Inducing Unstable Grassland Equilibrium States Due to Nonlinear Optimal Patterns of Initial and Parameter Perturbations:Theoretical Models

Due to uncertainties in initial conditions and parameters, the stability and uncertainty of grassland ecosystem simulations using ecosystem models are issues of concern. Our objective is to determine the types and patterns of initial and parameter perturbations that yield the greatest instability and uncertainty in simulated grassland ecosystems using theoretical models. We used a nonlinear optimization approach, i.e., a conditional nonlinear optimal perturbation related to initial and parameter perturbations （CNOP） approach, in our work. Numerical results indicated that the CNOP showed a special and nonlinear optimal pattern when the initial state variables and multiple parameters were considered simultaneously. A visibly different complex optimal pattern characterizing the CNOPs was obtained by choosing different combinations of initial state variables and multiple parameters in different physical processes. We propose that the grassland modeled ecosystem caused by the CNOP-type perturbation is unstable and exhibits two aspects： abrupt change and the time needed for the abrupt change from a grassland equilibrium state to a desert equilibrium state when the initial state variables and multiple parameters are considered simultaneously. We compared these findings with results affected by the CNOPs obtained by considering only uncertainties in initial state variables and in a single parameter. The numerical results imply that the nonlinear optimal pattern of initial perturbations and parameter perturbations, especially for more parameters or when special parameters are involved, plays a key role in determining stabilities and uncertainties associated with a simulated or predicted grassland ecosystem.

Effect of Autumn Cutting Date on Regrowth, Turning Green, Yield and Quality of <i>Leymus chinensis</i>Grassland in Songnen Plain, Northeast China

A field study was carried out to quantify the effects of different cutting time on Leymus chinensis population and community characteristic in Songnen grassland of northeast China from August, 2006 to August, 2007. The treatment interval was ten days with the remaining stubble height of 5 cm from 15th August to 4th October in 2006. Results showed that the L. chinensis made up about 90% of the dry matter of aboveground biomass, and there were about ten species in the L. chinensis community in the 1 m × 1 m plot. The L. chinensis and Kalimeris integrifolia regrew rapidly after autumn cutting in 2016. In the second year, the coefficients of the community similarity were high between the different cutting time treatments. The density, height, aboveground biomass, stem/leaf ratio, and crude protein of L. chinensis were not significant at the turning green stage and harvesting stage, the companion species of L. chinensis community contained higher crude protein, but the crude protein of the plant community were not significant. Thus, considering the weather factor for haymaking, the harvest dates should be concentrated from the middle ten days of August to the first ten days in September.

Construction of Forest and Grass Industry Economic Belt Using Land Resources in Road Side Slope

The construction of expressway and high-speed rail is at the sacrifice of the soil ecological environment. It brings about much damaged land and bare slope. It is necessary to restore vegetation and rebuild landscape. In the design of target plant community and configuration plants,it is required to select as far as possible plants that can blossom and bear fruit or pods. Then seeds of these plants can be harvested,processed and sold,and applied for other projects,so as to develop into a complete forest and grass seed industry chain. This not only reasonably utilizes land resources,but also provides a new approach to the problem of insufficient fine forest seed sources in China. This paper discussed the use of land resources in road side slope and forest and grass seed selection and breeding technology,and elaborated the industrialized development paths for forest and grass seed industries in road side slope. Finally,it arrived at following recommendations.( i) The construction of forest and grass industry economic belt using land resources in road side slope can realize maximum land value. Building a road can help people there get rich,and the type of land and water cultivates its type of forest and grass.( ii) It can make up for the losses incurred from construction of expressway and high-speed rail or destroying forest land,and it can increase farmers' income.( iii) It can increase the supply of domestic seeds,reduce seed import,save foreign exchange,and partly solve the problem of insufficient supply of forest and grass seeds.( iv) It is able to form a complete forest and grass seed industry economic cycle chain,increase employment,and provide new approaches for enriching and benefiting farmers.

