小叶碱蓬和白麻土壤—叶片生态化学计量学特征对不同盐生境的响应

[目的] 分析干旱区盐生植物生境土壤与叶片生态化学计量特征在不同盐生境下变化趋势及主要限制因子,为研究干旱区盐生植物生长发育过程中养分限制因子和适应机制提供基础研究资料,同时为荒漠植物的生态保育和恢复提供参考。[方法] 选取艾比湖湿地国家级自然保护区稀盐盐生植物小叶碱蓬(Suaeda microphylla)和拒盐盐生植物白麻(Apocynum pictum),测定其生境土壤pH值、含水量、盐分、速效磷、铵态氮、有机碳、全氮、全磷以及植物叶片有机碳、全氮、全磷,分析两种植物叶片与生境土壤生态化学计量特征的关系,探究植物叶片生态化学计量特征的土壤限制因子。[结果] ①随着盐分增加,两种植物生境土壤磷下降,有机碳、氮及化学计量比呈上升趋势,土壤养分含量受盐渍化程度影响显著; ②两种植物叶片氮受土壤盐分影响显著,随盐分降低呈下降趋势,与土壤氮含量的变化趋势一致,叶片N/P平均值均小于14,表明研究区两种植物均受土壤氮含量限制; ③RDA分析表明,影响小叶碱蓬叶片生态化学计量的主要因子为土壤pH值(p=0.034)、含水量(p=0.002),而白麻主要受土壤磷(p=0.002)、铵氮(p=0.048)影响。[结论] 不同类型盐生植物在土壤—植物生态化学计量特征耦合关系上存在差异。稀盐盐生植物小叶碱蓬主要受土壤pH值、含水量的影响,拒盐盐生植物白麻主要受土壤磷、铵态氮含量影响。     

崀山丹霞地貌区天然常绿阔叶林群落物种多样性研究

 采用样方法采集数据,以重要值为测度指标,以丰富度指数D2、Simpsom指数D1、Shannon-Wiener指数H′、Sheldon均匀度指数JSW和Pielou均匀度指数E为测度指数,研究了崀山丹霞地貌14个天然常绿阔叶林群落物种多样性。结果表明:1)在相似生境中,随着群落演替至亚顶极阶段,物种多样性的变化趋势是增加的,顶极群落中,生境变优,灌、草层物种多样性的变化趋势为增加,而乔木层无明显变化规律;2)群落物种多样性随海拔的变化,除一般常见的变化模式外,还出现一种双峰曲线模式;3)H′较D1,E较JSW具有较高的敏感度。D1与H′在描述群落乔、灌、草,H′与E、D1与E、JSW与E在描述乔木,JSW与E在描述草本之间物种生物多样性上有相似的作用。表明:丹霞地貌中海拔、生境和演替影响植物群落物种多样性,H′、D1JSW与E能单独表达丹霞地貌群落物种多样性。     

围封对荒漠草原物种多样性和功能多样性的影响

为揭示荒漠草原区域围封对不同土壤生境物种多样性和功能多样性的影响,以荒漠草原不同土壤生境下围封（15年、10年、6年）和放牧（15年、6年、5年）的草地植物群落为研究对象,基于方差分析和主成分分析的基础上,通过函数拟合分析,探讨植物物种多样性与功能多样性之间的关系。结果表明：（1）围封相对于自由放牧条件,灰钙土生境植物功能多样性显著增加（P<0.05）。随着封育年限的增加,物种多样性呈显著降低趋势（P<0.05）,功能多样性未发生显著变化（P>0.05）;风沙土生境植物功能多样性和物种多样性未发生显著变化（P>0.05）。（2）功能离散度表征的功能多样性与物种丰富度关系可用二次多项式Y=aX²+bX+c形式表示,随着封育年限的增加,二者的相关系数在灰钙土和风沙土生境均呈增加趋势。荒漠草原物种多样性与功能多样性整体正相关,且符合二次函数关系,物种多样性可以用来反映植物群落功能多样性的水平高低,但这种替代作用受封育年限和放牧的影响,随着封育年限增加,物种多样性反映功能多样性水平的能力增加,在未来荒漠草原多样性与生态系统功能关系及维持机制中,需要同时考虑多样性的多维度特征以及不同土壤生境类型。     

