Comparative Growth Behaviour and Leaf Nutrient Status of Native ...

Annals of Botany 87: 777±787, 2001 doi:10.1006/anbo.2001.1414, available online at http://www.idealibrary.com on

Comparative Growth Behaviour and Leaf Nutrient Status of Native Trees Planted on Mine Spoil With and Without Nutrient Amendment A RV IN D S IN GH and J . S. S IN GH * Department of Botany, Banaras Hindu University, Varanasi 221 005, India Received: 7 November 2000

Returned for revision: 13 December 2000 Accepted: 23 February 2001

The eect of nutrient amendment on growth of nine indigenous tree species planted on coal mine spoil was studied. Greater growth in fertilized plots was accompanied by greater foliar N and P concentrations in all species. The response to fertilization varied among species and was greater in non-leguminous than in leguminous species. Furthermore, leguminous species exhibited higher growth rates compared to non-leguminous species. The logtransformed height-diameter relationships were signi®cant for all tree species and treatments. Acacia catechu, Dalbergia sissoo, Gmelina arborea and Azadirachta indica ®tted the elastic similarity model of tree growth; whereas Pongamia pinnata and Phyllanthus emblica followed the constant stress model. Tectona grandis was the only species which ®tted the geometric similarity model. In Albizia lebbeck and Terminalia bellirica, the b-values (the gradients of the log-transformed height to diameter relationships) were considerably lower (50.5), and these two species did not ®t any model of tree growth. In several cases, the b-values were considerably in¯uenced by nutrient amendment. The log-transformed crown mass and trunk mass relationships were signi®cant for all treatments and species. The slope of the crown mass:trunk mass relationship was near unity in A. indica, D. sissoo, G. arborea, P. emblica, P. pinnata, T. grandis, and T. bellirica. However, in A. catechu and A. lebbeck, this slope was well below unity suggesting a greater allocation to non-photosynthetic tissue. Fertilizer amendment resulted in a heavier crown relative to trunk in A. indica, # 2001 Annals of Botany Company T. grandis and T. bellirica. Key words: Diameter increment, fertilizer application, foliar N, foliar P, height increment, tree growth, volume increment.

I N T RO D U C T I O N During mining, overburden material (spoil) overlying the coal seam is often removed and dumped in a haphazard manner. Mine spoil is nutritionally and microbiologically poor (Wali, 1975; Singh and Jha, 1993), and it needs to be stabilized to prevent erosion and contamination of rivers and adjoining agricultural lands from harmful leachates. Natural restoration is a slow process (Iverson and Wali, 1982; Jha and Singh, 1991, 1992), but it can be accelerated by planting trees and herbaceous species. This two-tiered vegetation increases the biological fertility and biodiversity of the mine spoil (JS Singh et al., 1996). To overcome the problem of nutritional de®ciency, fertilizers are often applied. Several studies have demonstrated that fertilization promotes establishment and increases biomass production of herbaceous species (Schoenholtz et al., 1992; Piha et al., 1995; A Singh et al., 1996). However, fertilization of woody species planted on mined land has a variable eect on growth (Vogel, 1981). A number of fertilization studies on nutrient-poor habitats other than mine spoil have suggested increased growth rates in woody species (Vitousek et al., 1987, 1993; Gerrish et al., 1988; Tanner et al., 1990, 1992; Raich et al., 1996; Vitousek and Farrington, 1997). In the absence of shelter from existing vegetation, young trees raised on mine spoil face pronounced wind stress. * For correspondence. Fax (91) 542 368174, e-mail jssingh@ banaras.ernet.in

0305-7364/01/060777+11 $35.00/00

Architectural traits are important for wind stability (McMahon, 1973; King, 1986; Niklas, 1992). Trees dier in relative allocation of resources to supporting vs. photosynthetic tissues, and thus has implications for growth rates and the ability to resist buckling or breaking under wind loads (King, 1981; Niklas, 1992; O'Brien et al., 1995). Nutrient amendments are likely to in¯uence the allocation patterns and hence the wind stability. The objective of the present study was to evaluate the in¯uence of nutrient amendment on growth of nine native tree species planted on mine spoil. The following questions were addressed: (1) do woody species dier in the degree of their response to fertilization of mine spoil; (2) do leguminous species and non-leguminous species dier in their response; (3) does fertilization alter tree architectural traits; and (4) does leaf nutrient status act as an indicator of growth on mine spoil? M AT E R I A L S A N D M E T H O D S Site description The study was conducted at the Jayant coal mine in the Singrauli Coal®elds, India. Singrauli extends over 2200 km2 (238470 ±248120 N, 818480 ±828520 E and elevations of 280± 519 m above mean sea level), of which 80 km2 lie in Uttar Pradesh and the rest in Madhya Pradesh (Fig. 1). The climate is tropical monsoonal and the year is divisible into a mild winter (November±February), a hot summer # 2001 Annals of Botany Company

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Singh and SinghÐEect of Fertilization on Tree Growth on Mine Spoil INDIA

N

GO

82° 45'

T O OB R A

82° 35'

RB

I

TO

RE

NU

KO

OT

JHINGURDA

Revegetation site Coal mines

M.P. U.P.

KAK

RI

Road

24° 10'

24° 10'

JAYANT DUDHICHUA NIGAHI

MOHER

BINA

AMLOHRI

KHADIA

82° 35'

MARRAK

82° 45'

F I G . 1. Location of study site (revegetation site) within Jayant coal mine. Jayant coal mine is one of the 11 coal mine blocks of the Singrauli Coal®elds. M.P., Madhya Pradesh; U.P., Uttar Pradesh.

