).
Height of protected plants increased significantly
compared to non-protected plants during the first year
after planting, when mean seedling height was below
the length of the shelter (60 cm). This response of
protected plants is associated with reduction in light
availability within the tubes, which stimulates height
growth (Potter, 1991; Jacobs, 2004). Furthermore,
reduced height development in non-protected seed-
lings during the first year may be associated with
transplanting stress caused by desiccation in the very
windy conditions of the experimental field. For the
continued duration of the study period, height
differences remained relatively constant. Various
results have been reported in previous studies,
suggesting species and/or site specificity. Gillespie
et al. (1996) found that protected Q. rubra trees were
still significantly taller 5 years following planting than
non-protected trees. Dupraz (1997) reported that
Juglans regia L. trees emerged from the top of the
shelter during the first growing season, but the height
advantage of protected trees diminished after 10 years.
J.A. Oliet et al. / Forest Ecology348Similarly, Ponder (2003) reported significant differ-5. Conclusions
Seedling quality attributes of nursery-stock and
application of tree shelters at planting each affected
outplanting response of A. salicina throughout several
years. In particular, while the effect of mineral
nutrition in the nursery on height growth diminished
after 34 years, the differences in survival were
maintained for the 9-year study duration. The effect of
tree shelters on survival became apparent after several
years, while differences in growth were established
after the first year and remained consistent throughout
the study for many morphological traits. This response
suggests that more than one or two seasons provides a
more useful assessment of the effects of nursery
practices and stock quality variables, as well as
silvicultural treatments applied in the field, on
response following planting and should therefore be
emphasized in afforestation and reforestation experi-
mental trials.
In arid and windy areas, A. salicina establishment is
enhanced by protecting seedlings after planting with
tree shelters and by nursery cultural treatments whichences in first year height of Q. rubra, J. nigra L. and F.
pennsylvanica, though in year 10 the differences were
significant only for Q. rubra. Further, non-protected P.
halepensis plants outperformed protected plants 5
years following planting (Oliet et al., 2000). Stimula-
tion of height within the tree shelter environment may
subside once the plant reaches the top of the shelter.
Wind-induced stem and leaf movement of non-
protected trees promotes greater diameter growth
(Kjelgren and Rupp, 1997; Bergez and Dupraz, 2000).
Since shelters were not removed in our study,
continuous dynamic pressure on the basal stem
provoked by wind enhanced sturdiness at the expense
of height growth by allocating more carbon to
diameter growth and less to height growth (Gillespie
et al., 1996). This helps to explain how differences in
stem diameter among protected and non-protected
trees increased with time and differences in slender-
ness quotient were high compared to other long-term
studies (Oliet et al., 2000; Johansson, 2004). In spite of
differences in height and slenderness quotient, stem
volume was not affected by sheltering after 9 years.
anagement 215 (2005) 339351promote high seedling P content. Mineral nutrition of
naturally seeded to planted container Pinus taeda with and
without release. Can. J. For. Res. 26, 12371247.
Agrimed Research Programme. Commission of European Com-
munities Brussels Belgium.
J.A. Oliet et al. / Forest Ecology and Management 215 (2005) 339351 349Costello, L.R., Peters, A., Giusti, G., 1996. An evaluation of tree
shelter effects on plant survival and growth in a mediterranean
climate. J. Arboriculture 22 (1), 19.
Domnguez-Lerena, S., Oliet, J., Carrasco, I., Penuelas, J.L., Ser-Cherbuy, B., Jofrew, R., Gillon, D., Rambal, S., 2001. Internal
remobilization of carbohydrates lipids nitrogen and phosphorus
in the Mediterranean evergreen oak Quercus ilex. Tree Physiol.
21, 917.
Close, D.C., Beadle, C.L., 2004. Total and chemical fractions of
nitrogen and phosphorus in Eucalyptus seedlings leaves: effects
of species nursery fertilizer management and transplanting.
Plant Soil 259, 8595.
