Relationship between some Growth Parameters and Browse Biomass Produced from Ailanthus excelsa Tree in Kordofan , Sudan

This study was conducted in Elobeid town, Sheikan Locality, North Kordofan State (29.35 0 -30.30 0 E and 12.25 0 -13.45 0 N) and Dilling town, Dilling Locality, South Kordofan State (alt. 9-12 N and lat. 29-31E) during 2009-2010 with the objective of studying browse biomass production, estimation of Ailanthus excelsa as affected by location and development of Regression equations for prediction of biomass from the tree depending on growth parameters. From the two sites, forty similar aged, normally growing trees were selected and leaf biomass was harvested, weighed fresh, sun dried and oven dried. Stem diameter, twig diameter, crown diameter and tree height were measured for each tree. T test was used to examine the effects of site on foliage biomass production that was calculated as ton/hectare. The estimated foliage biomass was correlated to the physical parameters measured. Regression equations were developed between the estimated foliage biomass and the growth parameters of the tree. The results indicated that trees in Dilling produced greater amount of foliage biomass than those in Elobeid. The study revealed that biomass production in Elobeid was 1.2 ton per hectare, compared to 2.3 ton per hectare in Dilling. It was found that in Elobeid, the biomass production was highly correlated to twig diameter and least correlation was observed between biomass and tree height whereas in Dilling, biomass production was highly correlated to tree height and least correlations were observed between biomass and the other parameters. The study concluded that site of growth had significant effects on foliage biomass production of A. excelsa. The amount of biomass was highly correlated between twig diameter in Elobeid and tree height in Dilling and the twig diameter developed best regression equations for biomass estimation for Ailanthus excelsa in Elobeid and El Dilling. Therefore, it can be recommended that more research should be carried out in different areas of the country where this tree is naturalized to investigate the effects of site and ecological factors on biomass production of the species and relationship between biomass produced and growth parameters in each site.


INTRODUCTION
The large livestock population in Sudan is mainly dependent on natural grazing derived from grasses, forbs, shrubs and trees.Browse is of special importance since most trees and shrubs are evergreen; contain high levels of proteins, vitamins and minerals that are necessary for animals when the natural grasses are nutritionally deficient.Many native trees and shrubs are considered browse species (O'Neill 1988).Some imported trees and shrubs are also grown on a limited scale for that purpose.Ailanthus excelsa was introduced to the country for its timber.In India, it is grown to be harvested or feed goats.The empirical observations have shown that A. excelsa is increasingly used for browse (Vogt, 1996).This fast growing naturalized species is not investigated in Sudan neither for determination of its production potential nor its nutritive value.

THE OBJECTIVE OF THE STUDY
To identify Relationship between some Growth Parameters and Browse Biomass Produced from Ailanthus excelsa Tree in Kordofan, Sudan.

Justifications
Production is a factor which is generally understood despite the considerable role of browse for livestock feeding especially during the dry season where most animals are dependent on low quality roughage that need to be supplemented.The browse is very important in terms of its protein supply which is often the factor enhancing livestock survival.In areas around water points, browse can also be used for better utilization of the natural grazing.For all those reasons, assessment of biomass production from trees becomes essential for proper management of livestock, range and forests.

MATERIALS AND METHODS
Indirect method of foliage biomass was used to determine amount of biomass produced from Ailanthus excelsa, this can be summarized as follows: A small unit of a plant (such as an average sized branch) is designated as the reference unit and clipped from the plant.This unit is 10-20% of the foliage weight of the average plant and is then held up against plants for which phytomass estimates are required.The number of reference units in other plants of interest is recorded.The weight of current season's growth or total mass of the reference unit is then determined.The weight of estimated plants equals the number of reference units multiplied by weight of the reference unit.The techniques works well for some shrubs, but is not well suited for compact, dense, un-segmented growth forms.