(April±June) and a warm rainy season (July± September). March and October are transitional months. Mean monthly minimum temperature within an annual cycle ranges from 6.4 to 28 8C and mean monthly maximum from 20 to 42 8C. The annual rainfall averages 1069 mm, 90 % of which occurs during the period between June and September. The texture of the spoil material was 80 % sand, 10 % silt, and 10 % clay, with a pH of 7.4, total N 0.018 % and total P 0.01 % (Singh, 1999). Soil cores to a depth of 10 cm consisted of 75 % of particles greater than 2 mm in diameter. The potential natural vegetation is a tropical dry deciduous forest. Experimental design and methods Nursery-raised 1-year-old individuals of the following nine tree species were planted on fresh ¯at mine spoil in July 1993: Albizia lebbeck, Acacia catechu, Azadirachta indica, Dalbergia sissoo, Gmelina arborea, Phyllanthus emblica, Pongamia pinnata, Tectona grandis and Terminalia bellirica. All species are native, and are natural components of a dry tropical deciduous forest. The seedlings were planted in

20 m 20 m plots with a spacing of 2 m 2 m. Plots were separated from each other by a 5 m strip. Fertilizer treatment was applied annually in July in 1994±1996, and consisted of a full dose of NPK, a half dose of NPK, and a control without fertilizer amendment. Full dose fertilizer treatment was 60 kg ha ÿ1 N as urea, 30 kg ha ÿ1 P as single super phosphate, and 40 kg ha ÿ1 K as muriate of potash. Urea and single super phosphate were applied in granular form and muriate of potash in powder form. Three replicate plots were maintained for each treatment. Thus, at the rate of 7 kg ha ÿ1 for all nine species there was a total of 81 plots. From July 1994, the grass Pennisetum pedicellatum was seeded in 20 cm wide belts between rows of trees to avoid root competition with trees. The aim behind grass seeding was to increase organic matter input into the mine spoil. Besides this, grass cover would serve as a mulch, nurse crop, and a trap for wind-blown seeds and other materials. Furthermore, ground cover decreases leaching losses of nutrients in young plantations (McLaughlin et al., 1985). A total of 15 individuals for each species, distributed equally between the three replicate plots, and selected

Singh and SinghÐEect of Fertilization on Tree Growth on Mine Spoil at random avoiding edge-rows, was used for growth measurements for each treatment. Height and diameter measurements were made in April 1996 (33 months after plantation) and in December 1997 (53 months after plantation). Diameter (d) was measured at 20 cm above the ground surface. Height (h) was measured using a scaled bamboo stick. During the second sampling (53 months after plantation) crown diameter and area were also measured. Crown area (CA) was estimated as CA Cd1 Cd2 =42 p, where Cd1 and Cd2 are crown diameters at two perpendicular axes beneath the canopy at ground surface. Volumes of trees (V) were calculated as a cone (V d 2 h). Two architectural traits, viz. slopes (b) of the relationships between the log-transformed height and diameter values, and between log-transformed crown mass and trunk mass values were determined through regression analysis. Harvesting of trees from the restoration site was prohibited, hence we used proxy variables for crown mass and trunk mass. For a variety of tropical trees, ranging from understorey to emergent, the square of canopy area is nearly equal to the crown mass and d 2h approximates the trunk mass (O'Brien et al., 1995). Therefore, in our study, the square of crown area served as a proxy variable for crown mass. Mature, healthy leaves were collected from exposed, midcanopy positions of the tagged trees in September 1997, dried at 80 8C and powdered for chemical analysis. Foliage N was estimated with the microkjeldahl method of Jackson (1958). Phosphorus was analysed after digestion in a mixture of HClO4 , HNO3 and H2SO4 (1 : 5 : 1), using the phosphomolybdic acid blue method of Jackson (1958). Tree growth was assessed as increments in height, diameter and volume from the values measured in April 1996 and December 1997. Annual increments of the above variables were calculated from the dierences between the two measurements. The in¯uence of height and diameter attained by the trees at the ®rst sampling (33 months after planting) on subsequent annual growth, and the in¯uence

779

of leaf nutrient status on annual growth were explored through regression analyses. Data from individual trees were subjected to analysis of variance using the General Linear Model of the SPSS package (SPSS/PC, 1993). The overall restoration plan for the site did not permit mixing of plots of dierent species in a block. Therefore, the plots of the nine species were in eect blocks, and the treatments were randomized within the blocks. Because of this, plot was not included as a source of variation in the analysis and 15 individuals were treated as replicates. Dierences between treatment means were tested for signi®cance through a two-tailed Student's t-test.

R E S ULT S Height, diameter and volume Analysis of variance revealed signi®cant eects of treatment and sampling date on height, diameter and tree volume. Species treatment and species sampling date interactions were signi®cant for height, diameter and volume, but the sampling date treatment interaction was signi®cant only for volume (Table 1). Leguminous species. The leguminous trees in fertilized plots were 7±15 % taller than control trees on the ®rst sampling date (33 months after plantation) and 4±16 % taller than controls on the second sampling date (53 months after plantation) (Table 2). Compared to controls, the tree diameters were 4±27 % greater at the ®rst and 4±31 % greater at the second sampling in fertilized plots. A. catechu did not show a signi®cant response to fertilization, whereas the full NPK dose had a signi®cant eect on diameter and volume of D. sissoo at the ®rst sampling only. In A. lebbeck, full NPK treatment had a signi®cant eect on height, diameter and volume. In P. pinnata, diameter and volume were signi®cantly increased by full NPK treatment. Halfstrength NPK treatment had no signi®cant eect on any of the species.

T A B L E 1. Summary of ANOVA on height diameter and volume, and growth rates (height, diameter and volume increments) for nine tree species grown with two levels of NPK and a control Height Source of variation

d.f.