Correal, E., Sanchez Gomez, P., Alcaraz, F., 1988. Les especes
ligneuses a usages multiples des zones arides Mediterraneannes.seedlings for plantation establishment must be
optimized to match both species necessities and site
ecological conditions.
Acknowledgments
We gratefully acknowledge the financial support
of the National Institute for Agriculture and Food
Technology and Research (Spanish Department of
Science and Technology). The comments of two
anonymous reviewers substantially improved the
manuscript.
References
Bergez, J.E., Dupraz, Z.C., 1997. Transpiration rate of Prunus avium
L. seedlings inside an unventilated tree shelter. For. Ecol.
Manage. 97, 255264.
Bergez, J.E., Dupraz, Z.C., 2000. Effect of ventilation on growth of
Prunus avium seedlings grown in treeshelters. Agric. For.
Meteorol. 104, 199214.
Bigg, W.L., Schalau, J.W., 1990. Mineral nutrition and the target
seedling. In: Rose, R., Campbell, S.J., Landis, T.D. (Eds.), Target
Seedling Symposium. Proceedings of the Combined Meeting of
the Western Forest Nursery Association. USDA Forest Service.
Gen. Tech. Re RM-200, pp. 139158.
Birchler, T., Rose, R., Royo, A., Pardos, M., 1998. La planta ideal:
revision del concepto, parametros definitorios e implementacion
practica. Invest. Agric., Sist. Recur. For. 7 (12), 109121.
Burdett, A.N., 1990. Physiological processes in plantation establish-
ment and the development of specifications for forest planting
stock. Can. J. For. Res. 20, 415427.
Cain, M.D., Barnett, J.P., 1996. An 8-year field comparison ofrada, R., 2000. Influencia de la relacion N-P-K en el desarrolloen vivero y en campo de planta de Pinus pinea. Actas del 1er
Simposio del pino pinonero (Pinus pinea L.) Tomo I 195202.
Dupraz, C., 1997. Abris-serres: ce quen pensent les arbres. Rev. For.
Fr. 49 (5), 417432.
Dupraz, C., Bergez, J.E., 1999. Carbon dioxide limitation of the
photosynthesis of Prunus avium L. seedlings inside an unventi-
lated tree shelter. For. Ecol. Manage. 119, 8997.
Floistad, I.S., Kohmann, K., 2004. Influence of nutrient supply on
spring frost hardiness and time of bud break in Norway spruce
(Picea abies (L.) Karst.) seedlings. N. For. 27, 111.
Folk, R.S., Grossnickle, S.C., Arnott, J.T., Mitchell, A.K., Puttonen,
P., 1996. Water relations gas exchange and morphological
development of fall and spring planted yellow cypress steck-
lings. For. Ecol. Manage. 81 (13), 197213.
Folk, R.S., Grossnickle, S., 2000. Stock-type patterns of phosphorus
uptake retranslocation net photosynthesis and morphological
development in interior spruce seedlings. N. For. 19, 2749.
Gillespie, A.R., Rathfon, R., Myers, R.K., 1996. Rehabilitating a
young northern red oak planting with tree shelters. North. J.
Appl. For. 13 (1), 2429.
Green, T.H., Mitchell, R.J., 1992. Effects of nitrogen on the response
of loblolly pine to water stress. I. Photosynthesis and stomatal
conductance. N. Phytol. 122, 627633.
Green, T.H., Mitchell, R.J., Gjerstad, D.H., 1994. Effects of nitrogen
on the response of loblolly pine to drought. II. Biomass alloca-
tion and C:N balance. N. Phytol. 128, 145152.
Grigg, A.H., Mulligan, D.R., 1999. Biometric relationships for
estimating standing biomass litterfall and litter accumulation
of Acacia salicina on mined land in Central Queensland. Aust. J.
Bot. 47, 807816.
Grossnickle, S.C., 2000. Ecophysiology of Northern Spruce Spe-
cies: The Performance of Planted Seedlings. NRC Research
Press, Ottawa, Ont., Canada.