Characteristics of change of humic substance in soil in degraded grass lands

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Modeling Water Quality Impacts of Growing Corn, Switchgrass, and <i>Miscanthus</i>on Marginal Soils

The goal of the study was to model water quality impacts of growing perennial grasses on marginal soils. The GLEAMS-NAPRA and RUSLE models were used to simulate long-term surface runoff, percolation, erosion, total phosphorus (TP), and nitrate (NO3-N) losses associated with the production of corn-based bioenergy systems (i.e. conventional tillage corn and corn grain plus stover removal), switchgrass and Miscanthus on three marginal quality soils and one good quality soil in Indiana. Simulations showed that switchgrass and Miscanthus had no effect on annual runoff, but decreased percolation by at least 17%. Results also suggested a potential for reduction in erosion for Miscanthus across the soil types examined when compared to corn-based bioenergy production. The production of switchgrass and Miscanthus did not have significant effects on the simulated TP and NO3-N losses in runoff compared to corn production systems. Nitrates leached from fertilized Miscanthus production were approximately 90% lower than NO3-N leached from the production of fertilized switchgrass and corn systems. Additional studies are needed to better understand the hydrology, erosion and nutrient responses of Miscanthus and switchgrass production to meet bioenergy demands.

Anion Content in Surface and Subsurface Water Flows in Grassland

Grassland devoted about 90% of agricultural Irish land. Anion retention capacity of most agriculture soils is less than cation retention capacity, therefore chemical analyzed for anion （NO3 （nitrate）, CI- （chloride）, SO42 （sulphate） and HPO4 （biphosphate）） in different water flow types （overland flow, interflow and vertical flow or drainage） samples. In this work, simple equipment was used to operationally distinguish between overland flow and interflow while vertical flow collected in different depths using soil water sampler equipments. Episodes of overland flow and interflow occurred even though the site is located in the lowest rainfall in Ireland and on well-drained soil. Samples of different origin showed marked differences in their anion contents, while HPO4 concentrations were almost equal to zero in all water flow types, nitrate where relatively high in overland and interflow samples and was very high in drainage samples. No sampling was carried out below the root zone but it must be assumed that the high concentrations measured in drainage samples would constitute a threat to groundwater resources. When overland flow and interflow did occur, NO3 concentrations were usually close to or in excess of the maximum admissible concentrations for drinking water and it will be constituted a threat to inland surface water bodies.

Improvement of Native Pasture Productivity through Introduction of Various Types of Palatable Species on Dry Lands in Timor

This research was aimed to evaluate the productivity of native pasture in Timor Island by introducing various palatable species.The study was carried out on native pasture in Tuatuka,Timor Island for seven months.The study was performed by using randomized block design(RBD)with eight treatments(S0:no introduction,S1:Cynodon dactilon,S2:Dicanthium aristatum,S3:C.plectotachyus,S4:Brachiaria decumbens,S5:Desmanthus virgatus,S6:Macroptilium atropurpureum,S7:Clitoria ternatea)with four replications.Procedures on this study include trial plots preparation,tillers preparation for each species,introduction of species in trial plots,maintenance and observation of the productivity.Variables observed were forage production(fresh and dry matter(DM)in ton/ha),nutrient content(%)and stock capacity(animal unit(AU)/ha).Data were analyzed for variance based on RBD and followed by Duncan’s test.Analysis of variance showed that introduction of species had a very significant effect(p<0.01)on all observed variables.The introduction of M.atropurpureum produced the highest fresh forage(2.1 t/ha)and DM production(0.69 t/ha).M.atropurpureum also had the highest DM content(43.61%),nitrogen free extract(52.52%)and stock capacity(1.06 AU/ha).The highest crude protein and crude fiber content were found in D.virgatus(4.31%and 36.62%).The highest extract ether was observed in D.aristatum(1.48%).No introduction had the lowest productivity,but demonstrated the highest ash content.The introduction of palatable species increased the productivity of native pasture in Timor and M.atropupureum was the best introduced species.

