Long-Term Vegetation Recovery and Invasive Annual Suppression in Native and Introduced Postfire Seeding Treatments

Seed mixes used for postfire seeding in the Great Basin are often selected on the basis of short-term rehabilitation objectives, such as ability to rapidly establish and suppress invasive exotic annuals (e.g., cheatgrass, Bromus tectorum L.). Longer-term considerations are also important, including whether seeded plants persist, continue to suppress invasives, and promote recovery of desired vegetation. To better understand long-term effects of postfire seed mixes, we revisited study sites in Tintic Valley, Utah, where seeding experiments had been initiated after the 1999 Railroad wildfire. Four different mixes, including two comprised entirely of native species, had been applied using rangeland drills at a shrubland site and aerial seeding followed by one-way Ely chaining at a woodland site. New vegetation data collected 16 years post fire revealed changes relative to 3 years post fire. We found significant increases in total cover of seed-mix species in all treatments, including the unseeded control where these species were present as residual populations or had spread from seeded treatments. Significant increases of seed-mix species cover and density were observed in blocks where seeding treatments had previously been considered unsuccessful. Some seed-mix species, particularly rhizomatous grasses, increased while others declined. Exotic annual forb cover decreased in all treatments while cheatgrass increased in the unseeded control and to a lesser extent in the native-only seeded treatments. Recruitment of non-seed-mix native perennials was highest in the unseeded control. Results indicate that postfire seeding has lasting effects on vegetation composition and structure, implying that seed mixes should be carefully formulated to promote long-term management objectives. Seed mixes containing large amounts of competitive introduced species may be especially effective for long-term cheatgrass suppression, but native-only mixes can also serve this purpose to a lesser degree while avoiding drawbacks of non-native species introductions.     

矿区排土场植被恢复方式对土壤非植物寄生线虫种类及数量的影响

非植物寄生线虫是土壤中的有益线虫。在2018年对锡盟露天煤矿不同植被恢复方式下排土场非线虫种类及数量进行了研究,结果表明:排土场的植被恢复区非植物寄生线虫种类、数量高于无恢复区;在0~10cm土层处,恢复4年、恢复8年及天然草地有3个优势属,而无恢复区有2个属;10~20cm土层中恢复8年区优势属为3个,而恢复4年区优势属为2个,天然草地及无恢复区优势属均为1个;矿区排土场种植被恢复区出现土壤cp值为4的线虫类型,而无恢复区没有此类线虫。由此可见,植被恢复使土壤非植物寄生线虫种类及数量发生了改变,有利于排土场土壤的改善。     

退化高寒草甸暖季休牧恢复过程中植被和土壤特性

为探讨暖季休牧恢复过程中退化高寒草甸植被和土壤恢复特性,本研究对泽库县退化高山嵩草草甸暖季休牧样地不同恢复阶段植被和土壤特性进行调查,结果显示植被高度、地上生物量、土壤含水量、土壤有机碳含量等生态功能属性随自然恢复时间的延长不断得到改善(P<0.05),在恢复末期(9—10年)恢复最好;植被盖度、地下生物量、多样性、土...     

北京西北浅山区退化草地植被恢复对土壤微生物群落多样性的影响

为了揭示退化草地生态系统恢复过程中土壤微生物群落对植被恢复的响应变化,本研究以补播建植6年的紫花苜蓿(Medicago sativa L.)草地(AF)和无芒雀麦(Bromus inermis Leyss.)草地(SB)为研究对象,采用高通量测序的方法分析土壤微生物细菌和真菌(群落多样性)在不同草地群落中的特征,结合地上植物多样性和土壤理化性质的变化,研究植被恢复对土壤微生物群落多样性的影响。结果表明：无芒雀麦和紫花苜蓿草地的土壤微生物量碳含量和微生物量氮含量要显著高于自然演替地(P<0.01);2种人工草地(AF,SB)中土壤真菌和细菌的OTU数量显著地高于自然演替地(CK)(P<0.01);不同植被恢复群落间的土壤细菌和真菌群落的β多样性差异显著。本研究结果表明利用紫花苜蓿和无芒雀麦进行植被恢复均对土壤微生物群落产生了显著的影响,且不同植被类型对土壤细菌和真菌的群落结构影响不同。     

荒漠草原区不同植被恢复模式土壤微生物菌落分布特征及其与土壤理化性质的相关性

研究土壤微生物菌落变化对土壤肥力的影响,对荒漠草原区草地的恢复管理具有重要的意义.本文以宁夏典型荒漠草原区的天然草地为对照,以平茬人工柠条林地、人工柠条林地、天然柠条林地为研究对象,采用稀释平板法估算各样地0～5,5～10,10～20,20～40 cm土层中微生物菌落数量,并测定对应土层的土壤理化性质及6种可溶性氮组分...     

