火烧和施氮对内蒙古半干旱草原土壤微生物群落碳源利用潜力的影响

火烧是草原生态系统中最常见的一种自然现象,而氮素通常被认为是干旱、半干旱地区的主要限制因子。在中国北方草原生态系统相对干旱、长期处于氮素限制条件下,对火干扰和氮沉降非常敏感。通过在内蒙古多伦县半干旱草原地区进行火烧和施氮的野外控制试验,采用BIOLOG微孔板技术探讨火烧与施氮对土壤微生物量及其碳源利用的影响。结果表明：火烧和施氮处理显著降低生长季初期土壤微生物量;但是施氮显著促进了土壤细菌类群对多聚物、糖类、酚类和胺类碳源的利用,及真菌类群对胺类碳源的利用;而且火烧与施氮处理在影响土壤细菌碳源利用上表现出明显的交互效应,火烧削弱了施氮对细菌碳源利用的促进作用。火烧与施氮对生长季初期土壤微生物的这些影响,可能通过影响有效养分的释放而影响后期植物生长,但由于火烧与施氮处理在影响土壤微生物过程中表现出来的复杂性,这种对植物后期生长的影响可能存在较大的不确定性。     

Influence of Wildland Fire Along a Successional Gradient in Sagebrush Steppe and Western Juniper Woodlands

Western juniper (Juniperus occidentalis Hook. var. occidentalis) has been expanding into sagebrush (ArtemisiaL. spp.) steppe over the past 130 yr in Idaho, Oregon, and California. Fuel characteristics and expected fire behavior and effects change as sagebrush steppe transitions into juniper woodlands. Little is currently known about how wildfire influences burn severity and ecosystem response in steppe altered by woodland conversion. In 2007, the Tongue-Crutcher Wildland Fire burned 18890 ha along a successional gradient ranging from sagebrush steppe to mature juniper woodlands, providing a unique opportunity to evaluate the effects of prefire vegetation on burn severity and ecosystem response across spatial scales. Plot-scale burn severity was evaluated with the composite burn index (CBI) in locations where prefire vegetation data were available, and landscape-scale burn severity was estimated via remotely sensed indices (differenced normalized burn ratio [dNBR] and relative differenced normalized burn ratio [RdNBR]). Strong positive relationships exist between CBI and remotely sensed burn severity indices in woodlands, whereas the relationships are weaker in steppe vegetation. Woodlands in late structural development phases, and sagebrush patches near developed woodlands, incurred higher burn severity than steppe and young woodlands. The results support the idea that a threshold exists for when juniper-encroached sagebrush steppe becomes difficult to restore. Implications for fire management in sagebrush/juniper ecosystems are discussed.     

祁连山东段不同类型灌丛斑块土壤特征对围封的响应

土壤作为高寒带植被的立地条件,是高寒灌丛生态系统发挥其生态功能的重要基础之一。本研究选取祁连山东段头花杜鹃、山生柳和金露梅3种典型灌丛斑块土壤作为研究对象,系统分析围封前后其理化性质分布特征。结果表明:土壤含水量、有机碳、全磷、全钾、速效氮5个理化指标在灌下、灌外差异显著;土壤含水量、容重、有机碳、全磷、速效氮、速效磷6个理化指标在围栏内外差异显著。主成分分析进一步表明,围栏内速效氮与孔隙度的贡献率较高,表明围封后速效氮与孔隙度是影响祁连山东段3种灌丛斑块土壤理化性质的重要环境因子;围栏外速效氮与全磷的贡献率较高,表明有放牧干扰时速效氮与全磷是影响祁连山东段3种灌丛斑块土壤理化性质的重要环境因子。头花杜鹃灌丛斑块不论是否受到放牧干扰,均能保持其良好的土壤理化性质,表明头花杜鹃灌丛斑块抗外界干扰能力较强。短期围封能够显著增加灌丛斑块土壤含水量和速效养分含量,从而改善立地条件,也进一步证明围封更加有利于退化灌丛草地的恢复与重建。     

Prescribed Fire,Soil, and Plants: Burn Effects and Interactions in the Central Great Basin

