九段沙芦苇湿地生态系统N、P、K的循环特征

对九段沙(上沙、中沙、下沙)芦苇湿地土壤、植物中N、P、K含量进行了测定,研究其分布规律.结果表明:水平分布上,湿地土壤全量养分与速效性养分含量均是中沙最低,并以中沙为中心向两端递增,速效性养分的这种变化尤为显著.垂直分布上,土壤全N和全K含量的分布规律一致,为上层＞下层＞中层;全P含量分布为中层＞上层＞下层.速效N含量分布为上层＞中层＞下层;速效P含量上层土壤最高,中、下层土壤含量因湿地类型而异;速效K含量多以中层土壤最低,上、下层土壤含量变化不稳定,以不同湿地而异.不同芦苇湿地的土壤速效性养分含量差异显著大于全量养分的差异,0～60 cm深度土壤的全量养分和速效性养分含量排序均为K＞N＞P.中沙湿地植物中养分含量最低,与土壤中营养元素总体水平分布一致;多数芦苇湿地植物中营养元素含量排序为N＞K＞P,与土壤养分含量排序不一致.不同芦苇湿地的吸收系数排序均为N＞P＞K;芦苇湿地利用系数排序为P＞K＞N;循环系数排序为N＞K＞P.     

九段沙上沙湿地植物N、P、K的分布特征与季节动态

2005年4-12月逐月对长江口九段沙上沙湿地生态系统主要植物进行定位样品采集与生态环境因子监测.通过对该区典型湿地植物群落海三棱蔗草(Scirpusmariqueter)、互花米草(Spartina aherniflora)和芦苇(Phragmites australis)3种植物样品中N、P、K元素含量的分析,揭示了上沙主要类型湿地植物N、P、K元素的分布特征与季节变化规律.结果表明:3种湿地植物N、P、K元素分布特征不同,不同植物以及同一植物的不同构件营养元素含量随植物生长节律发生变化.植物中元素贮量与含量之间分布特征并不相同,其原因主要在于生物量是制约元素贮量的主要因素,N、P、K贮量排序均为芦苇＞互花米草＞海三棱蔗草.不同构件营养元素含量的变化规律存在差异:4-5月茎中K含量逐渐减少,N含量呈现增加趋势;5-6月各构件P含量呈减少趋势;6-10月叶中N含量普遍高于其他构件.     

长江河口九段沙下沙湿地植物N、P、K的分布特征与季节动态

2005年4—12月逐月对长江河口九段沙下沙湿地生态系统主要湿地植物群落进行样方调查与样品采集,通过对海三棱藨草(Scirpus mariqueter)、互花米草(Spartina alterni-flora)和芦苇(Phragmites australis)3种植物样品中N、P、K元素含量分析与生物量测定,揭示了下沙主要类型湿地的植物N、P、K元素的含量、分布、贮量与动态变化特征。结果表明:3种湿地植物N、P、K元素含量、分布、贮量与动态特征均各具特点。不同植物以及同一植物不同构件营养元素含量与分布均存在较明显的差异。营养元素在不同植物与同一植物不同器官含量排序的差异明显。N、P、K贮量分布特征因湿地植物种类、构件以及生物量不同而异。植物中营养元素含量与贮量的分布特征存在差异,其原因在于,与营养元素含量相比,生物量是制约植物营养元素贮量的主要因子。下沙湿地3种湿地植物及其构件的营养元素含量与贮量一般都低于上沙湿地。3种湿地植物营养元素均表现出明显的季节动态,一般生长初期营养元素含量高,生长停滞期含量低。3种湿地植物N、P、K含量的动态特征存在差异,总趋势为N、P、K含量随生长过程的进行而下降,相对下降速度排序为:KNP。受局地环境条件影响,上沙与下沙湿地的植物N、P、K元素的含量、分布、贮量与动态变化特征存在差异。     

