Use of goats as biological agents for the renovation of pastures in the Appalachian region of the United States

Much of hill-land pasture in the Appalachian region of the United States is dominated by herbaceous weeds and brush. Low cost, low input and environmentally acceptable reclamation procedures are needed to maintain the productivity of these pastures. This experiment evaluated the effectiveness of using goats (Capra hircus hircus) alone (30 mature, brush does/ha) or cattle (Bos taurus) with goats (17 mature, brush does/ha + two to three steers/ha -- 225 kg average live weight) to reclaim a pasture from an abandoned, overgrown 5.9 ha orchard left untouched for 15 years. Over four grazing seasons, managed defoliation resulted in a substantial increase in herbaceous vegetative cover in plots grazed by goats alone (65 to 86%) and by goats with cattle (65 to 80%) while vegetative cover decreased from 70 to 22% in the control plot. Similarly, the cover by grass species increased in the grazed plots (goats: 16 to 63%; goats + cattle: 13 to 54%) while averaging 10% in the control plot. Multiflora rose (Rosa multiflora Thumb.) bushes were practically eliminated after four grazing seasons as quantified by an average reduction in height from 2.1 m to 0.6 m, and by the number of dead canes (stems) in both the goat (100%) or goat + cattle (92%) treatments. Results indicated that the foraging habits of goats resulted in the elimination of multiflora rose bushes and in a significant increase in desirable forage species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Forage production and small ruminant grazing responses in Mediterranean shrublands as influenced by the reduction of shrub cover

Reduction of shrub cover in Mediterranean shrublands is considered as a method of optimising forage and animal production. In this study, forage production in grazed and protected plots and grazing responses of small ruminants in cleared (25% shrub cover), slashed (34% shrub cover) and not treated (control, 55% shrub cover) kermes oak (Quercus coccifera L.) shrublands were compared during the spring seasons of 1992, 1993 and 1994. The alterations in shrub density were done in October 1991 and pastures remained ungrazed until spring of 1992. Clearing and slashing of shrub vegetation resulted in higher amounts of available herbaceous forage and useable browse. At the end of the growing season, averaged across years, herbaceous biomass was generally two to three times higher in the treated shrublands than in the control; also, browse biomass was slightly less (1,078 vs 1,533 kg/ha) but easily accessible because of the open structure and the lower height of the sprouting shrubs. There were generally no grazing response differences between the cleared and slashed pastures. However, grazing animals (sheep and goats) had a higher bite rate (bites/min; P 0.05) in the treated pastures than in the control. Levels of crude protein in the forage selected by animals were higher (P 0.05) in the treated pastures than in the control. Animals in the improved pastures maintained diets that were significantly more digestible (53.5%) than those in the control pasture (48.5%). Neutral detergent fibre and lignin contents of animal diets were similar in the improved pastures but lower (P 0.05) than those of the control. It is concluded that removing of woody vegetation in Mediterranean shrublands results in increased forage production (available herbage and useable browse) and improved forage quality and availability for small ruminants.     

Potential contribution of <Emphasis Type="Italic">Quercus durata</Emphasis> and <Emphasis Type="Italic">Adenostoma fasciculatum</Emphasis> supplemented with <Emphasis Type="Italic">Medicago sativa</Emphasis> on intake and digestibility in sheep and goats

