Woody Rangeland Research Articles

Contribution of woody plants to horses’ diets in Mediterranean rangelands

In Mediterranean countries, shrubby and woody areas provide herds with cheap fodder. However, some horse farmers are reluctant to use woody rangelands, which they associate with low-quality feed. In this article, we explore some aspects of the feeding behavior of horses on Mediterranean shrubby and woody rangelands, in order to document their pastoral interest for horses. We observed the feeding choices of young horses grazing on typical peri-Mediterranean rangelands. Observations were repeated at two sites, with four horses per site, over four days with two observers. At each site, two horses were fitted with GPS (positioning system) collars to determine their presence in different areas of the paddocks. Ingested plants were classified in a coding grid. The chemical characteristics of each feed item were estimated by near-infrared spectroscopy (NIRS). A hierarchical classification of NIRS spectra defined four classes. Leaves, twigs, and flowers of several woody species were ingested (1‒18% of recorded bites), although herbaceous species were preferred (> 80% of bites). Horses explored the entire paddocks but grazed preferentially in open areas. The differences observed between sites suggested a strong effect of local grazing conditions. The chemical composition of feed from shrubs and trees was close to that of herbaceous forbs but quite different from that of grasses. Three out of four classes associated woody plants and forbs. These classes had interesting nutritional characteristics (protein > 12%). These results confirm the positive contribution of woody plants to horses' nutrition, in addition to the other roles of woody plants in the well-being of horses on pasture.

Corrigendum to “Grazing behaviour, forage selection and diet composition of goats in a Mediterranean woody rangeland” [Small Ruminant Res. 145, 2016, 142–153

Corrigendum to “Grazing behaviour, forage selection and diet composition of goats in a Mediterranean woody rangeland” [Small Ruminant Res. 145, 2016, 142–153

Effects of grazing management on leaf litter decomposition and soil microbial activities in northern Iranian rangeland

The effects of rangeland management on biogeochemical processes that control the exchange of C and nutrients between the soil and plant are not well understood. For this purpose, aboveground litter properties and decomposition of three dominant species (Artemisia aucheri, Astragalus podolobus, and Eurotia lanata) were studied in four rangeland management systems of northern Iran including continuous grazing, intermittent grazing, and two non-grazing sites (i.e. woody and non-woody rangelands). We tested the following hypotheses: (i) woody rangeland improves litter quality, with a higher rate of decomposition, soil fertility and biochemical functions compared to non-woody rangeland and grazed sites, and (ii) continuous grazing reduces microbial C and N turnover. Plant residues from all rangeland species in the grazing and non-grazing areas were collected and soil samples were taken and analyzed for chemical properties and microbial activities. Based on the obtained data, litter decomposition was faster under woody rangeland ecosystem (Artemisia aucheri > Astragalus podolobus > Eurotia lanata) compared with the other study sites. The results revealed improved litter quality and increased soil available nutrients, as well as C and N mineralization for the woody rangeland, whereas under intermittent grazing the soil C/N ratio, microbial basal respiration (BR), substrate induced respiration (SIR) and microbial biomass C (MBC) increased. Soil pH, EC, qCO2 (BR: MBC) were significantly higher under continuous grazing, but with lower contents of soil organic C, total N, and available Mg. Furthermore, C and N stocks, microbial entropy (MBC: organic C), C availability index (BR: SIR), particulate organic matter C, dissolved organic C, mineral N (i.e., NH4 and NO3), microbial biomass N, particulate organic matter N and dissolved organic N were decreased in the continuous grazing site. Thus, we concluded that continuous grazing might depress soil C and N microbial activity, but woody rangeland could improve soil quality.

Relationships among nutritive value of selected forages, diet composition and milk quality in goats grazing in a Mediterranean woody rangeland