Growth Parameters of Ailanthus excelsa in Kordofan
The result of the effects of site growth condition on the growth parameters of Ailanthus excelsa in Kordofan are presented in table (4.1).Crown diameter in (m), tree height in (m), twig diameter in (cm), foliage biomass in (ton/ha) and stem diameter in (cm) were determined and their analysis of variance through T test has shown significant (<0.01) differences.The average value of total dry matter obtained was 10.20 and 5.16 kg per tree, (i.e., 2.82 and 1.34 ton /ha respectively).The foliage biomass was significantly (P<0.01)greater in Dilling than in Elobeid.Similarly, stem diameter (cm) and twig diameter (cm) had significant differences as affected by site.They were greater in Dilling than in Elobeid.There were no significant differences (p>0.05)observed in trees' height that could be attributed to the location of growth.Stem average diameter was 29.62cm in Dilling compared with 24.42cm for trees in Elobeid; crown diameter being 4.65m for A. excelsa in Dilling and 5.16m in Elobeid with tree heights of 6.18 and 6.63m in Dilling and Elobeid respectively.

The Correlation between Growth Parameters and Foliage Biomass excelsa Ailanthus
The results of correlation coefficient among parameters of Ailanthus excelsa grown in Elobeid are presented in table (4.2).The results on this aspect indicated that the correlation (both Para-metric and non-parametric) of tree twig diameter with biomass was positively (r =0.495) high and significant (p<0.01)indicating that twig diameter is a major and best indicator of biomass for Ailanthus excelsa in Elobeid while the correlation of height and stem diameter with biomass were low, indicating that it was not good indicators for biomass for this tree in the area.The result of correlation coefficient parameters of Ailanthus excelsa growing in Dilling are presented in table (4.3).The results indicated that the correlation (both Para-metric and non-parametric) of tree height with biomass was positively (r =0.69) high and significant (p<0.01)indicating that height was a major indicator of biomass for Ailanthus excelsa in Dilling while the correlation of twig diameter and stem diameter with biomass were low, indicating that they were not good indicators for biomass of the tree in the area.

The Regression Equations for Ailanthus excelsa in Elobeid and Dilling
For the purpose of development of the regression equations that could assist in reliable non-destructive method of estimation for foliage browse biomass produced from Ailanthus excelsa tree, the foliage biomass was analyzed using regression of foliage biomass produced against the growth parameters and were illustrated in figure (4.1).

The Regression Equations in Elobeid
The regression equations for prediction of foliage biomass values for Ailanthus excelsa tree grown in Elobied are presented in table (4.3).The equation for biomass prediction using twig diameter was Y=0.585+0.524Twith SE=0.219, while the equation for biomass prediction using tree height was Y=0.505-0.390H,SE= (0.418), whereas the equation for biomass prediction using crown diameter was Y=1.424+0.833C,SE= (0.66) and the regression for biomass prediction using stem diameter was Y=_0.093-0.279SSE= (0.117).It was found that in all those equations the best one for foliage biomass value predication of the tree could be obtained using twig diameter, while the poorest prediction value could be obtained using stem diameter and height.

Regression Equations for Ailanthus excelsa in Dilling
The regression equations for prediction of foliage biomass values for Ailanthus excelsa tree grown in Dilling are presented in table (4.4).The equation for biomass prediction using twig diameter was Y=0.621+0.228Twith SE=0.562, while the equation for biomass prediction using height was Y=2.703 + 0.678 H, SE= (1.209) whereas the equation for biomass prediction using crown diameter was Y=0.752 + 0.135 C, SE= (1.447) and the regression for biomass prediction using stem diameter was Y= -0.079 -0.083 S with SE= (0.214).It was found that in all those equations the best of foliage biomass value prediction of the tree could be obtained in Dilling using tree height, while poorest prediction value could be obtained using stem diameter and twig diameter.