闽江河口湿地不同植被带土壤全硅的含量及分布特征

硅是湿地系统元素循环所关注的重要内容之一,土壤全硅的分布特征与湿地土壤-植物系统活跃程度密切相关。于2016年1-12月,以闽江河口鳝鱼滩湿地为研究对象,通过野外原位采样及室内实验分析,对短叶茳芏、短叶茳芏与互花米草交错带、互花米草3种植物类型湿地的土壤全硅含量和储量的变化特征进行观测。结果表明：短叶茳芏、短叶茳芏与互花米草交错带、互花米草湿地土壤全硅的年平均含量依次为197.67、201.21、210.33 mg/g,表现为由陆向海方向逐渐增加的趋势;季节上均呈现秋冬高于春夏的趋势;土壤全硅含量和储量均表现为上部土层（0-30cm）高于下部土层（30-60cm）。经统计分析发现,湿地土壤全硅含量与有机质显著负相关（P < 0.05）,与含水率和pH有极显著正相关关系（P < 0.01）。除短叶茳芏湿地外,其余2种湿地土壤全硅含量与有效硅含量显著负相关（P < 0.05）。研究闽江河口湿地不同植被带土壤全硅含量和储量及其分布特征,旨在揭示湿地土壤全硅水平在不同类型湿地植被生长影响下的变化过程,为本研究区的硅素研究补充关键数据。     

不同生境下骆驼刺与花花柴生态化学计量学特征的比较

以塔克拉玛干沙漠南缘典型荒漠豆科植物骆驼刺(Alhagi sparsifolia)和菊科植物花花柴(Karelinia caspia)为对象,研究单一骆驼刺种群(LTC)、单一花花柴种群(HHC)及骆驼刺-花花柴群落(GSQL)中植物及土壤中碳(C)、氮(N)、磷(P)、钾(K)等养分的生态化学计量学特征。结果表明:骆驼刺-花花柴群落中土壤有效N(AN)、有效K(AK)含量及N∶P、N∶K显著高于单一花花柴种群;骆驼刺-花花柴群落中花花柴叶片的全N含量显著高于单一花花柴种群,骆驼刺-花花柴群落中骆驼刺叶片的全P含量显著高于单一骆驼刺种群。相关性分析显示:不同生境土壤的AK含量与N∶P及AN含量呈显著正相关,而与SOC呈负相关;不同生境下叶片中的全K含量与SOC、全N、全P含量呈显著正相关,叶片中的全N含量与SOC、全P亦呈显著正相关,而N∶P与SOC、全P含量呈显著负相关;土壤中SOC含量与叶片中全P、全K含量呈正相关,而与N∶K呈负相关;土壤有效N含量与叶片N∶K呈正相关,而与叶片4种元素含量均呈显著负相关;土壤有效K含量与叶片中4种元素含量均呈显著负相关,而与叶片N∶K呈正相关;土壤N∶P、N∶K则分别与叶中全C、全P、全K呈显著负相关。综合分析认为:相较于单一种群,骆驼刺与花花柴的群落能够在一定程度上提高土壤养分,改善植物的营养状况,显示出豆科植物骆驼刺在群落演替中重要作用。     

河口湿地植物活体-枯落物-土壤的碳氮磷生态化学计量特征

碳(C)、氮(N)、磷(P)生态化学计量比是生态系统过程及其功能的重要特征.以闽江河口的芦苇(Phragmites australis)和短叶茳芏(Cyperus malaccensis var.brevifolius)湿地为对象,开展植物活体-枯落物-土壤系统的C、N、P季节动态研究.结果表明:芦苇和短叶茳芏植物活体、枯落物和土壤年均C、N、P含量为C＞N＞P,两种湿地系统C、N含量均为植物活体和枯落物高于土壤,但与土壤P含量大小关系因植物构件差异而不同;芦苇和短叶茳芏植物活体、枯落物和土壤的C、N、P生态化学计量比表现为C∶P＞C∶N＞N∶P;芦苇湿地C∶N为枯落物＞植物活体＞土壤,短叶茳芏为植物活体＞枯落物＞土壤,而C∶P和N∶P均为枯落物＞植物活体＞土壤;C、N、P化学计量比可以反映湿地C、N、P交换过程和植物群落的生态功能.     