Woody rangelands are important forage resources for grazing goats in the Mediterranean basin. Goats are well adapted in these heterogeneous and complex ecosystems due to their particular anatomic characteristics, metabolic efficiency and browsing ability. However, the mechanism of grazing behavior and forage selection in goats is quite complex and depends on several factors. The present study deals with the seasonal changes of chemical composition in the selected forages and ingested diets as well as their effects on milk yield and composition of goats grazing in a Mediterranean woody rangeland. Hand plucked forage samples similar to those consumed by the goats were collected for chemical analysis. The nutritive value of consumed forages, in combination with the different feeding and grazing system per trial period, influenced milk quality and performance. The replacement of feed supplementation with an increase of the contribution of grazing in the rangeland could maintain the milk yield and quality at the late stage of lactation. In addition, this paper focuses on the influence of the chemical composition of selected forages on the diet selection of goats using a modeling approach. The model showed a high interpretative accuracy and explanatory value (R2 = 0.923) and was able to distinguish the goats' most important criteria for selecting among the forage plant species in relation to several factors. The results indicate that the dietary preferences of goats were influenced, not only by the seasonality of nutritive value and availability of forages in the rangeland, but also by the plant origin of each nutrient source. The selection of Quercus frainetto was highly correlated with its NDF content. Herbaceous species, Cistus creticus and other woody species were mainly selected due to their CP content. The ADL content seemed to have the lowest influence of all nutritive variables on the selection among groups of plant species. The modeling approach, apart from the understanding of grazing behavior of goats, offers additional information that can be useful to the shepherds in order to manage more effectively the feeding and grazing system of their goat's flock.

Grazing behavior, forage selection and diet composition of goats in a Mediterranean woody rangeland

The grazing behavior and the diet selection of goats are affected by numerous factors associated with animal characteristics, climate conditions and rangeland features as well as their interactions. Moreover, the special feeding behavior of goats due to their particular anatomic and physiologic characteristics, allow them to be highly selective, to consume lignified forages and to utilize woody plant species. The study of above traits is of great interest especially when goats browse in a complex Mediterranean environment with high seasonal changes. The objectives of the present study were to investigate the grazing behavior, the forage selection and the diet composition of goats browsing in a Mediterranean woody rangeland of Northern Greece. Grazing behavioral data were recorded using the direct observation method of a flock of local breed goats and the measurements were performed during three seasons (spring, summer and autumn) for two consecutive years. The purpose was to evaluate the seasonal differences taking into account not only the different seasons but also the different climate parameters within the two years. According to the results, Quercus frainetto was the most important part of the diet of goats despite the fact that they were able to utilize various nutritive resources such as herbaceous species and acorns. Goat is a particular versatile herbivore that is well adapted to the seasonality of complex Mediterranean landscape.

Soil Physical Changes After Conversion of Woodlands to Pastures in Dry Chaco Rangelands (Argentina)

The conversion of dry woody rangelands into pastures can alter key soil physical properties that regulate ecosystem water circulation and storage. Based on three paired stands of native woodlands and pastures established 20 years ago in the southern Dry Chaco (San Luis, Argentina), we described contrasts in five soil physical properties using a systematic sampling of soil patches (9−18 patches along a single transect within each of the three paired 1-ha stands). Compared with woodlands, pastures displayed flatter microtopography (mean ± standard deviation [SD]: 3.7 ± 0.34 vs. 5.0 ± 0.67% slope; P < 0.05), lower infiltration rate (mean ± SD: 71.6 ± 9.0 vs. 139.9 ± 37.2 mm h−1; P < 0.05), and higher penetration resistance (mean ± SD: 4.2 ± 0.10 vs. 1.9 ± 0.17 kg cm−2; P < 0.01) and bulk density (mean ± SD: 1.39 ± 0.05 vs. 1.16 ± 0.04 g cm−3; P < 0.0001). On average, topsoil water content at field capacity was similar for both types of cover (mean ± SD: 16.3 ± 0.21 vs. 17.1 ± 1.12%, pastures and woodlands, respectively; P = 0.29). However, at similar bulk density values, pastures presented a ~20% reduction in volumetric water content at field capacity (16.3%) compared with woodlands (19.7%). The establishment of pastures led to more homogenous soils, with most variables having reduced spatial variability in comparison with woodlands. Our observations showed how the conversion of native woodlands to pastures produced strong physical changes in the soils of Dry Chaco and help to understand the mechanisms that are most likely influencing the surface-soil water dynamics of these, and perhaps other, dry rangelands.

Streeter Basin Grassland Experiment

Streeter Creek Basin Experiment began as a paired basin experiment studying the effects of woody vegetation removal and rangeland improvements on streamflow. However, complex groundwater systems and inter-basin transfer of subsurface flow negated the paired basin design. The new objective of the research was to determine if tree removal on the upper slopes would impact the contact springs lower in the basin. Snow accumulation was measured in clear-cut patches and the timing of flows and water yield from springs were monitored.

