Relationship between soil and plant geography on Clark Peninsula

New soil studies in the cold suggest that in the terrestrial ecosystems of the coastal regions of the antarctic continent soil formation and chemical weathering occur to a greater extent than previously expected. This study summarises and discusses the paedogenic results of two (including some aspects of an earlier expedition) Australian funded expeditions (austral summer 1995/1996 and 1998/1999) to Casey Station in the coastal and ice-free area at Wilkes Land (Latitude 66 degrees 17 minutes S, Longitude 110 degrees 32 minutes E) and presents a soil formation sequence on a small-scale database. Soil organic matter (SOM) accumulation and podzolisation are important soil forming processes up to the antarctic polar desert. This study has revealed a high variability in soil geography and soil properties on both, profile and landscape level. However, previous results indicate a weak correlation between the soil cover and the vegetation pattern. Nutrient supply in soil is affected by the high contents and availability of N, P, K, and Mg due to an input by seabirds. More detailed results suggest that in the coastal region of Continental Antarctica (ca. 65 degrees -70 degrees S) the soil water contents are higher than the more arid environment of the Ross Sea section and the Dry Valleys (77 degrees S). Colonisation by lower plants such as mosses, lichens and algae is greater in the more northerly latitudes. Soil formation is mainly restricted by low temperatures and a relatively short period of vegetation colonisation. To some extent SOM accumulation is correlated with the vegetation cover. However, the high SOM content without any vegetation at the soil surface suggest additional inputs from seabirds, microorganisms or the occurrence of relic carbon. The origin of carbon and nitrogen in antarctic soils should be a major topic of future investigations in order to understand nutrient cycling in these coastal ecosystems. Antarctic soils in the coastal region may be sinks for carbon, nitrogen, phosphorus and other nutrients. For improving the global database on soil carbon and nitrogen stocks it is desirable to collect more precise information on soils of the southern circumpolar region. These data are still available for the northern polar regions. The suggested high to very high C and N concentration in the antarctic soils of an earlier expedition (austral summer 1990/1991) were confirmed. The organic matter accumulation in soils of the coastal antarctic region is suggested to be similar to that of comparable arctic regions. Soil formation in the ice-free areas of coastal East Antarctica is characterised by a tremendous humus accumulation in the landscapes. The very narrow C-to-N ratio indicates a higher accumulation of nitrogen than in the northern polar regions. This suggest a potentially high availability of the organic matter observed with the occurrence of nitrogen compounds such as -NH2-N moieties and uric acid. The humus is probably only preserved due to the prevailing cold, but this might be changed by global climate warming trends.Small-distance variation of the topographical, geomorphological, geological and pedogenic patterns induce a great variation in the carbon, nitrogen, potassium and phosphorus concentration and storage. This fact complicates a calculation