Precipitation Regulates the Response of Net Ecosystem CO2 Exchange to Environmental Variation on United States Rangelands

Rangelands occupy 50% of Earth’s land surface and thus are important in the terrestrial carbon (C) cycle. For rangelands and other terrestrial ecosystems, the balance between photosynthetic uptake of carbon dioxide (CO₂) and CO₂ loss to respiration varies among years in response to interannual variation in the environment. Variability in CO₂ exchange results from interannual differences in 1) environmental variables at a given point in the annual cycle (direct effects of the environment) and in 2) the response of fluxes to a given change in the environment because of interannual changes in biological factors that regulate photosynthesis and respiration (functional change). Functional change is calculated as the contribution of among-year differences in slopes of flux-environment relationships to the total variance in fluxes explained by the environment. Functional change complicates environmental-based predictions of CO₂ exchange, yet its causes and contribution to flux variability remain poorly defined. We determine contributions of functional change and direct effects of the environment to interannual variation in net ecosystem exchange of CO₂ (NEE) of eight rangeland ecosystems in the western United States (58 site-years of data). We predicted that 1) functional change is correlated with interannual change in precipitation on each rangeland and 2) the contribution of functional change to variance in NEE increases among rangelands as mean precipitation increases. Functional change explained 10–40% of the variance in NEE and accounted for more than twice the variance in fluxes of direct effects of environmental variability for six of the eight ecosystems. Functional change was associated with interannual variation in precipitation on most rangelands but, contrary to prediction, contributed proportionally more to variance in NEE on arid than more mesic ecosystems. Results indicate that we must account for the influence of precipitation on flux-environment relationships if we are to distinguish environmental from management effects on rangeland C balance.     

Summer-Time Carbon and Water Fluxes in Sagebrush Ecosystems Spanning Rain- to Snow-Dominated Precipitation Regimes

Sagebrush ecosystems consist of different communities of species and subspecies of sagebrush marked by distinct ecotones along elevation gradients, yet few studies have quantified how ecosystem-scale carbon dioxide (net ecosystem exchange, NEE) and water fluxes (evapotranspiration, ET), as well as their environmental drivers, vary among communities dominated by different sub/species of sagebrush at daily and seasonal time scales. To address this knowledge gap, we measured daytime (6 a.m.–6 p.m.) NEE and ET using a tent chamber and associated environmental drivers in three sagebrush communities spanning an elevation gradient of 1 425–2 111 m at the Reynolds Creek Critical Zone Observatory in southwestern Idaho. Daytime NEE and ET were greatest at the highest elevation (snow-dominated) site during the study period except NEE in June. By late summer, NEE declined by > 80% at the lower (rain-dominated) sites but only 50% at the highest site, compared with maximal values in June. In contrast, ET declined ∼95% in late summer compared with June at all three sites. Ecosystem-scale NEE and ET were mainly controlled by soil moisture and vapor pressure deficit at the rain-dominated sites and by deep soil moisture and air temperature at the snow-dominated site. Cumulative (June−August) modeled daytime NEE was greatest at the midelevation site, whereas cumulative daytime ET was greatest at the highest-elevation site. Ecosystem models often assume that sagebrush landscapes are homogeneous and do not differ in fluxes and controls, yet our data demonstrate that there are fundamental differences in CO₂ and water fluxes and their controls among different shrub communities that should be accounted for in these models.     

Fungal Facilitation in Rangelands: Do Arbuscular Mycorrhizal Fungi Mediate Resilience and Resistance in Sagebrush Steppe?

Arbuscular mycorrhizal fungi (AMF) may exert profound influences on ecosystem resilience and invasion resistance in rangelands. Maintenance of plant community structure through ecological feedback mechanisms such as facilitation of nutrient cycling and uptake by host plants, physical and chemical contributions to soil structural stability, and mediation of plant competition suggest AMF may be important facilitators in stressful arid environments. Plant-AMF interactions could influence succession by increasing native plant community resilience to drought, grazing, and fire and resistance to exotic plant invasion. However, invasive exotic plants may benefit from associations with, as well as alter, native AMF communities. Furthermore, questions remain on the role of AMF in stressful environments, specifically the mycorrhizal dependency of sagebrush (Artemisia spp.) steppe plant species. Here, we review scientific literature relevant to AMF in rangelands, with specific focus on impacts of land management, disturbance, and invasion on AMF communities in sagebrush steppe. We highlight the nature of AMF ecology as it relates to rangelands and discuss the methods used to measure mycorrhizal responsiveness. Our review found compelling evidence that AMF mediation of resilience to disturbance and resistance to invasion varies with plant and fungal community composition, including plant mycorrhizal host status, plant functional guild, and physiological adaptations to disturbance in both plants and fungi. We conclude by outlining a framework to advance knowledge of AMF in rangeland invasion ecology. Understanding the role of AMF in semiarid sagebrush steppe ecosystems will likely require multiple study approaches due to the highly variable nature of plant-AMF interactions, the complex mechanisms of resilience conference, and the unknown thresholds for responses to environmental stressors. This may require shifting away from the plant biomass paradigm of assessing mycorrhizal benefits in order to obtain a more holistic view of plant dependency on AMF, or lack thereof, in sagebrush steppe and other semiarid ecosystems.     