湿地土壤全氮和全磷含量高光谱模型研究

氮磷是湿地生态系统土壤中的重要营养元素,其对湿地植被生长、湿地生态系统生产力、区域富营养化变化、湿地环境生态净化功能等具有重要的影响作用。研究氮磷营养物质在湿地土壤中的分布变化特征,对湿地生态系统评估、恢复和管理具有重要的意义。以中国高纬度地区面积最大的滨海芦苇湿地——盘锦湿地为研究区,采用不同建模方法(再抽样多元逐步回归模型bootstrap SMLR和再抽样偏最小二乘回归模型bootstrap PLSR)和光谱变换技术(包络线去除CR、光谱一阶微分FD和光谱倒数的对数LR),分别建立了湿地土壤全氮和全磷含量的估算模型。基于湿地土壤实测光谱,模拟高光谱Hyperion数据和多光谱TM数据,在此基础上进行湿地土壤营养元素含量估算。对比所建反演模型的估算精度,探讨高光谱遥感技术对湿地土壤营养元素组分的估算能力和适用性。研究结果表明:bootstrap PLSR相比于bootstrap SMLR建模方法,其对研究区湿地土壤全氮和全磷含量的估算获得了较高精度;对盘锦湿地土壤全氮含量的估算,最高估算精度产生于CR光谱变换技术结合bootstrap PLSR建模;对湿地土壤全磷含量的估算,最高估算精度产生于原光谱数据结合bootstrap PLSR建模;模拟高光谱数据Hyperion对湿地土壤全氮和全磷含量的估算精度均高于模拟多光谱数据TM,模拟Hyperion的估算精度更接近于实测光谱的估算精度。     

长江河口九段沙互花米草湿地生态系统N、P、K的循环特征

研究了九段沙外来入侵种互花米草（Spartina alterniflora）湿地生态系统的营养元素含量、分布规律与循环特征。结果表明,九段沙的上沙、中沙和下沙互花米草湿地土壤全量养分含量差异相对较小,而速效性养分含量差异相对较大。土壤剖面中TK含量大大高于TN和TP含量,排序为:TK＞TN＞TP。各沙洲速效性养分含量排序为：速效K＞速效N＞速效P。土壤速效性养分与全量养分的空间分布规律并不一致,土壤剖面营养元素的垂直分布差异比较明显,速效性养分土壤剖面垂直分异比全量养分显著。各深度土壤营养元素含量均存在差异,不同沙洲同一深度土壤营养元素含量也存在差异。各沙洲不同深度土壤TN含量的差异明显大于TP和TK含量差异。植物中3种营养元素含量以K最高,N其次,P最低。湿地生态系统营养元素归还量远大于存留量。吸收系数排序为：N＞P＞K。不同沙洲营养元素的利用系数和循环系数存在明显差异,上沙P元素、中沙与下沙K元素利用系数最大,上沙K元素、中沙P元素与下沙N元素循环系数最大。     

辽河口不同类型湿地土壤碳氮磷生态化学计量学特征

为阐明不同类型湿地土壤碳氮磷生态化学计量特征,以辽河口湿地为研究对象,对自然芦苇湿地、油田区芦苇湿地、退化芦苇湿地、碱蓬湿地、滩涂和稻田等六类湿地的土壤有机碳(TOC)、全氮(TN)、全磷(TP)含量及其生态化学计量学特征进行测定和分析。结果表明,辽河口湿地土壤TOC、TN、TP含量分别为1.612～167.832、0.159～4.452和0.021～0.093 g·kg-1,其含量因湿地类型和土壤深度而异。自然芦苇湿地和油田区芦苇湿地土壤TOC含量较高,自然芦苇湿地和稻田土壤TN含量较高,而碱蓬湿地、滩涂TOC和TN含量较低;不同类型湿地表层土壤(0～10 cm) TOC和TN含量显著高于下层土壤(10～40 cm)。TP含量在不同类型湿地和不同深度土壤间均无明显差异(P0.05)。C/N、C/P、N/P值分别为28、364和13,在不同类型湿地中差异显著(P0.05)。相关分析表明,TOC、TN与C/P、N/P呈正相关,电导率(EC)与土壤TOC、TN、TP、C/N、C/P和N/P呈弱的负相关。研究表明,盐度增加可能会削弱土壤中氮磷等营养元素对碳累积过程的控制,引起湿地土壤的碳损失。     

沙田湖人工湿地植物-土壤有机碳库

在人工构建的用于处理水产养殖废水的表面流和水平潜流湿地复合系统中,对湿地植物各组织、湿地表层土壤(0～10 cm)、湿地植物根际土壤的有机碳含量季节变化规律进行研究,并对湿地植物表层土壤和湿地植物对有机碳的固定作用进行了分析.结果表明:湿地植物地上部分组织固定的有机碳含量表现为在生长期迅速增加,8月较高,进入成熟期(11月)后保持稳定,8月有机碳含量与5月有显著性差异、与11月差异不显著;湿地植物地下部分组织固定的有机碳含量低于地上部分,但季节变化与地上部分相似,5月含量最小,8月达到一个较高的值,11月与8月有机碳含量差异不大.植物进入生长期后,湿地表层土壤有机碳含量显著高于湿地上无植物时期,各湿地植物根际土有机碳含量均高于表层土,但差异不显著(睡莲除外).湿地表层土壤有机碳密度介于0.96～1.67 kg·m-2,受植物种类、植物生长季节等因素的影响.根据湿地面积和表层土壤有机碳含量,估算出沙田湖人工湿地(表面流湿地部分面积为3592 m2)0～10 cm土壤有机碳总量为5.61 t,通过植物吸收每年固定的碳量为10.34 t.     

