唐古拉山冬克玛底地区冰川变化遥感监测

利用1973年MSS、1992年TM、2001年ETM＋、2007年TM数字遥感影像资料以及数字高程模型（DEM）,结合第一次冰川编目资料,通过地理信息系统和遥感图像处理技术提取了唐古拉山冬克玛底地区不同年份的冰川分布范围。结果表明：研究区内的冰川面积1976年比1969年减小了0.84%,1992年冰川面积比1976年的减小了1.77%,2001年冰川面积比1992年减小了4.24%,2007年冰川面积比2002年减小了3.31%。结合气象资料和有限的野外资料进行分析,该地区冰川退宿趋势同气温升高趋势基本一致。1969年到2007年近40年时间里,冰川面积总共减小17.61km^2,占1969年面积的9.81%,冰储量减少5.75km3,相当于水资源损失5.17km3。     

额济纳三角洲土地荒漠化预警分析

运用逆向因子修正法,在GIS的支持下,结合地下水的动态,研究额济纳三角洲土地的现状生产潜力和3种分水方案下2015年的生产潜力状况,分析了该地区在3种分水方案下土地荒漠化的发展趋势。结果表明,2015年,在狼心山来水2.5×10^8m^3/a的情况下,额济纳三角洲的土地生产潜力将大幅度下降,土地荒漠化问题将继续加重;在狼心山来水5×10^8m^3/a的情况下,额济纳三角洲基本上可以保持现状,不进一步发生荒漠化;在狼心山来水7.5×10^8m^3/a的情况下,额济纳三角洲的土地生产潜力将有较大幅度的提高,荒漠化现象将得到抑制。该结果可为整个黑河流域合理的发展规划和额济纳三角洲的良好发展提供理论依据。     

区域净初级生产力动态及其与气象因子的关系

基于MODIS遥感影像、气象数据和基础地理数据,采用CASA模型估算山东省2000-2005年净初级生产力(NPP),定性与定量相结合分析其时空格局及变化趋势,探讨温度、降水、地表太阳辐射与NPP时空分布的关系。研究表明:山东省NPP年累积碳量平均为252.1 g/m2,NPP总碳量在0.031~0.039 Pg/a,占全国总量的0.85%~1.47%;NPP年累积量在波动中上升,增加区域占研究区的78.8%,环渤海地区增势明显;NPP季节变化较大,7-9月上旬形成峰值区,占NPP年累积量的57.1%;NPP空间分布不均,除黄河三角洲为低值区外,其余地区呈现出由四周向中部递减的趋势;相关性分析表明温度和降水是研究区NPP季节分布的主导气象因子,温度在影响研究区NPP地理分布方面占据主导地位。     

Restoring Tallgrass Prairie and Grassland Bird Populations in Tall Fescue Pastures With Winter Grazing

Restoration of grasslands dominated by tall fescue (Schedonorus phoenix [Scop.] Holub) to native tallgrass prairie usually requires burning, herbicides, or reseeding. We tested seasonal grazing by livestock in winter, combined with cessation of fertilization, as a restoration tool for modifying the competitive dynamics among herbaceous plants to restore tallgrass prairie communities in southeastern Kansas. In 2004–2005, we compared responses of grassland plants and birds across a chronosequence of pastures that were winter-grazed from 1 yr to 5 yr. We compared winter-grazed pastures to pastures grazed year-round and to local native prairie remnants as starting and endpoints for restoration, respectively. Abundance of native warm-season grasses increased from 2% to 3% mean relative frequency in pastures grazed year-round to 18% to 30% in winter-grazed pastures, and increased with duration of winter-grazing. Native warm-season grasses accounted for 1–6% of total live aboveground biomass in pastures grazed year-round, 1–34% in winter-grazed pastures, and 31–34% in native prairie remnants. Tall fescue abundance and biomass were similar among grazing treatments, with a trend for tall fescue to be less dominant in winter-grazed pastures. Tall fescue made up 9–40% of total aboveground biomass in year-round grazed pastures and 10–25% in winter-grazed pastures. Grassland birds showed variable responses to winter-grazing. Dickcissels (Spiza americana) and Henslow’s sparrows (Ammodramus henslowii) were more abundant in winter-grazed pastures, whereas eastern meadowlarks (Sturnella magna) and grasshopper sparrows (A. savannarum) had similar abundance in pastures grazed year-round and during winter. Winter-grazing of pastures dominated by tall fescue combined with suspension of nitrogen fertilization could be an effective restoration technique that allows use of prairie rangeland while improving habitat for sensitive grassland birds.     

