基于东北漫岗黑土区坡耕地沟蚀防治的防护林带布局优化

防护林带体系是东北漫岗黑土区坡耕地的重要组成部分,对坡耕地上侵蚀沟的发生、发展具有重要影响.本文以黑龙江省鹤山农场典型小流域为研究对象,基于Quickbird高精度遥感影像和数字高程模型,结合实地调查结果,分析防护林带分布对坡耕地侵蚀沟发生、发展的影响,并根据坡耕地沟蚀特点及其与防护林带分布的相关关系,提出防护林带分布的优化方案.结果表明:当前不合理的防护林带布局,直接或间接地促进了坡耕地浅沟和切沟的发生和发展.优化方案包括:调整防护林带走向为横坡林带,加强林带维护和更新,以减少林带间断,增加林带条数,减小林带间距等,同时提出了坡面林带条数和林带间距的计算方法.研究结果可为典型漫岗黑土区坡耕地的沟蚀防治和防护林带规划提供科学依据.     

Modification of water flows and nitrogen fluxes by shelterbelts

The introduction of shelterbelts (mid-field trees linear structures) in a uniform agricultural landscape composed mainly of cultivated fields is one of the best tools for managing heat balance and water regime in the landscape. Evapotranspiration rates, surface runoff and percolation of water across a soil profile are controlled by shelterbelts. The heat transfers from cultivated fields to shelterbelts by advection processes enhance evapotranspiration rates from trees. Depth of groundwater table and thermal conditions have important bearing on the uptake of groundwater by trees. The studies showed that in the Turew agricultural landscape, located near Poznan, Poland, shelterbelts use for evapotranspiration 40 percent more water than cultivated fields. For air heating cultivated fields use 280 percent of solar energy more than shelterbelts. The shelterbelts limit N-NO₃⁻ spreading with groundwater very effectively. Concentrations of inflowing nitrates with groundwater dropped to 2.3–24.4 percent of the input from fields. In contrast to nitrate ions the ammonium behave entirely different. Often concentration of ammonium increased in groundwater under shelterbelts. Higher concentrations of N-NH₄⁺ under shelterbelts than under field indicated that ammonium ions were released during decomposition of organic matter. This supposition was directly proved by estimates of very high rates of urease activity which enzyme converts urea nitrogen into NH₃ in the final stages of protein decomposition. It was estimated that N₂O fluxes from soil of shelterbelts are much smaller than from cultivated fields. The balance of nitrogen inputs and outputs in a shelterbelt indicated that the internal recycling of this element is of crucial importance for the controlling efficiency of nitrogen compounds spreading in an environment.     

林带空间配置与布局优化研究

农田防护林(林带)的空间配置与布局是影响防护林结构和防护效益发挥并持续的关键因素．为达到农田防护林防护效益最大并持续的经营目标。在保证林分多样性和稳定性的条件下．林带必须具有空间上布局的合理性和时间上的连续性．经过多年防护林营林研究实践．在对1992年于辽宁省昌图县双井子乡设计营造的试验示范林带调查的基础上．对农田防护林单条林带方向的设置、带内树木的空间搭配方式、树种组成形式,多条林带或林网的带间距离以及大面积或区域防护林体系的空间景观布局等进行了综合研究．结果表明,单条林带和林网走向都应以垂直主害风作为设计的原则;林带内树木的空间搭配以“品”字型为佳,在不同树种混交的同一条林带中,可利用“边行优势”将生长相对缓慢的树种配置于边行．生长相对迅速的树种配置于内行;多条林带或林网空间配置参数——带间距离的设计应以林带达到初始防护成熟龄时的树高作为成林高．以林带结构变化规律和降低害风比例作为林带设计关键参数;区域防护林体系的空间布局应以景观生态学原理为基础．对林网体系进行评价与调控．     

Degrading seagrass (<Emphasis Type="Italic">Posidonia oceanica</Emphasis>) ecosystems: a source of dissolved matter in the Mediterranean