Seasonal dynamics of arbuscular mycorrhizal fungi in differing wetland habitats

The dynamics and role of arbuscular mycorrhizal fungi (AMF) have been well described in terrestrial ecosystems; however, little is known about how the dynamics of AMF are related to the ecology of wetland ecosystems. The seasonal dynamics of arbuscular mycorrhizal (AM) colonization within different wetland habitats were examined in this study to determine the factors that influence AM associations and to further assess the ecological role of AMF in wetlands. Fen and marsh habitats of four wetlands in west central Ohio were sampled monthly from March to September. AMF were found at all four sites for each month sampled and were present in all of the dominant plant species. A significant effect of month (P<0.001) on AM colonization did occur and was attributable to maximum colonization levels in the spring and minimum levels in late summer. This trend existed in all four wetlands in both fen and marsh habitats, regardless of variation in water levels, percent soil moisture, or available phosphorus levels. Because abiotic factors had minimal influence on AM colonization variation and the level of AM colonization paralleled plant growth patterns, we conclude that the AM seasonal dynamic was in response to plant phenology. Our data suggest that AM associations in temperate fen and marsh habitats are prevalent in the spring during new root and vegetative growth, even for plants experiencing flooded conditions. Evidence of an overriding AM seasonal trend indicates that future studies should include a seasonal component to better assess the role and distribution of AMF in wetland ecosystems.     

Soil and Hydrological Drivers of Typha latifolia Encroachment in a Marl Wetland

Aggressive species competition by Typha latifolia in wetland systems on marl-derived soils may threaten the unique vegetation in these areas. We examined historic water and land use, soil chemistry, soil genesis, and topography in a wetland (Harewood Marsh) that is under encroachment by T. latifolia. An earthen road that bisects the wetland and active pastures in and around the wetland were also considered in the study due to their potential influence on wetland hydrology and nutrient inputs. Historic land uses and trends in surface water patterns were determined via aerial photography. In addition local landowners and city officials were contacted for information about historic water use in the area around the marsh. Soils were augered and sampled in seven locations in the wetland, and at each auger site, vegetation was described. Six wells were installed near the earthen road and weekly water depth measurements were taken from January 2002 to January 2003. In February 2002, 10 A-horizon soil samples (per transect) were taken from three 150-m transects that spanned areas with and without T. latifolia. Results indicate that T. latifolia encroachment is facilitated by a rising water table (the result of the termination of a local municipal water supply source) and N and P inputs, most likely from cattle grazing on the wetland. An increase in the numbers of rare plant species associated with marl wetland habitats appears to have also occurred and is believed partly due to current wetter conditions. Our study provides insight into the dynamics of T. latifolia encroachment in a unique marl wetland habitat and demonstrates how local factors controlling nutrient and hydrologic dynamics can have significant effects on changes in plant community composition.     

滇西北高原纳帕海湖滨湿地退化特征、规律与过程

采用双向指示种分析(TWINSPAN)和典范对应分析(CCA)方法,研究了滇西北高原纳帕海湖滨湿地退化特征、规律与过程.结果表明: 纳帕海湖滨湿地植物群落可以划分为4个群丛,群落演替规律为水生植物群落→沼泽植物群落→沼泽化草甸植物群落→草甸植物群落.随植物群落演替,群落盖度、密度、多样性指数、物种丰富度和地上生物量均增大,群落高度减小;植物水分生态型演替规律为水生植物→沼生植物→湿生植物→中生植物.随群落演替,湿地水体矿化度、硬度和碱度均降低,氨氮和总磷含量升高,总氮和硝态氮含量变化不明显;土壤pH、有机质和全氮含量逐渐降低,全磷和全钾含量逐渐升高,速效氮和速效磷含量先增大后减小.CCA分析表明,群落结构和物种组成主要受水分梯度影响,土壤pH、全磷和湿地水的总氮、氨氮对湿地植物物种分布和群落演替影响显著.     