不同结皮类型对植被混凝土基材团聚体及有机碳的影响

[目的] 分析土壤团聚体分布和有机碳含量特征,揭示生物结皮对边坡稳定和养分固持的影响,为生物结皮在修复工程中的运用提供参考和指导意见。[方法] 以植被混凝土基材修复边坡为例,运用土壤干筛法、土壤湿筛法分别对结皮覆盖和无结皮覆盖坡面土壤的结皮层(0—2 cm)和结皮下层(2—7 cm)团聚体和有机碳特征进行研究。[结果] ①生物结皮的存在明显影响了土壤团聚体分布、机械稳定性及R_0.25含量。结皮覆盖层较CK(无结皮覆盖坡面)稳定性指标分别增加27.42%~33.51%(MWD),21.66%~28.88%(GMD),大团聚体含量(R_0.25)增加10.68%,且苔藓类结皮影响最为显著。②湿筛法测定的不同结皮类型土壤团聚体均以＞0.25 mm粒径为主,其中结皮覆盖边坡的团聚体水稳性参数MWD,GMD,R_0.25分别介于1.93~5.33 mm,0.85~3.16 mm,70.97%~87.50%,以苔藓覆盖边坡最大,D_d值介于2.48~2.74间,以苔藓类值最小。团聚体水稳定性表现为苔藓覆盖边坡最好,裸坡最差。③结皮的存在促进了土壤有机碳累积,有机碳含量是CK组的两倍以上。其中对表层土壤有机碳水平提升作用明显,对下层土壤作用较低。④土壤有机碳含量与土壤水稳性参数MWD,GMD,R_0.25呈显著正相关性(p＜0.05),有机碳水平和团聚体稳定性联系密切,相互影响,有机碳水平的提高对增加团聚体稳定性具有重要作用。[结论] 生物结皮的存在对修复边坡团聚体稳定和有机碳累积具有促进作用,结皮对生态修复边坡稳定和养分固持有一定的作用,且不同结皮类型作用强度不一,其中苔藓类和混生结皮固土和固碳效果最优。     

太行山低山丘陵区不同植物群落物种多样性研究

 通过样地法对小浪底水库库区山地生态系统不同群落间的Shannon-Wiener指数(H′)、Simpson指数(D1)、Margalef物种丰富度(D2)、种间相遇概率(P)和Pielou均匀度指数(Jsw)等多样性指数进行研究,利用统计方法分析不同群落的物种多样性指数与其所处环境的关系。结果表明:1)物种多样性指数和丰富度指数与群落类型有密切关系,同一类型的群落中,多样性指数随演替时间表现出复杂的关系;2)土壤含水量对H′、P、Jsw、D1等呈极显著的正相关性,土壤厚度与H′、D1、P呈显著正相关性;多样性指数与坡度无相关性;土壤有机质、速效氮、速效磷等养分指标与多样性指数H′、D1有显著的正相关;3)多样性指数H′与乔木、灌木群落生物量表现为正相关关系,草本群落与D1相关性不显著;4)乔木林群落的恢复时间与Jsw、H′呈正相关关系,其余多样性指数(P、D1、D2)与恢复时间关系不显著(P>0.05);恢复时间每增加10a,群落物种数平均增加约6种;5)物种多样性指数H′与灌木的盖度和高度呈极显著正相关性;有些单优群落随高度增加和盖度提高,多样性指数反而表现出降低;6)草本植物群落的高度和盖度与物种丰富度指数D2与呈显著的负相关关系,与H′相关性不显著。     

阿勒泰林区放牧前后草地生态系统健康评价

[目的] 对阿勒泰林区放牧前后的草地生态系统进行健康评价,为该区退化草地恢复与管理提供科学依据。[方法] 运用了VOR综合指数生态系统健康评价模型,并结合物种多样性测度中的Margalef丰富度指数、Simpson优势度指数、Shannon-Wiener多样性指数和Alatalo均匀度指数,对阿勒泰林区草地生态系统整体状况进行了评估。[结果] ①各监测点Margalef指数差异表现在旅游区放牧前后差异极显著（p<0.01）,牧道放牧前后差异显著（p<0.05）;前山山坡、牧道的Simpson指数和Shannon-Wiener指数的放牧前后均表现出差异极显著（p<0.01）;各监测点Alatalo指数放牧前后差异不显著。②阿勒泰林区放牧后草地生态系统结构较稳定;阿勒泰林区放牧前后草地生态系统健康的组织力（O）、恢复力（R）值差异显著（p<0.05）。③VOR指数表现为牧道放牧前后差异极显著（p<0.01）,其他监测点的VOR指数放牧前后差异不显著。④各监测点放牧前后草地健康状况评价结果一致,为“健康”状态,但各监测点的VOR综合指数值存在差异。[结论] 阿勒泰林区放牧后草地生态系统结构较稳定,监测点旅游区的Margalef丰富度放牧前后差异极显著（p<0.01）,前山山坡、牧道的Simpson优势度和Shannon-Wiener多样性放牧前后均差异极显著（p<0.01）;各监测点放牧前后草地健康状况评价为“健康”。     

