Responses and Indicators of Composition, Diversity, and Productivity of Plant Communities at Different Levels of Disturbance in a Wetland Ecosystem

Grassland tourism is a very popular leisure activity in many parts of the world. However, the presence of people in these areas causes disturbance to the local environment and grassland resources. This study analyzes the composition, diversity, and productivity under different levels of disturbance of the plant communities in the Kangxi Grassland Tourist Area and the Yeyahu Wetland Nature Reserve of Beijing, China. It aims to identify indicators of plant communities and their responses to different levels of disturbance. Our analysis shows that the plant community density and coverage have a certain compensatory increase under disturbed conditions. With the increase in disturbances, more drought-tolerant species have appeared (increased by 5.7%), some of which have become the grazing-tolerance indicator species in the trampled grazed area (TGA). For plant community productivity, biomass and height are good indicators for distinguishing different disturbances (p < 0.05). In addition, several diversity indices reveal the change of plant communities from different perspectives (three of the four indices were significant at the p < 0.05 level). For soil parameters, soil water content and organic matter concentration help to indicate different disturbance levels (the former has a 64% change). Moreover, the standard deviation of the plant community and soil parameters is also a good indicator of their spatial variability and disturbance levels, especially for the TGA. Our analysis confirms that the indicators of productivity, diversity, and soil parameters can indicate the disturbance level in each subarea from different perspectives. However, under disturbed conditions, a comprehensive analysis of these indicators is needed before we can accurately understand the state of health of the plant community.

Use of Sericea Lespedeza (Lespedeza Cuneata) as a Nutraceutical Forage for Livestock

Sericea lespedeza (SL; Lespedeza cuneata) is a widely-adapted warm season perennial legume that can be used for grazing, hay, or as a conservation plant. Planted extensively for erosion control in the Southeast in the 1930s and 1940s, SL was considered an inexpensive, but relatively low-quality feed for livestock due to high fiber (thick stems) and tannin content. Over the last 60 yr, an SL breeding program at Auburn University resulted in release of improved cultivars with lower fiber (1960s), less tannin (1970s), and improved grazing tolerance (1990s), although interest in SL as a forage crop remained relatively low. This has changed recently as research over the last 10–15 yr has demonstrated the excellent bioactivity of this plant against infection with gastrointestinal nematodes (Haemonchus contortus) and protozoan parasites (Eimeria spp.) in livestock. This bioactivity, which has been attributed to a unique type of condensed tannins, has been confirmed in fresh (grazed), dried (hay, meal, pellets), and preserved (ensiled) forms of SL in a number of studies with sheep, goats, and cattle. The tannins in SL have also been reported to prevent bloat, reduce ruminal methane production, and kill housefly larvae in manure, further contributing to the renewed interest in SL as a nutraceutical (nutritional + pharmaceutical) forage for livestock. Animal performance of SL for cattle was described as similar to bermudagrass (Cynodon dactylon) in a number of studies in the 1970s and 1980s, but more recent cattle performance data with SL are not available. A recent study with goats showed higher animal performance with no reduction in anti-parasitic bioactivity with well-fertilized SL compared with SL produced under normal (low-input) conditions. Future work on SL will focus on optimizing nutritional and bioactivity (nutraceutical) properties of this forage for different species of livestock.

Rotational grazing management of forage peanut

The perennial forage peanut is a stoloniferous, perennial tropical legume with potential for use in pastures. Based on the hypothesis that under intermittent stocking herbage accumulation would follow a similar pattern to that described for tropical forage grasses, the objective of this study was to evaluate canopy characteristics and herbage accumulation of forage peanut subjected to strategies of rotational grazing management. Treatments corresponded to all possible combinations of two grazing frequencies (regrowth interrupted at 95% and maximum canopy light interception – LI95% and LIMax) and two grazing severities (post-grazing canopy heights (CHs) equivalent to 40 and 60% of the pre-grazing heights). Treatments were imposed to experimental units during an adaptation period (from November 2014 to January 2015) and the subsequent experimental period lasted from February 2015 to April 2016, comprising two consecutive pasture growing seasons with no interruption between them (summer I to summer II). The pre-grazing targets of LI95% and LIMax corresponded to CHs of 13 and 18 cm, respectively. Forage peanut showed high grazing tolerance as pre-grazing leaf area index (except during summer I and autumn/winter), total herbage, and leaflet dry matter accumulation varied only with seasons. Higher rates of herbage production were recorded during summer I and summer II, followed by those during late and early spring and autumn/winter. Since there was no difference in the pattern of herbage accumulation between LI95% and LIMax and stolons predominated at the bottom of the canopies, forage peanut may be rotationally grazed with greater flexibility than most tropical forage grasses. Recommended pre-grazing CHs are within 13 and 18 cm, and post-grazing heights between 40 and 60% of the pre-grazing height.