of soil carbon and nitrogen storage of the total landscape.However, the survey on a landscape level suggests that at 75% of the landscape sites the carbon and nitrogen stock is very similar, but a wide-spread podzolisation and/or extraordinary organic matter accumulation may increase these stocks to a great extent. A storage estimation could be improved by using a more detailed soil survey. This knowledge would be useful with respect to modelling carbon and nitrogen release in the case of a globally rising temperature level and/or anthropogenic disturbances. Within the few, statistically not significant, soil mesofaunal investigations Pseudechinicus suillus, Acutuncus antarcticus, Diphascon chilenense langhadvensis were found to be typical for tardigrades, Plectus murray for nematodes and Nanorchestes antarcticus for mites. The simple LAMINA-BAIT-test was used in order to assess the biological activity. The mesofaunal abundancies showed a huge range as well as the biomass estimation. Water tension and the soil temperature regime had a significant impact on the mesofauna. Only mites seemed to have the capability to survive under active cryoturbation. The results showed no or only weak correlations between the colonisation by mesofauna and the biological activity.The theories of soil formation in Antarctica suggested from Bockheim and Ugolini (1990) need to be extended. Podzolisation is an important soil forming process in the coastal region of the antarctic continent. In addition, there is a strong enrichment of organic matter in many soils of the same region. In the coastal region of the antarctic continent we did not find the ahumic red soils of the cold antarctic polar desert described in detail by Campbell and Claridge (1987). The recent data suggest a correlation between the soil cover and the vegetation pattern. Nutrient supply in soil is affected by the high availability of potassium, magnesium and phosphorus due to the input by seabirds and eolian distribution in the whole landscape. Soil forming processes in the coastal region of Continental Antarctica (eg podzolisation, redoximorphism) indicate the occurrence of free and available water during the short thawing period. To a certain extent the moisture regime allows the transfer of weathering products and nutrients into the subsoil or to the lowest positions on the landscape. A detailed investigation of the water, air, thermal and nutrient regime would enable a better understanding of the soil input/output balance as well as transfers in the landscape for developing ecosystem models. These models would enable the prediction of increased temperatures and/or human disturbances on terrestrial ecosystems in coastal Antarctica.Antarctic soils provide clear evidence of the direct importance of solar energy in soil processes. In soils with a predominantly light colored surface pavement, the thermal regime, salinity and ice-cemented permafrost depth differ from those in soils with dark colored surface pavement. This suggests a strong link between available energy and soil properties in Antarctica. Antarctic soils are particularly sensitive to human disturbances which may be long lasting. Continued human activities in this region must be kept at low levels and within the capacity for natural ecosystems to recover. This will require a greater level of understanding of soil ecosystem