Pinyon and juniper expansion into sagebrush ecosystems results in decreased cover and biomass of perennial grasses and forbs. We examine the effectiveness of spring prescribed fire on restoration of sagebrush ecosystems by documenting burn effects on soil nutrients, herbaceous aboveground biomass, and tissue nutrient concentrations. This study was conducted in a central Nevada woodland and included control and burn treatment plots sampled before and after a prescribed fire. Six native understory plant species (Crepis acuminata, Eriogonum umbellatum, Eriogonum elatum, Poa secunda secunda, Festuca idahoensis, and Lupinus argenteus) important for native sagebrush obligate foragers were chosen to represent the understory plant community. L. argenteus is also important for system nutrient cycling and nitrogen fixation. Plants were collected from three microsites (under tree canopy, under shrub canopy, and interspace) common in transitional woodlands during peak growth the summer before a spring prescribed burn and each of two summers following the burn. Soils were collected from corresponding locations at two depth intervals (0–8 and 8–52 cm) to determine the relationships between soil and plant nutrients following fire. Microsite affected soil nutrients but did not influence plant tissue concentrations with the exception of F. idahoensis. Burning resulted in increases in soil surface NH+4, NO₃⁻, inorganic N, Ca²⁺, Mn²⁺, and Zn²⁺. Increases in NO₃⁻, inorganic N, and Zn²⁺ were also observed in deeper horizons. Burning did not affect aboveground plant biomass or nutrient concentrations in the first year with the exception of F. idahoensis, which had increased tissue P. By the second year, all species had statistically significant responses to burning. The most common response was for increased aboveground plant weight and tissue N concentrations. Plant response to burning appeared to be related to the burn treatment and the soil variables surface K⁺, NO₃⁻, and inorganic N.     

Driving Factors That Reduce Soil Carbon,Sugar, and Microbial Biomass in Degraded Alpine Grasslands

Soil carbon and sugars play key roles in carbon (C) cycling in grassland ecosystems. However, little is known about their changes in quantity and composition in degraded alpine meadows in the Tibetan plateau. We compared vegetation C density, soil organic carbon (SOC) density, and soil sugars in nondegraded (ND), degraded (DA; following artificial restoration), and extremely degraded (ED) grasslands and analyzed the relation among these parameters by redundancy analysis (RDA) and structural equation models (SEMs). Belowground biomass, soil microbial biomass C, soil microbial biomass nitrogen (N), belowground biomass C density, SOC density, and soil sugars were lower in DA and ED grasslands than in ND grasslands. In addition, the ratio of belowground biomass to aboveground biomass (BAR) decreased with an increase in degradation. The ratio of belowground biomass to aboveground biomass was identified as the main indirect driving force of ecosystem C density by affecting total vegetation C and SOC densities. Soil dissolved organic carbon (DOC), microbial biomass carbon (SMBC), neutral sugars (NS), and total nitrogen (TN) were identified as main direct driving forces. The ratio of belowground biomass to aboveground biomass altered DOC, SMBC, NS, and TN and, consequently, was the primary driving force for the alpine meadows’ ecosystem C density. It was concluded that land management in alpine meadows should include practices that maintain a relatively high BAR in order to curb degradation and increase ecosystem C density.     

Change in Piñon-Juniper Woodland Cover Since Euro-American Settlement: Expansion Versus Contraction Associated with Soil Properties

Woodland and forest ecosystems across western North America have experienced increased density and expansion since the early 1900s, including in the widely distributed piñon-juniper vegetation type of the western United States. Fire suppression and grazing are often cited as the main drivers of these historic changes and have led to extensive tree-reduction treatments across the region. However, much of the scientific literature on piñon-juniper expansion dates back only to the early 1900s, which is generally half a century after Euro-American settlement. Yet US General Land Office (GLO) surveys provide valuable insight into the historical extent and density of woodland and forest ecosystems as surveyors would note where on the landscape they entered and exited woodlands or forests and provided qualitative estimates of relative tree density. This study uses these GLO surveys to establish piñon-juniper woodland extent in the late 19th century at the incipient stages of Euro-American settlement in southeastern Colorado and compares these data with 2017 aerial imagery of woodland cover. We found substantial amounts of woodland contraction, as well as expansion: ≈61% of historically dense woodland is now savanna or open (treeless), whereas ≈57% of historically open areas are now savannas or woodlands. The highest rates of expansion occurred on shallow, rocky soil types with low soil available water capacity, which support little herbaceous vegetation and were consequently less likely to be affected by fire suppression or grazing. Meanwhile, the significant contractions in woodland extent occurred on deeper, upland soils with higher soil available water capacity, which were likely where early settlement and tree cutting was most prevalent. Our results provide mixed support for the widespread assumption of woodland expansion since Euro-American settlement in southeast Colorado and suggest that the expansion that has occurred in our study area is unlikely a result of past grazing or fire suppression.     