子午岭地区植被演替的土壤碳汇效应

为明确黄土高原地区植被长期恢复的土壤碳汇效应,采用时空互代的方法,研究子午岭地区150年以来8个植被演替序列的土壤有机碳含量及储量的变化特征,分析影响土壤有机碳储量变化的植被因素。结果表明:从农地演替到气候顶级辽东栎(Quercus wutaishanicaMary.)群落,土壤有机碳含量和储量明显增加,表现为演替前期(草本群落)快速增加,后期(乔木群落)趋向稳定的变化特征。剖面上来看,随着土层加深,土壤有机碳含量迅速减少。0—5 cm土层土壤有机碳含量与5—20,20—40 cm土层差异显著(P＜0.05),表明土壤有机碳积累存在明显的表聚效应。枯落物蓄积量与细根生物量均随演替时间呈现出增加的变化特征,前者更有利于提高土壤有机碳储量。0—5 cm土层与0—20 cm土层土壤有机碳储量与演替时间均存在极显著的幂函数关系,不同土层之间土壤有机碳储量线性相关关系显著(P＜0.001)。植被长期演替具有显著的土壤碳汇功能。未来黄土高原地区林、草地的恢复应根据植被带的分异规律,促进自然演替,以进一步提升该地区的土壤碳汇潜能。     

喀斯特槽谷区岩层倾向对土壤入渗特性的影响

为了解岩层倾向对喀斯特槽谷区土壤入渗特性的影响,以重庆市青木关岩溶槽谷区顺/逆层坡为研究对象,分析5种典型土地利用方式裸地(AL)、辣椒地(PL)、玉米地(CL)、林地(FL)、草地(GL)在顺/逆层坡的土壤入渗能力差异,并探讨土壤物理性质对土壤入渗能力的影响。结果表明:(1)＞0.25 mm水稳性团聚体含量、毛管持水量、黏粒以及粉粒含量在顺/逆层坡存在显著差异(p<0.05),其中在>0.25 mm水稳性团聚体含量和毛管持水量方面,分别为PL与FL的顺/逆层坡差异最大,在黏粒和粉粒方面,CL的顺/逆层坡差异最大,且均为逆层坡＞顺层坡。(2)除FL顺层坡的土壤渗透能力低于逆层坡外,其余4种土地利用方式下的土壤入渗能力均表现为顺层坡高于逆层坡。(3)土壤渗透特性在顺/逆层坡均与容重呈极显著负相关关系(p<0.01),在顺层坡与总孔隙度、非毛管孔隙度、＞5 mm水稳性团聚体含量和饱和持水量呈极显著正相关关系(p<0.01),在逆层坡与非毛管孔隙度、饱和持水量、粉粒含量呈极显著正相关关系(p<0.01);通过多元逐步回归分析与通径分析发现,顺/逆层坡土壤入渗能力的首要决策因素均为容重,其次分别为>5 mm水稳性团聚体含量和粉粒含量。(4)对比4种土壤入渗过程的拟合模型,Philip模型对顺/逆层坡的土壤入渗过程拟合效果最佳。研究结果可为喀斯特槽谷区不同岩层倾向的水土流失防治以及植被恢复提供数据支撑。     