Effects of Long-Term Livestock Grazing on Fuel Characteristics in Rangelands: An Example From the Sagebrush Steppe

Livestock grazing potentially has substantial influence on fuel characteristics in rangelands around the globe. However, information quantifying the impacts of grazing on rangeland fuel characteristics is limited, and the effects of grazing on fuels are important because fuel characteristics are one of the primary factors determining risk, severity, continuity, and size of wildfires. We investigated the effects of long-term (70+ yr) livestock grazing exclusion (nongrazed) and moderate levels of livestock grazing (grazed) on fuel accumulations, continuity, gaps, and heights in shrub-grassland rangelands. Livestock used the grazed treatment through 2008 and sampling occurred in mid- to late summer in 2009. Nongrazed rangelands had over twofold more herbaceous standing crop than grazed rangelands (P < 0.01). Fuel accumulations on perennial bunchgrasses were approximately threefold greater in nongrazed than grazed treatments. Continuity of fuels in nongrazed compared to grazed treatments was also greater (P < 0.05). The heights of perennial grass current year’s and previous years’ growth were 1.3-fold and 2.2-fold taller in nongrazed compared to grazed treatments (P < 0.01). The results of this study suggest that moderate livestock grazing decreases the risk of wildfires in sagebrush steppe plant communities and potentially other semi-arid and arid rangelands. These results also suggest wildfires in moderately grazed sagebrush rangelands have decreased severity, continuity, and size of the burn compared to long-term nongrazed sagebrush rangelands. Because of the impacts fuels have on fire characteristics, moderate levels of grazing probably increase the efficiency of fire suppression activities. Because of the large difference between fuel characteristics in grazed and nongrazed sagebrush rangelands, we suggest that additional management impacts on fuels and subsequently fires need to be investigated in nonforested rangelands to protect native plant communities and prioritize management needs.     

Characteristics of Forage Nutritional Quality and Digestibility in Different Types of Grassland in Qinghai Tibet Plateau and their Correlation北大核心CSCD

In order to explore the differences of forage nutritional quality and digestibility among different types of rangelands, five typical rangeland types (alpine meadow, alpine steppe, warm steppe, desert steppe and warm desert steppe) in Qinghai-Tibet Plateau were used as research objects. The characteristics of forage nutritional quality and digestibility of typical rangelands and their correlation were analyzed. The results showed that: there were significant differences in crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF) and dry matter digestibility (DMD) among different types of rangeland (P<0.01). The results of Pearson correlation analysis showed that there was a significant positive correlation between DMD and CP (P<0.05), and a significant negative correlation between DMD and NDF and ADF (P<0.05). Elevation (ELE) was positively correlated with DMD and CP (P<0.05), but negatively correlated with NDF and ADF(P<0.05). In conclusion, there were significant differences in CP, ADF, NDF and DMD among different types of grasslands in Qinghai-Tibet Plateau, and it mainly manifested that with the increase of altitude, ADF and NDF gradually decreased, while CP and DMD gradually increased, and forage quality gradually increased. © 2019 Authors. All rights reserved.     

巴什吐格草原草场类型及其资源开发利用

对巴什吐格草地自然地理环境、植被分布规律与草场类型特点研究结果表明，该区草地是中昆仑山北坡自然环境最好、植被发育最好、放牧地形最好和供水条件最好的典型草场之一。自南向北，草场植被垂直分布十分明显，东、西部植被水平分布亦有较显著差异。根据新疆草地分类系统可划分为：山地荒漠、山地草原化荒漠、山地荒漠草原、山地典型草原、高寒草原和高寒草甸６类及６个亚类、１１个组、１４个型。。山地荒漠草原和山地典型草原分别是冬春场和夏秋场的主体类型，各占冬春场和夏秋场草地可利用面积的４８２２％和６６７１％。结合当地草场实际，提出了草地合理开发利用的意见。     