Effects of smoke,ash and heat shock on seed germination of seven species from Central Zagros rangelands in the semi-arid region of Iran

Fire products have been widely identified as germination cues for a number of species from both fire-prone and fire-free ecosystems. However, there is uncertainty about the effects of fire products on seed germination of semi-arid rangeland species. We examined the germination of seven dominant species from Central Zagros rangelands in the semi-arid region of Iran under various heat shock (60, 80 and 120 °C), aerosol smoke, ash and control treatments. Our findings showed that fire products could enhance, inhibit or not affect the seed germination of rangeland species in this area. The germination percentage of Astragalus adscendens increased following 60 °C heat treatment in comparison with the control. The germination of Astragalus verus, Bromus tectorum, B. tomentellus and Phlomis olivieri were increased significantly using smoke treatment (P<0.0001). The seed germination of B. tomentellus and B. tectorum was promoted by ash treatment, whereas the other species exhibited no response or were inhibited by fire products. In addition, smoke treatment shortened the overall germination time of B. tectorum. These findings suggest that fire products affect the germination of several species and can serve as potential tools for understanding the vegetation dynamics and restoration of disturbed semi-arid rangelands.     

青藏高原"黑土滩"退化草地植物和土壤对秃斑面积变化的响应

在青藏高原典型"黑土滩"区对93个秃斑块及周边的土壤和植被特征以及变化规律进行了调查分析.结果表明,高寒草地草毡层消失后形成的"黑土滩"秃斑在草地中形成一个"负肥力岛",秃斑块内土壤养分低于秃斑周边有草皮层覆盖的草地,其中全氮、铵态氮、有机碳差异显著;同时秃斑内pH显著高于秃斑块外水平.秃斑块是草地养分流失的通道.当秃...     

基于DNDC模型的高寒草甸土壤有机碳含量动态研究

研究发现以气温升高为主导的气候变化严重影响高寒草甸土壤有机碳含量的动态变化,然而,关于气候变化和放牧对土壤有机碳的耦合效应知之甚少。本研究采用增温-放牧试验结合DNDC(denitrification-decomposition)模型,检测气候变化和放牧对青藏高原高寒草甸土壤有机碳含量的影响,并评估气候变化和放牧对土壤有机碳含量变化的贡献率。结果表明:气候变化对土壤有机碳产生负面影响;放牧强度通过增加践踏、落叶和粪便返还影响土壤有机碳含量。温度、降水结合放牧强度,解释了高寒草甸土壤有机碳含量变化的63.4%。气候变化是导致土壤有机碳波动的主要因素,该因素解释了土壤有机碳变化的61.9%。相比之下,放牧强度解释了其变化的1.6%。持续的气候变化和放牧会影响土壤有机碳的动态变化,进而影响草地生态系统的服务功能。草地生态系统管理应考虑到潜在的气候变化,以实现该系统的可持续发展。     

新疆土壤有机碳与土壤理化性质的相关性

根据全国第2次土壤普查新疆维吾尔自治区的相关土壤资料数据,分析了新疆(0!50cm)土壤有机碳与土壤理化性质的相关性,以期对研究区土壤进行科学管理,从而有助于合理地耕作和科学地施肥,同时也为研究新疆碳循环机制提供丰富而准确的信息。相关性分析表明,研究区土壤全氮、阳离子交换量均与土壤有机碳含量存在着显著的正相关关系(P0.05)。其中,土壤有机碳与全氮的相关性最大(P0.000 1,R2=0.936 7);土壤pH、土壤容重与土壤有机碳含量呈显著负相关关系(P0.05);全磷、全钾、土壤孔隙度与土壤有机碳含量未达到显著相关水平(P0.05)。本研究结果有助于系统、科学地分析干旱区土壤生态系统在全球气候变化中的贡献及生态意义。     