Diurnal variation of dissolved oxygen (DO), organic and inorganic carbon (DOC, DIC), nitrogen (DON, DIN), and phosphorus (DOP, DIP) flux across the sediment–water interface was assessed in fish farm impacted and pristine seagrass (Posidonia oceanica) meadows in the Aegean Sea (Greece). DIC consumption decreased by 52% and DO production decreased by 60% in the light, suggesting reduced photosynthetic performance of the plant community under the fish cages probably due to organic matter loading. In light there was 4 and 15 times higher release of dissolved inorganic and organic matter, respectively, compared to dark incubations under the cages, indicating that fish farming impact is more intense during daytime. DO was taken up, while DIC was released in the dark in both stations, representing a direct measure of mineralization. Dissolved inorganic matter flux (as the sum of DIN and DIP fluxes) was positively related to DIC flux, rendering mineralization as the main driver of nutrient flux under the cages. On average, the impacted meadow released DIN and DIP both in light and dark, while efflux of dissolved organic matter (as the sum of DOC, DON, and DOP fluxes) increased by 132% in the light and by 21% in the dark, implying that the degrading seagrass meadow is a source of dissolved matter to the surrounding water. Shoot density and leaf production were negatively correlated with both diel DIN and DIP fluxes, showing that meadow regression is accompanied by DIN and DIP release from the sediment. Hence, nutrient efflux can adequately illustrate meadow deterioration and, therefore, can be used as indicator of P. oceanica community health.     

林带疏透度数字化测度方法的改进及其应用研究

在大量野外调查基础上,用数码相机拍摄林带相片,采用CIAS软件测定林带疏透度,对已有“数字图像处理法”进行了改进,并对疏透度的变化规律进行了深入研究。结果表明,用改进的数字化方法测定林带的疏透度,比用光学相机所进行的“数字图像处理法”精度高,更经济,简捷;林带疏透度β与相对枝下高x(枝下高／林带平均高）的关系无叶期可表达为β＝1.0681x^0.4304(r=0.9763,r0.01=0.4073);有叶期可表达为β＝0。672^0.469(=0.9851,0.01=0.4073)(0≤β≤1）;β随着林龄α呈抛物线式变化,β＝0.0009α^2-0.0364α 0.6828(0≤β≤1);提出的林带断面疏透度β0是定量反映林带断面结构的定量评价指标,同时可作为评价林带结构的辅助指标;提出混交林带的疏透度计算式β＝（β1n1 β2n2)/(n1 n2);在相同配置不同树种的纯杨,柳,榆林带结构以杨树林带结构较好,柳树林带结构次之,疏透度值βPPP＜βSSS＜βUUU;在树种相同,配置不同时,品字形优于矩形;杨柳榆的混交林带中杨榆株间,杨柳对称式行间SPPS混交方式结构防护效果较好。     

农田防护林的可持续经营管理

林带更新的时空布局对持续发挥林网的防护效益具有重要意义。本文提出用拟法正林思想经营农田防扩林,以行政村为组织经营单位,通过逐步更新调整组织经营单位管理的林带,使整个林网体系形成自幼龄到成熟龄各龄级林带条数基本相等,空间上均匀配置的格局,从而确保时间上农田防护林生态服务的稳定和持续发挥。     

东北地区农田防护林结构对林网内积雪分布格局的影响

东北地区冬季降雪是农田土壤水分的重要来源．探索农田防护林结构对林网内积雪分布格局的影响,是经营实践中如何依据疏透度指标来指导农田防护林结构调控的关键问题．通过由3个不同疏透度林带组成的林网内积雪深度的测定,对农田积雪分布格局进行了研究．结果表明,林网的结构对农田积雪分布产生较大影响．疏透度不同的林网内积雪分布的空间格局有明显差别。而且疏透度差异越大。分布格局的差异越显著．其中,在疏透度为φ2w=0．579、φ2s=0．268的林网内,农田积雪分布比较均匀,总体上整个农田积雪深度较为一致．这样,可依据疏透度与积雪分布格局的这种关系。指导冬季防护林带的结构调控与优化经营．     