Bluebunch Wheatgrass Response to Spring Defoliation on Foothill Rangeland

Spring elk grazing may reduce forage availability for wildlife or livestock in summer and may harm forage resources on foothill rangeland. We quantified bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love) response to spring defoliation on foothill rangeland in southwestern Montana. Two experiments were conducted simultaneously on a foothill grassland site and a foothill sagebrush steppe site. Bluebunch wheatgrass plants (n = 800) were selected and excluded from wild and domestic ungulates. Clipping treatments were applied in either early spring (mid- to late April) or late spring (mid- to late May), and plants were clipped to 1 of 3 residual heights (3, 6, or 9 cm) for 1, 2, or 3 successive years. Unclipped plants served as controls. Plant response was measured in late June and late July on both sites. April clipping for 3 successive years did not adversely affect bluebunch wheatgrass in June or July (P > 0.05) at either site. On foothill grassland, May defoliation to 3 cm for 2 consecutive years reduced leaf height (P = 0.04) in July. May defoliation for 3 successive years to 3 or 6 cm reduced plant yield (P < 0.05) and leaf height (P < 0.05) in June, and May defoliation for 3 successive years to 3 cm reduced leaf height (P = 0.02) in July. On foothill sagebrush steppe, 3 successive years of May defoliation to ≤ 9-cm stubble heights decreased leaf height in June (P < 0.05). We conclude that foothill rangelands where bluebunch wheatgrass receives moderate or light defoliation (6–9-cm residual stubble heights) in mid- to late May should be limited to no more than 2 successive years of mid- to late May grazing, whereas sites that receive heavy to severe defoliation (≤ 3-cm residual stubble heights) in mid- to late May should not be grazed for 2 successive years during mid- to late May.     

青藏高原典型草地牧草营养品质和消化率特征及其相关性

为探究不同类型草地牧草营养品质和消化率的差异,本研究以青藏高原典型的高寒草甸、高寒草原、温性草原、荒漠草原和温性荒漠草原为研究对象,对不同类型草地牧草营养品质和消化率及其相关性进行研究。结果表明：不同类型草地间牧草粗蛋白（Crude protein,CP）、酸性洗涤纤维（Acid detergent fiber,ADF）、中性洗涤纤维（Neutral detergent fiber,NDF）和干物质消化率（Dry matter digestibility,DMD）含量差异显著（P<0.01）。Pearson相关性分析表明,DMD与CP呈显著正相关（P<0.05）,而与NDF,ADF之间呈显著负相关（P<0.05）;海拔高度（Elevation,ELE）与DMD,CP显著正相关（P<0.05）,而与NDF和ADF显著负相关（P<0.05）。综上所述,青藏高原不同类型草地间牧草CP,ADF,NDF和DMD均存在显著差异,且主要表现为随着海拔的升高,ADF和NDF逐渐降低,而CP和DMD逐渐增高,牧草品质逐渐升高。     

Bunchgrass Root Abundances and Their Relationship to Resistance and Resilience of Burned Shrub-Steppe Landscape

Invasion of exotic annual grasses (EAG) and increased wildfire have led to an emphasis on managing rangeland plant communities for resistance to invasion and resilience to disturbances. In sagebrush steppe and similar rangelands, perennial bunchgrasses and particularly their roots are hypothesized to be primary contributors to resistance and resilience. We asked how bunchgrass root abundance relates to annual grass invasion and aboveground indicators of bunchgrass vigor that are more readily measured, such as plant height. We used a standardized US Department of Agriculture protocol for root measurement in 445 excavations made in 2016 ? 2018 across a topographically and ecologically varied region of sagebrush steppe burned in the 2015 Soda fire in the Northern Great Basin, United States. Nearly all (99%) bunchgrasses, including seedlings, had deeper roots than the surrounding annual grasses (mean depth of annuals = 6.8 ± 3.3 cm), and 88% of seedlings remained rooted in response to the “tug test” (uprooting resistance to ~ 1 kg of upward pull on shoot), with smaller plants (mean height and basal diameters < 20 cm and < 2 cm, respectively) more likely to fail the test regardless of their root abundance. Lateral roots of bunchgrasses were scarcer in larger basal gaps (interspace between perennials) but were surprisingly not directly related to cover of surrounding EAG. However, EAG cover increased with the size of basal gaps and decreased with greater basal diameter of bunchgrass (in addition to prefire EAG abundance), albeit with a low r². These results provide some support for 1) the importance of basal gaps and bunchgrass diameters as indicators of both vulnerability to annual grass invasion and bunchgrass root abundance and 2) the need for more detailed methods for root measurement than used here in order to substantiate their usefulness in understanding rangeland resistance and resilience.     

