Native forage shrub species in south-eastern Spain: forage species, forage phytomass, nutritive value and carrying capacity

Journal ofArid Environments (1995) 30:191-196

Native forage shrub species in s o u t h - e a s t e r n Spain: forage species, forage p h y t o m a s s , nutritive value and carrying capacity

A. B. Robles* & C. B. Passerat *Estacitn Experimental del Zaidin, CSIC, Box 419, 18008 Granada, Spain, ]'Instituto Argentino de lnvestigaciones de las Zonas Aridas, CONICET, P.O. Box 507, 5500 Mendoza, Argentina (Received 26 October 1993, accepted 27 December 1993) This study provides data on plant density, vegetation cover, total and forage phytomass for the main rangelands and shrubs of a 'pilot zone' (Almeria, Spain) in the south-east of Spain. Carrying capacity has been calculated for each rangeland, and for two different levels of energy requirements: maintenance (from 0.29 to 1.28 goats ha -l ) and production (from 0.20 to 0-88 goats ha-~). The nutritive value was determined for the most representative shrubs in the area

Keywords: carrying capacity; goats; Mediterranean Basin; nutritive value; phytomass; rangeland; shrubs

In~oducdon T h e natural rangelands in arid and semi-arid lands are c o m p o s e d essentially of perennial plants, which m a k e the best use of soil and climate (Salem & Palmberg, 1985). T h e shrubs are very efficient in erosion control, and offer standing green fodder reserve for the dry season in animal p r o d u c t i o n systems (Le H o u t r o u , 1991). T h e m a i n objective of this work is to contribute to a better understanding of plant communities and their use in the sustenance of livestock in the semi-arid Spanish south-east, it offers data on total and forage phytomass, nutritive value of the principal forage shrubs in the site and estimates of carrying capacity for each type of rangeland.

Material a n d m e t h o d s

Study area T h e study site is representative of the agrosystems in m o u n t a i n areas in the south-east of the Iberian Peninsula, and was carried out on a 130 ha pilot farm, in the Sierra Los 0140-1963/95/020191 + 06 $08.00/0

© 1995 Academic Press Limited

192

A.B. ROBLES&C. B. PASSERA

Filabres, Almeria province, with altitudes ranging from 705 to 1206 m. The mean annual precipitation is 324 ram. Seventy-five goats were grazed for almost the whole year. The present vegetation is the result of agrarian practices in the area over centuries. It is entirely deforested because of cycles of use-abandonment. The vegetation serie is a 'coscojar' or 'garrigue' of Quercus cocciferae (Rhamnus lycioidis-Quercetum cocciferae sigmetum). The landscape is now dominated by ,4nthyllis cydsoides and Artemisia barrelieri, small, xerophytic shrubs. The map of the rangelands units was obtained using aerial photography (1:5000) following the methodology of Etienne & Prado (1982). The botanical binomials of species cited in the text are presented in Table 1.

Table 1. Spedes cited in the text: botanical binomial and author

Anthyllis cytisoides L. Artem~'a barrelien" Besser Artemisia campestris L. Avenula bromoides (Gouan) H. Scholz. Ballota hirsuta Benth. Brachypodium retusum (Pets.) Beauv. Dactylis glomerata L. subsp, hispanica (Roth) Nyman Helichrysum swechas (L. ) Moench Lavandula muldfida L. Lavandula stoechas L Lygos sphaerocavpa (L.) Heywood Phagnalon saxatile (L.) Cass. Quercus cocciferae L. Rosmarinus officinalis L. Stipa tenacissima L. Teucrium capitamm L. Thymus baeticus Boiss. ex Lacaita Thymus zygis Loefl. ex L. Ulex pa~viflorus Pourret

Biomass production Sampling was carried out during the spring of 1988 and 1989. Destructive harvesting of shrubs was combined with the non-destructive method. Point-Centred Quarter method (Cottan & Curtis, 1956), along 50-m long transects, with observations every 2 m. Plant density, height and average diameter of plants (aerial cover and phytovolume) were also taken to establish weight/volume relationship. Ten plants of each species were harvested. Total and forage phytomass were measured, simulating the browsing of goats (Robles, 1991). Phytomass of perennial and annual were also obtained from 50 × 50 cm plots.

NutffticJe value The chemical analysis carried out were: organic matter, crude protein, neutral detergent fibre, acid detergent fibre, acid detergent lignin, in vitro dry and organic matter digestibility (Tilley & Terry, 1963).

SPANISHFORAGESHRUBS

193

The values of in vivo O M D were obtained from Molina & Aguilera (unpublished data) regression analysis in vivo/in vitro, and the metabolizable energy of each forage obtained.

