广西北海西村港互花米草对红树林湿地大型底栖动物群落的影响

为了解互花米草(Spartina alterniflora)入侵红树林的生态影响, 作者对位于北海市西村港的红树林湿地以及周边互花米草盐沼的大型底栖动物群落多样性和群落结构进行了研究。2012年10月至2013年9月连续4次取样, 按照取样时间研究大型底栖动物的种类、物种组成、生物量和生物多样性等群落特征的差异, 探讨互花米草入侵红树林湿地对大型底栖动物的影响。本研究共采集底栖动物16种, 隶属于5门7纲15科, 其中互花米草群落10种, 红树林湿地12种。研究发现互花米草入侵后中国绿螂(Glauconome chinensis)个体数量剧增, 导致不同采样时间互花米草盐沼的大型底栖动物生物量均显著高于红树林湿地; 除个别月份外, 红树林湿地大型底栖动物的Margalef丰富度指数、Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数均显著高于互花米草群落。基于生境-采样时间的双因素方差分析结果表明, Shannon-Wiener多样性指数和Simpson指数在两种生境间差异显著; 两种生境的Margalef丰富度和Pielou均匀度指数在不同采样时间差异显著; 大型底栖动物生物量和物种数量在两种生境间和不同采样时间差异均显著。基于多元回归分析的研究结果表明, 互花米草密度是影响大型底栖动物生物量的关键因子, 而互花米草株高可以解释物种个体数量、Shannon-Wiener多样性指数和Simpson指数在两种生境的变化。对不同采样时间大型底栖动物群落结构的非度量多维度(non-metric multidimensional scaling, NMDS)分析结果表明, 红树林与互花米草群落的大型底栖动物群落相似性很低。总而言之, 在西村港地区, 互花米草入侵虽然增加了大型底栖动物的生物量, 但由于优势物种的凸显, 显著降低了大型底栖动物群落的多样性, 且种类组成与群落结构与红树林群落相比已有差异。由此可见, 互花米草入侵红树林对当地的大型底栖动物群落多样性造成影响。     

长江口新生湿地大型底栖动物群落时空变化格局

为了解长江口新生湿地大型底栖动物时空变化格局,2004年11月—2005年10月对九段沙湿地的3个沙洲以及各主要生境进行了调查。结果表明:九段沙湿地大型底栖动物密度和生物量均呈春季最高,夏、秋季下降,秋季末和冬季回升的趋势,整体生物多样性水平较低,分布不均匀。夏季上沙和中沙底栖动物密度存在显著差异,四季生物密度和生物量空间梯度为下沙>上沙>中沙。由物种组成分析可知,九段沙湿地大型底栖动物群落时空变化与优势种的消长有关。各季海三棱藨草带和藨草带底栖动物密度和生物量最高,芦苇和互花米草次之,光滩区域最低,且群落季节波动大。外来物种互花米草生境下底栖动物群落特征与土著种芦苇生境下无显著差异。     

