复合微生物肥料对科尔沁羊草割草场植物群落多样性和生产力的影响

为了解复合微生物肥料在天然草场改良中的效果,本研究设置对照(CK)、腐殖酸(F)、糖蜜发酵(T)、海藻酸(H)和3种复合微生物肥料混合施入(A)5种处理,研究其对科尔沁羊草(Leymus chinensis)割草场草地生产力、植物群落特征和物种多样性的影响。结果表明:复合微生物肥料对天然草地的改良有一定促进作用。T处理地上生物量较CK显著增加了27.18%(P0.05);复合微生物肥料增加了群落高度、盖度和密度,T处理显著增加了群落高度和盖度(P0.05),各处理间群落密度无显著差异;T、H和A处理增加了群落中羊草的重要值,其中T处理显著增加了20.46%(P0.05);群落Margalef丰富度指数、Shannon-Wiener多样性指数、Pielou均匀度指数和Simpson优势度指数都没有显著变化。综上所述,本研究选取的几种复合微生物肥料以糖蜜发酵(T)改良效果最佳。     

Butterflies and diurnal moths along road verges: Does road type affect diversity and abundance?

Roadsides form potential habitats for several grassland species adapted to regular mowing management. We studied the communities of butterflies and day-active moths in 51 sites along the verges of the three road types, i.e., highways, urban roads and rural roads. Despite different traffic densities and widths of the road and verge, the groups were rather similar with regard to soil properties, vegetation structure and mowing intensity. The species richness and total abundance of butterflies (53 species, 5964 individuals) and diurnal moths (46 species, 4626 individuals) were also rather similar in each road type, although a preference for wider verges was observed. Butterfly diversity increased (but not significantly) from the verges of narrow rural roads to wider highways. The highest numbers of meadow species were recorded along highways and the total abundance, especially of diurnal moths, decreased in accordance with the road size. High nectar abundance was the most important factor increasing the numbers of meadow butterflies along road verges, while meadow moths were mostly favoured by shelter provided by tall vegetation. Verges surrounded by cultivated fields were generally related to low numbers of both Lepidoptera groups, whereas adjacent forests increased the total number of all species and favoured several butterflies inhabiting forest edges. The adjacent environment inflicted compositional differences on the Lepidoptera fauna of the three road types. The results indicate that road verges should be considered an important reserve for species dependent on semi-natural grasslands in Finland. A growing interest in accommodating current roadside management for conserving biodiversity is likely to benefit Lepidoptera communities in the verge habitats.     

不同刈割年限天然草地土壤呼吸特性研究

通过对呼伦贝尔草甸草原土壤呼吸特性及土壤微生物的测定,研究4种不同刈割方式对天然草地土壤呼吸特性及土壤微生物的影响,为草甸草原碳收支研究提供基础理论依据。结果表明:刈割对天然草地土壤呼吸速率、微生物量碳氮、土壤酶活性和微生物数量存在一定影响。4种不同刈割年限的天然草地土壤呼吸速率的日最高值均出现在12:00-14:00之间,对照区最高为4.874 mg·m^-2·h^-1,两年刈割区为4.603 mg·m^-2·h^-1,一年刈割区为4.230 mg·m^-2·h^-1,三年刈割区最低为4.154 mg·m^-2·h^-1;随着刈割年限的增加土壤呼吸速率呈现降低趋势。土壤微生物量碳、氮含量、土壤酶活性(除脲酶)以及微生物数量在表层(0~10 cm)含量最高(活性最强、数量最多),均表现出随土壤深度增加而降低(活性下降、数量减少)。微生物数量变化规律与土壤呼吸速率变化结果一致,而微生物量碳、氮含量则是两年刈割区最高,除脲酶其他3种酶也是两年刈割区酶的活性最强,而脲酶各层酶活性变化不规律。土壤呼吸速率与微生物量碳、氮,蛋白酶、转化酶、过氧化氢酶、微生物数量呈正相关,与脲酶呈负相关。     