Integrated Grazing and Prescribed Fire Restoration Strategies in a Mesquite Savanna: III. Ranch-Scale Cow–Calf Production Responses

Beef cattle production from rangelands in the Southern Great Plains has decreased in concert with herbaceous forage production declines in response to woody plant encroachment by honey mesquite (Prosopis glandulosa Torr.) over the past 120 yr. Combinations of livestock overstocking and fire suppression are considered to be primary drivers of these changes. This experiment evaluated cow–calf production responses over a 7-yr (1995–2001) period to ranch-scale (1 294–2 130 ha) integrated restoration strategies involving prescribed fire and grazing management. Restoration strategies tested in this year-round grazing ecosystem were 4-pasture, 1-herd rotation with fire (25% of pasture acreage burned each year; 4:1F); an 8-pasture, 1-herd rotation, with fire (8:1F); and a 4-pasture, 1-herd, with fire and aerial application of 0.28 kg · ha^?1 clopyralid + 0.28 kg · ha^?1 triclopyr herbicide (4:1F / H). Restoration strategies were compared to a continuous grazing strategy with no mesquite treatment. All cattle stocking rates were moderate (7.5–15 ha · animal unit^?1 · year^?1) and all fires were applied during late winter. Beef cattle (cow–calf) production variables measured included conception rate, weaned calf percentage, weaning weight, weight of calf per exposed cow, weight of calf per hectare, and supplement fed per cow. We observed significant differences in beef production among strategies primarily during the first 2 yr where the continuous grazing strategy exhibited better overall livestock production than the integrated restoration strategies. Differences in livestock production among strategies were minimal over the last 5 yr of the study. These livestock production results suggest livestock and management adapted to restoration strategies after the first 2 yr. Results point to the need to cautiously transition into integrated grazing and fire restoration strategies when cattle and management are changed and intensified from prior historical protocols.     

Lack of Native Vegetation Recovery Following Biological Control of Leafy Spurge

Leafy spurge (Euphorbia esula L.) is an aggressive exotic species that has been successfully suppressed in a variety of situations using classical biological control (flea beetles; Aphthona spp.). This 9-yr study investigated patterns of vegetation responses following significant reductions in leafy spurge cover and density by flea beetles in southeastern Montana. We hypothesized that the vegetation following leafy spurge suppression would be dominated by species and plant functional groups able to persist through heavy infestations. Flea beetles were first released in 1998, and by 2006 leafy spurge foliar cover was reduced 80% to 90% compared to 1998 values on both release and nonrelease plots. Although total cover of the resident vegetation, excluding leafy spurge, increased 72% to 88%, relative cover of the functional groups (native forbs, native sedges, native grasses, and non-native species) was similar among years and between release and nonrelease plots. Mean diversity and mean species richness values did not differ among years or between release and nonrelease plots (P < 0.05), but mean diversity on both release and nonrelease plots was significantly less than noninfested plots, although richness was similar (P < 0.05). Indicator species analysis revealed that non-native Poa spp. replaced leafy spurge as the dominant species on release and nonrelease plots. Conversely, noninfested plots contained a variety of native species with high indicator values. Although total abundance of the resident vegetation in 2006 was significantly greater than 1998, plant species composition and relative cover showed little change for the duration of the study. Failure of the native vegetation to recover to a community that approached nearby noninfested conditions may be attributed to a variety of interacting scenarios, some of which may be ameliorated by treating infestations as soon as possible to avoid long-term residual effects.     