崇明东滩盐沼湿地大型底栖动物功能群分布特征及其影响因子

以长江口崇明东滩典型盐沼分布区为研究区域,在不同站位固定样地月际取样调查基础上,分析了大型底栖动物食性功能群沿高程梯度的分布特征及其主要影响因子,特别是外来入侵植物的影响。结果表明,不同高程区域,大型底栖动物优势种不同,除中潮带分布区以杂食性和植食性功能群为主外,其余各区域均以杂食性功能群为主。沿高程梯度,大型底栖动物各功能群的多度和生物量均发生极显著的变化(P0.01),而不同功能群在不同植被带间的差异情况有所不同。其中,高程最低的光滩区域,肉食性功能群多度和生物量均显著高于高程相对较高的植被带(P0.05);中潮带海三棱藨草分布区植食性功能群多度和生物量均显著高于其他高程区域(P0.05)。主要生境因子,包括沉积物总磷、总氮、有机质、速效磷、硝态氮、铵态氮、中值粒径,以及植物的植株高度和地上部分生物量干重等指标,均随高程梯度变化显著(P0.05),但不同因子变化特征有所不同。外来种互花米草的入侵并未造成相应区域大型底栖动物优势功能群的改变,但区域内杂食性功能群的多度和生物量均显著增加(P0.05);环境因子中的部分因子,包括沉积物速效磷、硝态氮、铵态氮和有机质含量,表现出与同高程的本地种芦苇分布区间的显著差异(P0.05)。导致大型底栖动物食性功能群组成及分布发生变化是多种生境因子综合作用的结果,而对不同食性功能群起作用的主要影响因子存在差异。沉积物营养盐含量差异是造成大型底栖动物食性功能群多度变化的最主要因素;沉积物盐度是影响大型底栖动物食性功能群生物量的最主要因素。要完整揭示底栖动物功能群分布特征及其影响因子的作用机理,需要综合考虑水文、植被、沉积物等多种生境因子。     

长江河口湿地不同植被中无齿螳臂相手蟹的分布及其洞穴利用

无齿螳臂相手蟹(Chiromantes dehaani)是长江河口中、高潮滩的优势底栖动物之一,具有重要的生态功能.由于其经济价值较低,所受关注很少.本文调查了相似高程芦苇(Phragmites australis)带、芦苇斑块、菰(Zizania aquatica)植被以及裸地4种生境中无齿螳臂相手蟹的数量分布及其洞穴的利用情况.有植被分布的3种生境间植株密度、植株高度和植物干重生物量(地上部分)差异显著(P＜0.001);4种生境问,陷阱桶采样获取的无齿螳臂相手蟹数量分布(P＜0.001)和性比(P=0.001)差异显著;裸地区域没有无齿螳臂相手蟹可用的洞穴分布,芦苇带、芦苇斑块和菰植被间无齿螳臂相手蟹可用的洞穴密度(P＜0.019)、单位洞穴蟹个体数(P＜0.001)差异显著,挖掘洞穴采样获取的无齿螳臂相手蟹密度差异接近显著水平(P=0.067),洞穴占用率(P=0.667)、不同洞穴占用方式频次组成(P＞0.05)差异不显著;无齿螳臂相手蟹可利用洞穴密度与植株密度、植物干重生物量显著负相关(P＜0.05),而挖掘洞穴采样获取的无齿螳臂相手蟹密度与植株高度(P=0.077)相关性接近显著水平且与洞穴密度(P＜0.001)显著正相关.这些结果表明盐沼植被对无齿螳臂相手蟹的分布和洞穴利用存在影响.而进一步探讨盐沼不同植被对无齿螳臂相手蟹分布的影响,需要先了解无齿螳臂相手蟹在不同植被中分布格局在时间上的变化,并结合无齿螳臂相手蟹在不同植被间的迁移行为以及繁殖周期等进行探讨.     

崇明东滩盐沼湿地大型底栖动物功能群分布特征及其影响因子

以长江口崇明东滩典型盐沼分布区为研究区域,在不同站位固定样地月际取样调查基础上,分析了大型底栖动物食性功能群沿高程梯度的分布特征及其主要影响因子,特别是外来入侵植物的影响。结果表明,不同高程区域,大型底栖动物优势种不同,除中潮带分布区以杂食性和植食性功能群为主外,其余各区域均以杂食性功能群为主。沿高程梯度,大型底栖动物各功能群的多度和生物量均发生极显著的变化(P<0.01),而不同功能群在不同植被带间的差异情况有所不同。其中,高程最低的光滩区域,肉食性功能群多度和生物量均显著高于高程相对较高的植被带(P<0.05);中潮带海三棱藨草分布区植食性功能群多度和生物量均显著高于其他高程区域(P<0.05)。主要生境因子,包括沉积物总磷、总氮、有机质、速效磷、硝态氮、铵态氮、中值粒径,以及植物的植株高度和地上部分生物量干重等指标,均随高程梯度变化显著(P<0.05),但不同因子变化特征有所不同。外来种互花米草的入侵并未造成相应区域大型底栖动物优势功能群的改变,但区域内杂食性功能群的多度和生物量均显著增加(P<0.05);环境因子中的部分因子,包括沉积物速效磷、硝态氮、铵态氮和有机质含量,表现出与同高程的本地种芦苇分布区间的显著差异(P<0.05)。导致大型底栖动物食性功能群组成及分布发生变化是多种生境因子综合作用的结果,而对不同食性功能群起作用的主要影响因子存在差异。沉积物营养盐含量差异是造成大型底栖动物食性功能群多度变化的最主要因素;沉积物盐度是影响大型底栖动物食性功能群生物量的最主要因素。要完整揭示底栖动物功能群分布特征及其影响因子的作用机理,需要综合考虑水文、植被、沉积物等多种生境因子。     