Haase, D.L., Rose, R. (Eds.), 1997. Forest seedling nutrition from
the nursery to the field. Symposium Proceedings. Nursery
Technology Cooperative, Oregon State University.
Irwin, K.M., Duryea, M.L., Stone, E.L., 1998. Fall applied nitrogen
improves performance of 1-0 slash pine nursery seedlings after
outplanting. South. J. Appl. For. 22 (2), 111116.
Jacobs, D.F., Steinbeck, K., 2001. Tree shelters improve the survival
and growth of planted Engelmann spruce seedlings in south-
western Colorado. West. J. Appl. For. 16 (3), 114120.
Jacobs, D.F., 2004. Restoration of a Rocky Mountain Spruce-Fir
forest: sixth-year Engelmann spruce seedling response with or
without tree shelter removal. In: Riley, L.E., Dumroese, R.K.,
Landis, T.D. (Coords.), National Proceedings: Forest and Con-
servation Nursery Associations 2003. USDA Forest Service.
Rocky Mountain Research Station. Tech. Proc. RMRS-P33. Fort
Collins, CO, pp. 5763.
Jacobs, D.F., Ross-Davis, A.L., Davis, A.S., 2004. Establishment
success of conservation tree plantations in relation to silvicul-
tural practices in Indiana, USA. N. For. 28, 2336.
Johansson, T., 2004. Changes in stem taper for birch plants growing
in tree shelters. N. For. 27, 1324.
Jose, S., Merritt, S., Ramsey, C.L., 2003. Growth nutrition photo-
synthesis and transpiration responses of longleaf pine seedlings
to light water and nitrogen. For. Ecol. Manage. 180, 335344.
J.A. Oliet et al. / Forest Ecology and Management 215 (2005) 339351350Kavanagh, K.L., Zaerr, J.B., 1997. Xylem cavitation and loss of
hydraulic conductance in western hemlock following planting.
Tree Physiol. 17, 5963.
Kjelgren, R., Rupp, L.A., 1997. Establishment in treeshelters I:
shelters reduce growth, water use, and hardiness but not drought
avoidance. Hortscience 32 (7), 12811283.
Landis, T.D., 1989. Mineral nutrients and fertilization. In: Landis,
T.D., Tinus, R.W., McDonald, S.E., Barnett, J.P. (Eds.), The
Container Tree Nursery Manual, vol. 4. Agriculture Handbook
674. USDA Forest Service, pp. 170.
Larsen, H.S., South, D.B., Boyer, J.N., 1988. Foliar nitrogen content
at lifting correlates with early growth of loblolly pine seedlings
from twenty nurseries. South. J. Appl. For. 12 (3), 181185.
Le Houerou, H.N., 1986. Salt tolerant plants of economic value in
the Mediterranean basin. Reclam. Reveg. Res. 5, 319341.
Malik, V., Timmer, V.R., 1998. Biomass partitioning and nitrogen
retranslocation in black spruce seedlings on competitive mixed
wood sites: a bioassay study. Can. J. For. Res. 28, 206215.
Marques, P.M., Ferreria, L., Correia, O., Martins-Loucao, M.A.,
2001. Tree shelters influence growth and survival of carob
(Ceratonia siliqua L.) and cork oak (Quercus suber L.) plants
on degraded Mediterranean sites. In: Villacampa, Y., Brebbia,
C.A., Uso, J.L. (Eds.), Ecosystems and Sustainable Develop-
ment III. Wit Press, Southampton, Boston, pp. 635644.
McAlister, J.A., Timmer, V.R., 1998. Nutrient enrichment of white
spruce seedlings during nursery culture and initial plantation
establishment. Tree Physiol. 18, 195202.
McDonald, P.M., 1991. Container seedling outperform bareroot
stock:survival and growth after 10 years. N. For. 5 (2), 147156.
Oliet, J., Planelles, R., Lopez-Arias, M., Artero, F., 1997. Efecto de
la fertilizacion en vivero sobre la supervivencia en plantacion de
Pinus halepensis. Cuadernos de la S.E.C.F. 4, 6980.