Fodder Biomass Monitoring in Sahelian Rangelands Using Phenological Metrics from FAPAR Time Series

Timely monitoring of plant biomass is critical for the management of forage resources in Sahelian rangelands. The estimation of annual biomass production in the Sahel is based on a simple relationship between satellite annual Normalized Difference Vegetation Index (NDVI) and in situ biomass data. This study proposes a new methodology using multi-linear models between phenological metrics from the SPOT-VEGETATION time series of Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) and in situ biomass. A model with three variables—large seasonal integral (LINTG), length of growing season, and end of season decreasing rate—performed best (MAE = 605 kg·DM/ha; R2 = 0.68) across Sahelian ecosystems in Senegal (data for the period 1999–2013). A model with annual maximum (PEAK) and start date of season showed similar performances (MAE = 625 kg·DM/ha; R2 = 0.64), allowing a timely estimation of forage availability. The subdivision of the study area in ecoregions increased overall accuracy (MAE = 489.21 kg·DM/ha; R2 = 0.77), indicating that a relation between metrics and ecosystem properties exists. LINTG was the main explanatory variable for woody rangelands with high leaf biomass, whereas for areas dominated by herbaceous vegetation, it was the PEAK metric. The proposed approach outperformed the established biomass NDVI-based product (MAE = 818 kg·DM/ha and R2 = 0.51) and should improve the operational monitoring of forage resources in Sahelian rangelands.

Season and rainfall gradient effects on condensed tannin concentrations of woody rangeland species

Shrubs and trees in warm climate rangelands play multiple roles including providing ruminants with forage. Condensed tannins (CT) in these species can have negative and positive effects on those ruminants so quantifying them is crucial to their management. The objective of this study was to measure CT concentrations of key woody perennials during distinct seasons in Pernambuco, Brazil. The species were collected along a 432 to 607 to 1200-mm rainfall gradient. When season differences were identified, CT concentration declined (P ? 0.05) during the dry season compared to the rainy season. There was distinct correlation in CT concentration and aridity with dissimilarity cluster formation. Myracrodruon urundeuva Allemao [62.3 ± 8.5 g kg-1 dry matter (DM)] and Schinopsis brasiliensis Engl. (61.53 ± 14.8 g kg-1 DM) had the greatest (P ? 0.05) concentration of CT while Cordia leucocephala Moric (10.9 ± 10.9 g kg-1 DM) and Oxalis insipid St. Hil. (19.3 ± 8.2 g kg-1 DM) had the least. Conservation or reseeding these species in rangeland may depend on whether their CT concentrations are beneficial to wildlife or domesticated livestock.

The influence of grazing exclosure on soil C stocks and dynamics, and ecological indicators in upland arid and semi-arid rangelands

Soil carbon (C) storage and quality in rangeland ecosystems may change as a result of long-term heavy grazing, especially in upland arid and semi-arid rangelands characterized by low soil organic C contents. The impact of grazing exclosure on soil C stock and mineralization, microbial biomass C and the activities of invertase and alkaline phosphatase involved in C and P cycling as soil ecological indicators were studied in woody and non-woody rangeland ecosystems of two sites (viz., Sabzkouh with woody cover and Boroujen with non-woody cover) located in Zagros Mountains, Central Iran. At each site, soil samples were taken from 0 to 15cm depth of the two rangelands including heavy grazing (HG) and ungrazed (UG) regimes, and analyzed for their chemical and microbial properties. Results demonstrate that soil organic C and total N contents, and C/N ratios were not affected by grazing regime at Boroujen, while ungrazed rangelands had higher C (17%) and N (19%) contents compared with heavily grazed rangelands at Sabzkouh. Grazing exclosure increased soil C mineralization (44.7–73.6%) and turnover (24–64%) at both study sites, and increased the amount of soil microbial biomass C (5.4-fold) and decreased the metabolic quotient (90%) only at Sabzkouh. Soil invertase activity was significantly higher (1.3–2.1 times) in ungrazed than heavily grazed rangelands at both sites, whereas ungrazed rangelands had significantly greater soil alkaline phosphatase activity (19%) compared with heavily grazed rangelands only at Sabzkouh. The variations in the effect of grazing exclosure on soil organic matter (SOM) dynamics and C sequestration in these upland arid and semi-arid rangelands were due to differences between rangelands in initial SOM contents, and probably could be due to differences in plant productivity and composition, and the amount of rainfall between the study sites. Non-woody rangelands contained less soil C and N contents, and C mineralization but greater microbial biomass C than woody rangelands, reflecting a clear difference in substrate quality and soil C availability. Soil biochemical and microbial indices as ecological indicators can reflect grazing exclosure effects on soil restoration only in woody rangelands.