Diameter

Volume

F

P

F

P

F

P

Dimension Species Sampling date Treatment Species sampling date Species treatment Sampling date treatment Species sampling date treatment Residual

8 1 2 8 16 2 16 756

120.07 563.48 59.48 7.25 4.41 2.68 0.47

0.000 0.000 0.000 0.000 0.000 0.069 0.959

58.76 251.36 74.34 3.07 2.43 2.87 0.28

0.000 0.000 0.000 0.002 0.001 0.057 0.998

60.46 250.20 53.10 14.41 6.05 12.34 2.23

0.000 0.000 0.000 0.000 0.000 0.000 0.004

Growth rates Species Treatment Species treatment Residual

8 2 16 378

132.14 48.94 8.66

0.000 0.000 0.000

75.74 70.81 6.98

0.000 0.000 0.000

46.15 39.53 7.15

0.000 0.000 0.000

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Singh and SinghÐEect of Fertilization on Tree Growth on Mine Spoil

T A B L E 2. Height, diameter, volume and crown cover for nine tree species of two dierent ages grown on mine spoil with two levels of NPK and a control 33 months after plantation Species Legumes Acacia catechu Albizia lebbeck Dalbergia sissoo Pongamia pinnata Non-legumes Azadirachta indica Gmelina arborea Phyllanthus emblica Tectona grandis Terminalia bellirica

53 months after plantation

Treatment

Height (m)

Diameter (cm)

Tree volume (d 2h) (cm3)

Height (m)

Diameter (cm)

Tree volume (d 2h) (cm3)

Control Half NPK Full NPK Control Half NPK Full NPK Control Half NPK Full NPK Control Half NPK Full NPK

2.49a 2.74a 2.73a 3.24a 3.46ab 3.74b 3.21a 3.67a 3.42a 2.67a 2.92a 2.94a

5.14a 5.68a 5.50a 6.01a 6.73ab 7.66b 4.84a 5.03ab 5.65b 4.11a 4.49a 5.92b

8460a 9727a 9699a 13 024a 18 504ab 24 061b 7985a 10 081ab 12 171b 4919a 6468ab 8877b

3.74a 4.33a 4.21a 4.32a 4.58ab 5.01b 4.67a 5.3a 4.85a 3.92a 4.09a 4.24a

6.89a 8.34a 7.81a 7.66a 8.78ab 10.01b 6.48a 6.73a 7.42a 5.63a 6.23ab 7.55b

22 33 30 28 41 54 20 26 29 13 17 25

Control Half NPK Full NPK Control Half NPK Full NPK Control Half NPK Full NPK Control Half NPK Full NPK Control Half NPK Full NPK

2.47a 2.95b 3.05b 3.05a 3.15a 4.03b 2.21a 2.54b 2.48ab 1.63a 2.07b 2.45b 1.70a 1.92ab 2.07b

4.44a 5.42b 6.23b 6.28a 6.90a 8.59b 3.49a 4.63b 4.72b 3.67a 4.22a 5.09b 4.27a 4.66a 5.77b

5304a 9180b 13 433b 15 799a 17 137a 31 533b 3505a 6050a 6644a 2486a 4207b 7728c 3484a 4741a 7462b

3.23a 3.97b 4.05b 4.08a 4.55a 6.05b 2.77a 3.35b 3.25ab 2.13a 2.8b 3.17b 2.25a 2.52ab 2.78b

5.86a 7.11b 7.88b 8.35a 9.91a 12.52b 4.41a 6.17b 6.21b 4.41a 5.12ab 6.17b 5.53a 5.96a 7.96ab

11 903a 20 660b 27 823b 36 754a 49 950a 99 741b 6995a 12 152ab 14 963b 4677a 8336b 14 737b 7656a 10 137a 18 860b

825a 086a 092a 107a 664ab 964b 320a 060a 310a 389a 098a 685b

Crown cover (m2) 4.58a 5.64a 5.87a 5.91a 5.93a 7.15a 7.30a 8.08a 8.69a 5.57a 6.69a 7.30a 3.85a 5.60b 6.74b 7.19a 7.69a 11.26b 4.74a 6.42b 6.63b 1.18a 1.85b 2.69b 1.48a 1.73ab 2.0b

Values in a column for each species suxed with dierent letters are signi®cantly dierent from each other at P 5 0.05.

Non-leguminous species. Trees in fertilized plots were 3± 50 % taller at the ®rst sampling and 12±49 % taller at the second sampling compared to controls. In fertilizer amended plots the diameters were 9±40 % greater at the ®rst sampling and 8±50 % greater than controls at the second sampling. The full NPK treatment had a signi®cant impact on height, diameter and volume in all nonleguminous species (Table 2). The eect of half-strength NPK treatment was signi®cant on height, diameter and volume in A. indica, on height and volume in T. grandis, and on height and diameter in P. emblica.

P. pinnata. In this species full strength NPK resulted in an increase in b-value from around 0.5 to 0.7. Non-leguminous species. The log-transformed height : diameter relationships were signi®cant for all three treatments in all non-leguminous species (Table 3). The b-values in control trees were 0.67 for A. indica and G. arborea, between 0.4 and 0.57 for T. bellirica and P. emblica, and almost 1.0 for T. grandis. Application of NPK resulted in a decrease in b-values in A. indica, G. arborea and P. emblica. But in T. bellirica, fertilizer treatment increased the slope from 0.4 to around 1. In T. grandis, half-strength NPK reduced the slope whereas the full NPK dose increased it.

Height : diameter relationships Leguminous species. The log-transformed height:diameter relationships were signi®cant for all three nutrient treatments in leguminous tree species for both sampling periods (Table 3), and slopes (b-values) were consistent between the sampling periods. In P. pinnata the slope was around 0.50, in D. sissoo and A. catechu it was nearer to 0.67, and in A. lebbeck it was less than 0.50. Compared to controls, application of half-strength NPK resulted in increased b-values for all the leguminous species except

Crown mass : trunk mass relationships Leguminous species. The log-transformed crown mass and trunk mass relationships were signi®cant for all three nutrient treatments in all leguminous species (Table 4). The slope of the relationship increased from control to full NPK treatment in A. catechu, A. lebbeck and D. sissoo. In P. pinnata, the slope was greater in the full NPK treatment than in half-strength NPK as compared to the control.