连续14年黑土坡耕地秸秆覆盖免耕水土保持效应

为探究长期秸秆覆盖免耕对黑土坡耕地土壤结构的影响以及水土保持效应,通过秸秆覆盖免耕(NT)和传统顺坡耕作(CT)2组长期定位田间试验,对土壤结构、土壤保水能力、保土效应作对比分析。结果表明:NT与CT相应性状比较,土壤容重没有显著增加(P＞0.05),在0—20 cm土层,虽总孔隙度和非毛管孔隙度低,但增加了土壤毛管孔隙度和水稳性大团聚体(WR_0.25)含量,WR_0.25含量和平均重量直径(MWD)差异均达到显著水平(P＜0.05);分别提高了垄台土壤初始入渗和稳定入渗速率28.8%,24.7%;0—10 cm土层,饱和含水量和田间持水量差异均达到显著水平(P＜0.05);减少了产流次数、径流量和土壤流失量分别为11次,86.6%和98.9%,有效地遏制了水土流失。研究结果表明,长期连续秸秆覆盖免耕是一项有利于土壤结构稳定和遏制土壤侵蚀的黑土地保护措施。     

不同生态修复措施对藏东南工程边坡植被重建的作用

[目的] 评价青藏高原派墨公路生态恢复过程中环境因素对边坡植物群落的影响,为藏东南工程扰动区生态恢复计划提供理论依据。[方法] 以藏东南新修派墨公路为研究对象,基于沿线边坡生态恢复植物群落调查,分析群落盖度、物种多样性指数(Shannon-Wiener指数、Simpson多样性指数、Margalef丰富度指数、Pielou均匀度指数)、群落加权性状值(比叶面积、叶干物质含量、叶氮含量、叶磷含量)与环境变量(海拔、修复措施)的关系,探究当前恢复重建植物群落对环境变量及工程措施的响应。[结果] ①海拔显著影响Margalef丰富度指数、叶干物质含量(p＜0.05); ②高强度的措施显著提高群落盖度、比叶面积、叶氮含量(p＜0.05),但对叶磷含量有显著负向作用(p＜0.05); ③人为高度干预的SJP技术能够显著增加高海拔植物的叶干物质含量,对群落修复效果总体较好。[结论] 海拔高度和修复措施是派墨公路沿线边坡植物群落恢复的主要影响因素。随着海拔升高,植被自然恢复难度增大。应加大人为修复措施强度,避免引起高寒地区生态退化。     

保水剂和微生物菌肥配施对旱作燕麦土壤微生物生物量碳、氮含量及酶活性的影响

为探讨保水剂和微生物菌肥配施后旱作燕麦土壤微生物生物量碳、氮含量及酶活性的影响,在内蒙古黄土高原旱作农田设置不施用保水剂和微生物菌肥(CK)、保水剂和微生物菌肥配施(A)、单施微生物菌肥(B)和单施保水剂(C)4个处理,分析燕麦全生育期内0—10,10—20,20—40 cm土壤微生物生物量碳、氮含量及酶活性时空动态变化和产量变化。结果表明:(1)全生育期,土壤微生物量碳含量呈"双峰"曲线变化,峰值均出现在孕穗期和灌浆期;氮含量呈先降低后升高再降低趋势,苗期含量最高;过氧化氢酶、蔗糖酶、脲酶活性均呈"单峰"曲线变化,过氧化氢酶、土壤蔗糖酶峰值在孕穗期,土壤脲酶则在抽穗期。(2)除CK外,土壤微生物量碳、氮含量及过氧化氢酶、蔗糖酶和脲酶活性表现为0—10 cm10—20 cm20—40 cm,其中配施(A)对0—10,10—20 cm影响均显著(p0.05),单施(B、C)仅对10—20 cm土层影响显著(p0.05)。(3)10—20 cm土层,配施(A)与其他3个处理间差异均显著(p0.05),提高微生物量碳含量4.82%～40.28%、微生物生物量氮含量8.44%～68.66%、过氧化氢酶活性13.32%～60.16%、蔗糖酶活性10.45%～39.14%、脲酶活性12.40%～55.62%。(4)配施(A)能同时显著(p0.05)提高燕麦籽粒产量和生物产量,提高幅度分别为8.40%～20.12%和10.80%～25.09%。因此,保水剂和微生物菌肥配施在黄土高原旱作区具有较好改善土壤微生物活性效果,提高旱作燕麦产量。     

Epiphyte communities on the trunks of retention trees stabilise in 5 years after timber harvesting, but remain threatened due to tree loss