不同人为干扰下纳帕海湖滨湿地植被及土壤退化特征

以滇西北高原纳帕海湖滨退化湿地为研究对象,对比分析了人为隔断水源补给、牛羊过度放牧和家猪拱地三种人为干扰下湿地植被和土壤退化特征。结果表明：三种干扰方式下,纳帕海湖滨湿地植物群落类型多样性、物种丰富度、物种数、Shannon-Wiener指数、沼生植物重要值以及土壤有机质、全氮、速效氮、含水率、毛管孔隙度变化规律为：人为隔断水源补给＞牛羊过度放牧＞家猪拱地,而土壤容重和全钾含量变化规律完全相反。Pearson相关性分析表明,不同人为干扰下相同土壤指标之间相关性质和相关强度不同;CCA分析表明植物群落种类组成和分布与土壤含水率和全磷含量显著相关。以原生湿地样点为对照,人为隔断水源补给、牛羊过度放牧和家猪拱地样带土壤退化指数分别为-7.40%、-14.53%、-45.01%。认为纳帕海湖滨湿地退化是三种干扰协同作用结果,但作用程度不同,其顺序为家猪拱地＞牛羊过度放牧＞人为隔断水源补给。     

Effects of water depth and livelihood activities on plant species composition and diversity in Nyando floodplain wetland,Kenya

The influence of water levels and livelihood activities on plant species composition, diversity and structuring of wetland ecosystem is a concern as wetlands undergo human exploitation and the increasing threat from climate change. To evaluate the effect of seasonal changes in water depth and human activities, plant density and species composition were assessed in wet and dry seasons and in natural and converted wetland zones of the Nyando papyrus wetland, Kenya. Three transects with different water regimes and livelihood activities were identified. Overall, 30 plant species were identified. In the less disturbed zone, differences between transects were small and 79 % (dry season) to 99 % (wet season) of the plant density consisted of obligate and facultative wetland plants. These groups were dominated by Cyperus papyrus and Vossia cuspidata. In the converted zone, facultative, facultative upland and upland plants became more important with 36 % of the plant density. The seasonally inundated zone had species diversity and species richness increased under dry conditions with more facultative upland species. In the converted zone, disturbance caused by vegetation removal, cropping and other livelihood activities lead to lower soil moisture and more colonization opportunity for facultative and upland species that are more adapted to dry conditions.     

黄河口盐地碱蓬湿地土壤-植物系统重金属污染评价

以黄河口盐地碱蓬湿地为例,评价了淹水和非淹水区湿地表层土壤As、Cd、Cu、Cr、Pb和Zn 6种重金属的污染程度及其在土壤-植物系统中的迁移、富集特征,分析了不同积水深度和土壤理化性质对研究区土壤重金属含量的影响.研究结果表明,与土壤或沉积物质量标准相比,黄河口盐地碱蓬湿地土壤受As和Cd污染最严重,而其它重金属污染较轻;非淹水土壤Cd、Cr和Zn含量高于淹水湿地,而As、Cu和Pb则较低;而且淹水土壤As含量随积水深度增加而呈下降趋势,但积水深度对其他重金属含量的影响不明显.相关性分析结果表明,按照受土壤关键影响因子的不同重金属(除As外)可以分为两类:第一类为Cd、Cr和Zn,这些重金属含量受土壤pH值和盐分影响较大,且相互间存在显著正相关关系,表明它们可能有相同的来源;第二类为Pb和Cu,它们受土壤pH值、盐分和有机质的影响,且Pb和Cu之间存在显著正相关关系.除Cr、Cu和Zn外,重金属在盐地碱蓬的根系内一般不发生显著富集,但绝大多数重金属都表现出地上部分的含量比根系更高的现象.     

艾比湖湿地典型植物群落土壤酶活性季节变化特征

对艾比湖湿地典型芦苇和柽柳群落土壤过氧化氢酶、磷酸酶和脲酶及其影响因素进行了分析.结果表明: 在植物不同的生长期,土壤酶活性具有明显的季节变化特征,芦苇群落土壤过氧化氢酶、磷酸酶和脲酶峰值均出现在生长旺盛期(3.26、0.60、0.33 mg·g^-1),谷值出现在萌芽期和展叶期,而柽柳群落的峰值出现在枯黄期(6.33、0.58、0.21 mg·g^-1),谷值出现在开花期和生长旺盛期;脲酶在不同生长期较为稳定,是湿地土壤酶活性差异的指示指标;芦苇和柽柳群落不同生长期土壤酶活性与土壤有机质和全磷含量呈显著正相关,而与土壤含水量的相关性不显著;芦苇群落迅速生长期土壤酶活性与土壤铵态氮呈显著正相关;两种植物群落土壤盐分与酶活性的相关性不显著.芦苇和柽柳群落不同生长期土壤酶活性受多因素的共同影响,土壤有机质和水热因子是影响艾比湖高盐湖泊湿地土壤酶活性的主导因子.     