Terminalia bellirica

Tectona grandis

Phyllanthus emblica

Gmelina arborea

Non-legumes Azadirachta indica

Pongamia pinnata

Dalbergia sissoo

Albizia lebbeck

Legumes Acacia catechu

Species



Treatment

ÿ0.038 + 0.22 0.104 + 0.27 0.069 + 0.23 ÿ0.212 + 0.27 ÿ4.066 + 0.18 0.606 + 0.19 0.091 + 0.11 0.108 + 0.18 0.111 + 0.16 ÿ0.698 + 0.26 ÿ0.377 + 0.17 ÿ0.721 + 0.21 ÿ0.054 + 0.14 ÿ0.786 + 0.20 ÿ0.938 + 0.35

ÿ0.070 + 0.16 ÿ0.070 + 0.25 ÿ0.224 + 0.32 0.522 + 0.18 0.310 + 0.16 0.350 + 0.22 ÿ0.010 + 0.23 ÿ4.480 + 0.34 ÿ0.075 + 0.29 0.255 + 0.13 0.355 + 0.15 ÿ0.130 + 0.21

Intercept

0.632 + 0.15 0.578 + 0.16 0.572 + 0.12 0.720 + 0.15 0.598 + 0.09 0.367 + 0.09 0.568 + 0.09 0.539 + 0.11 0.518 + 0.10 0.910 + 0.20 0.768 + 0.12 0.989 + 0.13 0.406 + 0.10 0.932 + 0.13 0.948 + 0.20

0.605 + 0.10 0.619 + 0.15 0.717 + 0.19 0.365 + 0.10 0.493 + 0.09 0.477 + 0.11 0.745 + 0.14 0.800 + 0.21 0.751 + 0.17 0.517 + 0.09 0.478 + 0.10 0.726 + 0.13 0.57 0.50 0.61 0.65 0.75 0.56 0.75 0.62 0.65 0.60 0.76 0.81 0.57 0.79 0.63

0.73 0.57 0.52 0.49 0.71 0.59 0.67 0.53 0.60 0.70 0.62 0.72 0.001 0.003 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000

0.000 0.000 0.002 0.003 0.000 0.000 0.000 0.002 0.000 0.000 0.000 0.000 0.0641 + 0.26 0.266 + 0.31 0.228 + 0.25 ÿ0.155 + 0.31 0.153 + 0.22 0.897 + 0.23 0.201 + 0.13 0.232 + 0.21 0.277 + 0.17 ÿ0.592 + 0.29 ÿ0.214 + 0.19 ÿ0.623 + 0.24 0.110 + 0.16 ÿ0.751 + 0.23 ÿ0.962 + 0.42

0.145 + 0.19 0.170 + 0.31 ÿ0.011 + 0.37 0.741 + 0.20 0.470 + 0.18 0.530 + 0.11 0.168 + 0.26 0.118 + 0.39 0.089 + 0.33 0.495 + 0.16 0.561 + 0.19 ÿ0.049 + 0.26

Intercept

0.626 + 0.15 0.567 + 0.17 0.571 + 0.12 0.733 + 0.15 0.595 + 0.09 0.358 + 0.09 0.556 + 0.10 0.537 + 0.11 0.496 + 0.12 0.903 + 0.20 0.762 + 0.12 0.972 + 0.14 0.410 + 0.10 0.935 + 0.13 0.954 + 0.20

0.612 + 0.10 0.609 + 0.14 0.702 + 0.18 0.355 + 0.10 0.487 + 0.08 0.470 + 0.11 0.734 + 0.13 0.807 + 0.20 0.742 + 0.16 0.506 + 0.09 0.464 + 0.11 0.739 + 0.12

Slope

0.57 0.48 0.61 0.64 0.74 0.54 0.73 0.62 0.66 0.60 0.75 0.80 0.57 0.79 0.62

0.74 0.56 0.53 0.47 0.71 0.57 0.68 0.53 0.60 0.68 0.60 0.71

r2

P

r2

Slope



0.001 0.003 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000

0.000 0.001 0.002 0.004 0.000 0.001 0.000 0.001 0.000 0.000 0.000 0.000

P

T A B L E 3. Regression of log10 height (m) and log10 diameter (cm) for nine tree species of two dierent ages grown on mine spoil under two levels of NPK and a control

Singh and SinghÐEect of Fertilization on Tree Growth on Mine Spoil 781

782


T A B L E 4. Regression of crown mass ( proxy variable: log10 crown area in m2) to trunk mass [ proxy variable: (d2 in cm2) (h in cm)] for nine tree species grown on mine spoil under two levels of NPK and a control Treatment Legumes Acacia catechu Control Half NPK Full NPK Albizia lebbeck Control Half NPK Full NPK Dalbergia sissoo Control Half NPK Full NPK Pongamia pinnata Control Half NPK Full NPK Non-legumes Azadirachta indica Control Half NPK Full NPK Gmelina arborea Control Half NPK Full NPK Phyllanthus emblica Control Half NPK Full NPK Tectona grandis Control Half NPK Full NPK Terminalia bellirica Control Half NPK Full NPK