Revegetation of Medusahead-Invaded Sagebrush Steppe

Medusahead (Taeniatherum caput-medusae [L.] Nevski) is an exotic annual grass invading western rangelands. Invasion by medusahead is problematic because it decreases livestock forage production, degrades wildlife habitat, reduces biodiversity, and increases fire frequency. Revegetation of medusahead-invaded sagebrush steppe is needed to increase ecosystem and economic productivity. Most efforts to revegetate medusahead-infested plant communities are unsuccessful because perennial bunchgrasses rarely establish after medusahead control. The effects of prescribed burning (spring or fall), fall imazapic application, and their combinations were evaluated for medusahead control and the establishment of seeded large perennial bunchgrasses. One growing season after treatments were applied, desert wheatgrass (Agropyron desertorum [Fisch. ex Link] Schult.) and squirreltail (Elymus elymoides [Raf.] Swezey) were drill seeded into treatment plots, except for the control treatment. Vegetation characteristics were measured for 2 yr postseeding (second and third year post-treatment). Medusahead was best controlled when prescribed burned and then treated with imazapic (P < 0.05). These treatments also had greater large perennial bunchgrass cover and density compared to other treatments (P < 0.05). The prescribed burned followed by imazapic application had greater than 10- and 8-fold more perennial bunchgrass cover and density than the control treatment, respectively. Prescribed burning, regardless of season, was not effective at controlling medusahead or promoting establishment of perennial bunchgrasses. The results of this study question the long-term effectiveness of using imazapic in revegetation efforts of medusahead-infested sagebrush steppe without first prescribed burning the infestation. Effective control of medusahead appears to be needed for establishment of seeded perennial bunchgrasses. The results of this study demonstrate that seeding desert wheatgrass and squirreltail can successfully revegetate rangeland infested with medusahead when medusahead has been controlled with prescribed fire followed by fall application of imazapic.     

Sage Grouse Groceries: Forb Response to Piñon-Juniper Treatments

Juniper and piñon coniferous woodlands have increased 2- to 10-fold in nine ecoregions spanning the Intermountain Region of the western United States. Control of piñon-juniper woodlands by mechanical treatments and prescribed fire are commonly applied to recover sagebrush steppe rangelands. Recently, the Sage Grouse Initiative has made conifer removal a major part of its program to reestablish sagebrush habitat for sage grouse (Centrocercus urophasianus) and other species. We analyzed data sets from previous and ongoing studies across the Great Basin characterizing cover response of perennial and annual forbs that are consumed by sage grouse to mechanical, prescribed fire, and low-disturbance fuel reduction treatments. There were 11 sites in western juniper (Juniperus occidentalis Hook.) woodlands, 3 sites in singleleaf piñon (Pinus monophylla Torr. & Frém.) and Utah juniper (Juniperus osteosperma [Torr.] Little), 2 sites in Utah juniper, and 2 sites in Utah juniper and Colorado piñon (Pinus edulis Engelm). Western juniper sites were located in mountain big sagebrush (A. tridentata ssp. vaseyana) steppe associations, and the other woodlands were located in Wyoming big sagebrush (A. tridentata ssp. wyomingensis) associations. Site potential appears to be a major determinant for increasing perennial forbs consumed by sage grouse following conifer control. The cover response of perennial forbs, whether increasing (1.5- to 6-fold) or exhibiting no change, was similar regardless of conifer treatment. Annual forbs favored by sage grouse benefitted most from prescribed fire treatments with smaller increases following mechanical and fuel reduction treatments. Though forb abundance may not consistently be enhanced, mechanical and fuel reduction conifer treatments remain good preventative measures, especially in phase 1 and 2 woodlands, which, at minimum, maintain forbs on the landscape. In addition, these two conifer control measures, in the short term, are superior to prescribed fire for maintaining the essential habitat characteristics of sagebrush steppe for sage grouse.     