Live retention trees are expected to support the recovery of epiphytes in regenerating stands by retaining a part of the populations in cutover sites and receiving propagules from adjacent forests. So far, the research has been focused on immediate post-harvesting mortality caused by microclimatic stress while a broader perspective on epiphyte community dynamics is lacking. We studied lichen and bryophyte communities on the trunks of retention trees and adjacent forest trees in Estonia, where significant desiccation (particularly of bryophytes) had been documented within 2-3 years after timber harvesting. The resampling 5-6 years after harvesting indicated that, during the 3 years passed, (1) lichen species richness per surviving tree increased and bryophyte species richness stabilised, (2) there were no clear successional changes in the composition of the communities and (3) retention trees were more frequently colonised than forest trees. Most epiphyte extinctions between the sampling years were related to the death of trees (particularly in the forests because of harvesting) and stochastic disappearances of the smallest populations. Also, retention trees were very rarely colonised by species of conservation concern. We conclude that, in addition to addressing the microclimatic stress in the first post-harvesting years, crucial elements in sustaining epiphytic bryophyte and lichen populations in green-tree retention systems include careful selection of the retention trees and a supportive reserve network. The selection of the trees should assure representativity and long-term survival of local populations, while reserves should host the most demanding species and be stable colonisation sources in general.     

大桥水库消落带不同水位高程柳树林地土壤团聚体组成与分形特征

为研究植被恢复对水库消落带土壤团聚体组成及稳定性的影响,利用干筛和湿筛法,测定了大桥水库消落带不同水位高程下柳树林地土壤团聚体组成分布,并基于分形理论分析了土壤团聚体分形特征。结果表明:(1)消落带柳树林地土壤0.25 mm非水稳定性团聚体和水稳性团聚体分别为73.13%～93.69%和47.62%～82.06%,较对照无植被样地土壤均有所增加,但两者差异不明显;消落带土壤大团聚体含量随水位高程升高而降低,随土层深度增加而减少,但在不同水位高程和不同土层间均无显著性差异(p0.05)。(2)消落带柳树林地土壤水稳性团聚体分形维数(D)为2.51～2.82,平均值为2.67,低于对照的2.75;土壤水稳性团聚体分形维数(D)在不同水位高程和不同土层间均无显著性差异(p0.05),整体呈现出随水位高程升高而降低的趋势,且0—10 cm土层D值低于10—20 cm土层。(3)消落带柳树林地土壤MWD、GMD平均值分别为0.81,0.24 mm,高于对照的0.71,0.15 mm,柳树林地土壤团聚体稳定性高于对照;土壤团聚体稳定性在消落带内部具有一定空间差异,MWD与GMD均表现为高水位(2 016～2 019 m)中水位(2 010～2 013 m)低水位(2 007 m),且0—10 cm土层MWD与GMD大于10—20 cm土层的,但不同水位高程和不同土层间均无显著性差异(p0.05)。综上,大桥水库消落带植被恢复对土壤团粒结构有一定程度改善,且随淹水深度的增加,消落带柳树林地土壤团聚体稳定性降低。     

Impacts of Industrial Polluters on Bryophytes: a Meta-analysis of Observational Studies

Identifying the factors responsible for the diversity of responses of biota to industrial pollution is crucial for predicting the fates of polluted ecosystems. A meta-analysis based on 49 field studies conducted around 47 point polluters demonstrated that the individual (growth and reproduction) and community (abundance and species richness) characteristics of bryophytes in polluted habitats are reduced to about a half of the values observed in unpolluted sites. Non-ferrous smelters cause a stronger reduction in species richness and larger changes in species composition than other types of polluters. The magnitudes of the effects of pollution on the abundances of individual bryophyte species are not linked with their taxonomic position, life form or Ellenberg indicator values for light, moisture and nitrogen. The variation in species?? responses to pollution is mostly explained by differences in their reproductive characteristics; bryophyte species that possess special forms of vegetative reproduction and those that produce abundant sporophytes are more successful in polluted habitats. Ranking of bryophyte species according to their sensitivity to pollution is independent of the type of the polluter. Changes in bryophyte cover follow changes in tree cover, but not changes in the cover of the vascular field layer in the same pollution gradients. Pollution impacts cause stronger adverse effects on bryophytes in warmer climates.     