Intercept

Slope

r2

P

ÿ4.83 + 1.16 ÿ7.47 + 2.02 ÿ7.84 + 1.8

0.79 + 0.12 1.05 + 0.19 1.11 + 0.17

0.77 0.69 0.75

0.000 0.000 0.000

ÿ3.23 + 1.55 ÿ4.87 + 1.41 ÿ6.63 + 1.63

0.67 + 0.15 0.80 + 0.13 0.97 + 0.15

0.59 0.73 0.76

0.000 0.000 0.000

ÿ4.94 + 0.29 ÿ7.07 + 2.19 ÿ7.93 + 2.67

0.89 + 0.29 1.10 + 0.21 1.19 + 0.26

0.42 0.66 0.61

0.009 0.000 0.000

ÿ5.85 + 2.58 ÿ3.34 + 2.94 ÿ9.82 + 2.96

0.98 + 0.27 0.73 + 0.30 1.35 + 0.29

0.49 0.30 0.62

0.003 0.032 0.000

ÿ8.19 + 2.13 ÿ10.91 + 1.77 ÿ10.42 + 1.22

1.16 + 0.22 1.44 + 0.18 1.39 + 0.12

0.66 0.82 0.91

0.000 0.000 0.000

ÿ6.99 + 1.81 ÿ5.79 + 1.91 ÿ5.03 + 2.12

1.05 + 0.17 0.91 + 0.18 0.86 + 0.18

0.73 0.66 0.62

0.000 0.000 0.000

ÿ4.55 + 1.24 ÿ2.78 + 2.38 ÿ5.06 + 1.22

0.88 + 0.14 0.68 + 0.25 0.93 + 0.13

0.74 0.36 0.79

0.000 0.018 0.000

ÿ9.61 + 1.42 ÿ10.29 + 1.44 ÿ12.26 + 1.34

1.18 + 0.17 1.28 + 0.16 1.49 + 0.14

0.79 0.83 0.89

0.000 0.000 0.000

ÿ6.54 + 1.71 ÿ11.21 + 1.42 ÿ13.18 + 2.22

0.84 + 0.19 1.34 + 0.15 1.48 + 0.23

0.59 0.85 0.75

0.000 0.000 0.000

Non-leguminous species. The log-transformed crown mass and trunk mass relationships were signi®cant for all three nutrient treatments in all non-leguminous species (Table 4). The slope of the relationship increased from control to full NPK treatment in T. grandis and T. bellirica, whereas it decreased from control to full NPK treatment in G. arborea. In A. indica, fertilizer application resulted in an increase in slope but the value was only slightly higher in half-strength NPK compared to full NPK treatment. In P. emblica, the slope was greater in full NPK but lower in half NPK in comparison to the control. Foliar N and P concentrations Leguminous species. The foliar N and P concentrations increased from control to full NPK treatment in all leguminous species (Table 5). The eect of both NPK treatments was signi®cant on foliar N concentration in A. lebbeck and D. sissoo, whereas in A. catechu and P. pinnata the eect of half-strength NPK was not signi®cant. The eect of both NPK doses was signi®cant

on foliar P concentration in all leguminous species except for D. sissoo, whereas half-strength NPK treatment did not have a signi®cant eect and dierences between halfstrength NPK and full NPK treatments were generally not signi®cant. Non-leguminous species. Foliar N and P concentrations increased from control to full NPK treatment in all nonleguminous species (Table 5). The eect of both half- and full-strength NPK treatments was signi®cant on foliar N concentration in all species. Application of half-strength NPK fertilizer did not have a signi®cant eect on foliar P concentration in any species, whereas full NPK dose had a signi®cant eect on foliar P concentration in all species. Tree growth Analysis of variance indicated a signi®cant eect of treatment on height, diameter and volume growth (annual increments). The species treatment interaction was also signi®cant for height, diameter and volume growth

Singh and SinghÐEect of Fertilization on Tree Growth on Mine Spoil T A B L E 5. N and P concentrations in mature foliage for nine tree species grown on mine spoil under two levels of NPK and a control Species Legumes A. catechu A. lebbeck D. sissoo P. pinnata

Non-legumes A. indica G. arborea P. emblica T. grandis T. bellirica

T A B L E 6. Annual height, diameter and volume increments per tree species grown on mine spoil under two levels of NPK and a control

Treatment

N ( %)

P ( %)


2.19a 2.28ab 2.34b 2.05a 2.13b 2.19b 1.95a 2.04b 2.12c 2.14a 2.20ab 2.27b

0.134a 0.178b 0.196b 0.143a 0.183b 0.201b 0.160a 0.183ab 0.205b 0.138a 0.183b 0.196b

Legumes A. catechu


1.76a 1.88b 1.98b 1.82a 1.91b 2.05c 1.20a 1.31b 1.39c 1.01a 1.19b 1.27b 1.10a 1.25b 1.33b

0.165a 0.178ab 0.196b 0.165a 0.174ab 0.192b 0.111a 0.134ab 0.147b 0.103a 0.125ab 0.134b 0.107a 0.129ab 0.138b

Non-Legumes A. indica


suggesting that the eect of nutrient amendment depended upon the species (Table 1). Leguminous species. The height growth among legumes in control treatments ranged from 0.64 to 0.87 m per year (x 0.75 m per year per tree), diameter growth from 0.91 to 1.05 cm per year (x 0.98 cm per year per tree) and volume increment from 5116 to 9020 cm3 per year (x 7567 cm3 per year per tree) (Table 6). Half-strength NPK treatment increased the annual height increment by 1.6±28.4 %, diameter increment by 3.10±52.4 % and volume increment by 26.4±62.6 %, whereas full NPK treatment increased the height increment by 4.0±20.3 %, the diameter increment by 8.2±65.9 % and the volume increment by 38.5±105.3 % over controls. Height, diameter and volume increments in D. sissoo, height increment in P. pinnata and volume increment in A. catechu were not signi®cantly aected by fertilization. In A. lebbeck, halfstrength NPK treatment did not have a signi®cant eect on height and volume increments but signi®cantly aected the diameter increment. In P. pinnata, only full NPK treatment had a signi®cant eect on diameter and volume increments. Only half-strength NPK treatment had a signi®cant eect on height increment in A. catechu, whereas both levels of NPK had a signi®cant eect on diameter increment.

783

Species

A. lebbeck D. sissoo P. pinnata

G. arborea P. emblica T. grandis T. bellirica

Treatment

Height (m)

Diameter (cm)

Volume (cm3)


0.74a 0.95b 0.89ab 0.64a 0.65a 0.76b 0.87a 0.98a 0.86a 0.75a 0.70a 0.78a

1.05a 1.60b 1.38b 0.98a 1.22b 1.4b 0.98a 1.01a 1.06a 0.91a 1.04a 1.51b

8618a 14 016a 12 236a 9020a 13 825ab 18518b 7514a 9587a 10 404a 5116a 6467a 10 149b


0.45a 0.60b 0.58b 0.61a 0.83b 1.19c 0.32a 0.47b 0.44b 0.29a 0.43b 0.43b 0.32a 0.35a 0.42b

0.85a 1.01b 0.93ab 1.24a 1.8b 2.35b 0.55a 0.92b 0.89b 0.44a 0.53b 0.65b 0.76a 0.77a 1.3b

4004a 7012b 8583b 12 525a 18 642a 40 930b 2086a 4756b 4967b 1314a 2478b 4205b 2519a 3237a 6871b