北方农牧交错带典型草地土壤呼吸及其组分对刈割强度的响应

为探究草地土壤呼吸及其组分对不同刈割强度的响应，本试验以山西省右玉县农牧交错带典型草地生态系统为研究对象，于2016年按照留茬高度设置4个刈割强度（不刈割、轻度刈割（留茬10 cm）、中度刈割（留茬5 cm）和重度刈割（留茬2 cm）），用浅环和深环区分草地土壤的总呼吸和异养呼吸，分别在2017和2018年的5—9月利用Li-840静态箱法测定土壤呼吸速率。研究结果表明：土壤呼吸及其组分的速率受土壤温度的调控表现出明显的季节动态，峰值均出现在8月初；刈割主要通过影响土壤异养呼吸对土壤总呼吸产生影响；轻度刈割有降低土壤呼吸及其组分速率的趋势，在中度刈割下，土壤异养呼吸速率有增加趋势，而土壤自养呼吸速率有降低的趋势，土壤总呼吸速率没有明显变化，在重度刈割下，土壤总呼吸和异养呼吸的速率均有增加的趋势，而土壤自养呼吸的速率呈降低趋势。因此，中度刈割对土壤CO₂的排放影响较小，建议中国北方农牧交错带典型草地割草利用留茬5 cm。     

Short-term successional change does not predict long-term conservation value of managed arable field margins

Field margins have been widely advocated as a means of integrating agronomic and biodiversity objectives and are included in agri-environment schemes across Europe. However, information on the long-term development of field margin plant communities remains limited. We describe a long-term experiment on the effects of field margin management on biodiversity and weed species. Swards were established by natural regeneration or sowing a grass and wildflower seed mixture, and treatments manipulated the frequency and timing of mowing, application of herbicide and leaving of hay. Vegetation was monitored to evaluate the extent to which early conclusions remained valid after 13 years. Although early successional trends suggested that naturally regenerated swards would rapidly become dominated by pernicious perennial weeds, and that sown swards would exclude such species, neither was true in the longer term. Sown swards were eventually invaded by unsown perennials, but they remained distinct from naturally regenerated swards. Plant species richness declined throughout the experiment. Annuals were lost most rapidly from sown swards but, under natural regeneration, loss could be modified by mowing. Perennial species initially increased during natural regeneration before stabilising. In sown swards they declined under all treatments. Species richness in naturally regenerating swards was promoted initially by mowing twice annually. After 13 years, timing and frequency of mowing had no significant effect on species richness although it still influenced sward composition. Leaving cut hay lying produced species-poor swards. We conclude that the choice of establishment and management methods for arable field margins significantly affects the long-term conservation value of the swards.     

Contributions of biotic and abiotic factors to soil aggregation across a land use gradient

Soil aggregation is a major ecosystem process that can be impacted by intensified land use directly through soil disturbances, or indirectly through impacts on biotic and abiotic factors that affect soil aggregation. We collected soils from 27 grassland sites across a range of land use intensities including varying levels of mowing, grazing, and fertilization in order to test the importance of selected direct and indirect effects on soil aggregation. We measured root length and mass, root colonization by arbuscular mycorrhizal fungi (AMF), extraradical AMF hyphal length, soil aggregation, and soil hydrophobicity. We also quantified levels of phosphorus, nitrogen, organic carbon, carbonate carbon, and sand in the soil.As land use intensity (defined as a multivariate index combining mowing, grazing, and fertilization intensities) increased, root mass decreased and length of extraradical hyphae increased. Total colonization by AMF was unaffected by land use intensity, but vesicular colonization tended to increase while arbuscular colonization declined. Soil aggregation increased with increasing land use intensity. We used structural equation models to explore mechanisms of soil aggregation and found that extraradical AMF hyphal length contributed to soil aggregation in models containing only biotic explanatory factors. When we also included abiotic factors in the model, no biotic factor was significant, and soil aggregation decreased as levels of sand and carbonate increased, likely due to concurrent decreases in levels of clay in the soil.In summary, we have shown that agricultural measures such as mowing, grazing, and fertilization can increase soil aggregation in managed grasslands. Furthermore, abiotic factors can be more important for determining soil aggregation than biotic factors, especially in highly aggregated soils. Aggregate turnover may be reduced in such highly aggregated soils past the point required to ensure efficient integration of new labile C into stable aggregates.     

不同资源条件下刈割对植物再生能力的影响

以甘南地区高寒草甸中10种常见植物为对象,通过田间模拟试验,对不同生长期内的植物个体进行不同程度的刈割、施肥处理,以探讨不同资源条件下刈割对植物再生能力的影响.结果表明:多数情况下,适口性较好的植物的补偿能力较高,适口性较差的补偿能力较低.垂穗披碱草、燕麦、多枝黄芪、矮嵩草在高资源条件下的生物量补偿程度低于低资源条件,金花苜蓿、珠芽蓼、中华羊茅、獐牙菜、细叶亚菊及藏蒲公英则相反;中华羊茅、细叶亚菊、珠芽蓼在高资源条件下繁殖部分的补偿程度较高,其余7种则相反.不同资源条件下10种植物在总生物量、现存生物量方面的补偿能力排序一致,说明综合补偿指数能较好地反映刈割后植物在总生物量、现存量方面补偿能力的种间差异.本研究结果说明不同资源条件下,生存对策是影响植物再生能力的主要因素,且综合补偿指数可以更客观地反映植物的再生特点.     