长江口九段沙湿地不同生境中大型底栖动物群落结构特征分析

2004年10月至2005年1月对九段沙湿地大型底栖动物的群落分布特征及环境因子进行了调查。选取6种主要生境的57个样方,分析大型底栖动物的种类、密度、生物量、多样性指数及均匀度指数等群落特征。共记录到28种大型底栖动物,主要由甲壳动物、环节动物、软体动物及昆虫幼体组成,优势种为谭氏泥蟹(Ilyrplaxdeschampsi)、光滑狭口螺(Stenothyraglabra)、堇拟沼螺(Assimineaviolacea)、绯拟沼螺(A.latericea)和霍甫水丝蚓(Limnodriuhoffmeisteri)。6种生境类型中以低潮位光滩大型底栖动物种类最为丰富,但其密度最低;海三棱藨草(Scirpusmariqueter)带底栖动物密度最高,并且其均匀度与其他生境存在显著差异;互花米草(Spartinaalterniflora)带下底栖动物的种类组成与其他生境有一定差异,但种类数、密度和多样性处于平均水平,总体群落结构没有显著差异。     

褐家鼠挖掘活动对上海九段沙湿地植物群落与土壤水盐的影响

上海九段沙是长江口的新生岛洲,目前处于草本植物群落演替阶段。为了探讨登岛褐家鼠的挖掘活动对九段沙湿地植物群落与土壤水盐的影响,我们调查了褐家鼠洞穴区的植物盖度、密度、高度、重要值、物种丰富度、物种均匀度、物种多样性、表层土壤含水量和电导率等与对照区的差异;同时,通过调查褐家鼠洞穴与潮沟在空间位置上的关系探讨了褐家鼠的栖息地选择策略。结果表明:在单一芦苇群落中,洞穴区芦苇的高度和盖度显著低于对照;在芦苇和海三棱藨草混合群落中,洞穴区芦苇的密度、相对密度、重要值和群落总盖度显著低于对照,而洞穴区海三棱藨草的密度、盖度、相对密度、相对高度和重要值显著高于对照;在碱菀和互花米草优势群落中,洞穴区碱菀的相对密度、相对盖度、重要值和群落的物种多样性指数显著高于对照,而互花米草的密度和盖度、芦苇的盖度、高度和相对盖度以及群落总盖度显著低于对照。距洞穴区中心区域洞口不同距离梯度的表层土壤含水量和电导率差异均显著。褐家鼠偏向于将洞穴营造在邻近潮沟处,这有利于提高褐家鼠在九段沙湿地的适应能力。褐家鼠的挖掘活动有利于增加碱菀和互花米草优势群落的物种多样性,会降低植物群落总盖度和表层土壤的水盐含量,对九段沙湿地植物群落的组成与演替具有重要影响。     