A digestion trial was conducted to estimate the potential contribution of the chaparral browse Quercus durata (leather oak) and Adenostoma fasciculatum (chamise) on intake and nutrient digestion in goats and sheep. Four wether Kiko goats (avg. wt. 22.9 kg) and four wether Targhee sheep (avg. wt. 39.6 kg) were housed in metabolism cages. Alfalfa pellets were used as a dietary supplement. Digestibility of the shrubs was measured by difference and metabolizable energy (ME) and ME intake (MEI) were calculated from digestibility and plants intake values. Oak and chamise had low crude protein (CP) content (6.5 and 4.3% DM) and high content of extractable condensed tannins (17.8 and 9.8% DM). In vitro organic matter digestibility (OMD) and ME for oak and chamise were 35.6 and 33.1% and 5.0 and 4.7 MJ/kg DM, respectively. In vivo OMD (calculated by difference with alfalfa) and MEI, for browse were greater (P < 0.01) for goats fed chamise compared to sheep. In oak, OMD was similar for both animal species but MEI was greater (P < 0.01) for goats. Greater (P < 0.05) DM and CP intakes (per kg BW^0.75) were observed for goats fed either oak or chamise compared with sheep. When an energy source was given as supplement, the potential contribution of chamise and oak to total ME requirements for maintenance was about 58.3 and 60.4% in goats and about 17.1 and 32.9% in sheep, respectively. In consequence, metabolizable energy supplied by these shrubs may not be adequate for maintenance when, during grazing, they are consumed in high proportions with other chaparral plants that may have lower nutritional value than the alfalfa supplemented in this study. Under an appropriate supplementation program, goats could be more effective than sheep to control fuel load in California chaparral, as they consume more chamise and leather oak and obtain more nutrients from them.     

Plant species cover,frequency, and biomass: Early responses to clearcutting,burning, windrowing,discing, and bedding in Pinus elliottii flatwoods

Pinelands in a 49 ha naturally-regenerated, mature flatwoods forest in north Florida were clearcut harvested in the fall of 1978, site prepared by burning, shearing and piling, discing, and bedding, and planted to slash pine (Pinus elliottii) in 1979. Three vegetation surveys were conducted: one prior to harvest in the summers of 1977 and 1978, and two subsequent to planting in the summers of 1980 and 1981.Cover and frequency of all plant species encountered were assessed on permanent transects. Foliage biomass by species was assessed by destructive sampling of distinct subplots within permanent plots. The aim was to assess plant species cover, frequency, and biomass responses to the forest operations imposed.Pine was eliminated as a dominant genus by harvesting. Planted pines were a fast increasing, but not dominant, component of the vegetation at 2 years of age. Previously dominant shrubs were severely reduced — often by approximately two orders of magnitude. Indeed, woody species were severely reduced: woody cover from 151 to 12% of surface area at plantation age 2 years; woody biomass from 6223 to 521 kg/ha.Conversely, herbaceous species were substantially increased: herbaceous cover from 38 to 51% of surface area at 2 years; herbaceous biomass from 382 to 1439 kg/ha. Thus, a predominantly woody ecosystem was converted to a predominantly herbaceous one for 2 years following planting.There was little change in plant species richness as a result of forest operations. Plant diversity changes were mixed the 1st year but diversity substantially increased the 2nd year. Comparisons with a companion study (Conde et al., 1983) suggest that, while increases in diversity following maximum site preparation may lag increases following minimum site preparation, cover, frequency, and biomass diversity all converge to common values after 2 years despite disparity in treatments.     

Soil fertility under Calliandra calothyrsus hedgerows and other land-use treatments following forest clearance in Jamaica

An experiment in the Blue Mountains of Jamaica investigated the consequences of three land-use treatments applied following forest clearance on soil fertility and resulting crop growth over a five year period. The treatments were: maintained weed-free without cultivation (bare); cultivated with herbaceous crops (agriculture); and cultivated with herbaceous crops and intercropped with Calliandra calothyrsus contour hedges (agroforestry) and compared with an uncleared secondary forest control (forest). Nitrogen mineralisation rates declined over time since forest clearance in the cleared treatments, but not in the forest. In the second and third years after clearance nitrogen mineralisation was higher under the hedgerows than all other treatments. However, by the fifth year this had reduced to net immobilization (both under and between hedgerows). Under controlled shade-house conditions bioassay plant growth was similar in soil from agricultural plots and from forest plots. In all the soils bioassay plant growth showed a slight (not significant) positive response to P addition. However, it did show a large positive response to N addition in all soils: most for agriculture soils, least for forest soils and intermediate for agroforestry. Crop plants growing in the agroforestry plots had significantly higher growth than those in the agriculture plots. This was sufficient to lead to grain yield per hectare being only 5% lower in agroforestry plots despite there being c. 20% fewer maize plants per hectare than in the agriculture plots. However, the results suggest that there was no clear positive effect of C. calothyrsus on soil fertility five years after establishment.This revised version was published online in November 2005 with corrections to the Cover Date.     

