贵州喀斯特石漠化防治的国家重点生态功能区生态系统健康度评价

文章以桂黔滇喀斯特石漠化防治的国家重点生态功能区贵州区为研究对象,以2010、2015年遥感影像、基础地理信息、降水、土壤等数据资料为基础,集成3S技术和生态评估模型,对水源涵养、土壤侵蚀和石漠化进行定量和定位研究。结果表明:研究区4个亚区的水源涵养功能等级处于“中”、“高”等水平,2015年比2010年的水源涵养指数有所提高;威宁—赫章区、关岭—镇宁区和册亨—望谟区3个亚区的土壤侵蚀模数较大,水土保持功能等级处于“低”等,罗甸—平塘区的土壤侵蚀模数最低,其水土保持功能等级为“中”等;威宁—赫章区2010年中度以上石漠化比重达16.36%,2015年降为8.74%,生态系统健康度从“低”转为“中”;关岭—镇宁2010年和2015年中度以上石漠化比重分别为8.64%和4.49%,生态系统健康度从“中”转化“高”;册亨—望谟和罗甸—平塘的健康度均为“高”,2015年相比2010年均有所提升;4个亚区的石漠化恶化面积所占比重均不到1.00%,石漠化好转区域分别占27.00%、14.10%、10.24%和5.13%,石漠化得到了有效遏制。今后应继续因地制宜,恢复植被和生态系统,巩固和扩大石漠化防治成果。      

典型岩溶断陷盆地农作物生态需水研究——以蒙自地区为例

从合理调控生态用水角度出发,探讨典型岩溶断陷盆地区农作物生态需水问题。根据蒙自断陷盆地的岩溶地貌特征,分别选取位于盆地、坡面和高原面的大洼子、朵古、牛耳坡3个观测点,利用Penman-Monteith公式、作物系数（FAO推荐）及同期有效降雨量,估算3个观测点2018年的参考蒸散量、生态需水量以及不同作物生长所需的人工灌溉水量。结果表明:（1）大洼子、朵古及牛耳坡的参考蒸散量分别为1 346.10 mm、1 200.00 mm、1 064.30 mm,远大于同期降水量,均呈现出蒸发旺盛的特点,加大了作物对于水分的需求;同时三者的参考蒸散量表现出较为明显的时空差异,使得3个观测点的农业种植条件存在差异;（2）大洼子种植的水稻、小麦、花生、油菜、大豆、马铃薯、葡萄等作物的生态需水定额均远大于大洼子同期的有效降水,在大洼子种植的作物均需要大量人工浇灌才能正常生长,而农作物的种植与其种植条件匹配度不高;（3）朵古及牛耳坡种植的玉米、万寿菊的生态需水定额与同期有效降水之间的差值较小甚至完全满足,表明玉米、万寿菊在高原山区的种植是与当地种植条件相匹配的;而种植在朵古及牛耳坡的苹果、烤烟的生态需水定额与同期有效降水之间的差值较大,表明在高原山区大量种植苹果及烤烟对于人工浇灌要求较高;（4）研究区大部分农作物在生长发育阶段内所需的水分主要依靠人工灌溉,与本地降水分布规律匹配度不高,区内农业结构与种植模式有待调整。在岩溶断陷盆地内要种植耗水较少,对热量要求较高的作物,山区则需要发展具有生态保护和经济效益的作物,但种植的重点区域仍是盆地区。      

若尔盖风成砂-古土壤序列的古气候与古环境记录研究

通过对若尔盖盆地中部辖曼地区风成砂-古土壤沉积序列的粒度分析、孢粉鉴定、磁化率测定以及AMS 14C年代测定,探讨了该地区末次冰消期以来古气候与古环境的演化过程。研究结果表明,若尔盖地区的土地沙化现象至少在距今16 ka余年的末次冰消期就已经出现。地层结构、粒度、磁化率皆指示该区古气候在末次冰消期以来经历了多次冷暖交替变化,沙地也经历了多次的固定与活化过程,其中16130~6460 aB.P.、3445 aB.P.前后以及700 aB.P.前后气候较为温暖湿润,在8170~6460 aB.P.期间有一次极暖事件。自11.3 kaB.P.开始,古土壤中的喜暖型乔木花粉含量明显降低,草本植物、尤其是狐尾藻属和莎草科等沼泽植物孢粉含量明显增多,指示该区古环境发生明显变化,开始发育沼泽泥炭。      

岩溶断陷盆地典型县域石漠化治理综合效益评价 ——以云南建水县为例

云南省建水县境内分布有建水盆地、曲江盆地两大盆地,是岩溶断陷盆地区的典型代表,并且是石漠化综合治理工程"十三五"建设的重点县域,近十年来石漠化治理产生了明显的成效.为探究岩溶断陷盆地石漠化治理的成效,文章以建水县为例,基于2007—2017年Landsat TM数据,森林资源二类调查数据、石漠化监测数据及社会经济年鉴数...     