Carrying capacity The carrying capacity (Coupland, 1992) was calculated in each type of plant community for two different levels of energy requirements. For maintenance purposes, reproductive female goats (Granadina race of 45 kg, neither pregnant nor lactating) were used. For production, a herd of 100 animals (80 females, 2 males and 18 kids), was assumed. The method integrates the values of the forage on offer (kg D M ha -I) from each rangeland with the results of the nutritive value (metabolizable energy, Mj) of its dominant species. The forage phytomass of each species was subjected to two 'correction' factors: acceptability and availability period (Robles, 1991). The animals' food requirements was as determined by ARC (1980), and the case of the Granadine goat energy requirement were taken from studies carried out by Agnilera et al. (1990, 1991) and Prieto et al. (1990). The carrying capacity (goats ha -I ) of the entire area under study was obtained from the average of the carrying capacities of each type of rangeland.

Results a n d d i s c u s s i o n

The dominant landscape is a shrubland formed by 'nanophanerophytes' and 'chamaephytes', with such species as Anthyllis cyrisoides, Artemisia barrelieri and Rosmarinus officinalis. Stipa tenacissima (alfa grass) was common. On the 'pilot farm' seven different types of rangelands were identified and characterized by dominant species and coverage (Table 2). The same table shows aerial and forage phytomass of shrubs, aerial phytomass of perennial and annual plants, total aerial and forage phytomass and carrying capacity of each rangeland. Tables 3 & 4 show the plant density, ground cover, aerial and forage phytomass and nutritive value of the principal shrubs of the most representative communities of the study area. The carrying capacity for the whole study area was 0.92 goats ha -1 (maintenance) and 0.63 goats ha -1 (production). The alfa grass steppe, dominated by Stipa tenacissima, provided the highest total phytomass but the lowest forage phytomass and carrying capacity. On the other hand, the area dominated by small shrubs (Thymus baeticus and Artemm'a barrelien), with perennial grasses (Dactylis glomerata subsp, hispanica and Avenula bromoides), offered the lowest total phytomass but the highest proportion of forage phytomass. The Rosmarinus officinalis shrubland presented the greatest forage, but not the highest carrying capacity. This is due to the scanty metabolizable energy of Rosmarinus officinalis and to the high contribution it makes to the total shrub community. The community dominated by Anthyllis cytisoides (half cover) the highest carrying capacity. Even though this species has better metabolizable energy than Rosmarinus officinalis, its percentage contribution to the total forage of the entire area is not as high. However, other associated species, such as Lygos sphaerocarpa (syn. Retama sphaerocarpa) and Helichrysum swechas, have good nutritive value. Lygos sphaerocarpa stands out among the shrubs because of its greater nutritive value, principally for its low acid detergent lignin content and high metabolizable energy. However, its relative importance is low owing to its low density and sparse ground cover.

194

A. B, ROBLES & C. B. PASSERA

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T a b l e 3. Forage shrubs: density and ground cover in the most representative communities of the

study area R o u n d cover (%)

D e n s i t y (plants h a - l ) Species

L+H/HC

Anthyllis cytisoides 15,800 Artemisia barrelieri 10,000 Lygos sphaerocarpa 470 Thymus baeticus 940 Thymus zygis 800 Lavandula stoechas 800 Lavandula multifida 330 Artemisia campestris 130 Helichrysum stoechas 470 Ballota hirsuta 70 Stipa tenacissima* 70 Phagnalon saxatile Rosmarinus officinalis Teucrium capitatum

L+H/LC 7300 7700 320 220

H

GS

4400 2200 460 920 230

530 530

L+H/HC

1760 530 180

830 40 110 290 320 40 300

460

9500 2600

26 18 3 1 < 1 < 1 < 1 < I < 1 < 1 < 1

13,640 350

L+H/LC 8 7 1 < 1

H

GS

7 9 < i 1 < 1

< 1 < 1 1 < 1 < 1 < 1

1

23 < 1

< 1 < 1 < 1 1 < 1 < 1 < 1

36 < I

L + H/HC = Low + Half shrubs/half cover; L + H/LC = Low + Half shrubs/low cover; H = Half shrubs; GS = Gramineous steppe. * Grass steppe.