Impact of Macrotermes termitaria as a source of heterogeneity on tree diversity and structure in a Sudanian savannah under controlled grazing and annual prescribed fire (Burkina Faso)

Macrotermes termitaria are conspicuous features of savannah ecosystems in the Sudanian and Sahelian zones of West Africa. The mounds, alive or abandoned, are a major source of heterogeneity in the landscape. The purpose of the present study was to assess the impact of termitaria on tree community in a state forest of the Sudanian regional centre (Tiogo forest, Burkina Faso), under controlled burning and grazing experiments. A comparative inventory was carried out in a split-plot experiment (16 subplots of 2500 m²): 8 subplots where fire regime and grazing were controlled and 8 subplots exposed to grazing and with annual prescribed fire since 1992. All tree individuals (≥1.5 m) were recorded, both on termitaria and outside and their basal area at stump level was measured. A total of 61 observed (or 65.7 ± 2.4 estimated) tree species were recorded on 28 Macrotermes subhyalinus mounds (54 observed species or 60.8 ± 3.3 estimated), the immediate surroundings (44 observed and 59.0 ± 0.0 estimated species) and the rest of subplots (56 observed and 63.6 ± 0.0 estimated). Specific density was higher on mounds in comparison with the surroundings (P < 0.05). Results showed that termitaria played a key role in maintaining higher species diversity as compared to their surroundings (P < 0.05). Differences in species diversity between termitaria and immediate surroundings appeared more pronounced in disturbed plots (submitted to both fire and grazing). Some species, such as Tamarindus indica, Boscia senegalensis, Cadaba farinosa, Capparis sepiaria and Maerua angolensis are found solely on termitaria. Besides, the density of trees was significantly higher on termitaria compared to the surrounding (P < 0.05), as well as total basal area per unit of 100 m² area (P < 0.05). We concluded that Macrotermes termitaria play an important role as a source of heterogeneity in this Sudanian savannah woodland ecosystem. This role is particularly important in ecosystems under stresses. Termitaria acted as refuge for tree vegetation. The density and dynamics of M. subhyalinus termitaria should, therefore, be taken into account in the global strategy of the forest resources management and conservation.     

Eight years of seasonal burning and herbicidal brush control influence sapling longleaf pine growth,understory vegetation,and the outcome of an ensuing wildfire

To study how fire or herbicide use influences longleaf pine (Pinus palustris Mill.) overstory and understory vegetation, five treatments were initiated in a 5–6-year-old longleaf pine stand: check, biennial arborescent plant control by directed herbicide application, and biennial burning in March, May, or July. The herbicide or prescribed fire treatments were applied in 1999, 2001, 2003, and 2005. All prescribed fires were intense and averaged 700 kJ/s/m of fire front across all 12 burns. Using pretreatment variables as covariates, longleaf pine survival and volume per hectare were significantly less on the three prescribed fire treatments than on checks. Least-square means in 2006 for survival were 70, 65, 64, 58, and 56% and volume per hectare was 129, 125, 65, 84, and 80 m³/ha on the check, herbicide, March-, May-, and July-burn treatments, respectively. A wildfire in March 2007 disproportionately killed pine trees on the study plots. In October 2007, pine volume per hectare was 85, 111, 68, 98, and 93 m³/ha and survival was 32, 41, 53, 57, and 55% on the check, herbicide, March-, May-, and July-burn treatments, respectively, after dropping trees that died through January 2009 from the database. Understory plant cover was also affected by treatment and the ensuing wildfire. In September 2006, herbaceous plant cover averaged 4% on the two unburned treatments and 42% on the three prescribed fire treatments. Seven months after the wildfire, herbaceous plant cover averaged 42% on the two previously unburned treatments and 50% on the three prescribed fire treatments. Before the wildfire, understory tree cover was significantly greater on checks (15%) than on the other four treatments (1.3%), but understory tree cover was similar across all five treatments 7 months after the wildfire averaging 1.1%. The greater apparent intensity of the wildfire on the previously unburned treatments most likely resulted from a greater accumulation of fuels on the check and herbicide plots that also collectively had a higher caloric content than fuels on the biennially prescribed burned plots. These results showed the destructive force of wildfire to overstory trees in unburned longleaf pine stands while also demonstrating the rejuvenating effects of wildfire within herbaceous plant communities. They caution for careful reintroduction of prescribed fire even if fire was excluded for less than a decade.     