Comparison of Postfire Soil Water Repellency Amelioration Strategies on Bluebunch Wheatgrass and Cheatgrass Survival

Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as “till”), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.     

贺兰山低山区土壤种子库与地上植被关系分析

土壤种子库是地上植被更新的潜在种源,它影响地上植被的自然恢复、植被群落的演替进程和区域生物多样性维持。通过对贺兰山低山区不同海拔高度植物群落进行室内种子萌发试验和野外植被调查,发现5个海拔高度的土壤种子库植物种均以一年生草本居多,而相对应的地上植被群落在5个海拔高度的物种重要值均呈现为一年生草本<灌木或半灌木<多年生草本;土壤种子库和相对应的地上植被的物种多样性指数均在海拔1 200 m处最高;土壤种子库种子密度与相对应的地上植被密度的关系可用对数曲线表示,随着地上植被密度的增加土壤种子库种子密度呈减少趋势。贺兰山低山区5个海拔高度土壤种子库种子密度和物种多样性均较低,无法满足植被自然恢复需求,可通过采取飞播等生态恢复措施来弥补表层土壤种子的不足,从而满足地上植被恢复所需种子数量。     

典型草原封育过程中土壤种子库的变化特征

研究内蒙古巴林右旗退化草原围封不同阶段土壤种子库的数量和物种组成以及其与地上植被的关系。结果表明:随着封育年限增加,土壤种子库中物种数目呈增加趋势,一年生植物种类逐渐减少,多年生植物种类逐渐增加,至封育6年时一年生植物在典型草原群落中基本消失;土壤种子库密度随着围封年限增加而逐渐增加,表现为围封1年时草地土壤种子库密度平均为1192粒·m^-2,而围封10年时草地土壤种子库密度达到2544粒·m^-2,较围封1年的群落增涨53.1%。     

Assessing the Success of Postfire Reseeding in Semiarid Rangelands Using Terra MODIS

Successful postfire reseeding efforts can aid rangeland ecosystem recovery by rapidly establishing a desired plant community and thereby reducing the likelihood of infestation by invasive plants. Although the success of postfire remediation is critical, few efforts have been made to leverage existing geospatial technologies to develop methodologies to assess reseeding success following a fire. In this study, Terra Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data were used to improve the capacity to assess postfire reseeding rehabilitation efforts, with particular emphasis on the semiarid rangelands of Idaho. Analysis of MODIS data demonstrated a positive effect of reseeding on rangeland ecosystem recovery, as well as differences in vegetation between reseeded areas and burned areas where no reseeding had occurred (P < 0.05). We conclude that MODIS provides useful data to assess the success of postfire reseeding.     

黄土高原水蚀风蚀交错区植被恢复中土壤水分变化

针对黄土高原生态恢复与重建过程中水资源短缺问题,本文采用空间代替时间序列的方法对地处黄土高原水蚀风蚀交错区的六道沟小流域在植被恢复过程中的土壤储水量和土壤垂直剖面含水量特征进行了研究,分析了紫花苜蓿地(12,15,17,21,26,41 a)、荒草地(15,32,41 a)、弃耕地(12,21,41 a)、杏树地(14 a)的土壤储水量和土壤垂直剖面含水量特征。结果表明:4种植被恢复方式下,土壤储水量的大小顺序为弃耕地 > 荒草地 > 杏树地 > 苜蓿地;苜蓿地、弃耕地0~200 cm储水量随着生长年限的延长先快速增加后缓慢减少,而荒草地的储水量随着生长年限的延长却持续减少。水蚀风蚀交错区植被恢复过程中,植被恢复方式是该地区土壤水分变化的主要影响因素,生长年限对土壤水分动态变化影响不明显。     