T a b l e 4. Forage shrubs: aerial and forage phytomass in the most representative communities of the

study area. Analytic determinations of species Aerial/Forage phytomass (kg D M ha -1) Species

L + H//HC L + H/LC

Anthyllis cytisoides 3100/290 Artemisia barrdieri 2900/220 Lygos sphaerocarpa 680/110 Thymus baeticus 70/10 Thymus zygu 30/5 Lavandula stoechas 50/5 Lavandula multifida 80/10 Artemisia campestris 20/1 Helichrysum stoechas 10/1 Ballota hirsuta 4/1 Stipa tenacissima* 320/10 Phagnalon saxatile Rosmadnus offidnalis TeucHum capitatum L + H/HC

980/90 90/20 70/10 7/1

Nutritive value

H

GS

CP I V D M D (g kg-1 D M )

810/80 1700/320 4/2 10/1 6/1

30/3 40/7

10.7 17.1 15.9 8"5 8"5 8"0 9"7 15"7 6.3 11.0 7.6 8.0 10"3 8.4

20/< 1 9/1 5/< I

20/5 < 1/< 1 16/8 3/2 1400/10

2200/20

29,900/320

2/1 80/5 7/1

11,500/950 5/2

= L o w + Half shrubs/half cover; L + H / L C

32.3 68"1 72"1 54"1 54"1 49"5 47"8 59"6 , 68"4 48" 1 43"5 53"3 30"1 55"8

= L o w + Half shrubs/low cover; H

EM (Mj kg-l DM) 4.4 9"3 10"4 7"4 '7"4 7" 1 6"4 8"3 9"4 6"6 6.7 7"7 4"6 8"0 = Half

shrubs; GS = Gramineous steppe; CP = Crude protein (g kg-1 DM); I V D M D = In vitro dry matter digestibility (g kg-l DM); M E = Metabolizable energy (Mj kg-l DM). * Grass steppe.

196

A. B. ROBLES& C. B. PASSERA

T h e forage phytomass results are comparable to those obtained by Le H o u r r o u (1975) for arid and semi-arid Mediterranean climates. T h e equation developed by Le Hoiarrou (1984), which relates rainfall to carrying capacity, provided values (0.65 goats ha -1) which are very similar to ours.

Conclusions T h e communities with the highest phytomass (alfa grass steppe) do not necessarily provide either the highest forage phytomass or the highest carrying capacity. T h i s is due firstly to the variable proportion of total to forage phytomass; and secondly because the nutritive value of the c o m p o n e n t s of each rangeland is the determining factor. The authors wish to acknowledge to Drs H. Le Hourrou and J.L. Gonzfilez Rebollar for reading the manuscript and suggesting some useful amendments. This work is part of a livestock planning research prograrnma called 'LUCDEME' (Fight against desertification in Southern Spain).

References Aguilera, J.F., Prieto, C. & Fonolla, J. (1990). Protein and energy metabolism of lactating granadina goats. British ffournal of Nut~tion, 63:165-175. Aguilera, J.F., Lara, L., Molina, E. & Prieto, C. (1991). Energy metabolism of the grazing Granadina goat at fattening and maintenance. Small Ruminant Research, 5" 109-115. ARC (1990). The Nutrient Requirements of Ruminant Livestock. Slough: Commonwealth Agricultural Bureaux. 351 pp. Coupland, R.T. (1992). Approach and generalizations. In: Coupland, R.T. (Ed.), Natural Grasslands, Introduction and western hemisphere. Ecosystems of the world 8A, pp. 1-6. Amsterdam: Elsevier Science Publishers. 469 pp. Cottan, G. & Curtis, J.T. (1956). The use of distance measures in phytosociological sampling. Ecology, 37: 451-460. Etienne, M. & Prado, C. (1982). Descripci6n de la vegetaci6n mediante la Cartografia de Ocupaci6n de Tierras. Conceptos y manual de uso pr~ctico. Universidad de Chile. Santiago de Chile, 120 pp. Le Hourrou, H.N. (1975). The rangelands of North Africa: typology, yield, productivity and development. Proceedings of the Internaffonal Symposium on the Evaluation and Mapping of Tropical Africa, pp. 41-55. Addis-Ababa: ILCA. Le Hourrou, H.N. (1984). Rain use efficiency: a unifying concept in arid-land ecology, ffourna/ of Arid Environments, 7:213-247. Le Hourrou, H.N. (1991). New, man-made agro-sylvo-pastoral production systems for the isoclimatic mediterranean arid zone. Proceedings IVth International Rangeland Congress. Monpellier, France. 17 pp. Pfieto, C., Aguilera, J.F., Lara, L. & FonoUa, J. (1990). Protein and energy requirements for maintenance of indigenous Granadina goats. British ffournal of Nutrition, 63" 155-163. Robles, A.B. (1991). Evaluaci6n de la oferta forrajera y Capacidad sustentadora de nn agrosistema semi~'ido en el Sudeste Ibrdco. 9 microfichas. Servicio de Publicaciones. Universidad de Granada. Espafia. Salem, B. & Palmberg, C. (1985). Place and role of trees and shrubs in dry areas. In: Wickens, G.E., Goodin, J.R., Field, D.V. (Eds), Plants for Arid Lands, pp 93-102. London: Allen & Unwin. Tilley, J.M. & Terry, R.A. (1963). A two stage technique for the 'in vitro' digestion of forage crops, ffournal of the British Grassland Society 18" 104--111.