Growth characteristics and allometry of <Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> as a silvopastoral system component

Demand for goat (Capra hircus) meat in the southeastern USA is steadily increasing as a result of preferences exhibited by ethnic communities. Feeding systems that include fodder trees can be developed to take advantage of the natural preference of goats for browse. Data were collected for 2 years on a 5-year old stand of Robinia pseudoacacia L. to evaluate growth characteristics for goat browse and to develop allometric relationships in a randomized complete block design (intra-row spacing 0.5 or 1 m and coppice height 0.25 or 0.50 m) replicated six times. Allometric equations were derived from destructive harvests of 68 trees. Main branch size was not affected by intra-row spacing when trees were coppiced at 0.25 m; however, when coppiced at 0.5 m, trees spaced at 1 m had more and larger branches (P < 0.05) than trees spaced at 0.5 m. Intra-row spacing did not influence tree herbage biomass when trees were spaced at 0.5 m whereas trees coppiced at 0.25 m and spaced at 1 m produced less woody and herbaceous biomass than trees spaced at 0.5 m (P < 0.05). A strong relationship (P < 0.0001) was found between tree herbage biomass and the number of main branches greater than 0.01 m (r ² = 0.80). The results, based on growth characteristics and tree herbage biomass production, suggest that Robinia pseudoacacia L. would be an excellent candidate as a silvopastoral component in the southeastern USA.     

The role of disturbance severity and canopy closure on standing crop of understory plant species in ponderosa pine stands in northern Arizona,USA

Concerns about the long-term sustainability of overstocked dry conifer forests in western North America have provided impetus for treatments designed to enhance their productivity and native biodiversity. Dense forests are increasingly prone to large stand-replacing fires; yet, thinning and burning treatments, especially combined with other disturbances such as drought and grazing, may enhance populations of colonizing species, including a number of non-native species. Our study quantifies plant standing crop of major herbaceous species across contrasting stand structural types representing a range in disturbance severity in northern Arizona. The least disturbed unmanaged ponderosa pine stands had no non-native species, while non-native grasses constituted 7–11% of the understory plant standing crop in thinned and burned stands. Severely disturbed wildfire stands had a higher proportion of colonizing native species as well as non-native species than other structural types, and areas protected from grazing produced greater standing crop of native forbs compared to grazed unmanaged stands. Standing crop of understory plants in low basal area thinned and burned plots was similar to levels on wildfire plots, but was comprised of fewer non-native graminoids and native colonizing plants. Our results also indicate that size of canopy openings had a stronger influence on standing crop in low basal area plots, whereas tree density more strongly constrained understory plant standing crop in dense stands. These results imply that treatments resulting in clumped tree distribution and basal areas <10 m² ha⁻¹ will be more successful in restoring native understory plant biomass in dense stands. Multiple types and severity of disturbances, such as thinning, burning, grazing, and drought over short periods of time can create greater abundance of colonizing species. Spreading thinning and burning treatments over time may reduce the potential for non-native species colonization compared to immediately burning thinned stands.     

Grazing impacts on spatial distribution of soil and herbaceous characteristics in an Australian tropical woodland

This study examined effects of different levels of applied grazing pressures on herbaceous vegetation (standing crop, basal area, size and spacing of grass tussocks) and soil properties (total soil C, total N, total P, and soil-borne plant material [roots and surface litter] in the A horizon) around grass tussocks of a dry eucalypt woodland (dominant woody components; Eucalyptus xanthoclada and Corymbia erythrophloia of northern Australia. Grass tussocks influenced total soil C and N at small (<20 cm) spatial scales, and applied grazing pressures significantly (p<0.05) affected all soil properties except total P. Concentrations of N and C were highest at locations close to plants, and levels in proximity to plants declined under sustained heavy grazing. Paddocks receiving heavier grazing pressures also produced less standing crop and tussocks were smaller and more widely dispersed. Further, areas with high amounts of soil C, N and soil-borne plant materials were smaller and more widely dispersed under heavy grazing. Alternatively, conservative grazing pressure in combination with wet season grazing deferments allowed conservation of landscape condition. Eucalypt woodlands in northern Australia have low resistance to disturbance, and limited resilience to recover following disturbance. As such, the effects of disturbance on these areas should be monitored by combinations of plant (basal area, plant spacing) and soil (soil-borne plant material, total N) characteristics capable of detecting degradation at the earliest stages possible.     