An Assessment of Land Cover Change in Gashaka-Gumti National Park, Nigeria

The paper assessed the land cover change in Gashaka-Gumti National Park between 1991 and 2021. To achieve this, LandSat data of years 1991, 2001, 2011 and 2021 were obtained from the United States Geological Survey online resource. The findings of the study revealed that there is decrease in the different land cover types over time as a result of anthropogenic activities of the enclave dwellers. The study observed that the continuous existence of enclaves within and around the Park constitutes a serious threat to the survival of the Park. The study recommended that the federal government should consider resettlement of the enclave dwellers to give way for the development of the Park.

人工和天然草地对青年女性跳跃落地时下肢生物力学表现的影响

背景:研究发现运动者解剖结构、激素水平、神经肌肉功能等内部因素与前交叉韧带损伤风险密切相关,而运动场地材质等外部因素也成为影响非接触性前交叉韧带损伤发生的危险因素之一,但目前研究中对其关注度相对不足。目的:探讨人工草地和天然草地对青年女性跳跃落地时下肢生物力学表现影响。方法:根据测试需要将符合GB/T 20033.3-2006以及GB/T 19995.1-2005标准的人工草地和天然草地平整固定于2块三维测力台上。21名青年女性自愿受试者分别在人工草地和天然草地完成跳跃落地任务。受试者站立于台阶上随后向前跳跃,跳落至测力台后立即全力纵跳并再次落至测力台上,2次落地均要求双脚分别落至2块测力台上,整个跳跃动作流畅无停顿视为成功。同步采集下肢落地过程中运动学、动力学及肌电数据,比较分析二者差异。结果与结论:①动力学方面,在天然草地进行跳跃落地任务时初始触地时刻后向地面反作用力、纵向地面反作用力显著低于在人工草地时(P<0.05;P<0.01);峰值地面反作用力时刻二者亦显著低于在人工草地时(P<0.05;P<0.05),且表现出更高的膝关节屈曲力矩(P<0.01)。②肌电方面,在天然草地进行跳跃落地任务时初始触地时刻后100 ms内股内侧肌、股外侧肌、胫骨前肌肌电活动水平显著低于在人工草地时(P<0.05;P<0.01;P<0.05)。③结果说明,在人工草地进行跳跃落地任务时较天然草地时会出现使前交叉韧带张力升高的生物力学表现。

高寒地区不同人工牧草种类对土壤酶活性及酶化学计量比的影响

[目的]探究青藏高原高寒草甸区不同人工牧草土壤酶活性及其化学计量特征,为深入认识高寒地区土壤养分状况及草地生态系统功能提供科学依据。[方法]以冷地早熟禾(Poa crymophila)、无芒披碱草(Elymus submuticus)、短芒披碱草(Elymus breviaristatus)、垂穗披碱草(Elymus nutans)、星星草(Puccinellia tenuiflora)、同德老芒麦(Elymus sibiricus)、贫花鹅观草(Roegneria pauciflora)7种人工牧草种植地土壤为研究对象,并以邻近的天然温带草原土壤作为对照(CK),探讨与土壤碳、氮和磷循环有关酶活性及其化学计量学特征。[结果](1)不同牧草种植地土壤酶活性差异较大〔(3~496 nmol/(g·h)〕,7种牧草土壤酶的活性均明显低于CK(13~506 nmol/(g·h))。(2)土壤碳氮酶活性比(E_(C∶N))在各样地之间无显著差异,冷地早熟禾样地的碳磷酶活性比(E_(C∶P))和氮磷酶活性比(E_(N∶P))最大(0.82,0.94);7种牧草土壤酶活性矢量角度均大于45°,表明牧区土壤微生物受到P元素限制。(3)土壤酶活性及其化学计量主要受土壤SOC,TN,W,MBC和MBN的影响,与MBC∶MBN,SOC∶TP和TN∶TP也显著相关。[结论]人工牧草的种植改变了土壤养分结构从而影响土壤酶的分泌,不同牧草种类种植地土壤酶活性及其化学计量存在显著差异。未来结合土壤微生物群落组成以及功能特征可进一步揭示青藏高原高寒草甸土壤养分循环及草地生态系统功能的影响机制。