WATER MOVEMENT AND VEGETATION PATTERNS ON SHRUBLAND AND AN ABANDONED FIELD IN TWO DESERTIFICATION-THREATENED AREAS IN SPAIN

Four large-scale rainfall simulation experiments were conducted in Spain to improve the understanding of the relationship between soil water dynamics, soil erosion and land degradation. On different shrublands and an abandoned field, hydrological characteristics were determined in relation to spatial patterns in soil, vegetation and morphology. During the experiments on shrubland, runoff at fine scales occurred shortly after the start of the experiments. Rapid and non-uniform infiltration near vegetation clusters, related to preferential flowpaths of water, was observed. This prevented the development of runoff over distances larger than 1 metre. The surface redistribution of water was not observed on the abandoned land. Here, little vegetation structure was present and infiltration rates were high below crusts as well as stones. We suggest that the development of spatial structures in vegetation and soil forms a positive feedback with non-uniform infiltration and increased soil water retention. The assessment of land degradation could benefit greatly from acknowledging the importance of non-uniformity in hydrological processes. Furthermore, the presented measurements indicate that in discontinuous environments runoff measurements at fine scales cannot be extrapolated directly. In these environments a scaled approach needs to be adopted emphasizing the importance of different hydrological processes at different scales.     

Spatial diversity of rocky midlittoral macro-invertebrates associated with the endangered species Patella ferruginea (Mollusca: Gastropoda) of Tunisian coastline

The present study focuses on horizontal spatial variability of benthic macrofauna associated with Patella ferruginea. Thirty-six samples collected at 12 transects belonging to 4 midlittoral sites along the rocky Tunisian coastline, were examined. A total of 44 species belonging to 5 taxa were found. Multivariate analysis applied on gathered data did not show a horizontal spatial variability at small scale (between transects), but at large scale, between sites as well as sectors. Thus, three groups of communities were identified (GI: Korbous and El Haouaria; GIIa: Zembra Island and GIIb: Kelibia). The distribution of species abundance within these groups revealed that crustaceans were the most abundant taxon, due to the overwhelming dominance of Chthamalus stellatus. This substratum appeared to create favourable micro-habitats for the installation of molluscs including gastropods. Regarding the low diversity index (H') and evenness (J), they seemed to reflect a disturbance and a demographic unbalance within these communities. The heterogeneity of substrate surface, created by C. stellatus specimens appeared to be caused by various complex interactions established between the key components of these communities in particular suspension feeders, predators, herbivorous molluscs and macroalgae. Thus, the dynamic status of each of these communities is the result of these complex interactions.     

Shore exposure affects mussel population structure and mediates the effect of epibiotic algae on mussel survival in SW Ireland

On rocky shores, the relative importance of abiotic and biotic processes that regulate community structure are thought to vary with levels of shore exposure. This can lead to characteristic features found on sheltered and exposed shores. This study identified differences in the population structure of mussels on exposed and sheltered rocky shores on Atlantic coasts of south-west Ireland. Direct interactions between epibiotic algae and their host mussels were also examined to test if potential effects varied with shore exposure. Mussel beds on sheltered shores were less dense and comprised larger mussels with greater rates of individual survival and growth than those on exposed shores. The results of a field experiment showed that algal epibionts had a negative effect on mussel survival on sheltered shores but not on exposed shores. Surprisingly, the presence of algal epibionts had no effect on mussel growth on either shore type. These findings contrast with those of previous studies. The effects of shore exposure and algal epibionts on mussels may be species-specific and may interact with other factors across different regions. This study shows that predictions of effects of exposure on mussel populations and their epibionts should only be based on specific experimental evidence and cannot be generalised across regions.     