Postfire Succession in Big Sagebrush Steppe With Livestock Grazing

Prescribed fire in rangeland ecosystems is applied for a variety of management objectives, including enhancing productivity of forage species for domestic livestock. In the big sagebrush (Artemisia tridentata Nutt.) steppe of the western United States, fire has been a natural and prescribed disturbance, temporarily shifting vegetation from shrub–grass codominance to grass dominance. There is limited information on the impacts of grazing to community dynamics following fire in big sagebrush steppe. This study evaluated cattle grazing impacts over four growing seasons after prescribed fire on Wyoming big sagebrush (Artemisia tridentata subsp. Wyomingensis [Beetle & Young] Welsh) steppe in eastern Oregon. Treatments included no grazing on burned and unburned sagebrush steppe, two summer-grazing applications after fire, and two spring-grazing applications after fire. Treatment plots were burned in fall 2002. Grazing trials were applied from 2003 to 2005. Vegetation dynamics in the treatments were evaluated by quantifying herbaceous canopy cover, density, annual yield, and perennial grass seed yield. Seed production was greater in the ungrazed burn treatments than in all burn–grazed treatments; however, these differences did not affect community recovery after fire. Other herbaceous response variables (cover, density, composition, and annual yield), bare ground, and soil surface litter did not differ among grazed and ungrazed burn treatments. All burn treatments (grazed and ungrazed) had greater herbaceous cover, herbaceous standing crop, herbaceous annual yield, and grass seed production than the unburned treatment by the second or third year after fire. The results demonstrated that properly applied livestock grazing after low-severity, prescribed fire will not hinder the recovery of herbaceous plant communities in Wyoming big sagebrush steppe.     

黄土高原森林草原区土壤有机碳库研究

森林土壤有机碳是陆地生态系统最大的有机碳库,对全球碳平衡有着重要的意义。研究对黄土高原森林草原子午岭地区天然柴松林、辽东栎林以及人工油松林土壤有机碳库及其影响因子之间的关系进行了研究。结果表明:柴松林、油松林和辽东栎林3种林地碳密度分别为10.76、9.382和11.43 kg/m2;且有机碳密度随着土壤深度的增加呈现递减趋势,不同土壤深度差异显著(P0.05);不同立地条件下,3种林地碳密度差异明显,柴松林和辽东栎林在整个剖面有机碳密度阴坡阳坡,而油松林在0~50 cm土层是阳坡阴坡,50~90 cm土层是阴坡阳坡;不同林地土壤有机碳密度与土壤含水量、pH值、全氮、全磷等理化指标在不同土层中相关性差异较大,而在整个土壤剖面,除pH值以外,3种林地土壤有机碳密度与理化指标呈极显著(P0.01)的正相关关系。     

管理措施对三江源区"黑土滩"土壤肥力及土壤酶活性的影响

对三江源区典型退化草地“黑土滩”采取施肥及种植垂穗披碱草的恢复措施,结果表明,土壤中的全氮与有机质的相关性显著,全磷与有机质的相关性较明显,变化趋势相一致。短期的恢复措施造成了恢复样地20~30 cm土壤层中有机质、全氮和全磷含量的下降,长期的恢复措施使恢复样地中的这3种营养物质的含量得到了上升;人工种植措施使土壤中的全钾含量显著下降(P<0.05)。此外,速效养分的变化不一致,其中速效氮的含量表现为先降低后升高,速效磷和速效钾的含量变化表现出升高趋势。植被恢复对土壤脲酶活性有促进作用,但蔗糖酶活性没表现出规律性变化;这2种酶的活性与速效养分的含量表现出较强的正相关,而与有机质和全价养分的含量相关性不显著。     

Recovery of Big Sagebrush Following Fire in Southwest Montana

Fire plays a large role in structuring sagebrush ecosystems; however, we have little knowledge of how vegetation changes with time as succession proceeds from immediate postfire to mature stands. We sampled at 38 sites in southwest Montana dominated by 3 subspecies of big sagebrush (Artemisia tridentata Nutt.). At each site we subjectively located 1 sample plot representing the burned area and an unburned macroplot in similar, adjacent, unburned vegetation. Canopy cover of sagebrush was estimated, and plants were counted in 10 microplots. Age and height of randomly chosen sagebrush plants in each size class were determined from 5 microplots. Average postfire time to full recovery of mountain big sagebrush (ssp. vasseyana [Rydb.] Beetle) canopy cover was 32 years, shorter for basin (ssp. tridentata) and much longer for Wyoming (ssp. wyomingensis Beetle & Young) big sagebrush. Height recovered at similar rates. There was no difference in canopy cover or height recovery between prescribed fires and wildfires in stands of mountain big sagebrush. We found no relationship between mountain big sagebrush canopy cover recovery and annual precipitation, heat load, or soil texture. Nearly all unburned sagebrush macroplots were uneven-aged, indicating that recruitment was not limited to immediate postfire conditions in any of the subspecies. Average canopy cover of three-tip sagebrush (A. tripartita Rydb.) did not increase following fire, and many three-tip sagebrush plants established from seed instead of sprouting. Our results suggest that the majority of presettlement mountain big sagebrush stands would have been in early to midseral condition in southwest Montana assuming a mean fire interval of 25 years. Only long fire-return intervals will allow stands dominated by Wyoming big sagebrush to remain on the landscape in our study area. We speculate that effects of site-specific factors conducive to sagebrush recovery are small compared to stochastic effects such as fire.     

