Proper grazing management practices can generate corresponding compensatory effects on plant community production, which may reduce inter-annual variability of productivity in some grassland ecosystems. However, it remains unclear how grazing influences plant community attributes and the variability of standing crop. We examined the effects of sheep grazing at four stocking rate treatments [control, 0 sheep ha(-1) month(-1); light (LG), 0.15 sheep ha(-1 )month(-1); moderate (MG), 0.30 sheep ha(-1) month(-1); and heavy (HG), 0.45 sheep ha(-1) month(-1)] on standing crop at the community level and partitioned by species and functional groups, in the desert steppe of Inner Mongolia, China. The treatments were arranged in a completely randomized block design over a 9-year period. Standing crop was measured every August from 2004 to 2012. Peak standing crop decreased (P < 0.05) with increasing stocking rate; peak standing crop in the HG treatment decreased 40 % compared to the control. May-July precipitation explained at least 76 % of the variation in peak standing crop. MG and HG treatments resulted in a decrease (P < 0.05) in shrubs, semi-shrubs, and perennials forbs, and an increase (P < 0.05) in perennial bunchgrasses compared to the control. The coefficients of variation at plant functional group and species level in the LG and MG treatments were lower (P < 0.05) than in the control and HG treatments. Peak standing crop variability of the control and HG community were greatest, which suggested that LG and MG have greater ecosystem stability.

Soil physical properties and soil organic carbon (SOC) are considered as important factors of soil quality. Arable land, grassland, and forest land coexist in the saline-alkali reclamation area of the Yellow River Delta (YRD), China. Such different land uses strongly influence the services of ecosystem to induce soil degradation and carbon loss. The objective of this study is to evaluate the variation of soil texture, aggregates stability, and soil carbon affected by land uses. For each land use unit, we collected soil samples from five replicated plots from “S” shape soil profiles to the depth of 50 cm (0–5, 5–10, 10–20, 20–30, and 30–50 cm). The results showed that the grassland had the lowest overall sand content of 39.98–59.34% in the top 50 cm soil profile. The content of soil aggregates > 0.25 mm (R0.25), mean weight diameter and geometric mean diameter were significantly higher in grassland than those of the arable and forest land. R0.25, aggregate stability in arable land in the top 30 cm were higher than that of forest land, but lower in the soil profile below 20 cm, likely due to different root distribution and agricultural practices. The carbon management index (CMI) was considered as the most effective indicator of soil quality. The overall SOC content and CMI in arable land were almost the lowest among three land use types. In combination with SOC, CMI and soil physical properties, we argued that alfalfa grassland had the advantage to promote soil quality compared with arable land and forest land. This result shed light on the variations of soil properties influenced by land uses and the importance to conduct proper land use for the long-term sustainability of the saline-alkali reclamation region.

Livestock performance is a critical indicator of grassland production systems and is influenced strongly by precipitation and stocking rates. However, these relationships require further investigation in the arid Desert Steppe region of northeastern China. We employed a randomized complete block design with three replications and four grazing treatments (nongrazed exclosure [Control]), lightly grazed [LG], moderately grazed [MG], and heavily grazed [HG]) by sheep in a continuously grazed system (June to November), to test the effect of stocking rate on sheep performance. The planned stocking rates were 0, 0.15, 0.30, and 0.45 sheep?ha 21 ?mo 21 , for the control, LG, MG, and HG treatments, respectively. However, actual stocking rates were calculated for each paddock in each year based on a 50-kg sheep equivalent (SE). Annual net primary production (ANPP) was determined at peak standing crop in August 2004 to 2008. Live weight gain was determined for the summer and fall periods, as well as the total grazing period, in each year. ANPP decreased with increasing stocking rate, and daily live weight gain per head decreased linearly with increasing stocking rates over the total grazing period but in a quadratic manner over the summer period with a plateau at the lower rates. Maximum sheep production per unit area over the total grazing season occurred at about 2 SE ha 21 for about a 5-mo grazing period, but individual gains per sheep were predicted to decline after about 1 SE ha 21 presumably because of forage limitations. However, in order to achieve stable annual production, we recommend that the Desert Steppe be grazed at about 0.77 SE ha 21 for a 5-mo period (0.15 SE ha 21 ?mo 21). This estimate is based on published grazing strategies that consider an average ANPP with a recommended utilization rate of 30%. Resumen El rendimiento del ganado es un indicador crucial de los sistemas de producción en los pastizales, y está vinculado definitivamente a la precipitación y a la carga animal. Sin embargo, esta relación requiere más investigación en la región árida de la estepa del desierto del noreste de China. Se utilizó un diseñ o de bloques completamente al azar con tres repeticiones y cuatro tratamientos de pastoreo (nopastoreo [Control], pastoreo ligero [PL], pastoreo moderado [PM] y pastoreo alto [PA] con ovejas en un sistema de pastoreo continuo (de Junio a Noviembre), para examinar el efecto de la carga animal en el rendimiento de las ovejas. La carga animal planeada fue 0, 0.15, 0.30, y 0.45 ovejas?ha 21 ?mo 21 para los tratamientos de control, PL, PM, y PA respectivamente. Sin embargo, la carga animal definitiva se calculó para cada potrero en cada añ o basándose en la equivalencia de una oveja (SE) de 50 kg. La producción anual primaria (ANPP) se determinó al final de la época de crecimiento en Agosto, del 2004 y del 2008. La ganancia de peso se obtuvo para los periodos del verano y del otoñ o, así como para el periodo total de pastoreo, en cada añ o. La ANPP disminuyó al incrementar la carga animal y la gananci...

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