The role of various meadow margin types in shaping carabid and staphylinid beetle assemblages (Coleoptera: Carabidae,Staphylinidae) in meadow dominated landscapes

Less intensively managed semi-natural habitats, e.g., field and meadow margins like hedgerows, are thought to be crucial landscape components for maintaining biodiversity in highly disturbed and intensively managed agricultural landscapes. In this study, we focused on the effects of three meadow margin types on activity-density, species richness and species composition of carabid and staphylinid beetles recorded by pitfall traps in Central European landscapes dominated by intensively managed meadows. Carabid activity-density was significantly higher in meadows than in meadow margins and within meadow margins their activity-density increased from grassy meadow margins via shrubby ones to woody meadow margins. We found that recorded species richness of both carabid and staphylinid beetles was not significantly affected by habitat identity (meadow margin or neighbouring meadow) and meadow margin type. Recorded species composition of both investigated taxa was significantly affected by habitat identity and interaction between habitat identity and meadow margin type (i.e. it differed between particular meadow margin types). Assemblages inhabiting various meadow margin types were more dissimilar between each other than assemblages from neighbouring meadows. Meadow margins within grassland dominated landscapes maintain local species richness by hosting different species from those living in surrounding meadows. Dissimilarity of carabid and staphylinid assemblages from meadows neighbouring both sides of particular meadow margin did not differ between meadow margin types. Our results indicate that semi-natural habitats play an important role in maintaining biodiversity not only in agricultural landscapes dominated by arable fields, but also in those dominated by meadows.     

三江源区高寒草甸退化对土壤水源涵养功能的影响

三江源区是我国重要的水源涵养区,研究草地退化对土壤水源涵养功能的影响,可为三江源区水源涵养功能的科学评估与合理监测提供科学依据。以实地采样与室内测试分析相结合的方法研究了三江源区内不同土壤类型高寒草甸生物量特征、土壤水文物理性质及土壤水源涵养量。结果表明:高寒草甸在重度退化阶段地上生物量、地下生物量、毛管孔隙度、总孔隙度、自然含水量、最大持水量、土壤水源涵养量显著低于未退化和中度退化阶段(P<0.05)。随着高寒草甸退化程度加剧,土壤容重逐渐增大,且非毛管孔隙度规律不显著。未退化、中度退化、重度退化草甸的土壤水源涵养量范围分别为1884.32—1897.44t/hm2、1360.04—1707.79t/hm2、1082.38—1550.10t/hm2。中度退化草甸土壤水源涵养量比未退化草甸低9.37%—10.35%,重度退化草甸低18.31%—27.82%。草甸退化进程中土壤总孔隙度与毛管孔隙度的降低是影响土壤水源涵养量下降的直接原因,而草甸退化进程中地上生物量与地下生物量的减少则是间接原因。度量三江源区高寒草甸土壤水源涵养功能时应着重考虑毛管孔隙度的蓄水作用。研究表明高寒草甸地上生物量与土壤水源涵养量之间存在显著的正相关关系(P<0.05),该结果能够推动水源涵养功能评估向空间化、精细化发展,为探索利用遥感技术监测三江源区水源涵养功能提供参考依据。     

Ground cover and floral resources in shelterbelts increase the abundance of beneficial hymenopteran families

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Production,nutrient availability,and elemental balances of two meadows affected by different fertilization and water table regimes in The Netherlands

