舟山岩相潮间带动物群落结构的研究

本文应用数理统计方法研究了舟山海区岩岸潮间带中26个测站的春季动物群落结构。根据26个站的位置分为近岸区、近外海区和外海区3个区域。各站均以软体动物和甲壳动物为群落主要组成成分,群落种类组成数从近岸到外海呈增长趋势,且优势种亦从低盐种类向高盐种类演替。近岸区群落主要优势种为短滨螺Littorina brevicula、粗糙滨螺L.scabra、僧帽牡蛎Ostrea cucullata、白脊藤壶Balanus albicostatus等;近外海区为短滨螺、粒结节滨螺Nodilittorinaexigua、僧帽牡蛎、鳞笠藤壶Tetraclita squamosa squamosa、白脊藤壶等;外海区为粒结节滨螺,疣荔枝螺Purpura clavigera、条纹隔贻贝Septifer virgatus、日本笠藤壶T.japonica及藻类等。但群落个体密度和生物量从近岸到外海呈减少趋势。从近岸到外海,群落的Shannon-Wiener多样性指数H和Pielou均匀度J均增加,而McNaughton优势度D减少。群落结构从近岸到外海渐趋复杂。但整体上,舟山海区岩岸春季动物群落结构是比较简单的(绝大多数断面H值小于2.50,J值小于0.5。而D值大于0.6)。近外海区的群落结构比较相似于外海区的群落。根据平均聚类分析,这26个群落可以分为三个生态类型,即隐蔽性岩岸群落,半隐蔽性岩岸群落及开敞性岩岸群落。     

Size Selective Predation by the Asteroid Pisaster ochraceus on the Bivalve Mytilus calif ornianus: A Cost-Benefit Analysis

Abstract. When simultaneously presented with equal numbers of four sizes of clumped Mytilus californianus (20, 35, 55 and 85 mm shell length), Pisaster ochraceus (arm length of 70-110mm R) showed a preference for the medium sizes (35 and 55mm length). Prey-size preference was positively correlated with predator size. Mean prey-digestion times (insertion of the stomach, opening of the valves and digestive period) decreased significantly following fiiing of an artificial gape between the valves of mussels. When presented with different sizes of clumped filed mussels, starfish still chose medium mussels, indicating that stomach insertion, valve opening, and digestion rate may not be important constraints determining size selective predation. Measurements of the force required to dislodge mussels from the substratum and conspecifics showed an increasing exponential relationship with mussel size. Size selective feeding may be an energy maximizing and time minimizing strategy, where energy gained from choosing larger mussels is balanced against disproportionately increased costs in energy and time of removing large mussels from the substratum.     

渔山列岛夏季潮间带大型底栖生物群落结构研究

于2014年8月,在浙江宁波渔山列岛布设4个岩礁断面开展潮间带大型底栖生物调查,分析其种类组成、丰度、生物量、优势种、生物多样性和群落结构特征等。该调查共采集到潮间带大型底栖生物98种,包括大型底栖动物70种和大型底栖藻类28种;其中优势种有9种,分别为小结节滨螺[Echinolittorina radiata(Souleyet)]、条纹隔贻贝[Septifer virgatus(Wiegmann)]、厚壳贻贝[Mytilus coruscus(Gould)]、带偏顶蛤[Modiolus comptus(Sowerby)]、栗色拉沙蛤[Lasaea nipponica(Keen)]、日本笠藤壶[Tetraclita japonica(Pilsbry)],刺巨藤壶[Megagbalanus volcano(Pilsbry)],以及珊瑚藻[Corallina officinalis(Linnaeus)]和小石花菜[Gelidium divaricatum(Marteus)]。潮间带大型底栖生物平均生物量为8 515.50 g/m~2,平均丰度为6 841.63个/m~2;各断面Shannon-wiener指数(H′)、Pielou均匀度指数(J)和Margalef丰富度指数(d)平均值分别为1.89±0.14、0.38±0.01和3.66±0.52。ABC曲线分析表明,4个断面受到一定扰动。与历史资料相比,该区域物种数减少明显,生物量和丰度有所增加,优势种被个体较小的日本笠藤壶、条纹隔贻贝等物种所演替。上述结果可为渔山列岛潮间带开发保护管理及其生物资源的可持续利用提供重要参考。     