Determining spatial changes in the diet of nearshore suspension-feeders along the South African coastline: Stable isotope and fatty acid signatures

Mesoscale oceanographic features, such as upwellings, are known to play an important role in regulating the structure and productivity of nearshore marine communities. Stable isotope (δ¹³C and δ¹⁵N) and fatty acid analyses were employed to assess the influence of an upwelling cell along the south-eastern coastline of southern Africa on the diet of the mussel, Perna perna. Eight sites were sampled: two upstream, three in the vicinity and three downstream of the upwelling cell. Stable isotope and fatty acid signatures indicated that the mussels consumed a diet of detritus derived mainly from macroalgae, diatoms and dinoflagellates. One-way ANOVA on the δ¹³C and δ¹⁵N signatures and the principal component analysis of the fatty acid profiles of the mussels identified distinct groups corresponding to the above mentioned regions. The proportion of diatom biomarkers in the fatty acid profiles decreased downstream of the upwelling region while the proportion of dinoflagellate biomarkers increased. Upwelling regions are typically associated with elevated levels of productivity; however, these systems usually become silicon depleted and result in the replacement of diatoms with dinoflagellates. The highest proportions of the dinoflagellate markers were recorded in the two furthest sites downstream of the upwelling cell. The spatial variation in the diet of the mussels, therefore, appears to reflect the presence of the upwelling cell in the nearshore biology of the region.     

Experimental investigations into the influence of biofilms and environmental factors on short-term microtopographic fluctuations of supratidal sandstone

In this study laboratory experiments were used to explore the role of biofilms, formed by lithobiontic microorganism communities, in causing hourly surface changes of supratidal sandstone and the potential linkage to long-term rock decay. To isolate the influence of individual environmental factors (temperature and humidity) on rock surface changes (expansion and contraction), a colonized (biofilm-covered) and a non-colonized sandstone block (biofilm-free) underwent the same univariate microclimatic simulations closely controlled by an environmental chamber. Simulations were run under three different light conditions, with a natural light lamp on, on and off at 20-min intervals and off, to investigate the impact of light on rock surface dynamics. Measured with a traversing micro-erosion meter (TMEM), two-hourly microtopographic fluctuations of these two sandstone blocks were compared in the same environment. Induced by microclimatic variations, surface movements of significantly higher magnitude (12–120% under varying tempeature and 121–154% under varying humidity) and different change patterns were observed on the colonized block, indicating the primary role of biofilm in driving microtopographic fluctuations of supratidal sandstone. However, thermally driven changes of similar magnitude and pattern were observed on both surfaces, suggesting other mechanisms also operating on the non-colonized rock surface in this process. Due to the sensitivity of biofilm microorganism communities to light, the magnitude and pattern of surface changes was impacted by light condition. Because biofilms increased the magnitude and number of cycles of expansion and contraction of the experimental rock surface, we propose that lithobiontic biofilms facilitate the detachment of grains and granular disintegration on the rock surface, consequently contributing to rock decay and accelerating the rate of breakdown of supratidal rock. This short-term episode therefore needs to be superimposed on longer term studies to fully understand the role of biofilms in rock surface change. © 2019 John Wiley & Sons, Ltd.     

近45a内蒙古浑善达克沙地湖泊群的变化

浑善达克沙地处于季风边缘区,其气候特性和人类活动决定了该地区生态系统的脆弱和环境变化的敏感性.目前,该区湖泊生态环境问题十分严重,对研究区的水资源、草原景观以及当地居民生产生活造成了严重影响.选取1969年1∶50000地形图所指示的面积≥0.01 km~2的175个湖泊为研究对象,结合1973-2013年的17期Landsat MSS/TM/ETM/OLI卫星遥感影像数据,对1969-2013年间的湖泊群变化进行了系统的研究和初步探讨.结果表明:1969年湖泊群总面积为502.04 km~2,而2013年其面积为303.42 km~2,总体呈萎缩趋势.其中面积萎缩和干涸的湖泊分别为88和85个,而面积扩张的湖泊仅有2个(人工筑坝所致).近45 a间,1970s-1980s湖泊面积波动性减少,而在1990s初期则出现持续上升状态.在1995-2011年湖泊面积总体下降,到2013年则出现微弱的扩张现象.从湖泊变化空间分布格局来看,萎缩和干涸的湖泊集中在该沙地腹地.