茅埏岛大型底栖动物次级生产力时空变化

2012年11月—2014年7月,分季度对茅埏岛潮间带不同生境大型底栖动物进行调查,对其物种组成、生物量、次级生产力和P/B值进行了比较分析。结果表明:大型底栖动物的生物量在生境间为红树林(16.58±6.21 g·m~(-2))互花米草(14.16±13.87 g·m~(-2))光滩(9.97±6.43 g·m~(-2)),各生境的生物量冬季时均最低;生物量在3种生境间差异不显著(P0.05),在季节间差异显著(P0.05);在站点中以南滩村红树幼林最高(52.22±28.00g·m~(-2)),电站互米花草最低(5.44±2.68 g·m~(-2));生物量在10个站点间差异极显著(P0.01),在季节间差异显著(P0.05);次级生产力在生境间为红树林(10.60 g AFDW·m~(-2)·a~(-1))光滩(9.00 g AFDW·m~(-2)·a~(-1))互花米草(8.99 g AFDW·m~(-2)·a~(-1)),3种生境次级生产力均在冬季时最低;P/B值为光滩(0.90)红树林(0.64)=互花米草(0.64);P/B值在春冬两季均高于夏秋两季;茅埏岛潮间带引种秋茄红树,形成的红树林生境具有较高的次级生产力,以人工红树林取代互花米草是治理其入侵的有效措施。     

滩涂湿地蟹类活动对表层土壤的扰动效应

为探究在不同植物群落中的大型底栖动物无齿螳臂相手蟹(Chiromantes dehaani)对滨海滩涂湿地表层土壤的生物扰动效应, 在江苏大丰糜鹿国家级自然保护区第三核心区的滩涂湿地潮坪区, 春季末期在潮沟附近的互花米草(Spartina alterniflora)群落、白茅(Imperata cylindrica)群落、芦苇(Phragmites australis)群落3个植物群落中, 分别设置多蟹围隔区、少蟹围隔区和无围隔区, 冬季采集并检测处理后围隔区蟹洞数量、土壤的理化性质及植物生物量等生态指标, 分析底栖动物对表层土壤的扰动效应。研究发现: 互花米草及白茅群落中土壤总有机碳(TOC)、总氮(TN)含量在多蟹区显著低于少蟹区, 蟹丘土壤的TOC及TN含量显著高于多蟹区表层土壤; 而在芦苇群落中则相反。互花米草群落多蟹区土壤C/N、白茅群落多蟹区土壤C/N及C/P显著低于少蟹区, 芦苇群落不显著。互花米草群落蟹穴数量与植物生物量呈显著正相关。研究结果显示, 相手蟹扰动降低了互花米草及白茅植物群落表层土壤的有机质稳定性, 加速碳氮分解, 降低表层土壤的碳氮含量, 并促进互花米草植物生物量的增长, 但对芦苇群落表层土壤扰动的影响则相反。     

互花米草生物量年动态及其与滩涂生境的关系

本文研究了不同滩涂生境对互花米草(Spartina alterniflora)群落特征及生物量的影响。其结果是：建立在小潮高潮线附近滩面的互花米草群落,其密度、高度、地上和地下生物量(本文生物量均为现存生物量),均比建立在偏低、偏高位置滩面的群落为高。在淡水、肥水来源丰富的河口潮滩上建立的互花米草群落,其群落特征更突出,生物量比建立在土壤肥力低、含盐量高的非河口潮滩上群落高。潮滩上的互花米草群落地下生物量随龄级的增加而增长,但地上生物量和总生物量以三年龄群落为最高,四年龄群落却比三年龄群落低。     

Exotic Spartina alterniflora provides compatible habitats for native estuarine crab Sesarma dehaani in the Yangtze River estuary