Variations in crab claw morphology and diet across contrasting inter‐tidal habitats

Crabs are important predators of inter‐tidal ecosystems, controlling the abundance and distribution of their prey populations. Often the same crab species occupies several habitats and, although their effects on prey have been quantified across habitats, crabs’ dietary and morphological responses to differing environmental influences have been overlooked. Here, we used the crabs Eriphia verrucosa and Pachygrapsus marmoratus as model species to examine differences in claw morphometry – size and wear – and diet between rocky shore and heterogeneous sand flat habitats. We predicted that, intra‐specifically, crabs from rocky shores would consume more hard‐shelled prey owing to their high availability and consequently, would display chelipeds with the following claw characteristics: a higher degree of claw damage, stronger musculature (higher propel height) and increased mechanical advantage (defined as the ratio of input lever length to output lever length) than crabs in the heterogeneous sand flat habitats. Sampling was performed in heterogeneous sand flat habitats and rocky shores of the Central Portuguese coast. For each crab species, carapace width, diet composition and several claw morphometric measures were recorded, revealing significant intra‐specific differences (using multivariate analysis) between shore types. We found that E. verrucosa and P. marmoratus consumed more hard prey on rocky shore than on sand flat habitats, which resulted in rocky shore crabs having more accentuated dentition wear and larger musculature than their sand flat habitat counterparts. We suggest that the strong response of crab claw morphometry to environmentally induced diet variations is an important mechanism in the successful adaptation of crab species to inhabit differing habitats. A major implication is that the impact of the same species on prey may vary largely with habitat type as a result of predation efficiency varying with claw condition.     

Polychaete Depth Distribution in a Posidonia oceanica Bed (Rhizome and Matte Strata) and Neighbouring Soft and Hard Bottoms

Abstract. The study was carried out in a Posidonia oceanica bed and in the neighbouring sandy and rocky bottoms, at Ponza Island (Central Tyrrhenian Sea), in order to investigate the distributional pattern of the polychaete community at different depths. A total of 15232 individuals of polychaetes belonging to 218 species was collected and three new species of Syllidae were found. The polychaete community of the matte can be clearly distinguished from the neighbouring communities; this is due to the high species richness in Posidonia , which is related to the heterogeneity of the biotope. In the Posidonia bed the shallow stations (1 m and 5 m depth) were the richest in terms of species numbers and individuals due to the high shoot density of the seagrass bed. In the shallow waters polychaete community structure changed according to the different exposure to water movement. Rocky bottom species, which preferentially inhabit crevices, were more abundant in the matte exposed to water movement (5–10 m depth). In contrast, soft-bottom species were more abundant in the sheltered zone (1 m depth) as well as in the deeper zone due to the reduction of the Posidonia bed.     

How complementary are epibenthic assemblages in artificial and nearby natural rocky reefs?

The present study analyses the composition, structure and trophic function of epibenthic assemblages in two artificial reefs (ARs) 16 years after deployment and in nearby natural reefs (NRs), aiming at providing insights on the complementarity between both habitats. Current findings suggest that after 16 years the ARs (concrete blocks), located in southern Portugal, do not act as surrogates for NRs, as epibenthic assemblages differed between reef types in composition, structure and trophic function. NRs showed higher diversity and complementarity (i.e. beta-diversity) than ARs, evidencing higher redundancy. Higher heterogeneity within NRs was also evidenced by the multi-dimensional scaling analysis based on abundance, biomass and trophic composition. NRs presented higher abundance of molluscs and biomass of sponges, resulting in differences in the trophic function: suspension-feeding dominated the NRs, while within ARs there was an ascendency of carnivory. Although not acting as surrogates for NRs and provided that no adverse effects (e.g. establishment of non-native species) were detected, ARs may have a significant contribution for the increase of regional diversity, as evidenced by the highest complementarity levels observed between assemblages in both reefs.     