放牧强度对不同草地类型生态系统气体交换影响的研究

为揭示不同放牧强度下不同草原类型气体交换的变化规律,在8月中旬采用Li-6400 便携式光合仪和密闭式箱法,分别对内蒙古草甸草原、典型草原和荒漠草原不同放牧强度下气体交换进行分析研究。结果表明:不同草原类型之间的生态系统净CO₂交换(NEE)、生态系统总呼吸(ER)和生态系统总初级生产力(GEP)均存在显著差异(P<0.05)。草甸草原的NEE和GEP随放牧强度增加呈现降低趋势,ER则呈现上升趋势;典型草原的NEE和GEP随放牧强度增加呈现上升趋势,ER则呈现下降趋势;荒漠草原的NEE和GEP除对照区外,随放牧强度增加呈现上升趋势,而ER呈降低趋势。放牧通过对草原生态系统植物、土壤等产生影响,从而影响生态系统气体交换。     

模拟降水对荒漠草原生态系统碳交换的影响

全球降水格局的改变势必会影响陆地生态系统的各项功能,而草地碳汇功能对水分的变化极为敏感.为探究不同降水梯度对生态系统碳交换产生的影响,于内蒙古四子王旗荒漠草原设置模拟降水试验(减水50％、自然降水、增水50％和增水100％),在2017年5月至9月,每隔15?d采用Li-6400便携式光合仪和密闭式箱法测定生态系统净碳...     

柴达木盆地草地类型及其分布规律

柴达木盆地天然草地面积696．9万公顷，依据中国草地类型分类系统，可分为温性草原类、高寒草原类、温性荒漠类、高寒荒漠类、低地草甸类、山地草甸类、高寒草甸类及沼泽类等8类、38个草地型。主要由于水分、热量条件的变化，导致柴达木盆地草地类型在东半部以温性草原类为主，西半部以温性荒漠类为主。受地形地貌特征及海拔高度的影响，草地类型垂直分布格局明显，从盆地中心至边缘呈现沼泽类、低地草甸类、山地草甸类、温性荒漠类或温性草原类、高寒草原类、高寒草甸类或高寒荒漠类。     

Net Carbon Fluxes Over Burned and Unburned Native Tallgrass Prairie

Prescribed burning of aboveground biomass in tallgrass prairie is common and may influence dynamics and magnitudes of carbon (C) movement between the surface and atmosphere. Carbon dioxide (CO₂) fluxes were measured for 2 yr using conditional sampling systems on two adjacent watersheds in an ungrazed tallgrass prairie near Manhattan, Kansas. One watershed was burned annually (BA) and the other biennially (BB). Leaf and soil CO₂ fluxes were measured in the source area. Net ecosystem exchange (NEE) of CO₂ reached a maximum daily gain of 26.4 g CO₂·m^?2·d^?1 (flux toward surface is positive) in July 1998 (year when both sites were burned and precipitation was above normal); gains were similar between sites in 1998. The maximum daily NEE loss of CO₂ was ?21.8 g CO₂·m^?2·d^?1 from BA in September 1997 (year when only BA was burned and precipitation was below normal). When data were integrated over the two years, both sites were net sources of atmospheric CO₂; NEE was ?389 g C·m^?2·2 yr^?1 on BA and ?195 g C·m^?2·2 yr^?1 on BB. Burning increased canopy size and photosynthesis, but the greater photosynthesis was offset by corresponding increases in respiration (from canopy and soil). Carbon losses from fire represented 6–10% of annual CO₂ emissions (bulk came from soil and canopy respiration). Data suggest that annual burning promotes C loss compared to less-frequently burned tallgrass prairie where prairie is not grazed by ungulates. Greater precipitation in 1998 caused large increases in biomass and a more positive growing season NEE, indicating that C sequestration appears more likely when precipitation is high. Because C inputs (photosynthesis) and losses (canopy and soil respiration) were large, small measurement or modeling errors could confound attempts to determine if the ecosystems are long-term CO₂ sources or sinks.     

Weed-Suppressive Bacteria Have No Effect on Exotic or Native Plants in Sagebrush-Steppe

Approaches and techniques for control of exotic annual grasses are a high priority in rangelands including sagebrush steppe. Strains of the soil bacterium Pseudomonas fluorescens have been proposed to be selectively pathogenic to multiple species of exotic annual grasses (“Pf,” weed-suppressive bacteria, “WSB”). However, defensible tests of the target and nontarget effects of these WSB strains in the field are needed. We evaluated the effects of D7 and MB906 strains of Pf WSB in sagebrush steppe invaded by cheatgrass (Bromus tectorum L), medusahead (Taeniatherum caput-medusae L. Nevski), and other exotic annual grasses. We evaluated the WSB strains with and without herbicides (imazapic, rimsulfuron) or discing to mix surface-spray of the WSB into deeper soils, and we replicated these tests in three ecoregions that differed in soils and climate. Over 3 yr after treatment, neither WSB strain affected cover of exotic annual grasses, perennial bunchgrasses, or the total community, either with WSB alone or in combination with herbicides or discing. WSB has received considerable attention and is being applied across large rangeland areas, but the WSB strains and methods applied here were ineffective. We recommend any future use of WSB be applied in an experimental fashion, with experimental design and measurement of responses, until its effects can be proven.     