Although the impact of plant invasions on benthic communities, especially burrowing crabs, has received increasing attention, the results from past studies are mixed. The exotic plant Spartina alterniflora has become the most abundant species in the salt marshes of the Yangtze River estuary since it was first found just over a decade ago, but its effects on crabs in the salt marshes is largely unknown. To examine whether the invasions of this exotic plant affected native crabs, we compared the biomass and abundance of the dominant burrowing crab Sesarma dehaani in an exotic Spartina marsh, native Phragmites australis marsh and mudflats of the Yangtze River estuary, China. To explain the differences of S. dehaani populations between different habitats, feeding preference of S. dehaani for Spartina and Phragmites was investigated. Results showed crab abundance and biomass in the Spartina marsh were significantly greater than those in the Phragmites marsh and mudflats. Soil water content and plant community characteristics in the Spartina marsh also significantly differed in the Phragmites marsh and mudflats. Moreover, the feeding preference experiment showed that crabs consumed Spartina more than twice as much as Phragmites. In summary, this study showed that Spartina provided compatible habitats for native crab S. dehaani through offering suitable food source and moderate environmental conditions.     

扎龙湿地保护区异质生境芦苇种群分株构件的数量特征

采用单位面积取样,计数和测量的调查与统计方法,对扎龙湿地保护区4个生境单优群落芦苇种群分株构件数量特征进行比较分析。结果表明,4个生境芦苇种群从5月10日左右返青后进入营养生长期,分株高度和分株密度均持续增加到生殖生长初期的8月份,其中6-8月份差异均达到显著水平(P0.05),8-10月份差异均未达到显著水平(P0.05),芦苇进入生殖生长期后,分株便停止高度生长,地下芽的输出也不再形成分株补充现实种群;分株生物量和种群生物量均持续增加到生殖生长旺盛期的9月份,至休眠期的10月份均有所降低,各月份间的差异均达到显著水平,芦苇种群在生长季末期,具有将生产的物质分配转移到地下储藏与营养繁殖器官的形成与生长上的特性。芦苇种群分株数量特征与返青后实际生长时间之间均较好地符合对数函数关系,R~2在0.818-0.994之间,拟合方程均达到了P0.05的显著水平。4个生境芦苇种群分株密度以湿生生境最大,依次为水生生境、旱生生境,盐碱生境最小,分株高度、分株生物量和种群生物量均以水生生境最大,依次为湿生生境、旱生生境,盐碱生境最小。因此,4个生境芦苇种群分株构件数量特征均表现出基本一致的生育期节律性,同时,芦苇种群的个体生长和种群动态存在明显的环境效应,土壤含水量、pH是影响该地区芦苇分株数量特征的主要因子。     

Habitat partitioning between prey soldier crab Mictyris brevidactylus and predator fiddler crab Uca perplexa

Interaction and habitat partition between the soldier crab Mictyris brevidactylus (prey) and the fiddler crab Uca perplexa (predator) were examined at a sandy tidal flat on Okinawa Island, Japan, where they co-occur. Both live in dense colonies. When the soldier crabs were released in the densely populated habitat of the fiddler crab, male fiddler crabs, which maintain permanent burrows in hard sediment, preyed on small soldier crabs and repelled large ones. Thus, the fiddler crabs prevented the soldier crabs from trespassing. It was also observed whether soldier crabs burrowed successfully when they were released 1) where soldier crab burrows just under the sand were abundant, 2) in a transition area between the two species, 3) an area without either species, and 4) where artificial tunnels simulated soldier crabs' feeding tunnels were made by piling up sand in the area lacking either species. In contrast to the non-habitat area, many soldier crabs burrowed in the sediment near the release point in the tunnel, transition and artificial tunnel areas. This indicates that the feeding tunnels on the surface attracted other crabs after emergence. When the large male fiddler crabs were transplanted into the artificial burrows made in soft sediment of the soldier crab habitat, all left their artificial burrows by 2 days. In the fiddler crab habitat, however, about one-third of the transplanted male fiddler crabs remained in the artificial burrows after 3 days. The soldier crabs regularly disturb the sediment by the up and down movement of their burrow (small air chamber) between tides. This disturbance probably prevents the fiddler crab from making and occupying permanent burrows. Thus, it appears that these crabs divide the sandy intertidal zone by sediment hardness and exclude each other by different means.     