Development of land desertification in Bashang area in the past 20 years

Natural conditions in Bashang area are characterized by zonal transitions which are liable to be impacted by natural disasters and intensified human activities. The extremely fragile eco-environment is also liable to have desertification formed and developed. In the 18 years from 1978 to 1996, the desertified land area of Bashang within the scope of the map nearly doubled, a total increase of 2199.11 km2, averaging an increase of 122.17 km2 per year. Moreover, the seriously desertified area increases rapidly. Land desertification in Bashang is the combined result of natural factors and irrational human economic activities. Cultivated land expansion, population growth, and overgrazing aggrevate desertification development.     

元谋干热河谷区土地荒漠化研究

干热河谷是我国西南地区特殊的生态类型,通过分析云南元谋干热河谷区土地荒漠的面积（海拔１３５０ｍ以下,荒漠化土地面积１００６．０２ｋｍ＾２,占该区总面积的７０．１５％）,表现特征（地形破碎,劣地广布,以肉质常绿灌丛为代表的类似荒漠植被,地表水分条件恶化,土壤贫瘠）及形成原因（自然原因：地质基础稳定性差,地貌类型多样,气候炎热干燥;人为原因：人口激增增加环境压力,垦荒,乱滥伐,过度放牧）,提出了土地荒     

北方农牧交错区沙漠化的生物过程研究

通过对不同土地利用/覆盖下4种类型沙漠化土地的土壤与植被特征、变化规律、动因和互动关系的调查研究,结果表明土地沙漠化导致了土壤环境和植被的明显退化。其中严重沙漠化农田和非沙漠化农田相比,土壤有机质含量、速效氮、生长季土壤含水量分别下降66.2%、69.0%、74.8%,地温由21.5 ℃上升到22.4 ℃,其中干旱期严重沙漠化农田土壤含水量仅为23%,已无法满足作物生长需要。土壤环境恶化首先威胁土壤微生物和土壤动物的生存,使土壤微生物和动物数量分别下降95.0%和75.9%,酶活力下降39.5%~ 90.6%。同时植物多样性、种的饱和度和初级生产力大幅度下降,如严重沙漠化草地和非沙漠化草地相比,3项指标分别下降85.5%~883%,87.5%~ 950%和80.6%~ 967%,植被开始发生逆向演替,群落优势种不断更替,最终形成耐牧耐风沙的沙生植物群聚。旱作农田虽采取了施肥、中耕等管理措施,但光合转化效率和初级生产力还是下降了567%和574%。这一过程因其动因不同可分为植被退化(如放牧)引起的土地沙漠化和裸露地表风沙流活动直接导致的土地沙漠化(如农田风蚀和流沙迁移),前者是植被先行退化进而影响到土壤环境,其过程较为缓慢,后者是土壤环境首先恶化进而导致植。     

2000—2020年中国荒漠化潜在发生范围区林草覆被时空变化特征

干旱地区林草植被生长动态变化是研究荒漠化形成发展和演变过程的重要依据。本文基于改进方向性像元二分模型构建的2000—2020年中国荒漠化潜在发生范围区（PEDC）年植被覆盖度数据集,采用Sen+Mann-Kendall时间序列趋势变化检测方法,分析了2000—2020年PEDC,特别是林草覆盖区的植被生长状况时空变化特征。研究结果表明：① 2000—2020年,PEDC平均植被覆盖度为0.284,改进的植被覆盖度估算结果能够较好地反映研究区植被覆盖状况,估算精度为86.98%。PEDC植被生长状况不断趋好,其中干旱区表现最为突出,显著增加区域达到了48%,而亚湿润干旱区平均增长量最大为0.1。② 林草生态恢复工程措施效果显著,但植被恢复是个长期缓慢的过程,特别是林草面积的恢复。2000—2010年林草面积增加较少（0.002%）;2010—2020年增加较多（0.371%）。③ 2000—2020年PEDC林地植被改善最明显,草地则较为稳定,植被覆盖度显著性增加区域分别为76.4%和71.8%。其中林地植被覆盖度在亚湿润干旱区增长量最大为0.15,而整个研究区草地增长了0.06。本文更深入地掌握PEDC林草覆盖区长时间序列植被生长状况,为进一步制定和实施各项生态工程提供重要信息参考。