Aboveground and belowground carbon dynamics in response to fire regimes in the grazed rangelands of northern Australia: initial results from field studies and modelling

The world’s rangelands are often seen as offering considerable potential as a carbon (C) sink, which could contribute to the management of atmospheric C levels, but there are often few data available to assess this potential or to inform the type of management regimes that would be necessary. This paper reports on a review of the literature, a field study and modelling of C stocks under a selection of experimental fire regimes in two plant communities in Australia’s northern rangelands. The field study on an open eucalypt savanna woodland and a savanna grassland-open shrubland suggested that fire regime had no effect or an inconsistent effect on aboveground C stocks. However, modelling using the Century model for the open woodland site showed that increasing fire frequency was associated with reduced aboveground and soil C stocks. Thus, while infrequent fires allowed C stocks to increase (10-yearly fire) or remain stable (6-yearly fire) over a modelled 58-year period, a regime of more frequent fires (4- and 2-yearly fires) reduced C stocks over time. Simulation of C dynamics over 93 years of pastoral settlement suggested that total C stocks had increased by 9.5 t ha–1, largely due to an increase in C in woody vegetation following a reduction in fire frequency associated with pastoral settlement. Frequent burning, as recommended to maintain low woody density and promote pasture production for grazing, will, therefore, reduce aboveground and to a lesser extent soil C stocks where there has been a history of infrequent fire. The opportunities for pastoralists to increase C stocks will depend on the frequency of fire and vegetation type, especially its woodiness or potential woodiness. Reducing fire frequency in woody rangelands will increase C stocks but may have adverse effects on pasture and livestock production. Reducing grazing pressure or destocking might also increase C stocks but may be relevant only when a property is overstocked or where relatively unproductive land could be taken out of livestock production. Any C gains from altering fire and grazing management are likely to be modest.

Spatial Distribution of Sheep, Feral Goats and Kangaroos in Woody Rangeland Paddocks.

The densities and distributions of sheep, kangaroos and feral goats were assessed from extensive dung surveys following dry, moderate and green seasons in three large paddocks in the wooded rangelands of north-westem New South Wales. Densities of sheep (21 9nanimals/km2) were around the long-term district average. Densities of goats (24 animals/km2) were often higher than sheep. Densities of kangaroos (1 1 animals/km2) were usually much lower than either sheep or goats. Animal density was usually related to vegetative cover (ground cover for sheep and kangaroos, shrub and tree cover for goats), but there were also differences among paddocks. Distribution of kangaroos showed the most differentiation according to vegetation type, with densities being consistently high on a small area of alluvial grassland and very low in the paddock with no alluvial plains and the lowest levels of ground cover. The distributions of sheep and goats were correlated in the dry season and both species showed similar ranges in preferences for different vegetation types. Of the large herbivores present in these woody rangelands, kangaroos were the most selective in terms of the vegetation types they grazed, and goats were the least selective. Because their grazing activities are focussed on alluvial grasslands, kangaroos have potential to degrade this locally uncommon vegetation type. However, the densities of kangaroos in other, more widespread, vegetation types were uniformly low. Goats were frequently the most abundant large herbivores present and were also the least selective. Therefore goats probably have the greatest potential for causing widespread grazing impacts across much of these woody rangelands.

Chemical control of the poisonous plantDichapetalum cymosum(Hook) Engl

Abstract Granular formulations of ethidimuron (0.09–10–8 g a.i./m2) and tebuthiuron (0.06–1.2 g a.i./m2), a soil‐applied liquid formulation of tebuthiuron (0.3–0.9 g a.i./m2) and foliar applications of chlorfenac (15 and 30 g a.i. 1−1), glyphosate (10.7 and 21.5 g a.i. l−1), imazapyr (0.625 and 1.25 g a.i. l−1) and picloram (2.4 g a.i. l−1) spot‐sprayed to run‐off, were tested for the control of the poisonous, woody rangeland species Dichapetalum cymosum (Hook) Engl. at a number of sites in Botswana. The extent of regrowth was monitored for up to 7 years following treatment. No herbicide controlled the plant completely. Neither tebuthiuron nor ethidimuron had completely reduced spring shoot production 2 years following application, at the time of year when the plant is most of a threat to livestock. The effect of glyphosate was also short‐lived. Chlorfenac at 30 g a.i. l−1 resulted in up to 5 years suppression of shoot growth, but has subsequently been withdrawn from the market Imazapyr prevented D. cymos...