The restoration of degraded peat-grasslands is an important nature conservation goal in The Netherlands. We investigated the effects of ceased fertilization (15 years) combined with a groundwater-raised water table (6 years) on the production of the peat-grassland vegetation and soil nutrient availability in a meadow. Furthermore, we evaluated whether and how this difference between meadows affected the balances between nutrient inputs and outputs in the ecosystem. We used an adjacent fertilized meadow in which the water table followed agricultural practice as a control. Yield of the grassland vegetation was significantly lower in the wet than in the control meadow. The tissue concentrations of N, P, and K in the harvested vegetation were significantly lower, but those of Ca higher in the wet than in the control meadow. The difference between both meadows significantly affected the annual nitrification rate, but not the annual C and N mineralization rates and the annual net P and K release rates. The difference between both meadows also significantly affected the seasonal nitrification and K release rates. Season exerted a significant effect on the seasonal C and N mineralization and nitrification rates. The elemental balances and relative contributions of the balance terms to elemental inputs and outputs varied considerably with element. Annually, the wet meadow lost N, P and K, while the control meadow gained these elements. The elemental demand of the grassland vegetation in the wet meadow was met for N for a large part by mineralization and for the remainder by atmospheric deposition, for P it was in the same order of magnitude as the net soil-P release, as it was for K. It is to be expected that the soil resources of N, P and K will continue to decrease under a continued regime of ceased fertilization and a raised water table, with those of N decreasing with the same rate, of P morerapidly and of K more slowly than estimated from regressions.     

东北地区农田防护林高效多功能经营的指标体系及标准研究

从单条林带和林网两个尺度出发,建立了农田防护林高效多功能经营的指标体系,并通过分析各个指标之间的机理关系,提出了9个主要评价指标,对于单条林带,用林带疏透度,有效防护距离,初始防护成熟龄,防护成熟期,林带产投比,更新方式等可作为度量林带经营状态的指标;对于林网体系,用林网带斑比,林网连接度,环度,林网优势度等可作为度量林网经营状态的指标;依据主要指标的数量化界定,提出了农田防护林高效多功能经营的标准,可进行综合评价,这些评价指标及其标准,在宏观上确定了主要林网体系的布局,在微观上确定了单条林带的结构,成为衡量是否可持续经营的依据,为其高效多功能经营提供了导向。     

Restoration Potential of Sedge Meadows in Hand‐Cultivated Soybean Fields in Northeastern China

Sedge meadows can be difficult to restore from farmed fields if key structural dominants are missing from propagule banks. In hand‐cultivated soybean fields in northeastern China, we asked if tussock‐forming Carex and other wetland species were present as seed or asexual propagules. In the Sanjiang Plain, China, we compared the seed banks, vegetative propagules (below‐ground) and standing vegetation of natural and restored sedge meadows, and hand‐cultivated soybean fields in drained and flooded conditions. We found that important wetland species survived cultivation as seeds for some time (e.g. Calamogrostis angustifolia and Potamogeton crispus) and as field weeds (e.g. C. angustifolia and Phragmites australis). Key structural species were missing in these fields, for example, Carex meyeriana. We also observed that sedge meadows restored without planting or seeding lacked tussock‐forming sedges. The structure of the seed bank was related to experimental water regime, and field environments of tussock height, thatch depth, and presence of burning as based on Nonmetric Multidimensional Scaling analysis. To re‐establish the structure imposed by tussock sedges, specific technologies might be developed to encourage the development of tussocks in restored sedge meadows.     

农田防护林生态系统结构研究进展

农田防护林生态系统结构决定着生态功能,其时空结构是该领域研究的核心,旨在探讨形成结构的完整性、稳定性、持久性的组件间的相互关系,将其分为树体结构、林带结构、林网结构、景观结构4个层次,针对各层次中结构研究的原理、方法及成果进行了综述,通过树木个体的形态、质态结构研究,应用分形图形学的手段可实现动态结构的可视化,以研究林带树体结构的生成机理;精确界定林带结构的分维疏透度。探讨农田防护林带最佳结构理论,以构建防护林带最佳结构计算机生成模型;确立多物种、多层次的窄林带小网格的林网优化模式;评价农田防护林景观的合理性、稳定性、持续性,是今后的重要研究方向。     