Establishing American sycamore seedlings on land irrigated with paper mill sludge

A study was established to evaluate several management practices for improving American sycamore (Platanus occidentalis L.) establishment on land subjected to daily paper-mill sludge spray irrigation, and where a dense herbaceous cover dominated by pokeweed (Phytolacca americana L.) was nearly 2 m tall. Treatments studied included: two sludge application treatments (spray vs no spray), five weed control treatments (control, hand-release, oxyfluorfen, glyphosate and atrazine, and sulfometuron methyl), and two tree shelter treatments (control vs tree shelter). Survival and growth of sycamore seedlings were evaluated after one growing season. Sludge application treatment had the greatest effect on tree survival; survival was greatest on plots that were not sprayed during the year of tree growth. Among the weed control treatments, the hand-release treatment resulted in best survival; survival was 100% when hand release was used on unsprayed plots. Tree shelters provided no benefit to tree establishment.     

Establishing grazing and grazing-excluded patches increases plant and invertebrate diversity in a Mediterranean oak woodland

Grazing is a global, dominant land use affecting biodiversity and ecosystem processes. In Mediterranean ecosystems grazing is a major ecological and evolutionary driver but, surprisingly, there is little information on the use of grazing as a tool to manage biodiversity in these ecosystems. We conducted an experiment to assess if establishing grazing and small scale grazing-excluded areas would increase plant and invertebrate diversity in a Mediterranean evergreen oak woodland. Plant community traits were different between treatments. Biomass of herbs (176.7 ± 18.3 g m⁻²vs 100.4 ± 10.6 g m⁻²) and litter (291.0 ± 38.3 g m⁻²vs 186.8 ± 26.4 g m⁻²), as well as the total cover of legumes (0.83 ± 0.05 vs 0.91 ± 0.03) were higher, and the proportion of bare ground (0.83 ± 0.05 vs 0.91 ± 0.03) was lower, in ungrazed plots. There were no differences in the number of plant species between treatments. Some plant species and invertebrate taxa were recorded exclusively in grazed or ungrazed plots. Invertebrate detritivores and sap sucking insects were more abundant in ungrazed plots. Ant assemblages were functionally different between treatments: Honeydew-gatherer ants were associated with ungrazed and higher plant biomass plots, and seed-eaters as well as aggressive predator ant species were associated with grazed, open habitat, plots. Management practices that maintain grazing and small scale grazing-excluded areas can increase habitat heterogeneity and promote herbaceous plant and invertebrate diversity at the local level.     

Cutting and resprouting of Detarium microcarpum and herbaceous forage availability in a semiarid environment in Burkina Faso

The tree-shrub savanna ‘Forêt Classée de Nazinon’ (Burkina Faso) is submitted to a management of grazing and rotational cutting of Detarium microcarpum. This species resprouts after cutting. In order to investigate whether this silvopastoral land use system is sustainable, aboveground herbaceous biomass was measured on subplots under uncut trees (‘uncut’), next to the stubs of cut trees (‘cut’) and on subplots not influenced by the (former) crowns of trees (‘open grassland’) in four lots. These lots were cut one, three, six and seven years before the study. Vegetation composition of the lots and the composition of the diet of cattle were also determined. Comparisons were made between treatments and lots. Herbaceous biomass was lower in the open grassland subplots than in uncut or cut subplots. We speculate that soil enrichment and more efficient precipitation input in (former) tree crown zones could have resulted in this pattern. Cutting and subsequent resprouting of trees did not lead to significant differences in herbaceous biomass between cut and uncut subplots. The most simple explanation for this is that the trees could extend their roots beyond the location of their neighbouring trees. Biomass and coverage of perennial grasses, mainly Andropogon ascinodis and Andropogon gayanus, did not change in lots cut one, three or six years before the study, but decreased dramatically in lots that were cut seven years before the study. When foraging, cattle spent more than 90% of their time feeding on these species. This indicates that, as a consequence of tree cutting, forage availability may be reduced to the point where local herdsmen are forced to take their cattle to another region. This revised version was published online in August 2006 with corrections to the Cover Date.     