渭北旱塬区土壤质量对人工植被恢复模式的响应

以植被恢复土壤效果评价7种人工植被恢复模式,应用灰色关联模型和聚类分析方法研究渭北旱塬区植被恢复对土壤综合质量的影响,以确定最优植被恢复模式。结果表明：不同人工植被恢复模式对土壤质量有很大影响,与对照（农地）相比,恢复年限为5年、10年紫花苜蓿（Medicago sativa）草地和恢复年限为30年刺槐（Robinia pseudoacacia）林地均提高了土壤质量,其中10年紫花苜蓿草地恢复效果最好。随着退耕还林还草工程的实施,在渭北旱塬区,种植牧草、建植乔木是较好的生态重建和植被恢复方式。     

草原植被恢复对矿区排土场土壤线虫群落多样性的影响

矿区排土场是草原被开垦利用的产物,植被恢复对已破坏草原生态系统具有重要意义。线虫是草原地下生态系统的主要组成部分,对土壤环境反应敏感,可作为一种良好的指示性生物。通过对人工植被恢复8年、人工植被恢复4年、无植被恢复4年的矿区排土场和自然状态下的天然草地中0~10 cm和10~20 cm土层中线虫的数量、种类和群落结构多样性开展研究,旨在揭示草原植被恢复对矿区排土场土壤线虫的影响。结果表明：试验区共分离出土壤线虫51个属,不同草原植被恢复方式影响土壤线虫种类及优势度,不同恢复方式下土壤线虫的优势属有一定差异;草原植被恢复方式影响土壤线虫数量及营养类群,不同草原植被恢复方式下土壤线虫数量及属数从大到小依次为：人工恢复8年>人工恢复4年>天然草地>无恢复4年;人工恢复4年区及8年区捕食/杂食类线虫数量高于无恢复区,整个地下土壤线虫多样性增大;无恢复4年区的H′多样性指数显著（P<0.05）低于其他3种处理,反映出草原植被恢复对土壤线虫群落成熟稳定的作用,揭示了土壤恢复状况。研究结果为矿区排土场生态恢复措施的选择和实施提供了理论依据。     

Postfire Recovery of Sagebrush Communities: Assessment Using Spot-5 and Very Large-Scale Aerial Imagery

Much interest lies in long-term recovery rates of sagebrush communities after fire in the western United States, as sagebrush communities comprise millions of hectares of rangelands and are an important wildlife habitat. Little is known about postfire changes in sagebrush canopy cover over time, especially at a landscape scale. We studied postfire recovery of shrub canopy cover in sagebrush-steppe communities with the use of spectral mixture analysis. Our study included 16 different fires that burned between 1937 and 2005 and one unburned site at the US Sheep Experiment Station in eastern Idaho. Spectral mixture analysis was used with September 2006 Systeme Pour l’Observation de la Terre-5 (SPOT-5) satellite imagery to estimate percent shrub canopy cover within pixels. Very large-scale aerial (VLSA) imagery with 24-mm resolution was used for training and validation. SPOT-5 image classification was successful and the spectral mixture analysis estimates of percent shrub canopy cover were highly correlated with the shrub canopy cover estimates in the VLSA imagery (R² = 0.82; P < 0.0001). Additional accuracy assessment of shrub classification produced 85% overall accuracy, 98% user’s accuracy, and 78% producer’s accuracy. This successful application of spectral mixture analysis has important implications for the monitoring and assessment of sagebrush-steppe communities. With the use of the percent shrub canopy cover estimates from the classified SPOT-5 imagery, we examined shrub canopy recovery rates since different burn years. With the use of linear-plateau regression, it was determined that shrub cover in mountain big sagebrush (Artemisia tridentata Nutt. subsp. vaseyana [Rydb.] Beetle) communities recovered approximately 27 yr after fire, with an average shrub cover of 38%. These results are consistent with other field-based studies in mountain big sagebrush communities.     

百里香在草地植被恢复中的优势及展望

百里香为唇形科百里香属常见种,在我国分布较为广泛,其野生资源丰富。研究表明,百里香不仅是重要的香料和园林植物,还是很好的草地植被恢复植物。综述了百里香的生物学特性及其在草地植被恢复中的优势,并对其开发利用前景进行了展望,以期为全方位挖掘百里香的应用价值提供参考。     

