农业机械化对农业产业结构调整的支撑研究

通过农业机械化对农业劳动力的替代及其农业劳动力在农业产业结构中的数量调整关系研究,分析了农业机械化对农业产业结构调整的支撑作用;并简要探讨了农业机械化对农业生产布局、农业闲置资源利用、土地生产率和劳动力生产率提高的作用和农业产业结构调整的关系.     

毛竹林长期立地生产力评价和预测研究的评述

本文论述了我国毛竹林长期立地生产力评价和预测研究的背景、特点、面临的主要技术难点、可供利用的优势以及可能的研究策略和解决途径，为探索毛竹林在不同经营措施作用下长期立地生产力的评价和预测的理论及方法提供参考。     

Continental‐scale Impacts of Livestock Grazing on Ecosystem Supporting and Regulating Services

Grazing by livestock supports millions of people worldwide, particularly in drylands, but has marked negative effects on ecosystem services and functions. In Australia, its effects on ecosystem services have not been fully quantified. We examined the extent to which grazing by livestock influenced supporting (productivity, habitat for organisms and biodiversity) and regulating (carbon cycling and hydrological function) services, using data from published and unpublished studies on livestock grazing from a large number of sites across Australia. Grazing reduced our measure of supporting services by about 20% and regulatory services by 8%. On average, grazing reduced plant productivity by 40%, habitat value by 20%, and biodiversity, hydrological function and carbon sequestration by about 10%. Habitat and productivity showed strong declines with increasing grazing intensity, and carbon showed strong declines at the lowest and highest contrasts. Hydrological function and biodiversity did not decline with increasing grazing intensity. Overall, the results indicate that livestock grazing leads to substantial degradation at a continental scale by reducing ecosystem services associated with habitat provision, biodiversity, and soil and water functions. Management of livestock grazing will be critical if we are to retain functional levels of ecosystem services into the next century. Copyright © 2016 John Wiley & Sons, Ltd.     

中国北方沙尘暴的气候特征及其对春季青藏高原地面感热异常的响应

选用中国185个常规气象观测站,建站～2000年历年沙尘暴日数资料,分析了近50年来中国北方沙尘暴的气候特征及其对青藏高原地面感热异常的响应。结果表明虽然单个沙尘暴过程属于一次中尺度天气过程,但年沙尘暴日数具有较好的空间一致性,在空间上有五个自然尘源区,即河西走廊、南疆盆地南缘、阿拉善高原、鄂尔多斯高原和浑善达克沙地等沙尘暴高发区。比较近50年来中国沙尘暴日数的年代际变化,总体趋势在减少,20世纪90年代是近5个年代中最少的。但20世纪末至21世纪初,中国沙尘暴日数有明显的回升趋势。进一步研究表明,中国沙尘暴与春季青藏高原地面感热关系密切,当春季青藏高原地面感热呈EOF1模态时,当年中国北方沙尘暴日数明显较常年偏多。     

过渡地区采用狗牙根秋季交播黑麦草建植四季常绿草坪时应注意的几个问题

阐述了过渡地区气候特点以及冷暖地型草坪草在该地区的生长特点,建植四季常绿草坪常用的方法,提出了采用狗牙根Cynodon dactylon秋季交播黑麦草Lolium perenne建植草坪时应注意的问题:狗牙根建植方法、交播内涵的理解和2个过渡阶段的管理.     

禁牧对巴林右旗天然草地生产力及植被组成的影响

在内蒙古自治区巴林右旗不同草地类型测定了未禁牧、禁牧当年以及禁牧4年后草地生产力和植被群落构成的变化,结果表明：禁牧能够明显提高天然草地的草地生产力;对天然草地的植被组成有明显的改善作用。     

草坪过渡带优质草坪建植与管理综合技术研究—Ⅰ坪床配方

根据在草坪过渡带地区草坪草对床上要求较为严格和不同类型草坪草对床土要求不同的特点,选用２种冷季型草和２种暖季型草,在８种坪床配方处理下进行了连续３年的坪床配方筛选及对草坪质量的影响试验研究,测定再生速度,建坪速度和持续生存能力。结果表明：冷,暖季型草坪草的坪床配方均以４０％－６０％加沙＋复合化肥＝有机底肥＋泥炭为最好;床土中加入有机底肥和泥炭会明显提高草坪的质量和成坪速度;实际建坪时应根据草种类型     

Estimating regional forest productivity and water yield using an ecosystem model linked to a GIS

We used the PnET-II model of forest carbon and water balances to estimate regional forest productivity and runoff for the northeastern United States. The model was run at 30 arc sec resolution (approximately 1 km) in conjunction with a Geographic Information System that contained monthly climate data and a satellite-derived land cover map. Predicted net primary production (NPP) ranged from 700 to 1450 g m² yr¹ with a regional mean of 1084 g m² yr¹. Validation at a number of locations within the region showed close agreement between predicted and observed values. Disagreement at two sites was proportional to differences between measured foliar N concentrations and values used in the model. Predicted runoff ranged from 24 to 150 cm yr¹with a regional mean of 63 cm yr¹. Predictions agreed well with observed values from U.S. Geologic Survey watersheds across the region although there was a slight bias towards overprediction at high elevations and underprediction at lower elevations.Spatial patterns in NPP followed patterns of precipitation and growing degree days, depending on the degree of predicted water versus energy limitation within each forest type. Randomized sensitivity analyses indicated that NPP within hardwood and pine forests was limited by variables controlling water availability (precipitation and soil water holding capacity) to a greater extent than foliar nitrogen, suggesting greater limitations by water than nitrogen for these forest types. In contrast, spruce-fir NPP was not sensitive to water availability and was highly sensitivity to foliar N, indicating greater limitation by available nitrogen. Although more work is needed to fully understand the relative importance of water versus nitrogen limitation in northeastern forests, these results suggests that spatial patterns of NPP for hardwoods and pines can be largely captured using currently available data sets, while substantial uncertainties exist for spruce-fir.     

吐温60和吐温80对反刍动物瘤胃和生产性能的影响

非离子表面活性剂(NIS)已经作为添加剂能有效地刺激需氧微生物的生长。本文综述了非离子型表面活性剂吐温60和吐温80在反刍动物营养中的应用。     

全球变化下毛乌素沙漠气候变化特征

利用 1 961～ 2 0 0 1年毛乌素沙漠年平均气温、年降水量、各季平均气温、各季平均降水量和同期中国平均气温距平资料 ,分析对比了近几十年来毛乌素沙漠气温变化与同期中国气温变化 ,气温与降水之间的关系 ,及各季气温、降水的变化规律 ,揭示了全球变化背景下毛乌素沙漠气候变化的区域性特点及其暖干化趋势 ,为毛乌素沙漠的治理提供了气象上的依据。