Grazing exclosure increases fruit and seed production but reduces seed viability in <Emphasis Type="Italic">Myrtus communis</Emphasis>

Plants have compensating mechanisms to alleviate the loss of vegetative and reproductive tissues by herbivores. In this study, we evaluated how reproductive traits (size and production of fruit and seed, as well as germination and viability of seeds) of Myrtus communis (myrtle) were affected by goat grazing exclosure of forest understory in the Doñana Natural Park. One hundred and fifty myrtles were selected in three sites with similar environmental characteristics, although with a different length of grazing exclusion: (1) exclosure for 2 years (GE2); (2) exclosure for 3 years (GE3); and (3) long ago grazed plots (GE15): non-accessible to goat for at least 15 years. Fruit production, fruit and seed morphology and seed viability and germination were evaluated. Length of exclosure to goats increased fruit production, mass and volume of the fruits and seed, and endocarp mass. However, seed viability was higher in more recently grazed plots (70–90%) than in GE15 plots (51%). The final balance of viable/germinable seeds produced by an average sized myrtle in each treatment showed that the recently grazed myrtles (GE2) produced nearly five times less seeds (1200) than the myrtles grazed 15 years ago (5500). However, myrtles recovered the ability to produce viable seeds quickly, almost tripling, each year of non-grazing the number of viable/germinable seeds. The results of this study indicated that goat grazing could affect regeneration of myrtle because it reduced reproduction output and the number of viable propagules. Future studies should evaluate other related ecological aspects, such as fruit consumption by potential frugivores and seed dispersal (distance and place of seed deposition).     

Influence of herbicides and felling,fertilization, and prescribed fire on longleaf pine growth and understory vegetation through ten growing seasons and the outcome of an ensuing wildfire

Restoring longleaf pine (Pinus palustris Mill.) over much of its original range requires artificial regeneration. In central Louisiana, USA, two fertilization levels—No (NF) or Yes (F-36 kg/ha N and 40 kg/ha P) in combination with three vegetation treatments—Check, four prescribed fires (PF), or multi-year vegetation control by herbicidal and mechanical means (IVM) were applied to container-grown longleaf pine plantings in a grass savanna. After 10 years, P concentration in longleaf pine foliage was less on NF plots than F plots, but fertilization did not significantly affect tree stature. Survival was greater on NF plots than F plots, and so, NF plots were more productive (NF—63 m³/ha and F—45 m³/ha). Pine trees on IVM plots (37 dm³/tree) were significantly larger than on Check and PF plots, which averaged 17 dm³/tree. Survival was better on IVM plots (88%) than PF plots (78%), which was better than Checks (58%). Consequently, IVM plots were most productive (99 m³/ha), followed by PF plots (44 m³/ha), and lastly Checks (28 m³/ha). PF plots had greater grass cover (38%) than Check and IVM plots, which averaged 5%, whereas PF and IVM plots had less understory arborescent cover (an average of 25%) than Checks (91%). A wildfire in March 2007 reduced pine survival by 22, 14, and 1 percentage points on IVM, Check, and PF plots, respectively. Seven months later, longleaf pine production had decreased to 92 m³/ha on IVM plots while increasing to 55 m³/ha on PF plots and 30 m³/ha on Checks. Overall, the wildfire rejuvenated the herbaceous plant community. Grass cover on Check and IVM plots averaged 20% while grass cover on PF plots was 36%. Forb cover increased on all treatments from 2% before the wildfire to 13% seven months after the wildfire. Understory arborescent cover decreased on Checks to 62% but increased slightly on PF and IVM plots and averaged 30%.     