Characteristics of Desertification Change in Lake Basin Area in Gangcha County

Qinghai Lake Basin area in Gangcha county is selected as the study area in terms of desertification change features in this paper.Based on the remote sensing(RS)and global positioning system(GPS)technologies,the desertification information range from 1989 to 2014 in the study area is extracted.Using the method of the decision tree,the desertification in the research area is been divided into four grades including mild desertification,moderate desertification,severe desertification and serious desertification.The change characteristics of desertification in the study area were analyzed in detail,which showed that the desertification in the study area experienced a process of first development and then a reversal.The rapid development of desertification appears in the 1990s,where about 1101.22 kilometers of desertification area was increased in this stage.Since the twenty-first Century,the desertification is gradually significant recovered and local area exist intensified desertification.There are tendencies of interactive transform in different types of desertification.The tendencies of different degrees of desertification land are rising,and there’re some differences in rising rates,where the expansion rate of moderate desertification is the biggest,increasing by 7.27 kilometers per year.

Humidifying Effect of Green Space during Spring in Yuxi Park of Shijiazhuang City of China

As one of the important parts of urban ecosystem, urban green space plays an irreplaceable role in maintaining the balance of carbon and oxygen, absorbing the pollution and removing dust, killing bacteria, purifying soil and water. To analyze the spatio-temporal changes of humidifying effect of green lands at the spring daytime, the authors monitored the air humidity within 1.8 m high from various underlying surfaces, including arbor-grass lands, shrub lands, herb lands and a cement pavement, from late February to late April in 2015 and 2016, when it was sunny and windless, in the Yuxi park of Shijiazhuang. The results were compared with the monitoring data of a bare land(190 m×120 m) without environmental interventions such as vegetation and water. The results could be summarized as follows:(1) The humidifying effect of green spaces was the weakest at 8:00 a.m. during the late February, whereas it was the strongest at 10:00 a.m.; from late March to late April, the humidifying effect of green spaces strengthened with the increase of air temperature, and the strongest was noted around 12:00-16:00.(2) The humidifying effect of various types of green lands was the strongest close to the ground, and reduced from 0.2 m to 1.8 m. This vertical stratification became apparent after the plants sprouted, the vertical difference of humidifying effect was the most significant in the herb lands, less significant in arbor-grass lands, and least in the shrub lands.(3) Multiple comparison analysis of the humidity data showed that relative humidity of all green lands achieved the significant level(P < 0.05), indicating the strong effect of landscape plants in adjusting atmospheric humidity in spring.(4) The humidifying effect of the artificial lake was more remarkable before the plants sprouted, however, with the rapid growth of plant leaves, theeffect gradually reduced and became even weaker than the effect of vegetation. Although the humidifying effect in spring was weaker than that in summer and autumn, the effect of humidification was more complicated during the growth of green leaves in spring than in summer and autumn. This is useful to construct the theory system of ecological environment effect of green lands in spring, summer and autumn.

分级治理:乡村旅游开发中的基层治理秩序再造——基于豫北Y村的田野调查

产业兴旺、生活富裕与治理有序共同构成了乡村振兴的基础。基于豫北的田野调查发现,乡村旅游开发提高了农民的非农就业机会与家庭收入,但也造成了村庄开发的混乱局面,建立在土地之上单一利益主体间的互动转变为多方利益主体的博弈。在新的关系互动模式下,村庄内形成了土地利益分化的差序格局,集体土地分配规则的公共性与权威弱化,基于土地调整、分配的层级治理秩序受到冲击,导致了村级治理的困境。要实现不同利益主体博弈的平衡,必须重新构建发展型村庄的治理体系,即由村一级负责对接村庄发展性任务,承担村庄的土地经营与产业发展,同时落实相应基础设施建设和资源分配,保证村庄内部发展的整体性公平;而组一级负责对接村庄常规性事务,负责对农民的组织和动员,同时参与村庄经济发展的监督与收益分配,保证村庄事务推进的公开透明性,以此通过权力、责任和利益的协调,重构村组之间的利益连带关系,形成村组之间相互嵌入的新层级治理体系与基层治理效力。