Non-leguminous species. The height increment among non-legumes in the control treatment ranged from 0.29 to 0.61 m per year (x 0.39 m per year per tree), diameter increment from 0.44 to 1.24 cm per year (x 0.76 cm per year per tree) and volume increment from 1314 to 12 525 cm3 per year (x 4490 cm3 per year per tree). Compared to controls, the height increment was 9.4±48.3 % greater, the diameter increment 1.3±67.3 % greater and the volume increment 28.5±128.0 % greater under half-strength NPK treatment. Full NPK treatment increased the height increment by 29.9±95.0 %, the diameter increment by 9.4± 89.5 % and the volume increment by 114.4±226.8 % over controls (Table 6). The full NPK treatment had a signi®cant eect on height, diameter and volume increments in all the non-leguminous species (except for diameter increment in A. indica). Height, diameter and volume increments in P. emblica and T. grandis, height and diameter increments in G. arborea and height and volume increments in A. indica were signi®cantly aected by half-strength NPK treatment (no eect on T. bellirica). Eect of tree dimensions on subsequent growth Signi®cant positive relationships occurred between height and subsequent height growth and between diameter and


Height increment (m per year per tree)

1.5

A Control

C Control Diameter increment (cm per year per tree)

784

1.0

0.5

0.0 2

3

4

1

5

2

1

B Fertilized

3

4

5

D Fertilized Diameter increment (cm per year per tree)


2

0 1

1.5

3

1.0

0.5

0.0

3

2

1

0 1

2

3

4

5

Height (m)

3

6

9

12

Diameter (cm)

F I G . 2. Relationships between initial height (33 months after plantation) and subsequent annual height increment, and between initial diameter and subsequent annual diameter increment for trees planted on mine spoil with and without fertilizer ( full dose) application. Regression equations are (A) y 0.113 0.177x (r2 0.33, P 5 0.01); (B) y 0.353 0.119x (r2 0.121, P 5 0.01); (C) y 0.688 0.038x (r2 0.033, P 5 0.05); and (D) y 1.134 0.021x (r2 0.005, P 4 0.05). Data are for 135 (nine species 15 individuals) trees each from control and fertilized ( full dose) plots.

subsequent diameter increment among trees in unfertilized plots across all species (Fig. 2). These relationships were weaker or not signi®cant for plants receiving the full NPK dose (Fig. 2). Relationships between leaf nutrient status and tree growth Height, diameter and volume increments had signi®cant positive relationships with foliar N and P concentrations (Fig. 3). DISCUSSION Self supporting plants that allocate too little biomass to stems may buckle under their own mass or break, due to wind stress or other loads (O'Brien et al., 1995). Tree

architecture (height-diameter, crown mass-trunk relationships) is therefore of considerable importance in selecting species for plantation on mine spoils. The present species diered considerably in architectural traits, which were also in¯uenced by nutrient amendment. The slope (G) of logtransformed height : diameter relationships at the ®rst sampling varied from 0.365 to 0.989 and for the second sampling from 0.355 to 0.972, compared to the range 0.597 to 0.736 recorded for mature trees of eight neotropical tree species of Barro Colorado Island, Panama (O'Brien et al., 1995). The present analysis suggested that the legumes A. catechu and D. sissoo and the non-legumes A. indica and G. arborea followed the elastic similarity model of tree growth. According to Rich (1986), when the scaling exponent b between diameter and height is equal to 0.67, then the tree



1.5

Diameter increment (cm per year per tree)

D

B

E

C

F

1.0 0.5

2.4 1.6 0.8

45000 Volume increment (cm3 per year per tree)

A

785

30000 15000 0. 08

1.6 Leaf N (%)

2.4

0.08

0.16 Leaf P (%)

0.2

F I G . 3. Relationships between leaf nutrient status and growth parameters for trees planted on mine spoil. Regression equations are (A) y ÿ1.73 0.554x (r2 0.697, P 5 0.01); (B) y 0.027 0.587x (r2 0.376, P 5 0.01); (C) y ÿ7823.003 9530.92x (r2 0.273, P 5 0.01); (D) y ÿ2.55 5.625x (r2 0.554, P 5 0.01); (E) y ÿ0.31 8.725x (r2 0.431, P 5 0.01); and (F) y ÿ14 958 152 040x (r2 0.360, P 5 0.01). Data are treatment means for the nine species (n 9 3 27).

is said to maintain elastic similarity through ontogeny. Large arborescent growth forms usually follow an elastic similarity model (Norberg, 1988). An alternative model of tree growth is constant stress, where b 0.5. This model is based on the assumption that trunk taper is such that stress produced by wind pressure along the stem is equalized (Dean and Long, 1986). The legume P. pinnata and the non-legume P. emblica were found to follow this constant stress model of growth. According to Niklas (1992), the constant stress model is the most generally applicable model

in a windy habitat. A third model of geometric similarity, where b 1.0, presumes that the proportions of a tree remain constant through ontogeny. Smaller growth forms ( from mosses to small trees) are best described by this model (Norberg, 1988). T. grandis was the only tree species which exhibited a geometric similarity model. In A. lebbeck and T. bellirica, b-values were 50.5, ®tting none of the above three models of tree growth. These two species were shorter relative to their diameter suggesting a higher margin of safety against buckling than other species.