Oliet, J., Planelles, R., Lopez-Arias, M., Artero, F., 2000. Efecto de
la fertilizacion en vivero y del uso de protectores en plantacion
sobre la supervivencia y el crecimiento durante seis anos de una
repoblacion de Pinus halepensis. Cuadernos de la S. E.C.F. 10,
6977.
Oliet, J., Navarro, R., Contreras, O., 2003. Evaluacion de la aplica-
cion de mejoradores y tubos en repoblaciones forestales. Con-
sejera de Medio Ambiente de la Junta de Andaluca.
Perez, A., 1989. Proyecto LUCDEME. Mapa de suelos escala
1:100.000. Almera-1045 Ministerio de Agricultura Pesca y
Alimentacion. ICONA. Consejo Superior de Investigaciones
Cientficas. Madrid.
Planelles, R., 2004. Efectos de la fertilizacion N-P-K en vivero sobre
la calidad funcional de planta de Ceratonia siliqua L. Tesis
Doctoral. Universidad Politecnica de Madrid,
Ponder, F., 2003. Ten-year results of tree shelters on survival and
growth of planted hardwoods. North. J. Appl. For. 20 (3), 104
108.
Potter, M.J., 1991. Treeshelters. Forestry Comission. Handbook 7.
Puertolas, J., Gil, L., Pardos, J.A., 2003. Effects of nutritional status
and seedling size on field performance of Pinus halepensis
planted on former arable land in the Mediterranean basin.
Forestry 76 (2), 159168.
Puttonen, P., 1997. Looking for the silver-bulletcan one test do
it? N. For. 13 (1-3), 927.Quoreshi, A.M., Timmer, V.R., 2000. Early outplanting performance
of nutrient-loaded containerized black spruce seedlings inocu-
lated with Laccaria bicolor: a bioassay study. Can. J. For. Res.
30, 744752.
Racey, G.D., Gerum, C., 1983. The practicality of top-root ratio in
nursery stock characterization. For. Chron. 59, 240243.
Rehman, S., Loescher, R.N., Harris, P.J., 1999. Dormancy breaking
and germination of Acacia salicina Lindl. Seeds Seed Sci.
Technol. 27, 553557.
Rose, R., Atkinson, M., 1992. Nursery morphology and preliminary
comparison of 3-year field performance of 1+0 and 2+0 bareroot
ponderosa pine seedlings. Tree Planters Notes 43 (4), 153
158.
Rose, R., Ketchum, J.S., 2003. Interaction of initial seedling dia-
meter, fertilization and weed control on Douglas-fir growth over
the first four years after planting. Ann. For. Sci. 60, 111.
Roth, B.E., Newton, M., 1996. Survival and growth of Douglas-fir
related to weeding fertilization and seed source. West. J. Appl.
For. 11 (2), 6269.
Salifu, K.F., Timmer, V.R., 2003. Nitrogen retranslocation response
of young Picea mariana to nitrogen-15 supply. Soil Sci. Soc.
Am. J. 67, 309317.
Salisbury, F.B., Ross, C.W., 1994. Fisiologa Vegetal. Editorial
Iberoamerica.
Shaw, T.M., Moore, J.A., Marshall, J.D., 1998. Root chemistry of
Douglas-fir seedlings grown under different nitrogen and potas-
sium regimes. Can. J. For. Res. 28, 15661573.
Simpson, D.G., Thompson, C.F., Sutherland, C.D., 1994. Field
performance potential of interior spruce seedlings: effects of
stress treatments and prediction by root growth potential and
needle conductance. Can. J. For. Res. 24, 576586.
South, D.B., Mitchell, R.J., 1999. Determining the optimum slash
pine seedling size for use with four levels of vegetation manage-
ment on a flatwoods site in Georgia USA. Can. J. For. Res. 29,
10391046.