唐古特白刺种子浸提液对小麦种子发芽及生长的抑制效应

将唐古特白刺种子用蒸馏水浸种不同时间(12h、24h和36h),研究其浸提液对‘西旱1号’小麦种子发芽和幼苗生长的影响.结果表明:白刺种子水浸提液对小麦种子的发芽质量和幼苗生长均具有显著影响,随着白刺种子浸提时间的延长,其水浸提液对小麦种子发芽势和发芽率抑制作用增强.浸种36h的唐古特白刺种子水浸提液对小麦种子的发芽抑制作用最大,发芽率抑制活性达32.3%,浸种24h的水浸提液对小麦种子幼根的生长抑制作用最大,根长抑制活性达12.3%.     

诱抗剂对切花百合生长、抗病性及相关酶活性的影响

分别用DL-β氨基丁酸(DL-β-aminobutyric acid,BABA)、移栽灵(Isolane,有效成分:10%稻瘟灵,10%噁霉灵)、表油菜素内酯(epibrassino1ide,epi-BR)、水溶性壳聚糖(hydrosoluble chitosan,OS)、苯并噻二唑(acibenzolar,BTH)、脱落酸(abscisic acid,ABA)、MgO和NH4Cl浸泡切花百合种球根部与鳞片,通过盆栽、田间种植和鳞片包埋,测定其生长指标,POD、PAL、PPO等防御酶活性以及根腐病的病情指数。结果表明,各种试剂处理后,植株叶片防御酶活性增加,株高、叶片数、茎粗等生长性状得到改善,子球鳞片数增加,病情指数减小。其中OS400mg·L-1处理的百合在各个生理指标以及抗病性上明显高于对照。     

Soil macrofaunal response to sand dune conversion from mobile dunes to fixed dunes in Horqin sandy land,northern China

The response of macrofauna to dune conversion from mobile dunes to fixed dunes was investigated in Horqin sandy land, northern China. Macrofaunal communities were compared in four major stages: mobile dunes (MD), semi-mobile dunes (SMD), semi-fixed dunes (SFD) and fixed dunes (FD). Macrofauna were collected by hand in the field and identified in the lab on the basis of features observed under a magnifying glass. They were then classified into morphotypes at the order and family level. Environmental parameters indicated a significant alteration of the soil environment in the conversion process. A clear increasing trend in abundance, richness, and diversity of the macrofaunal community could be established from mobile dunes to fixed dunes. Data for the different taxa suggested specific responses to dune conversion. Specific groups in the initial stage were predators (Labiduridae and Myrmeleontidae larvae, presumably feeding on Noctuidae and other small flying insects), which in the intermediate stages were replaced by saprophagous taxa (Diptera larvae, feeding on many decaying roots buried in semi-mobile and semi-fixed dunes), and burrowing Tenebrionidae (adults, then larvae) with herbivorous Hemiptera in later fixation stages with higher plant density and cover. Overall, the conversion process, particularly the fixed dunes, provided more suitable habitats with greater soil organic matter and plant cover supporting macrofaunal communities with higher diversity, which further enhanced the stabilization process, benefiting the restoration of soil and vegetation in this semiarid sandy area.     

利用GRACE重力卫星监测新疆天山山区水储量时空变化

利用经过高斯平滑滤波处理的2003年1月至2010年12月逐月的GRACE卫星时变重力场数据,反演得到新疆天山山区水储量变化,其空间分辨率为1°×1°,结合同时间段该区域31个国家气象台站逐月降水资料,采用趋势分析方法,研究天山山区近8 a来的水储量时空变化特征。结果表明：天山山区水储量变化具有明显的空间差异性,总体表现为东、西部多,中部少的空间分布格局。在时间上,水储量变化与降水具有明显的季节性变化规律,两者变化过程基本一致。天山山区平均水储量变化趋势的年内分布总体上1-12月呈递增变化;1-3月为负增长,最大负增长为21.7 mm•a^-1,出现在2月;4-12月呈正增长,最大月份出现在11月,增长趋势达到29.9 mm•a-¹。水储量变化增加的主要原因是天山山区近几年夏季降水有所增加造成的。2003-2010年天山山区水储量变化总体上呈逐年下降趋势,平均每月下降速度为4.8 mm,8 a间水储量变化减少约13×10⁸ m³,其主要原因是由于气候转暖、冰川消融加速、山前绿洲灌溉及生活用水量增加,导致山区水储量变化减少。