Plant species decline due to abandonment of meadows cannot easily be reversed by mowing. A case study from the southern Alps

Abstract. We resumed mowing in two plots of ca. 100 m² in an abandoned meadow dominated by Brachypodium pinnatum on the slope of Monte Generoso (Switzerland). We monitored species composition and hay yield using point quadrats and biomass samples. Species frequencies changed little during 10 yr (1988–1997) while hay yields showed large fluctuations according to mean relative humidity in April-June. We performed a seed-addition experiment to test whether the establishment of meadow species is limited by lack of diaspores or favourable microsites for germination and recruitment from the seed bank. We sowed ca. 12 000 seeds of 12 species originating from a nearby meadow individually in plots of a 4 × 6 unbalanced Latin square with four treatments, burning, mowing, mowing and removal of a layer of decayed organic matter, and a control. We monitored the fate of seedling individuals for 24 months. Seedlings of all species were established and survived for 12 months, 10 species survived during at least 24 months, some reached a reproductive stage. Species responded to different qualities of microsites provided by the different treatments thus required different regeneration niches. Spontaneous long-distance immigration was insignificant. We conclude that the former species composition of abandoned meadows cannot easily be restored by mowing alone because many plant species of meadows do not have persistent seed banks and immigration over distances of more than 25 m and successful establishment is very unlikely.     

Effects of fertilization and afforestation on community structure of traditionally managed hay meadows in western Norway

The aims of this paper were to find the effects of artificial fertilizer, intensive cultivation and abandonment with afforestation on species composition of traditional meadows at a broad scale, and to describe the ecological variation of different meadow communities. The flora of 21 traditionally managed hay meadows was compared with that of 52 artificially fertilized hay meadows, 28 intensively cultivated grasslands and 29 afforested grasslands by means of classification. Predictors for differences in species composition were tested using multiple regression analyses with associated Monte Carlo permutation tests. Habitat diversity and Ellenberg N were the most important predictors for differences in species composition of traditional meadows. High habitat diversity was associated with maximum occurrences of all kinds of meadow species (high-productive, generalist, low-productive, habitat specialist, regionally rare, vulnerable and orchid species). These meadows are therefore of high conservation value. Traditional meadows contained also some nitrophilous species that dominate artificially fertilized meadows, but in small populations. Artificially fertilized meadows supported the generalist and productive subset of the species from traditional meadows. Thus, artificially fertilized meadows are of low conservation value. As regionally rare and vulnerable species were only recorded at sites with no use of artificial fertilizer, its application should be avoided whenever the aim is to recreate or maintain semi-natural grasslands of high conservation value. Regionally rare and vulnerable meadow species were not recorded in afforested sites, suggesting that afforestation of traditional meadows may have similar negative effects for the traditional meadow flora as the use of artificial fertilizer.     

Plant diversity and habitat structure affect tree growth,herbivory and natural enemies in shelterbelts

Shelterbelts have become a refuge and source of food for wildlife because of habitat loss in farmlands. However, effects of shelterbelt attributes such as plant diversity and habitat structure on different trophic levels within shelterbelts are unclear. Effects of shelterbelt woody plant diversity and habitat structure (lower vegetation strata, logs, litter and rocks) were measured on the growth and herbivory of Eucalyptus blakelyi saplings that were caged from birds, caged from birds and arthropods and un-caged. Arthropod diversity of E. blakelyi saplings and shelterbelts was evaluated. Height and stem diameter of saplings in all treatments was positively correlated with plant diversity. Habitat structure was negatively correlated with numbers of leaves on E. blakelyi saplings and positively correlated with herbivory, which was greater in saplings caged from birds. The overall abundance of arthropods inhabiting shelterbelts correlated positively with plant diversity, but negatively with habitat structure. Araneae and Formicidae were the most common taxa on E. blakelyi saplings and were more numerous on saplings caged from birds, suggesting an important role of these vertebrates as predators of shelterbelt arthropods.     