relationships. There is an urgent need to bring the soil ecological and microbiological aspects into the technical-orientated remediation design. Nevertheless, for soil protection and remediation there is still a lot to be done in the terrestrial ecosystems of Antarctica.The widespread occurrence of young, last glaciation aged, soils in the coastal region of East Antarctica and West Antarctica such as the Antarctic Peninsula illustrates that these areas are most likely to be influenced by global climate change. In addition, the SOM properties indicate narrow C/N ratios and a high potential availability, which is at present limited due to the cold climate conditions. Increased global warming is likely to be accompanied by an increased thawing depth, release of water from ice cemented permafrost, release of C, N and P, increased salinisation and extended colonisation of moistened sites by a range of soil organisms.A pdf copy (in 4 parts) of the C. Lucas thesis is also available as part of the download.

针对寒冷环境的全新土壤研究表明，南极大陆沿海区域的陆地生态系统中，土壤形成与化学风化的发生程度远超此前预期。
本研究总结并探讨了两项由澳大利亚资助的南极考察（含某次早期考察的部分内容）所获得的成壤相关结果：考察队于1995/1996年及1998/1999年的南极夏季，前往威尔克斯地（南纬66°17′，东经110°32′）的沿海无冰区凯西站开展考察；同时基于小型数据库构建了一套土壤形成序列。
土壤有机质（Soil Organic Matter, SOM）积累与灰化作用（podzolisation）均为关键的成壤过程，直至南极极地荒漠范围内。
本研究揭示，在剖面与景观两个尺度上，土壤地理学特征与土壤性质均存在高度异质性。但既往研究结果显示，土壤覆盖与植被格局之间的相关性较弱。
海鸟输入的氮、磷、钾、镁等高含量且高有效性的养分，会对土壤养分供给产生影响。
更细致的研究结果表明，南极大陆沿海区域（南纬约65°~70°）的土壤含水量，高于罗斯海区域与干谷（南纬77°）这类更为干旱的环境。
纬度更靠北的区域，苔藓、地衣、藻类等低等植物的定植程度更高。
土壤形成主要受限于低温与相对较短的植物定植周期。
土壤有机质积累在一定程度上与植被覆盖相关。但在无地表植被的区域仍存在高土壤有机质含量，这表明其额外养分输入可能来自海鸟、微生物或残遗碳的存在。
为明晰这些沿海生态系统的养分循环机制，南极土壤中碳与氮的来源应成为未来研究的核心议题。
南极沿海区域的土壤可能是碳、氮、磷及其他养分的汇。
为完善全球土壤碳氮储量数据库，亟需获取南环极地区域土壤的精准信息——目前北极高纬度区域的相关数据已较为完备。
某次早期考察（1990/1991年南极夏季）所提出的南极土壤碳、氮浓度处于高至极高水平的结论，已得到本研究的证实。
南极沿海区域土壤的有机质积累特征，与北极同类区域相近。
南极东部沿海无冰区的土壤形成以景观尺度上的大量腐殖质积累为特征。极窄的碳氮比表明，其氮积累量高于北极高纬度区域。
这意味着该区域土壤有机质可能具有较高的潜在有效性，且检测到了氨基-N基团、尿酸等含氮化合物。
这类腐殖质可能仅因持续低温得以保存，但全球气候变暖趋势可能改变这一现状。
地形、地貌、地质与成壤格局的小尺度差异，会导致碳、氮、钾、磷的浓度与储量产生显著波动，这使得全景观尺度的土壤碳氮储量计算变得复杂。
但景观尺度的调查显示，75%的样点土壤碳氮储量较为接近，而广泛分布的灰化作用或显著的有机质积累可大幅提升该储量。
通过更细致的土壤调查可优化储量估算方法，该研究结果可为全球升温及/或人为干扰情景下的碳氮释放模拟提供支撑。
在为数不多且统计学意义不显著的土壤中小型动物调查中，缓步动物（tardigrades）的典型类群为Pseudechinicus suillus、Acutuncus antarcticus与Diphascon chilenense langhadvensis，线虫（nematodes）的典型类群为Plectus murray，螨类（mites）的典型类群为Nanorchestes antarcticus。
研究采用简易的LAMINA-BAIT试验（LAMINA-BAIT-test）评估土壤生物活性，结果显示中小型动物的丰度与生物量估算值均存在极大波动；水势与土壤温度状况对中小型动物群落具有显著影响。
仅螨类似乎能够在活跃的冻融扰动（cryoturbation）环境中存活。
研究结果显示，中小型动物定植与土壤生物活性之间不存在或仅存在较弱的相关性。
Bockheim与Ugolini于1990年提出的南极土壤形成理论有待拓展。
灰化作用是南极大陆沿海区域的关键成壤过程，同时该区域多数土壤存在显著的有机质富集现象。
在南极大陆沿海区域，我们并未发现Campbell与Claridge在1987年详细描述的、寒冷南极极地荒漠特有的无腐殖质红壤。
本研究的最新数据表明，土壤覆盖与植被格局之间存在相关性；海鸟输入与全景观范围内的风成传输，使得土壤中的钾、镁、磷具有高有效性，进而影响土壤养分供给。
南极大陆沿海区域的成壤过程（如灰化作用、氧化还原作用（redoximorphism））表明，在短暂的解冻期内存在游离态有效水；在一定程度上，水分状况可促使风化产物与养分向底土层或景观最低处迁移。
为构建生态系统模型，需对水分、空气、温度与养分状况开展细致调查，以更好地理解土壤输入输出平衡及景观内的物质迁移过程；此类模型可用于预测全球升温及/或人为干扰对南极沿海陆地生态系统的影响。
南极土壤为太阳能在土壤过程中的直接重要性提供了明确证据：以浅色地表覆被为主的土壤，其温度状况、盐度与胶结冰永久冻土（ice-cemented permafrost）深度，与以深色地表覆被为主的土壤存在显著差异，这表明南极区域的有效能量与土壤性质之间存在紧密关联。
南极土壤对人为干扰极为敏感，且这种干扰可能持续较长时间。该区域的人类活动必须维持在低水平，且需控制在自然生态系统的恢复能力范围内。这要求我们加深对土壤生态系统关系的理解，亟需将土壤生态学与微生物学内容纳入以技术为导向的修复设计中。尽管如此，南极陆地生态系统的土壤保护与修复工作仍任重道远。
南极东部与西部沿海区域（如南极半岛）广泛分布着形成于末次冰期的年轻土壤，这表明这些区域极易受到全球气候变化的影响。此外，土壤有机质的性质显示其碳氮比极窄且潜在有效性较高，但当前因寒冷气候条件，该潜力受到限制。全球变暖加剧可能伴随解冻深度增加、胶结冰永久冻土释水、碳氮磷释放、盐渍化加剧，以及多种土壤生物在湿润生境的定植范围扩张。
本次下载资源还包含C. Lucas学位论文的PDF副本（分为4个部分）。