786


Nutrient enrichment appears to in¯uence the heightdiameter relationship considerably in some species. For example, in T. bellirica b increased from 50.5 (constant stress) to around 1.0 (geometric similarity) and in G. arborea b declined from around 0.7 (elastic similarity) to 50.5. As crown mass to trunk mass ratio is expected to remain constant during tree growth, the slope of regression between the proxy variables representing crown mass and trunk mass should not be signi®cantly dierent from unity (O'Brien et al., 1995). In this study the slope value was around unity in A. indica, D. sissoo, G. arborea, P. emblica, T. grandis and T. bellirica suggesting a constant crown mass to trunk mass ratio. In A. catechu and A. lebbeck, however, the slope value was well below unity suggesting that in these species allocation favoured trunk mass over crown mass. These two species may be highly resistant to wind action but at the cost of photosynthetic tissue. Application of NPK increased the slope value towards unity in A. catechu and A. lebbeck and beyond unity in A. indica, T. grandis and T. bellirica. Thus fertilizer amendment resulted in heavier crowns in these species. Hulm and Killham (1990) observed a similar pattern following fertilizer application in Sitka spruce. Trees with heavier crowns will be highly prone to wind action, particularly on a loose substratum such as mine spoil. In D. sissoo and G. arborea, fertilizer amendment did not cause any major shift in allocation between support and photosynthetic systems. Average height, diameter and volume increments for leguminous species were greater than those for nonleguminous species, suggesting that the leguminous species have a greater capacity for growth in nutrient-poor habitats. This may be due to the nitrogen ®xing ability of leguminous species. Our study also suggested that the foliar N concentration in leguminous species was greater than that of non-leguminous species. Fertilization of mine spoil promoted growth in all nine tree species, but the magnitude of the eect varied among species and ranged from non-signi®cant to highly signi®cant. The eect of fertilization on growth rates for height, diameter and volume was greatest in G. arborea and least in D. sissoo. Rates of growth under full NPK treatment in G. arborea were two±three times that of the control. Tanner et al. (1992) reported that trunk growth rate doubled following fertilizer application for all tree species in a Venezuelan montane forest. Studies indicate that N, in particular, limits production early in soil development (Vitousek et al., 1993) and that greatest growth occurs in plots receiving both N and P (Raich et al., 1996). Several other studies have also suggested that the diameter growth is greater in fertilized plants compared to control plants (Gerrish and Bridges, 1984; Tanner et al., 1990, 1992; Herbert and Fownes, 1995; Vitousek and Farrington, 1997). Hulm and Killham (1990) reported enhanced growth in trees of Sitka spruce fertilized with urea, as compared to controls over two growing seasons. In our study, the response to NPK fertilization was greater in nonleguminous than in leguminous species. Nitrogen ®xing species may overcome nitrogen de®ciency by virtue of their N2-®xing ability, hence they may remain unaected by

N fertilization but they may respond to P fertilization (McMaster et al., 1982). A large degree of variation occurred in tree volume (d 2h), which frequently ®gures as a proxy variable for biomass (Zavitkovski and Stevens, 1972; DeBell et al., 1989). In this study, this variability was greater among legumes than nonlegumes. Taking all species into consideration, full strength NPK increased tree volume by 15±211 % at the ®rst sampling and from 32 to 215 % at the second year sampling. Nambiar and Fife (1987) found that 2 years after planting, stem volume of fertilized Pinus radiata trees was 71 % greater than that of control trees, and by 3.8 years of age, stem volume and biomass of N fertilized trees were twice those of controls. In A. catechu and G. arborea, the growth response to fertilization for height, diameter and volume was greater at the second compared to the ®rst sampling, suggesting an age interaction in growth response. Similarly, Nommik and Moller (1981) observed a maximum growth response to fertilization 5 years after fertilizer amendment in Scots pine. The greater growth in fertilized plots was accompanied by increased N and P concentrations in the foliage. In our study there was a positive relationship between growth rates (height, diameter and volume increments) and foliar N and P concentrations. Evidently, higher leaf nutrient status increases photosynthetic eciency, particularly in trees on nutrient-poor soils. N supply can aect plant growth and productivity by altering both leaf area and photosynthetic capacity (Sinclair, 1990; Frederick and Camberato, 1995). The photosynthetic capacity of leaves is reported to be related to their N content primarily because enzymes of the Calvin cycle represent the majority of leaf N (Evans, 1989). Fahey et al. (1998) reported an increase in foliar nutrient concentrations (N, P and K) in ®ve northern hardwood forest tree species in response to NPK fertilization. Our study clearly indicated that the tree species with lower foliar N concentration responded more to N fertilization in terms of increase in foliar N concentration compared to those with a higher foliar N concentration. A similar trend was observed for P concentration. This suggests that response of foliar N and P concentrations to fertilization depends on the initial foliar nutrient status of the plants. We found positive relationships between initial height and the subsequent height increment, and initial diameter and the subsequent diameter increment for trees on control plots. This demonstrates that plants that are able to attain greater height and diameter initially will continue to grow more rapidly. The application of full dose NPK, however, weakened these relationships, suggesting that fertilization tended to bring more uniformity among the growth of individuals (i.e. it eliminated the nutrient poverty of suppressed individuals). A positive relationship between height and height increment has also been observed in saplings of Banksia grandis (Abbott, 1985). We conclude that nutrient amendment promoted growth in all the tree species studied, increased N and P concentrations in the foliage, and tended to bring more uniformity among the growth of individuals, by eliminating nutrient poverty of suppressed individuals. However, the response to fertilizer application varied between species.