防护林阶段定向经营研究Ⅱ. 典型防护林种--农田防护林

以防护林阶段定向经营理论为基础,对典型防护林种-农田防护林的防护成熟、经营阶段、更新方式、方法进行了研究讨论：通过对东北地区农田防护林长期调查积累资料的分析,确定了乡土杨和杂交杨（Populus spp.)农田防护林和初始防护成熟龄和终止防护成熟龄分别为16-24年和自然成熟龄,第一代农田防护要的更新龄为32-36年,以树木径级离散度,防护成熟龄和更新龄为主要依据定量划分了杨树农田防护林的3个经营阶段,并重点讨论了不同更新方式下3个经营阶段的变化情况,给出了维持农田防护林成熟状态的疏透度调控技术及其相关的林木分级依据与标准,同时为实现定向经营的目标,提出了各个经营阶段内应采取的系列经营管理措施。     

Bird response to hydrologic restoration of montane riparian meadows

Montane riparian meadows foster biodiversity and support critical ecosystem services. A history of exploitation has left most riparian meadows throughout the Mountain West of the United States with incised channels, severely compromising their functionality. Hydrologic restoration of riparian meadows aims to increase overbank flow during spring run‐off and elevate groundwater levels in the dry season. Outcome‐based evaluations of the dominant meadow restoration methods are lacking and needed to ensure objectives are being met and to guide modifications where needed. We completed 1,282 point count surveys from 2009 to 2017 at 173 sampling locations across 31 montane riparian meadows in California restored using partial channel fill techniques (e.g. pond‐and‐plug) to evaluate the expected outcome of increased abundance of meadow birds. We analyzed trends in abundance for 12 focal bird species from 1 to 18 years after hydrologic restoration, substituting space for time in our mixed effects Poisson regression models that included covariates for the amount of riparian deciduous vegetation (RDV) before restoration, stream flow, precipitation, and temperature. We found evidence for a positive effect of time since restoration on abundance for 6 of the 12 species. Although pre‐restoration RDV cover was the most frequently supported predictor of abundance, high pre‐restoration cover of RDV slowed response rates for only two species, suggesting other elements of hydrologic function are also important for meadow birds. Drawing on our results, we provide suggestions for enhancing hydrologic restoration efforts in riparian meadows so that benefits may accrue more quickly to more bird species.     

Seed bank diversity in mesic grasslands in relation to vegetation type,management and site conditions

Questions: 1. Do different management types (i.e. hay meadow, silage meadow, meadow‐pasture, pasture) have different impact on the size and composition of the seed bank of mesic grassland (Arrhenatheretalia)? 2. How strong is the effect of management on the seed bank in relation to above‐ground vegetation, edaphic factors and land‐use history? 3. Are there differences in C‐S‐R plant strategy types and seed longevity under different management regimes? Location: Lahn‐Dill Highlands in central‐western Germany. Methods: Above‐ground vegetation and the soil seed bank of 63 plots (at 21 sites) in mesic grasslands were studied. Differences between management types in quantitative seed bank traits and functional characteristics were tested by ANOVA. The impact of management, above‐ground vegetation, site conditions and land‐use history on seed bank composition were analysed by partial CCA. Results: Management had no significant impact on species richness and density of the seed bank but significantly influenced their floristic composition and functional characteristics. CCA revealed that even after adjustment for soil chemical parameters and above‐ground vegetation management still had significant impact on seed bank composition. ANOVA revealed that silage meadows contained higher proportions of R‐strategy compared to hay meadows. In contrast, in hay meadows and meadow‐pastures proportions of S‐strategy were higher than in silage meadows. Conclusions: The type of grassland management has little impact on quantitative seed bank traits. Management types with a high degree of disturbance lead to an increase of species following a ruderal strategy in the seed bank. Irrespective of management type only a limited proportion of characteristic grassland species is likely to re‐establish from the seed bank after disappearance from above‐ground vegetation.