不同种衣剂配方对达乌里胡枝子种子萌发的影响

为筛选出适宜的达乌里胡枝子（Lespedeza daurica）种衣剂配方,从而为达乌里胡枝子种衣剂的利用提供参考,进而解决达乌里胡枝子在推广种植上受限制的问题。试验材料为‘晋农一号’达乌里胡枝子（L.daurica ‘Jinnong No.1’,简称LD）,选用聚乙烯醇、高吸水性树脂、根瘤菌（Rhizobium）、硅藻土和膨润土对LD种子进行包衣（包衣剂与种子的质量比分别为1：1和2：1）,研究不同配方种衣剂对LD种子质量和萌发特性的影响。试验结果表明：4%的聚乙烯醇具有成膜性和粘结性,较低的水溶性和脱落率;5%的高吸水性树脂可以提高种子活力和萌发特性;膨润土与硅藻土按1：4的质量比混合最佳。药种比为1：1时发芽率和活力指数均显著提高。故LD种衣剂药种比的最佳配比为1：1,配方为：根瘤菌菌剂100 g·kg^-1、黏着剂300 mL·kg^-1、保水剂50 g·kg^-1、硅藻土440 g·kg^-1和膨润土110 g·kg^-1。     

Cattle Selection for Aspen and Meadow Vegetation: Implications for Restoration

There is concern over the decline of aspen and the lack of successful regeneration due to excessive browsing of aspen suckers by cattle and other wild and domestic ungulates. We conducted a 2-yr study on Lassen National Forest, California, to aid development of cattle grazing strategies to enhance aspen regeneration. We evaluated seasonal biomass, nutritional quality, and utilization by cattle of aspen suckers, aspen herbaceous understory vegetation, and meadow herbaceous vegetation within six aspen–meadow complexes. Aspen suckers had greater nutritional quality compared to aspen understory and meadow vegetation regardless of season or year. Nutritional quality declined with season in all three vegetation types. Early-growing season foraging by cattle focused on meadow and aspen understory vegetation. Mid-growing season decreases in meadow and aspen understory nutritional quality coincided with a marked increase in utilization of aspen suckers. By late-growing season, utilization on aspen suckers was significantly greater than aspen understory or meadow vegetation. Managers can use early-growing season grazing to reduce aspen consumption by cattle, set stocking rates so that adequate herbaceous vegetation is available throughout the growing season, provide nutritional supplements to reduce demand for nutritious aspen suckers, construct protective fencing, and implement grazing systems that insure years with mid- and late-growing season rest from heavy browsing.     

金沙江干热河谷封禁山地草地土壤种子库和植被特征

2004年在金沙江干热河谷地区选择典型退化山地草地封禁,在封禁后第1年和第2年对封禁山地草地土壤种子库、植被群落组成和密度等进行了调查和分析.结果表明:随着封禁年限的增加,土壤种子库密度、植被密度增加极显著(P＜0.001).扭黄茅的优势度随封禁年限的增加逐年升高,为优势种群;双穗雀稗、酢浆草种群优势度也逐年上升,而丝叶球柱草种群优势度有所降低.     

Evaluating a Seed Technology for Sagebrush Restoration Across an Elevation Gradient: Support for Bet Hedging

Big sagebrush (Artemisia tridentata Nutt.) restoration is needed across vast areas, especially after large wildfires, to restore important ecosystem services. Sagebrush restoration success is inconsistent, with a high rate of seeding failures, particularly at lower elevations. Seed enhancement technologies may overcome limitations to restoration success. Seed pillows are one such technology designed to improve seed-soil contact in broadcast seedings by providing a favorable medium for seedling establishment and growth. Seed pillows have shown promising results in greenhouse studies; however, they have not been evaluated in the field. We compared broadcast-seeding seed pillows with broadcast-seeding bare seed in 2 yr across a large, burned elevation gradient. Compared with bare seed, we found no evidence that seed pillows improved sagebrush establishment and growth across the elevation gradient. Though our results suggest that seed pillows do not increase the likelihood of successful sagebrush restoration, they were successful at times when bare seeds were not, and the same was true for bare seeds. At least one of the two treatments was successful at 50% of the elevations over the 2 seeding yr. This suggests that a bet hedging approach, seeding both bare seed and seed pillows, may increase the probability of success. Further supporting the use of bet hedging, if both methods were used and seeding occurred in both years, success would have been 86%. Sagebrush density and cover varied by elevation. In the first-yr seeding, sagebrush density and cover generally increased with increasing elevation. In the second-yr seeding, sagebrush density and cover were greatest at the lowest and highest elevations. We speculate that at the lower elevations an unusually wet spring combined with limited herbaceous vegetation provided an ideal environment for sagebrush establishment and growth. Our results also demonstrate, counter to common assumptions, that lower elevations sagebrush seedings can be successful.