贵州喀斯特山区天然草地的刈割管理初步研究

通过对贵州喀斯特山区天然草地植被的刈割试验,在无施肥、灌溉等农艺措施的条件下,对天然草地植被采取年刈割0次（对照CK）、1次、2次、3次、4次共5个处理,试验结果表明：刈割草地与对照相比,不同处理A1、A2、A3和A4间植被的黄枯期都推迟了18d,2009年返青期分别提前了15d、11d、9d和5d;天然草地植被产量与高度、盖度间存在线性关系,其方程为：Y=2．54X1＋4．38X2-94．74,R^2=0．9410。其风干重间差异显著（p〈0．05）,干鲜比随刈割次数的增加而降低。干鲜比越低,牧草含水量越高,牧草品质越好;A2、A3、A4处理间生长速率都在第2次刈割出现“峰值”,从A4得知,生长速率在5月12日形成一个拐点,过后生长速率迅速增加,到7月15日达到高峰。之后逐渐下降,9月19日形成另一个拐点。综合分析得出结论,在贵州喀斯特山区天然草地植被年刈割适宜次数为2次或3次,第1次刈割时期为7月中旬,可再增加0．7—1．1倍产量,实现经济效益与生态效益共赢。     

刈割留茬高度对大针茅草原物种多样性及地上生物量的影响

刈割作为草地有效管理手段之一,对生态系统功能与多样性均具有重要的影响。本研究以内蒙古锡林郭勒盟大针茅草原为研究对象,利用围封草地作为对照,探讨了不同刈割留茬高度（留茬8 cm、留茬5 cm和留茬2 cm）对群落生物量与多样性的影响。结果表明：与围封草地相比,留茬8 cm对地上生物量无显著影响,留茬5 cm和2 cm处理显著降低了群落地上生物量（P<0.05）;多年生禾草和大针茅生物量在留茬2 cm处理下显著降低（P<0.05）;留茬8 cm和5 cm处理显著提高了群落物种多样性指数（P<0.05）。相关结果表明合理的留茬高度对草原物种多样性和地上生物量有积极影响,本试验对指导当地生产实际、提高草地合理利用等方面具有重要意义。     

Future prospects for the rare, late-flowering Gentianella germanica and Gentianopsis ciliata in Dutch nutrient-poor calcareous grasslands

We discuss the population biology of two calcareous grassland gentians, Gentianella germanica and Gentianopsis ciliata, in relation to the habitat management currently practiced in The Netherlands. There, at the margin of their range, both species are rare. Gentianella germanica persists on six remaining locations, whereas Gentianopsis ciliata, with two populations, is nearly extinct. Gentianella germanica is a strict biennial, Gentianopsis ciliata an iteroparous perennial. Both species depend on insects for seed production and suffer from low insect visitation. Pollination experiments in one Dutch population demonstrated that Gentianopsis ciliata is self-compatible, but hardly sets any seed under natural conditions due to pollen limitation. The low reproductive success of both species is partly due to the low pollinator densities at their late flowering time, partly caused by the small population size of the gentians themselves, and partly a result of mowing too early. The latter has destroyed the seed crop of several subsequent years in one population of Gentianopsis ciliata and some of Gentianella germanica. In Gentianella germanica, the early mowing and low insect visitation seems to have resulted in selection of less herkogamous and consequently more autofertile individuals. The perspectives for Gentianopsis ciliata are currently extremely poor in The Netherlands. Under the present circumstances, extinction will most likely occur within 10-20 years. Population reinforcement (seeding, artificial cross-pollination with nearby populations) should be considered if we want to conserve this species. For both gentians, but also of other flagship species of nutrient-poor calcareous grasslands, the total grassland area needs to be enlarged and must constitute an interconnected network of reserves. The traditional management method, sheep grazing, is to be preferred over mowing, but only if the flock visits each grassland patch or reserve for only a short time of less than a day, and with intervals of more than 2 weeks between visits. If mowing is preferred for other reasons, it should be done rotationally, and not before October.