An evaluation of lucerne for persistence under grazing in New Zealand

The on-farm use of lucerne (Medicago sativa) for grazing and conserved feed has increased in New Zealand over recent years, with new cultivars coming onto the market, including more winter-active ones. The extent to which the winter active types contribute to annual feed production, and the relationship to critical traits like persistence, has not been systematically tested. Two concurrent trials over a 4-year period were used to evaluate a range of lucerne cultivars and elite experimental populations ranging in dormancy from 2 (highly dormant) to 10 (non-dormant) under contrasting grazing regimes near Lincoln, New Zealand. More winter-active cultivars in the higher fall dormancy (FD) classes had similar growth to lower FD classes in all seasons except autumn, where they exhibited 18% greater yield than the lowest FD entry. However, these higher FD populations do not persist as well under heavy grazing, with a reduction in ground cover of up to 90% after four years, compared with only a 25% loss in lower FD classes. There was a negative correlation between FD and persistence measured as plant survival over 4 years (R2=0.73). However, one high FD entry showed increased survival under grazing, suggesting there is scope for selection of types with improved cool season growth and grazing tolerance. The concurrent lucerne trial subjected to a low-frequency grazing/ cutting regime showed faster recovery from defoliation than the adjacent hard grazed regime, suggesting stored underground reserves were more available for regrowth. We concluded that lucerne cultivars with FD ratings in the 3 to 5 range are most suitable for yield and persistence under grazing in these conditions. There is also scope for breeding to improve plant survival and dry matter yield within FD class. Keywords: Lucerne (Medicago sativa), grazing tolerance, persistence, fall dormancy

Habitat and plant diversity of Trifolium tumens (Steven ex M. Bieb.) collected in Azerbaijan and its characterisation and field evaluation in Tasmania, Australia

Trifolium tumens (Talish clover) is a perennial legume species not previously domesticated for use in world agriculture. It is native to areas of the eastern Mediterranean, Caucasus and mountainous areas of the Middle East with a warm temperate or cool Mediterranean environment. The species has been identified by pasture researchers in Australia as a having sufficient drought and grazing tolerance to fill a gap created by the lack of a well adapted perennial legume for dryland pasture systems across low rainfall (450 to 750 mm annual average rainfall), temperate regions of Australia. The need to expand available genetic diversity of this species resulted in a germplasm collecting mission to Azerbaijan in 2004. The successful mission collected seed from 35 populations of T. tumens across 7 agro ecological zones, including 5 climatic zones. This collection increased the number of accessions held in ex situ local and international collections from 21 to 56. The range of adaptation and frequency of the collection of T. tumens was far greater than expected with accessions found at altitudes ranging from 12 to 1700 m above sea level, in soils with pH (1:5 H20) ranging between 5.0 and 9.0 and rainfall varying from 300 to 1300 mm. T. tumens was found growing alongside a diverse range of companion species in heavily grazed lowland pastures up to lightly grazed alpine meadows. This material has been characterised by the Tasmanian Institute of Agriculture (TIA), with promising accessions contributing to a breeding program to develop a commercial cultivar adapted to temperate environments (<750 mm rainfall).

Objectives and approaches in the breeding of perennial legumes for use in temporary pasturelands

Legumes are the major element of grassland ecosystem, on which the forage quality depends. Breeding of pasture varieties in perennial legumes firstly aims at achieving tolerance and persistence of the legume component in the pasture. In species having low natural grazing tolerance (lucerne and red clover) it is necessary to conduct breeding for biological, morphological and physiological characteristics, directly related to grazing tolerance. In the species having high grazing tolerance (white clover, birds foot trefoil, sainfoin), the pasture persistence is considered as a function of particular morphological characteristics, adaptive potential and stress tolerance. The indirect breeding for pasture persistence includes also breeding for competitive ability and co-adaptivity with grass pasture species adapted to the region and practices of cultivation, as well as breeding for improved nodulation and nitrogen fixation as an important element of the adaptive ability. The breeding for grazing tolerance and persistence is concentrated also on the mechanisms of self-maintenance of the legumes in the pasture - vegetative reproduction, spread and self-seeding. Many breeding programmes are concentrated also on morphology providing better intake by the animals, on main and specific quality characteristics, on anti-nutrient factors, on adaptation to systems and practices of pasture establishment and use. The breeding strategy using germplasm consolidated through the mechanisms of specific adaptation to unfavourable or specific agro-ecological conditions and influences - i.e. breeding through ecotypic selection is considered to be the most efficient for grazing purposes. The interactions in the system: pasture species - companion species in the pasture herbaceous community - grazing animals (kind, category, grazing style and behaviourial reactions) and the applied regime of use of the pasture are direct and strong. These interactions are of essential importance in genotypic differentiation of the pasture ecotypes. The adaptive variability of the pasture ecotypes is used directly, as well as in recombination breeding.