Small- and large-scale effect of the SW Atlantic burrowing crab Chasmagnathus granulatus on habitat use by migratory shorebirds

Here we address the question of whether the presence of the burrowing crabs Chasmagnathus granulatus affects small- and large-scale habitat use by migrant shorebirds. This crab is the dominant species in soft bare sediments and vegetated intertidal areas along the SW Atlantic estuaries (southern Brazil 28°S to the northern Argentinean Patagonia 42°S). They generate very extensive burrow beds in soft bottom intertidal areas. Our information shows that this burrowing crab affects the small-scale habitat use by shorebirds, given that shorebirds never walk through the funnel-shaped entrances of burrows. Given that crab burrow entrances occupy up to 40% of the intertidal area, there is a large decrease of available shorebird habitat in crab beds, restricting their activity to the spaces between the burrows. The southern migratory shorebird Charadrius falklandicus maximize the use of these areas by foraging closer to the burrows than the other bird species. Neotropical migrants, such as Calidris fuscicollis, Pluvialis squatarola and Tringa melanoleuca, used foraging paths that tended to maximize the distance from burrows, especially the distance to larger burrows. A field experiment showed that this was not necessarily due to a decrease in the availability of polychaetes near the crab burrows. A combination of landscape measurements and satellite images showed that crab beds covered up to 40% of the intertidal area of the Mar Chiquita coastal lagoon (37°40′S, Argentina), and nearly 100% of the intertidal area of the Bahia Blanca estuary (38°48′-39°25′S, Argentina). These two estuaries are located along the migratory flyway of Neotropical migratory shorebirds, but the Bahia Blanca estuary (area∼110,000 ha) shows a much lower shorebird diversity than Mar Chiquita (area∼4500 ha). The most common species in Bahia Blanca is the two-banded plover C. falklandicus, the species least affected by crabs at Mar Chiquita and which prefers to use high-density crab areas as foraging sites. The oystercatcher Haematopus palliatus was also most abundant in high-density crab areas, but they used these areas for resting. The abundances of preys varied during the study period and between the crab density areas, indicating that the use of these areas by birds is independent of crab density. However, burrowing crabs affect the depth distribution of polychaete and thus their availability to shorebirds. We suggest that this shorebirds-burrowing organism interaction could be generalized for other intertidal estuarine habitats.     

Spatial structure of a leaf-removing crab population in a mangrove of North-Brazil

The leaf-removing decapod crab, Ucides cordatus plays a key role as ecological engineer in Brazilian mangrove ecosystems. We analyzed the spatial distribution of a specific population at two different scales to observe how individual behavior could alter spatial population structure. First, we conducted a spatial point pattern analysis of the burrow entrances and the Rhizophora mangle prop roots on the mangrove floor at a scale of few meters. Secondly, we analyzed at a large scale (10–100 m) the potential effects of surface elevation, light intensity, prop root coverage, species of neighboring tree (R. mangle, Laguncularia racemosa, Avicennia germinans) and pneumatophore density on the size and number of burrow entrances. At the same large scale, we conducted an analysis of clustering of the crabs around the R. mangle trees. At small scale, the burrow entrances, although aggregated around the prop roots, showed a regularly spaced distribution (∼25 cm) signaling an intraspecific competition among the crabs. At large scale, crabs preferred to install their burrows at an intermediate level of surface elevation and prop root coverage, and in R. mangle-dominated areas. At the same kind of habitats, the largest burrows, and thus potentially the largest crabs, were found in higher number than on other habitats. The R. mangle-dominated areas preference was confirmed by an aggregating around R. mangle trees in R. mangle-dominated forest, but only of large individuals in L. racemosa-dominated forest. These observations lead us to the definition of a preferred habitat for U. cordatus. Competition leading to the small-scale regular patterns was proposed as an explanation for exclusion of smaller crabs from preferred habitats seen at large scale. We hypothesize that this preferred habitat might explain at regional scale the variation of U. cordatus importance in Neotropical mangroves.     