Intake and relative palatability indices of acacia species fed to sheep and goats

An experiment was conducted to determine preference intake and relative palatability indices of Acacia karroo, Acacia nilotica, Acacia tortilis, Acacia sieberiana and Acacia rhemniana in sheep and goats using a completely randomized design. The size of Experimental Farm from which the browses were harvested was 1842.75 ha. The leaf samples were randomly collected from various young trees. The samples were analysed for proximate composition, measured for intake and relative palatability indices of sheep and goats. Dry matter (DM) content ranged from 917.4 to 936.8 g/kg DM and organic matter from 822.9 to 892.2 g/kg DM. All acacia species contained crude protein content (CP) of more than 7–17% required for grazing animals. The content of neutral detergent fibre (ADF) and acid detergent fibre ranged from 372.8 to 658.1 and 150.0 to 464.6 g/kg DM, respectively and were significantly (P < 0.05) different among the species. All of the acacia species had low levels (0–5.57 g/kg DM) of condensed tannins. The intakes of all feeds except A. karroo and A. rhemniana were high in both sheep and goats. The leaves from A. sieberiana had the highest palatability indice (Pi) while those of A. rhemniana had the lowest Pi in both sheep and goats. It was concluded that there was an effect of acacia species on intake and relative palatability indices. Species A. sieberiana, A. nilotica and A. tortilis have potential as livestock fodder, based on moderate to high CP value, low ADF, low tannins, high intake and relative palatability indices.     

The establishment phase of a silvopastoral national network experiment in the UK

Silvopastoral agroforestry can satisfy some objectives required of European land-use systems: reduced agricultural production, increased timber production, increased product diversity and environmental enhancement. A national network experiment was set up on four sites, each representative of a UK grassland farming area, with three replicates of common treatments: sycamore (Acer pseudoplatanus L.) at two silvopastoral planting densities [100 (S100) and 400 (S400) stems ha^–1] protected by tree shelters and an agricultural control (ACONT) all with grazing sheep; a woodland control (WCONT, 2500 trees ha^–1) without grazing. Common management protocols were applied and common measurements recorded. Results are provided for the first six years. There were no significant differences between S100, S400 and ACONT in agricultural productivity, though there were significant differences between sites (P < 0.001). There were no significant differences in tree survival between the silvopastoral treatments and WCONT (mean 92.5% ± 0.74) but there was a difference between S100 and S400 (90.8 vs 94.7%: P < 0.001). There were significant differences between the sites (range 86.5–96.2%: P < 0.001) and between the first three years, when replacement of dead trees took place, (82.5, 95.1 and 96.9% for years 1, 2 and 3 respectively: P < 0.001). There were significant differences in the total height of the trees in years two to four between WCONT, S100 and S400 (113.5, 154.1 and 194.5 cm respectively in year four: P < 0.001). However, by year six WCONT and S100 were similar (180.7 ± 17.31 cm) while S400 were taller (219.0 ± 22.80 cm: P < 0.05). It is concluded that tree shelters maintained silvopastoral tree survival at the level of conventional woodland. Tree height extension was compromised on S100 where a higher animal:tree ratio resulted in greater animal activity and soil compaction around trees compared to S400. The site with poorly-drained soil proved to be unsuitable for sycamore-based silvopastoral agroforestry.This revised version was published online in November 2005 with corrections to the Cover Date.     

Plant community responses to a gradient of site preparation intensities in pine plantations in the Coastal Plain of North Carolina

Intensively managed loblolly pine (Pinus taeda) forests are common in the southeastern United States and offer opportunities for conservation of biologic diversity. Within intensively managed landscapes, stand establishment relies on combinations of mechanical and chemical site preparation and herbaceous weed control (HWC) to manage competing vegetation and increase pine production. However, few long-term studies have described relationships between intensity of stand establishment and effects on plant communities. Therefore, we examined effects of 6 treatments that varied in intensity via combinations of mechanical (wide spacing and strip shear or narrow spacing and roller chop) and chemical (application or no application) site preparation treatments with HWC (broadcast or banded) from 1 to 8 years after site preparation on plant communities in loblolly pine plantations (n = 6) in the Coastal Plain of North Carolina, USA. All treatments resulted in abundant and diverse plant communities. Chemical site preparation had short lived (?4 year) effects on the herbaceous community but long-term effects on woody plants and pine cover. Increasing management intensity by including broadcast HWC or roller chop/narrow spacing did not additively reduce woody vegetation cover or species richness. However, broadcast HWC reduced grass, vine, and forb cover in the first year post-treatment. Average Morista community similarity values ranged from 0.69 to 0.89 among treatments and plots receiving the same chemical site preparation contained the most similar plant communities. Banded HWC can be paired with wide spacing to maximize herbaceous plant growth important for many wildlife species, particularly in the first few years after site preparation. Site preparation techniques should be tailored to local site conditions, plant communities, and management objectives.     