利用盐碱地种草解决新疆饲草短缺问题的对策研究

【目的】为实现新疆盐碱地的高效利用,解决畜牧业发展中优质饲草短缺的难题。【方法】采用实地调研、文献检索等方法,对喀什地区、和田地区、阿克苏地区、克孜勒苏柯尔克孜自治州(简称克州)等地的盐碱地综合利用情况进行了梳理。【结果】初步掌握了新疆盐碱地概况及综合利用情况,总结了盐碱地种草的经验做法,分析了盐碱地种草存在的困难和问题,提出了推进盐碱地种草的对策措施。【结论】新疆盐碱地面积广阔,严重制约了绿洲农业的发展。未来需加强耐盐碱饲草品种的选育,快速建立分类治理技术体系,强化工程性治理措施,并总结推广成功模式,以实现盐碱地资源的高效利用。

不同灌草组合与行数比对多花木蓝灌草地牧草产量的影响

[目的]探明灌草组合和行数比对灌草地牧草产量的影响,为贵州中低海拔喀斯特地区多花木蓝灌草地建植与饲草生产提供依据。[方法]以黔南多花木蓝(I)、钻石T多花黑麦草(L)、宽叶雀稗(P)和WL525HQ紫花苜蓿(M)为试验材料,采用随机区组试验设计,研究7种灌草组合(A1,I 13.50kg/hm^(2)+L 24.00 kg/hm^(2);A2,113.50 kg/hm^(2)+P 9.00 kg/hm^(2);A3,113.50 kg/hm^(2)+P 9.00 kg/hm^(2)+M 7.50 kg/hm^(2);A4,I 13.50 kg/hm^(2)+P 11.70 kg/hm^(2)+M 3.00 kg/hm^(2);A5,I 13.50 kg/hm^(2)+L 8.40 kg/hm^(2)+P 8.10 kg/hm^(2)+M 3.75 kg/hm^(2);A6,I 13.50 kg/hm^(2)+L 12.00 kg/hm^(2)+P 4.50 kg/hm^(2)+M 7.50 kg/hm^(2);A7,I 13.50 kg/hm^(2)+L 14.40 kg/hm^(2)+P 4.95kg/hm^(2)+M5.25 kg/hm^(2))和5种行数比(B_(1),1:3;B_(2),1:2;B_(3),1:1;B_(4),2:1;B_(5),3:1)处理,多花木蓝混播灌草地牧草产量的变化。[结果]灌草组合和行数比对灌草地的灌草产量构成和总产量均有显著影响。多花木蓝与3种草本混播灌草地的总产量较高,其中,以A6生产表现最好,为15.25 t/hm^(2)。多花木蓝与草本牧草以行数比B_(1)(1:3)或B_(2)(1:2)混播效果较好,牧草产量为13.33 t/hm^(2)和14.13 t/hm^(2)。不同建植模式以A6B_(1)的总产量最高,为16.66 t/hm^(2);A6B_(2)(15.94 t/hm^(2))和A6B_(3)(15.77 t/hm^(2))其次。[结论]牧草产量以灌草组合13.50 kg/hm^(2)多花木蓝+12.00 kg/hm^(2)多花黑麦草+4.50 kg/hm^(2)宽叶雀稗+7.50 kg/hm^(2)紫花苜蓿按灌草行数比1:3混播的最高,可作为贵州中低海拔喀斯特地区多花木蓝灌草地建植的适宜模式推广应用。

重庆市级重大项目菖蒲盖景区农旅融合亚高山草场修复与养护

介绍重庆市酉阳县菖蒲盖亚高山草场概况,以及草场存在的水土流失、植被退化、景观效果不佳等问题。藉此提出清杂、整地、灌溉排水、土壤改造、植草等对草场加以生态修复的技术措施,以及相应的草场维护和景观养护措施。通过实施生态修复,认为初步取得了预期效果。