Singh and SinghÐEect of Fertilization on Tree Growth on Mine Spoil The species selected for this study also varied with respect to architectural traits and hence wind stability which was aected by nutrient perturbation. Fertilizer amendment might make those trees with high crown mass:trunk mass ratios (e.g. Azadirachta indica, Tectona grandis and Terminalia bellirica) susceptible to wind load. L I T E R AT U R E C I T E D Abbott I. 1985. Rate of growth of Banksia grandis Willd. (Proteaceae) in western Australian forest. Australian Journal of Botany 33: 381±391. Dean TJ, Long JN. 1986. Validity of constant-stress and elasticinstability principles of stem formation in Pinus contorta and Trifolium pratense. Annals of Botany 58: 833±840. DeBell DS, Whitesell CD, Schubert TH. 1989. Using N2-®xing Albizia to increase growth of Eucalyptus plantations in Hawaii. Forest Science 35: 64±75. Evans JR. 1989. Photosynthesis and nitrogen relationships in leaves of C3 plants. Oecologia 78: 9±19. Fahey TJ, Battles JJ, Wilson GF. 1998. Responses of early successional northern hardwood forests to changes in nutrient availability. Ecological Monographs 68: 183±212. Frederick JR, Camberato JJ. 1995. Water and nitrogen eects on winter-wheat in the south-eastern coastal plain. II. Physiological responses. Agronomy Journal 87: 527±533. Gerrish G, Bridges KW. 1984. A thinning and fertilizer experiment in Metrosideros dieback stands in Hawaii. Hawaii Botanical Science Paper 43: 1±107. Gerrish G, Mueller-Dombois D, Bridges KW. 1988. Nutrient limitation and Metrosideros dieback in Hawaii. Ecology 69: 723±727. Herbert DA, Fownes JH. 1995. Phosphorus limitation of forest leaf area and net primary productivity on highly weathered tropical montane soils in Hawaii. Biogeochemistry 29: 223±235. Hulm SC, Killham K. 1990. Response over two growing seasons of a Sitka spruce stand to 15N-urea fertilizer. Plant and Soil 124: 65±72. Iverson LR, Wali MK. 1982. Reclamation of coal mined lands: the role of Kochia scoparia and other pioneers in early succession. Reclamation and Revegetation Research 1: 123±160. Jackson ML. 1958. Soil chemical analysis. Englewood Clis, NJ: Prentice-Hall. Jha AK, Singh JS. 1991. Spoil characteristics and vegetation development of an age series of mine spoils in a dry tropical environment. Vegetatio 97: 63±76. Jha AK, Singh JS. 1992. In¯uence of microsites on redevelopment of vegetation on coal mine spoils in a dry tropical environment. Journal of Environmental Management 36: 95±116. King DA. 1981. Tree dimensions, maximizing the rate of height growth in dense stands. Oecologia 51: 351±356. King DA. 1986. Tree form, height growth, and susceptibility to wind damage in Acer saccharum. Ecology 67: 980±990. McLaughlin RA, Pope PE, Hansen EA. 1985. Nitrogen fertilization and ground cover in a hybrid poplar plantation: eects on nitrate leaching. Journal of Environmental Quality 14: 241±245. McMahon TA. 1973. Size and shape in biology. Science 179: 1201±1204. McMaster GS, Jow WM, Kummerow J. 1982. Response of Adenostoma fasciculatum and Ceanothus greggii chaparral to nutrient additions. Journal of Ecology 70: 745±756. Nambiar EKS, Fife DN. 1987. Growth and nutrient retranslocation in needles of radiata pine in relation to nitrogen supply. Annals of Botany 60: 147±156. Niklas KJ. 1992. Plant biomechanics, an engineering approach to plant form and function. Chicago, IL: University of Chicago Press.

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Nommik H, Moller G. 1981. Nitrogen recovery in soil and needle biomass after fertilization of a Scots pine stand, and growth responses obtained. Studies in Forest Science 159: 5±37. Norberg RA. 1988. Theory of growth geometry of plants and selfthinning of plant populations: geometric similarity, elastic similarity, and dierent growth models of plants. American Naturalist 131: 220±256. O'Brien ST, Hubbell SP, Spiro P, Condit R, Foster RB. 1995. Diameter, height, crown and age relationships in eight neotropical tree species. Ecology 76: 1926±1939. Piha MI, Vallack HW, Reeler BM, Michael N. 1995. A low input approach to vegetation establishment on mine and coal ash wastes in semiarid regions. I. Tin mine tailings in Zimbabwe. Journal of Applied Ecology 32: 372±381. Raich JW, Russell AR, Crews TE, Farrington H, Vitousek PM. 1996. Both nitrogen and phosphorus limit plant production on young Hawaiian lava ¯ows. Biogeochemistry 32: 1±14. Rich PM. 1986. Mechanical architecture of arborescent rain forest palms. Principes 30: 117±131. Schoenholtz SH, Burger JA, Kreh RE. 1992. Fertilizer and organic amendment eects on mine soil properties and revegetation success. Soil Science Society of America Journal 56: 1177±1184. Sinclair TR. 1990. Nitrogen in¯uence on the physiology of crop yield. In: Rabbinge R, Goudriaan J, van Keulen H, De Vries Penning FWT, van Laar HH, eds. Theoretical production ecology: re¯ections and prospects. Wageningen, Netherlands: Pudoc, 41±55. Singh A. 1999. Revegetation of coal mine spoil: in¯uence of nutrient amendment and neighbouring species on growth performance and foliar nutrient dynamics of woody species. PhD Thesis, Banaras Hindu University, India. Singh A, Jha AK, Singh JS. 1996. In¯uence of NPK fertilization on biomass production of Pennisetum pedicellatum seeded on coal mine spoil. Tropical Ecology 37: 285±287. Singh JS, Jha AK. 1993. Restoration of degraded land: an overview. In: Singh JS, ed. Restoration of degraded land: concepts and strategies. Meerut, India: Rastogi Publications, 1±9. Singh JS, Singh KP, Jha AK. 1996. An integrated ecological study on revegetation of mine spoil. Final Technical Report submitted to the Ministry of Coal, Government of India, New Delhi. SPSS/PC. 1993. SPSS/PC for the IBM PC/XT/AT. Chicago, IL: SPSS Inc. Tanner EVJ, Kapos V, Franco W. 1992. Nitrogen and phosphorus fertilization eects on Venezuelan montane forest trunk growth and litterfall. Ecology 73: 78±86. Tanner EVJ, Kapos V, Freskos S, Healey JR, Theobald AM. 1990. Nitrogen and phosphorus fertilization of Jamaican montane forest trees. Journal of Tropical Ecology 6: 231±238. Vitousek PM, Farrington H. 1997. Nutrient limitation and soil development: Experimental test of a biogeochemical theory. Biogeochemistry 37: 63±75. Vitousek PM, Walker LR, Whiteaker LD, Matson PA. 1993. Nutrient limitation to plant growth during primary succession in Hawaii Volcanoes National Park. Biogeochemistry 23: 197±215. Vitousek PM, Walker LR, Whiteaker LD, Mueller-Dombois D, Matson PA. 1987. Biological invasion by Myrica faya alters ecosystem development in Hawaii. Science 238: 802±804. Vogel WG. 1981. A guide for revegetating coal mine soils in the eastern United States. General Technical Report NE-68. United States Department of Agriculture Forest Service. Wali MK. 1975. Practices and problems of land reclamation in western North America. University Grand Forks: North Dakota Press, 1±17. Zavitkovski J, Stevens RD. 1972. Primary productivity of red alder ecosystems. Ecology 53: 235±242.