Effects of Site on Growth Parameters of Ailanthus excelsa in Kordofan
R value for relationship between height and browse biomass in Dilling is not significant due to over grazing and trees cutting.
The foliage biomass produced from trees sampled has indicated that trees could produce significantly (P<0.01)higher foliage biomass in Dilling than those species planted in Elobeid.The better performance of A. excelsa in Dilling could be attributed to differences in soil types and higher annual amount of precipitation.Similar to Anon, (1986),Vogot (1996), Elamin (1991) Wong and Sharudin (1986), the tree could grow well in different locations though Vogot (1996) reported that the tree could grow in a wide variety of soils, but thrived best in porous sandy loams that was similar to soil type in Dilling.The amount of foliage estimated from the two sites as average values of total dry matter obtained was 2.82, 1.34 ton /ha per tree cut once a year.The variation values in dry matter for the two sites could also be attributed to variations in soil type and precipitation.Similar observations were reported by (Lugo, 1986) who reported that higher biomass yield could be attributed to higher amount of rainfall and soil fertility.
The amount of foliage biomass estimated for A. excelsa for both sites was comparable to values reported by Wong and Sharudin (1986) who reported annual dry matter yield of gliricidia as being about 2 t/ha per year.Wan Mohamed and Ravoof (1987) reported an annual dry matter production of 3.7-9.8t/ha with an annual crude protein yield of 0.8-1.3t/ha from 6-to 8-week cutting frequencies for Cajanus cajan

2 Growth Parameters and Foliage Biomass of Ailanthus excelsa in Kordofan
R value for Regression between biomass (kg) and growth parameters of Ailanthus excels in Elobied is significant only in tree height among other parameters this mainly due to overgrazing and soil type.
The Correlation between physical parameters and foliage biomass production has indicated that twig diameter was best correlating with foliage production with r that was positive (r =0.495) and significant (p>0.01) in Elobied, indicating that twig diameter is a major indicator of biomass at that area.In Dilling, tree height was the best correlated parameter with tree foliage biomass.In Dilling, foliage biomass production as shown in table (4.3) has indicated best correlation with crown diameter and tree height and significant at (p<0.01), indicating that the higher trees had larger foliage biomass estimates that could attribute to better growing conditions at the site compared to Elobeid.On the other hand, the correlation of biomass to height or stem diameter was low in Elobeid.Similarly, Murphy and Lugo, (1986) found differences in correlation among growth parameters to foliage biomass and attributed that to the pattern of growth of the tree and effects of location.

The relation between Growth Parameters of Ailanthus excelsa and Foliage Biomass
The regression equations indicated that twig diameter could represent the best parameter for estimating foliage biomass of A. excelsa in Elobeid whereas in Dilling, tree height was the appropriate parameter for predicting the tree foliage biomass.
The establishment of relation between foliage biomass and physical parameters of ligneous plants was studied by Pressland (1975), who investigated amongst other things, the relation of foliage biomass and trunk circumference in Acacia aneura, and found high relation.Contrary to the finding of this study that observed higher relations between foliage biomass and twig diameter in Elobeid and tree height and crown diameter in Dilling. Rai (1981), studied relationship between physical parameters and tree foliage biomass and reported that the best regression could be established between tree foliage biomass and tree height.Similar regression values were also reported by (O'Neil andDeAngelis (1988) using height. Lazim. (2001) reported that there is strong positive

Table ( 4
.1).Growth parameters of Ailanthus excelsa as affected by site in Kordofan, Sudan .
** Correlation is significant at the 0.01 level (2-tailed

Table ( 4
.3) Correlation coefficient among different tree parameters of Ailanthus excelsa grown in Dilling ** Correlation is significant at the 0.01 level (2-tailed * Correlation is significant at the 0.05 level (2-tailed) Similarly, the regression equations for growth parameters studied in foliage biomass obtained from Ailanthus excelsa tree in Dilling were also developed as illustrated in figure (4.2).
Fig. 4.2 Relationship between height and browse biomass in DillingTable 4.4 Regression equations between biomass (kg) and growth parameters of Ailanthus excelsa in Elobied