Carbon, nitrogen, and phosphorus dynamics in a loblolly pine-goat silvopasture system in the Southeast USA

Agroforestry presents an opportunity to increase land productivity and improve cash flow by combining income from crop or animal production and forestry on the same land. In addition, agroforestry offers numerous environmental benefits such as increased diversity of plants and animals, nutrient recycling, erosion control, and carbon (C) sequestration. We investigated the effect of grazing and forage enhancement on total soil C (TSC), soil nitrogen (N), and phosphorus (P) dynamics in a goat (Capra aegagrus hircus)??loblolly pine (Pinus taeda L.) silvopasture system on a Kipling silt loam soil (fine, smectitic, thermic, Typic Paleudalfs) at Epes, Alabama from 2006 to 2010. In 2007, the soil in the silvopasture plots was characterized by low pH, low TSC, and was deficient in N and P. Four years after tree thinning and after 3?years of grazing in June 2010, the silvopasture plots still depicted low soil pH (<6) and TSC levels less than 20?g?kg^?1. TSC content in all the silvopasture plots in June 2010 were generally similar to levels obtained after thinning and prior to grazing in May 2007. However, soil disturbance for liming, fertilizer incorporation, and forage planting increased soil N and P levels, but resulted in lower TSC in the enhanced forage plots compared to the other treatments. Grazing increased N and P levels during the study period. Our study suggests that in the long-term, grazing without additional soil management practices can improve soil fertility through nutrient recycling and C sequestration and thereby making the goat-loblolly silvopasture system both environmentally and economically sustainable.     

Establishment and early growth characteristics of six Paulownia genotypes for goat browse in Raleigh, NC, USA

Meat goat production in the eastern USA is increasing as a result of growing demand from various ethnic groups. Because goats naturally prefer a high proportion of browse in their diets, research was initiated to investigate various silvopastoral production systems. The genus Paulownia contains several species which exhibit rapid juvenile growth and other characteristics that justify research into their potential use in meat goat feeding systems. In May 1997, six Paulownia genotypes were planted in a randomized complete block experiment with six replications. Trees were between 6 and 12 cm in height at planting. Genotypes included: P. fortunei seedlings, P. tomentosa seedlings, P. elongata seedlings and three P. elongata clones. Each 4-m wide plot contained a single row of 12 trees with an intra-row spacing of 1 m. Plant measurements included height, root collar diameter (RCD) at 3 cm above soil surface, and the number of main branches. Leaf samples were collected from all six replications for estimates of herbage quality. During 1998, trees were browsed with goats on two occasions to assess palatability of the herbage and to determine any preference for specific genotypes by the animals. Compared with seedling trees of all three species, the three P. elongata clones were taller (clones: 79.7 cm, seedlings: 55.9 cm; P < 0.01), had larger RCDs (clones: 18.4 mm, seedlings: 13.9 mm; P < 0.01) and had a higher branching frequency (clones: 4.9, seedlings: 1.5; P < 0.01) by the end of the first growing season. Mortality averaged 4.8% across all treatments and ranged between 0 and 8%. Early in the 1998 growing season before trees were browsed, P. elongata clones grew more rapidly than seedlings (clones: 116.4 cm, seedlings: 84.1 cm; P < 0.01). Estimates of herbage quality indicated favorable concentrations of energy and protein for lamina. In vitro true dry matter disappearance ranged from 85.4 (blades) to 71.5% (petioles) and crude protein from 25.1 (blades) to 4.9% (petioles). Animals readily browsed the lamina during two separate sessions, but no clear preference trends were observed among the different Paulownia genotypes.This revised version was published online in November 2005 with corrections to the Cover Date.