高分卫星监测大别山区西段土地利用时空变化研究

【目的】利用高分卫星监测大别山区西段林草湿地覆盖变化,对其生态环境进行定量评估,为后续生态环境保护及修复提供相关数据支撑。【方法】针对大别山西段典型生态屏障区,基于Landsat遥感影像,综合运用遥感图像处理技术制作了1980—2018年6期1:25万卫星遥感影像图和1:25万土地利用、覆盖遥感解译图。在此基础上,对大别山西段土地利用/覆盖各地类的面积进行统计计算,并对林草湿地覆盖的空间格局及时空变化进行了分析。【结果】从1980—2018年变化趋势来看:研究区内耕地总量持续减少,总面积减少了781.42 km2;草地呈先增加后减少的变化趋势,总面积减少了23.77 km~2;湿地呈现先减少后快速增加的趋势,总面积增加了168.43 km~2;林地面积呈波动变化,但整体上处于下降趋势;总面积减少了142.68 km~2。【结论】通过多期次遥感图像分析能够获取该地区土地利用和覆盖的空间分布格局及变化趋势,可为当地土地规划、利用和保护提供基础数据支撑,为生态保护和资源开发利用提供科学依据。

山水林田湖草沙一体化保护和修复工程对荆州市生态系统服务价值和稀缺价值的影响

以荆州市为研究区域,利用荆州市2021年相关数据计算和分析了荆州市生态系统服务价值(ESV)和生态系统服务稀缺价值(ESSV)指标,并运用地理信息图谱、景观格局指数、冷热点分析法、供给和需求弹性指数等方法评估和揭示ESV和ESSV的时空异质性变化及其原因和机制。结果表明,土地利用变化主要集中于耕地转变为林地或草地,未利用地转变为水域或其他类型,林地或草地转变为建设用地。各类型土地的多样性和均衡性均提高,山水林田湖草沙一体化保护和修复工程(SLCP)的综合治理和协调发展等措施的效果取得一定成效。ESSV在空间上呈现出由东部向西部递增的分布特征,且在空间上呈现出明显的聚集特征。

新疆生产建设兵团畜牧业高质量发展规划资源环境承载力研究

[目的]为科学制定新疆生产建设兵团(以下简称兵团)“十四五”畜牧业发展规划提供基本生产参数。[方法]以兵团及13个师2025年畜禽计划存出栏数为依据,从畜禽养殖饲草料资源承载力、水资源承载力、粪污土地承载力3个环境制约因素来分析兵团及各师未来畜牧业发展资源环境承载力。[结果]到2025年,兵团苜蓿缺口19.29万t,需种植21.43万hm^(2);玉米青贮缺口687.07万t,需种植11.452万hm^(2);秸秆等主要粗饲料原料盈余169.63万t;玉米籽实缺口为337.04万t,需种植42.80万hm^(2);棉粕盈余60.99万t。兵团2025年畜禽饮用水需要量增长39.63%,达563.41万t,其中第十二师增长率最大(294.94%),第八师增长量最大(88.52万t)。兵团整体畜禽粪污土地承载力不超载,达到2025年计划养殖量后仍可增加3053万个猪当量,土地消纳粪污的潜力仍很大,但第十二师以氮测算承载力指数为4.90>1,以磷测算承载力指数为3.26>1,属于严重超载,需要进行调整。[结论]“十四五”兵团及13个师的畜禽养殖数量设定与环境资源禀赋比较符合,但个别师仍需调整。

仪表着陆系统下滑信标保护区管控

仪表着陆系统是民航机场最常用的进近引导系统,是帮助航空器安全平稳度过最危险的降落前8 min的重要导航设备。下滑信标作为关键组成部分,对保护区要求较高,一旦保护区遭到破坏将引发导航信号不可用,甚至航空器可控飞行撞地等严重后果。本文就下滑信标保护区草高管控等方面做了一些浅显的思考,供广大读者探讨。