The validity of burrow counting in estimating the densities of Chiromantes dehaani and Ilyoplax deschampsi in tidal flat at Yangtze Estuary

It has been confirmed that the crabs play significant roles in the structure and function of coastal wetland ecosystems, such as mangroves and salt marshes. However it is not easy to estimate the abundance and density of burrowing crabs effectively, thus a further understanding of roles of crabs in these ecosystems has been lagged. Some studies have discussed the suitability of several census techniques, such as burrow counting method in estimating crab density in mangroves. The validities of burrow counting method and other census techniques in estimating crab density, however, has not been tested in salt marshes, especially where vegetation are dense. In this study, we tested the validity of burrow counting method in estimating the densities of Chiromantes dehaani and Ilyoplax deschampsi in tidal flat with dense vegetation of Phragmites australis and Zizania aquatica at Yangtze Estuary through comparing densities estimated by the burrow counting method and the excavation. Burrow counting averagely underestimated the density of C. dehaani by 15% and the degree of underestimation varied among vegetations and habitats (from an overestimate by 23% to underestimate by 41%). Burrow counting averagely overestimated the density of I. deschampsi by 43% and the degree of overestimate varied from 0% to 133% depending on the vegetations and habitats. The percentage of occupied burrows and the number of crabs sharing one burrow were important factors influencing the validity of estimating crab density through burrow counting method.     

扎龙湿地不同生境芦苇种群根茎数量特征及动态

采用单位土体取样,计测长度和生物量的调查与统计方法,对扎龙湿地保护区4个生境芦苇种群根茎数量特征进行比较分析。结果表明,芦苇5月10日左右返青后进入营养生长期,根茎长度6—8月份缓慢增加,8—10月份显著增加,后期是前期的3.5—10.3倍,生长季中后期是种群新根茎补充和生长的主要时期,不仅实现了种群空间扩展,并为营养繁殖储备更多繁殖芽;根茎生物量和干物质贮量6—8月份逐渐减少,8—10月份又逐渐增加,均以生长季末期的10月份最大,并均显著地(P0.05)高于其他月份,种群根茎养分的消耗主要供给根茎芽的萌发和幼株生长,根茎养分的储藏又为翌年种群的更新及扩展提供物质保障,种群对地下根茎存在明显的养分"超补偿性"贮藏现象。种群根茎长度和生物量均以湿生生境最大,依次为旱生生境、水生生境,盐碱生境最小,根茎干物质贮量以旱生生境最大,依次为湿生生境、水生生境,盐碱生境最小。种群根茎长度与返青后实际生长时间之间均较好地符合直线函数关系,种群根茎生物量和干物质贮量与生长时间之间较好地符合二次曲线函数关系,R2在0.804—0.997之间,拟合方程均达到了显著或极显著(P0.01)水平。4个生境芦苇种群在根茎长度、生物量、干物质贮量等数量特征均表现出由遗传因素控制的比较稳定的季节动态规律,在生境间的差异及其差异序位又均基本稳定,均表现出明显的土壤因子环境效应,其中土壤含水量、有机质、速效氮为正向驱动,p H、速效磷为负向驱动,土壤含水量、p H对根茎数量特征的驱动作用更突出。     