Different drivers create spatial vegetation cover and vertical structure in semi-arid African savannas

Important drivers of woody cover in African savannas are rainfall, soil and nutrients, and disturbance factors, such as fire and herbivory. However, very little is known about how these drivers influence woody cover at specific height classes. The main aim of this study was to identify which of these drivers are the best predictors of woody cover at three height classes: shrub (0.75–2.5 m), brush (2.5–5.5 m) and tree (>5.5 m). Percent woody cover estimates were collected using a rapid monitoring technique over 1 700 sites in Kruger National Park, South Africa. Geology (basalt and granite), mean annual rainfall, fire frequency and elephant density were analysed as potential drivers of woody cover. Results indicate that mean annual rainfall was negatively associated with shrub cover, fire frequency was negatively associated with brush cover, and elephant density was negatively associated with tree cover. Patterns of woody cover show that while geology influences the spatial distribution of horizontal woody cover, variation in vertical vegetation structure is created and maintained by top-down disturbance. This provides the first documentation of drivers associated with structurally differentiated woody cover at regional scales. Future studies on woody cover in disturbance-driven environments should not ignore vegetation structure.     

不同植被类型对毛乌素沙地土壤有机碳的影响

通过对比分析毛乌素沙地9种主要植被类型样地中的土壤有机碳含量和密度及其在土壤剖面上的分布差异,研究了不同植被类型对毛乌素沙地土壤有机碳的影响。结果表明,0~80 cm深度的土壤有机碳密度与平均土壤有机碳含量的大小关系均为:马蔺群落>芨芨草群落>旱柳群落>固定沙地油蒿群落>沙柳群落>半固定沙地油蒿群落>农田>中间锦鸡儿群落>流动沙地。随着土层加深,固定沙地油蒿群落、中间锦鸡儿群落、旱柳群落、芨芨草群落、马蔺群落和农田的有机碳含量均显著增加,而半固定沙地油蒿群落、流动沙地、沙柳群落的土壤有机碳含量随土层加深逐渐减少。各植被类型土壤有机碳密度在土壤剖面上的垂直分布格局和有机碳含量相似,但二者变化幅度不同。在流动沙地上进行植被建设有助于土壤固碳,且油蒿群落和沙柳群落的固碳效果较好。应尽量减少和避免强烈的人为干扰,以防止浅层土壤碳发生变化,维持土壤碳库稳定。     

Fire and the dynamics of a semi-arid grassland: influence on soil characteristics

The short-term impact of fire burning with the wind (head fire) and against the wind (back fire) on soil characteristics (soil-water content, soil compaction, soil temperature, organic matter, pH, exchangeable Ca, Mg, K, Na and extractable P) were determined in a semi-arid grassland. This study was conducted over two growing seasons (2000/01 and 2001/02) after only one burning treatment in August 2000. The back fire moved approximately 7.5 times slower than the head fire, leading to the greatest change in hydrological characteristics. The decline in plant cover due to the fire resulted in a considerable increase in soil compaction, soil temperature and a decrease in organic material in turn leading to a lowered soil-water content. Much of the influence of these variables had not been completely reduced two growing seasons after the fire. Burning reduced the soil-water content (0mm to 300mm soil depth) after one month and one year by 13.4% and 31% respectively. Temporary wilting for all grass species occurred more rapidly with burning. During March of the first year, the greatest soil temperature difference (50mm depth) occurred between burnt and unburnt grassland, with the highest soil temperatures recorded in January. The highest temperature on the surface of the soil for each year after burning also occurred during January. Over the first growing season burning significantly reduced organic carbon (C) and total nitrogen (N) content and extractable phosphate, but increased the pH and concentration of exchangeable Ca, Mg, Na and K in the soil, over the first 0–50mm layer. There were no differences in the soil properties of head and back fires, except for organic material that was further lowered by the back fire. With depth, organic matter and K decreased significantly and Ca increased between surface (0mm to 50mm) and lower (50mm to 100mm) layers due to burning. Thus, an unplanned event can increase the intensity and frequency of seasonal droughts in the ecologically sensitive semi-arid grassland areas leading to increase risk management in the short-term.     