湿地土壤种子库与地上植被相似性关系研究评述

土壤种子库与地上植被的关系是土壤种子库研究的重要组成部分。当前,湿地生态系统面临严重威胁,研究湿地土壤种子库和地上植被关系既可以加强对土壤种子库和植物群落特征的认识,又可以为湿地保护与管理提供理论指导。检索了科学引文索引扩展版(SCIE)数据库中收录的1900—2012年间研究湿地土壤种子库与地上植被关系的文献,通过分析土壤种子库与地上植被的Srensen相似性系数,结果发现:不同湿地类型的土壤种子库和地上植被的相似性存在显著差异,河流湿地中两者的相似性最小;不同植被类型中土壤种子库与地上植被的相似性差异显著:草本群落的相似性大于乔木群落;不同气候带的湿地中两者的相似性也存在显著差异,其中亚热带地区相似性最小。总结了湿地种子库与地上植被相似性关系的时空变化特征。二者的相似性通常随着植物群落的演替而减小,在空间上也随着环境梯度而变化。分析了两者关系的影响因素,如种子传播、环境条件和繁殖策略等。对研究中存在的问题及发展方向提出建议。     

Nitrogen, phosphorus and potassium nutritional status of semiarid steppe grassland in Inner Mongolia

In grazed semiarid steppe ecosystems, much attention has been paid to aspects of growth limitation by water. So far, potential limitation of primary production by plant nutrients was rarely considered. This knowledge is essential for identification of sustainable land-use practices in these large and important ecosystems on the background of over-exploitation and climate change. In the present study plant nutrient concentrations and ratios were investigated with factorial additions of water and N fertilizer at two sites with contrasting soil nutrient availability. Combined analysis of nutrient concentrations, contents, biomass production, and plant N:P ratios consistently confirmed primary growth limitation by water and a strong N limitation when sufficient amounts of water were supplied. P limitation only occurred at the site with low P availability when in addition to the natural supply, water and N fertilizer were given. According to reported thresholds of N:K and K:P ratios, K was not limiting in any plot. The observed nutritional patterns in the plant community were related to the dynamics of species composition and their specific nutrient status. Stipa grandis had the highest N:P ratio whereas Artemisia frigida showed lowest N:P. These nutrient characteristics were related to growth strategies of dominant species. Accordingly, the relative biomass contribution of S. grandis and A. frigida strongly affected the nutrient status of the plant community. Plant N:P ratios indicate the relative limitation by N or P in the semiarid grasslands under sufficient water supply, but other methods of nutritional diagnosis should be used when plant N:P ratios remain below critical values.     

Legacy phosphorus in subtropical wetland soils: Influence of dairy, improved and unimproved pasture land use

Wetlands provide various ecosystem services. One of these services includes nutrient storage in soils. Soils retain and release nutrients such as phosphorus (P). This dynamic can be controlled by soil characteristics, overlying water quality, environmental conditions and historical nutrient loading. Historical nutrient loading contributes to a legacy of P stored in soils and this may influence present day P dynamics between soil and water. We quantified P characteristics of wetland soils and determined the availability and capacity of soils to retain additional P loadings. We sampled surface (0-10) and subsurface (10-30) wetland soils within dairy, improved and unimproved pastures. Surface soils had much greater concentrations of organic and inorganic P. Wetland soils in dairy had greatest concentrations of Ca and Mg, probably due to inputs of inorganic fertilizer. They also had much greater total P, inorganic P, and P sorption capacity; however, these soils were P saturated and had little capacity to retain additional P loading. Improved and unimproved pasture wetland soils had greatest amounts of organic P (>84%) and a capacity to store additional P loadings. Using multivariate statistics, we determined that rather than being different based on land use, wetland soils in improved and unimproved pasture were dissimilar based upon organic matter, organic P fractions, residual P, and soil metal (Fe and Al) content. The legacy of stored P in soils, particularly wetland soils from dairies, combined with best management practices (BMPs) to reduce nutrient loading to these systems, could contribute to a short-term release of soil-stored P to overlying wetland water.