泉州湾蟳埔潮间带大型底栖动物群落的时空分布

为了比较泉州湾蟳埔潮间带沙滩、互花米草滩和牡蛎石泥滩3种生境(3个潮层)的大型底栖动物群落,2011年4月至2012年1月对3种生境的大型底栖动物进行了季度定量取样。在3种生境共获得85种大型底栖动物,其中环节动物39种,软体动物20种,节肢动物21种,刺胞动物、扁形动物、纽虫动物、星虫动物和脊索动物各1种。多维标度排序(MDS)分析表明,春季和冬季泉州湾蟳埔潮间带3种生境的大型底栖动物群落相似性较低;夏季和秋季互花米草滩与牡蛎石泥滩的大型底栖动物群落相似性较高,而与沙滩的大型底栖动物群落相似性较低。沙滩大型底栖动物群落的季节变化较明显,其次是牡蛎石泥滩,而互花米草滩大型底栖动物群落的季节变化较不明显。大型底栖动物栖息密度和生物量随着潮层降低而增加。单变量双因素方差分析(Two-way ANOVA)表明,不同生境之间的大型底栖动物物种数、栖息密度、多样性指数、均匀度指数和丰度指数有显著差异,但生物量无显著差异,这是因为沙滩的物种数较少,栖息密度较低,但优势种弧边招潮蟹(Uca arcuata)个体较大,互花米草滩和牡蛎石泥滩的优势种为加州中蚓虫(Mediomastus californiensis),个体相对弧边招潮蟹小。不同季节之间大型底栖动物物种数、栖息密度、生物量和丰度指数有显著差异,但多样性指数和均匀度指数元显著差异,这是因为沙滩物种数少,但个体分布比较均匀,而互花米草滩和牡蛎石泥滩物种数较多,个体分布较不均匀。以上结果表明,潮汐、沉积物粒径和生境是影响潮间带大型底栖动物群落的主要因素。潮汐导致潮间带的空间异质性,空间异质性导致大型底栖动物群落的差异。     

扎龙湿地芦苇分株生态可塑性及其对土壤因子的响应

扎龙湿地的芦苇既可形成大面积的单优群落,也可形成不同群落斑块。采用大样本抽样调查与统计分析方法,对湿地内水生生境、湿生生境、旱生生境和盐碱生境芦苇种群分株高度和生物量进行比较。结果表明,6—10月份,4个生境芦苇种群分株高度及生物量均以水生生境最高,盐碱生境最低,水生生境株高为盐碱生境的1.5—2.3倍,分株生物量为2.0—5.1倍,生境间的差异性以及差异序位均相对稳定。4个生境株高生境间变异系数(19.45%—31.56%)均高于生境内变异系数(8.07%—17.61%),分株高度在生境间的可塑性更大;分株生物量中水生生境、湿生生境和盐碱生境3个生境间的变异系数(33.43%—55.61%)均低于生境内变异系数(44.85%—79.82%),分株生物量在生境内的可塑性更大。不同生境条件下芦苇种群分株,在生长和生产上均存在较大的生态可塑性,表现出明显的环境效应,其中土壤含水量是该地区芦苇分株生态可塑性变异的主要驱动因子(R0.80),为正向驱动。     

高原鼠兔有效洞穴密度对高山嵩草群落及其主要种群空间分布特征的影响

高原鼠兔(Ochotona curzoniae)有效洞穴密度变化会引发高山嵩草(Kobresia pygmaea)草甸植物群落及其种群分布格局发生变化。采用野外调查法研究了高原鼠兔有效洞穴密度对高山嵩草群落特征及其主要种群分布格局的影响。结果表明:随高原鼠兔有效洞穴密度增加,高山嵩草草甸植物群落的优势种没发生明显变化,部分伴生种发生更替;高度、盖度、多样性指数和均匀度指数呈现降低态势;地上生物量和丰富度指数变化不明显;高山嵩草和矮火绒草(Leontopodium nanum)种群的盖度、密度以及生物量均呈现降低态势,而达乌里秦艽(Gentiana dahurica)和小花草玉梅(Anemone rivularis var.flore-minors)种群的盖度、密度和生物量呈增加趋势。高山嵩草和矮火绒草的种群分布格局从8个/625m2和14个/625m2的聚集分布分别变为34个/625m2时的均匀分布和随机分布,达乌里秦艽和小花草玉梅种群从8个/625m2和14个/625m2的随机分布变为23个/625m2和34个/625m2时的聚集分布,这说明高原鼠兔有效洞穴密度变化改变了高山嵩草群落的特征和主要植物种群的空间分布格局,而对应群落特征和种群分布格局改变的有效洞穴密度为14个/625m2和23个/625m2。