CENTURY模型在不同生态系统的土壤有机碳动态预测研究进展

CENTURY模型是国际上著名的生物地球化学模型之一。本研究系统介绍了CENTURY模型的运行机理及过程,分析和总结该模型在草地、农田、森林生态系统中土壤有机碳(SOC)的研究成果,并归纳了影响其模拟精度的主要因素。结果表明,土壤质地和土壤养分是影响CENTURY模型在草地生态系统应用的关键因素,且该模型在荒漠草原生态系统的适应性较高;不同农业管理模式是影响SOC模拟精度的因素之一,间作农业模式下模拟SOC的精度较高;CENTURY模拟森林生态系统的枯枝落叶层的有机质时存在结构缺陷,这导致CENTURY模型在草地和农田系统的模拟效果优于森林生态系统。由于CENTURY模型最初是基于草地生态系统而开发,其模型参数在不同地域的草地生态系统的普适性较高;过多的人为干预增加了CENTURY模型在农田生态系统模拟的不确定性,从而会出现模拟结果不稳定的现象;通过调查掌握详细的农田历史管理制度和方式,准确控制模拟进程,可以有效提高模拟精度;森林生态系统的模拟结果可以服务于管理措施的制定,CENTURY模型结合GIS可以实现单点模拟向区域模拟的转变。     

Is Altering Grazing Selectivity of Invasive Forage Species With Patch Burning More Effective Than Herbicide Treatments?

Invasion of rangeland by exotic forage species threatens ecosystem structure and function and can cause catastrophic economic losses. Herbicide treatments often are the focus of management efforts to control invasions. Management with the fire-grazing interaction (or patch burning) might suppress an invasive forage species that has grazing persistence mechanisms developed apart from the fire-grazing interaction. We studied tallgrass prairies invaded by sericea lespedeza (Lespedeza cuneata [Dum.-Cours.] G. Don) to compare rate of invasion between traditional management and management with patch burning, to evaluate the effect of burn season on sericea lespedeza invasion within pastures managed with patch burning, and to correlate canopy cover of sericea lespedeza to canopy cover of other functional groups with and without herbicides. Sericea lespedeza canopy cover increased from 1999 to 2005 in both traditional- and patch-burn pastures, but sericea lespedeza increased from 5% to 16% canopy cover in traditionally managed pastures compared to 3% to 5% in the patch-burn pastures. Rate of increase in canopy cover of sericea lespedeza was less in patches burned in summer (0.41% · year^-1) than in patches burned in spring (0.58% · year^-1) within patch-burn pastures. Most plant functional groups, including forbs, were weak-negatively correlated with canopy cover of sericea lespedeza. Although herbicide application reduced mass of sericea lespedeza, other components of the vegetation changed little. Herbicide treatments temporarily reduced sericea lespedeza but did not predictably increase other plant functional groups. Patch burning reduced the rate of invasion by sericea lespedeza by maintaining young, palatable sericea plants in the burn patch, and could play a vital role in an integrated weed management strategy on rangelands.     

Influence of Prescribed Fire on Ecosystem Biomass,Carbon, and Nitrogen in a Pinyon Juniper Woodland

Increases in pinyon and juniper woodland cover associated with land-use history are suggested to provide offsets for carbon emissions in arid regions. However, the largest pools of carbon in arid landscapes are typically found in soils, and aboveground biomass cannot be considered long-term storage in fire-prone ecosystems. Also, the objectives of carbon storage may conflict with management for other ecosystem services and fuels reduction. Before appropriate decisions can be made it is necessary to understand the interactions between woodland expansion, management treatments, and carbon retention. We quantified effects of prescribed fire as a fuels reduction and ecosystem maintenance treatment on fuel loads, ecosystem carbon, and nitrogen in a pinyon–juniper woodland in the central Great Basin. We found that plots containing 30% tree cover averaged nearly 40 000 kg · ha^?1 in total aboveground biomass, 80 000 kg · ha^?1 in ecosystem carbon (C), and 5 000 kg · ha^?1 in ecosystem nitrogen (N). Only 25% of ecosystem C and 5% of ecosystem N resided in aboveground biomass pools. Prescribed burning resulted in a 65% reduction in aboveground biomass, a 68% reduction in aboveground C, and a 78% reduction in aboveground N. No statistically significant change in soil or total ecosystem C or N occurred. Prescribed fire was effective at reducing fuels on the landscape and resulted in losses of C and N from aboveground biomass. However, the immediate and long-term effects of burning on soil and total ecosystem C and N is still unclear.