4种苔藓植物在喀斯特石漠化地区的生态修复意义

为探求苔藓植物在石漠化地区的生态修复意义,筛选出4种石漠化地区常见的苔藓,即美灰藓(Eurohypnum leptothallum)、小青藓(Brachythecium perminusculum)、双色真藓(Bryum dichotomum)和多疣细羽藓(Cyrto-hypnum pygmaeum),测定其生物量、饱和吸水率、根系密度、蒸腾速率和抗冲刷能力,并初次将该4种苔藓应用于石漠化修复的实践中,对其土壤酶活性进行了1年的跟踪监测。结果表明:(1)4种苔藓持水保水能力差异显著,其生物量由大到小依次为美灰藓双色真藓小青藓多疣细羽藓;饱和吸水率最低的是多疣细羽藓(660.78±3.46)%,最高的是美灰藓(1 627.82±4.68)%。(2)双色真藓的蒸发速率最高可达6.63g/(kg·h),其水分更容易丧失;美灰藓蒸发速率为0.93g/(kg·h),水分较其他苔藓不易丧失。(3)4种苔藓的抗冲刷能力与其假根的根长密度、根重密度、生物量存在显著正相关关系,美灰藓在各组冲刷试验中表现出较强的抗冲刷性,可以有效减少土壤流失。(4)4种苔藓均可有效提高被培养土壤的酶活性。苔藓层生物量、抗冲刷强化值、假根根系密度与土壤脱氢酶、脲酶呈正相关关系。4种苔藓均具有较高的水土保持效益,其中美灰藓的表现更为显著,建议利用物种演替规律将苔藓应用于石漠化修复的实践中。     

Bryophytes in a changing landscape: The hierarchical effects of habitat fragmentation on ecological and evolutionary processes

Testing the myriad predictions associated with the community, demographic and genetic impacts of habitat fragmentation remains a high conservation priority. Many bryophyte taxa are ideal model systems for experimentally testing such metapopulation-based and population genetic predictions due to their relatively fast colonisation-extinction rates, high substrate specificity, dominant haploid condition, and diminutive size. Herein, we review the community, demographic and population genetic impacts of habitat fragmentation on bryophytes, highlight the present knowledge gaps, and offer ideas on how experimental studies utilizing bryophytes may be used to address the broader conservation implications associated with fragmented ecosystems. Previous research suggests that dispersal limitation best explains observed patterns of abundance and distribution of bryophytes in some fragmented habitats. However, edge effects influence bryophyte community structure of border habitats especially where abrupt differences in micro-climatic conditions between the matrix and the forest remnant exist, or where the species pool contains members with inherently restricted ecological amplitudes. Existing studies do not agree on the relationship between basic attributes of bryophyte community structure (i.e., species richness and local density), and habitat area and degree of spatial-isolation. Demographic studies are a critical step in structuring conservation strategies, however surprisingly little empirical information exists as to the impacts of habitat fragmentation on plant population dynamics. We propose that bryophytes offer great potential for testing predictions with respect to plant population persistence in spatially-structured landscapes.     

芒萁侵入红壤退化裸地对土壤理化性质和细菌组成的影响

芒萁是最早侵入红壤退化裸地的先锋植物,其侵入过程对土壤环境的改变在退化裸地生态恢复进程中具有重要意义。以福建省长汀县红壤侵蚀裸地为研究对象,分析测定退化裸地中芒萁侵入区和非侵入区土壤理化性质和细菌组成及多样性。结果表明：芒萁侵入裸地显著提高土壤最大持水量、土壤含水率、全碳、全氮、全钾、有机质和pH,并显著降低土壤容重;芒萁侵入区增加根瘤菌目和慢生根瘤菌属等14种土壤优势细菌,变形菌门和甲型(α)变形杆菌的相对丰度显著提高(p<0.05),而土壤绿弯菌门和AD3菌纲的相对丰度显著降低(p<0.05),这些土壤细菌主要功能为化能异养、好氧化能异养和纤维素分解;芒萁侵入裸地显著提高土壤细菌群落结构多样性(p<0.05);芒萁侵入区和非侵入区土壤细菌群落结构差异显著(p<0.05);土壤细菌群落结构的主要影响因子是土壤含水率、全碳、有机质、土壤容重和pH。这些影响因子与疣微菌门、变形菌门、疣微菌纲和甲型(α)变形杆菌纲正相关。综上所述,芒萁侵入后可显著改善红壤侵蚀退化裸地的土壤理化性质,改善土壤细菌群落组成,增加土壤细菌群落多样性和优势菌群,对土壤细菌群落有积极效应。     