新疆昌吉州草地生产力年际动态分析

通过对新疆昌吉州草地生产力2006~2010年5年监测结果显示:各草地类型植被不同程度退化。植物种类减少,草群结构单一,优势种出现频率很低,一年生和短命植物比例增加,中山带毒害草(醉马草)大量出现;草层高度不同程度下降。除山地草甸外,高寒草甸、草甸草原、典型草原和荒漠草层高度下降明显,下降幅度都超过了10%;植被覆盖度降低。除荒漠外高寒草甸、山地草甸、草甸草原、荒漠草原和低地草甸下降明显,下降幅度都超过了10%;草地生产力不同程度下降,在2009~2010年草地生产力有所上升。     

Nutrient Limitations of Carbon Uptake: From Leaves to Landscapes in a California Rangeland Ecosystem

Nutrient controls of ecosystem pattern and process have been widely studied at the Jasper Ridge Biological Preserve, a well-studied California rangeland ecosystem. Here we review these studies, from leaf to landscape scales, with the intention of developing a deeper understanding of carbon (C)–nutrient interactions in such an ecosystem. At the leaf scale, several studies conducted on diverse plant species have revealed a strong positive relationship between leaf nitrogen (N) concentrations and maximal rates of photosynthesis. This relationship, which has subsequently been observed globally, can be explained by the nutritional requirements of photosynthetic machinery. Consistent with this local physiological constraint, N availability has been shown to limit carbon uptake of California rangeland ecosystems. In some cases phosphorus (P; and N plus P) limits productivity, too—particularly in serpentine soils, pointing to the importance of parent material in regulating CO₂ uptake at landscape scales. Nutrient dynamics are also affected by herbivory, which seems to accelerate N and P cycles over the short term (years), but may lead to nutrient limitation of plant production over the longer term (decades). Simulated global change experiments at Jasper Ridge have also provided insight into C–nutrient interactions in grasslands. In particular, several field-based experiments have shown that CO₂ doubling does not necessarily simulate productivity of California grasslands; rather, the strength and sign of net primary productivity (NPP) responses to CO₂ doubling varies across years and conditions. Although simulated N deposition stimulates NPP, N plus CO₂ combinations do not necessarily increase productivity beyond N treatments singly. Poorly understood feedbacks between plants, microbes, and P availability may underlie variation in the response of California grasslands to increasing atmospheric CO₂ concentrations. We conclude that interactions between C, N, and P appear especially vital in shaping plant productivity patterns in California rangelands and the capacity of this ecosystem to store additional C in the future.     

基于家畜生产优化管理模型的家庭牧场可持续发展研究

以内蒙古四子王旗的典型草原和荒漠草原两种草地类型的家庭牧场为研究对象,通过对牧户的实地问卷调查、模型模拟分析和文献查阅研究,深入剖析牧户家庭的草场参数、家畜参数、饲料参数、气象参数和经济参数等,利用模型模拟计算出草地生长速率、草畜能量平衡状况和经济效益收支现状,以期为指导当地的家庭牧场可持续经营提出可靠依据。结果表明：四子王旗牧草生长周期较短,夏季典型草原牧草生长速率大于荒漠草原,冬季两种类型草地牧草的抗寒能力较差,牧草大部分停止生长,地上部分基本枯死,家畜利用新鲜牧草得到的能量主要集中在夏秋牧草生长季节。中小牧户是草原超载过牧的主体,草地面积越小的牧户,其家畜载畜率越高。草料费支出与家畜载畜率也呈正相关关系,草料费支出越多,载畜率越高。典型草原区和荒漠草原区都呈现出夏季仅有短时间的草地供给能量大于家畜自身能量需求,可以满足家畜良好的生长状态;冬季寒冷且漫长,能量摄入量较低,典型草原地区在1月产羔期能量缺值高达10.5 MJ/（羊单位·d）,荒漠草原地区能量缺值高达9.5 MJ/（羊单位·d）。适当调整家畜载畜率有利于四子王旗地区家庭牧场提高草地综合生产能力和增加农牧民经济收入。