Steel, R., Torrie, J.H., 1989. Bioestadstica: principios y
procedimientos, second ed. Mc Graw Hill, Mexico.
Tan, W., Hogan, G.D., 1997. Physiological and morphological
responses to nitrogen limitation in jack pine seedlings: potential
implications for drought tolerance. N. Forests 14, 1931.
Thompson, B., 1985. Seedling morphological evaluation. What can
you tell by looking. In: Duryea, M.L., (Ed.), Evaluating Seedling
Quality: Principles, Procedures and Predictive Abilities of Major
Test. Forest Research Laboratory. Oregon State University, pp.
5969.
Tilstone, G.H., Pasiecznik, N.M., Harris, P.J., Wainwright, S.J.,
1998. The growth of multipurpose tree species in the Almeria
province of Spain and its relationship to native plant commu-
nities. Int. Tree Crops J. 9, 247259.
Timmer, V.R., Armstrong, G., 1987. Growth and nutrition of con-
tainerized Pinus resinosa at exponentially increasing nutrient
additions. Can. J. For. Res. 17, 644647.
Timmer, V.R., Aidelbaum, A.S., 1996. Manual for exponential
nutrient loading of seedlings to improve outplanting perfor-
mance on competitive forest sites. NODA/NFP Tech. Re TR-
25. Nat. Resour. Can. Canadian Forest Service Sault Ste. Marie
ON.
Tuttle, C.L., South, D.B., Golden, M.S., Meldahl, R.S., 1988. Initial
Pinus taeda seedling height relationships with early survival and
growth. Can. J. For. Res. 18, 867871.
Valladares, F., Villar-Salvador, P., Dominguez, S., Fernandez-Pasc-
ual, M., Penuelas, J.L., Pugnaire, F.I., 2002. Enhancing the early
performance of the leguminous shrub Retama sphaerocarpa (L.)
Boiss.: fertilisation versus Rhizobium inoculation. Plant Soil
240, 253262.
Vance, C.P., 2001. Symbiotic nitrogen fixation and phosphorus
acquisition. Plant nutrition in a world of declining renewable
resources. Plant Physiol. 127, 390397.
van den Driessche, R., 1980. Effects of nitrogen and phosphorous
fertilization on Douglas-fir nursery growth and survival after
outplanting. Can. J. For. Res. 10, 6570.
van den Driessche, R., 1988. Nursery growth of conifer seedlings
using fertilizers of different solubilities and application time,
and their forest growth. Can. J. For. Res. 18, 172180.
van den Driessche, R., 1991a. Effects of nutrients on stock perfor-
mance in the forest. In: van den Driessche, R. (Ed.), Mineral
Nutrition in Conifer Seedlings. CRC Press, pp. 229
260.
van den Driessche, R., 1991b. Influence of container nursery
regimes on drought resistance of seedlings following planting.
II Stomatal conductance specific leaf area and root growth
capacity. Can. J. For. Res. 21, 566572.
van den Driessche, R., 1992. Changes in drought resistance and root
growth capacity of container seedlings in response to nursery
drought nitrogen and potassium treatments. Can. J. For. Res. 22
(5), 740749.
Villar-Salvador, P., Domnguez, S., Penuelas, J.L., Carrasco, I.,
Herrero, N., Nicolas-Peragon, J.L., Ocana, L., 2000. Plantas
grandes y mejor nutridas de P. pinea L. tienen mejor desarrollo
en campo. 1er Simposio del Pino pinonero. Libro de Actas Tomo
I 219227.
J.A. Oliet et al. / Forest Ecology and Management 215 (2005) 339351 351
Nursery fertilization and tree shelters affect long-term field response of Acacia salicina Lindl. planted in Mediterranean semiarid conditionsIntroductionMaterials and methodsResultsSeedling morphologyOutplanted biomass after first summerPlanting response: survivalPlanting response: growth
DiscussionNursery fertilization and survival at plantingNursery fertilization and growth after plantingTree shelters and planting response
ConclusionsAcknowledgmentsReferences