Bryophytes on tree trunks in natural forests, selectively logged forests and cacao agroforests in Central Sulawesi, Indonesia

Forest disturbance and transformations into agricultural land alter tropical landscapes at drastic rates. Here, we investigate bryophyte assemblages on trunk bases in natural forest, selectively logged forest and cacao agroforests that are shaded by remnants of natural forest in Central Sulawesi. Overall, bryophyte richness per site did not differ between forest types. However, mosses and liverworts reacted differently in that moss richness was lowest in cacao agroforests, whereas liverwort communities were equally rich in all forest types. In terms of cover, mosses remained unaffected while liverwort cover decreased significantly in disturbed forest. Species composition of bryophytes clearly changed in cacao agroforests as compared to natural forests and selectively logged forests. In particular some drought-sensitive species were rare or absent in cacao agroforests and were replaced by drought-tolerant ones, thus underlining the importance of microclimatic changes. Moreover, differences in bryophyte species composition between large and small trees were only pronounced in cacao agroforests, presumably due to concomitant changes in stemflow of precipitation water. In conclusion, the bryophyte assemblages of selectively logged forests and cacao agroforests were as rich as in natural forest, but species turn-over was particularly high towards cacao agroforests probably due to microclimatic changes. Maintenance of shade cover is crucial to the conservation of the drought-sensitive forest species.     

Spring bryophytes in forested landscapes: Land use effects on bryophyte species richness, community structure and persistence

Many freshwater ecosystems face severe threats from anthropogenic disturbances, yet little is known about the degree to which their biotic communities have been degraded by human activities. We analysed temporal changes and persistence of bryophyte communities in 40 springs in eastern Finland by comparing field surveys conducted in 1986 and 2000. During that period, some springs had remained in a near-pristine state, while others had undergone varying degrees of disturbance from forest management, drainage, and water abstraction. Several spring bryophytes (e.g., Philonotis fontana) declined between the study years, whereas Sphagnum mosses (e.g., Sphagnum warnstorfii) increased in abundance. Species richness of spring bryophytes declined significantly from 1986 to 2000, irrespective of bryophyte group (spring vs. other bryophytes) and spring condition (severely disturbed vs. unaltered springs). Bryophyte cover also decreased dramatically from 1986 to 2000, but this effect was related to both spring condition and bryophyte type. Spring bryophytes lost much of their cover in severely altered springs, while in unaltered springs they remained relatively stable through time. No such trend was observed for other, habitat generalist bryophytes. Persistence and stability of bryophyte communities showed significant, albeit rather weak, relationships with spring condition, with communities in unaltered springs being more persistent than those in altered springs. Given the importance of springs to boreal forest and aquatic biodiversity, restoration of degraded springs is a major challenge to maintaining and conserving biodiversity of boreal landscapes.     

砒砂岩区典型坡面土壤颗粒组成空间分布特征研究

为揭示土壤颗粒组成在垂直和水平方向上的分布规律,采集砒砂岩区典型坡面0—100 cm剖面的土壤,运用经典统计学测定其颗粒组成。结果表明：坡面0—100 cm土壤质地主要为砂壤土(59.21%)和壤砂土(36.40%)。随土层深度增加,砂粒含量增加,粉粒和黏粒含量减少,土壤逐渐呈现粗粒化的趋势;坡面尺度上,表层0—10 cm砂粒为弱变异,其余各层各粒级均为中等程度变异,且随土层深度增加变异性增强,不同粒级的变异系数表现为砂粒<粉粒<黏粒。沿坡面等高线方向,样带B粗粒化程度最弱,10 cm土层以下,样带B粗粒化程度最强。沿垂直坡面等高线方向,坡中砂粒含量(73.60%)相比于坡上和坡下分别增加6.90%(p<0.05)和11.66%(p<0.05),坡下粉粒(31.85%)和黏粒(3.10%)含量相比于坡上和坡中分别增加13.13%(p<0.05),23.59%(p<0.05)和4.36%,51.70%(p<0.05),坡中粗粒化程度最强,坡下是细颗粒堆积的主要区域。研究结果可加强对砒砂岩区坡面土壤颗粒空间分布规律的认识。