首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
African Olive (Olea europaea ssp. cuspidata) is a densely crowned evergreen small tree, native to eastern Africa that is highly invasive in areas where it has been introduced, including Hawaii and Australia. Invasion by African Olive threatens Cumberland Plain Woodland, a critically endangered grassy eucalypt woodland from western Sydney, Australia, through the formation of a dense mid‐canopy excluding the regeneration of native species. We established a 3‐year field experiment to determine the effectiveness of direct seeding and fire, as techniques for early stage restoration of a 2 ha historically cleared and degraded Cumberland Plain Woodland site after the removal of African Olive. Direct seeding was able to re‐establish a native perennial grass cover which was resistant to subsequent weed invasion and could be managed as an important first stage in woodland restoration with fire and selective herbicide. Fire was able to stimulate some germination of colonising native species from the soil seed bank after 15 years of African Olive invasion; however, germination and establishment of native shrubs from the applied seed mix was poor. We propose a ‘bottom‐up’ model of ecological restoration in such highly degraded sites that uses a combination of direct seeding and stimulation of the soil seed bank by fire, which could be applicable to other degraded grassy woodland sites and plant communities.  相似文献   

2.
    
Grassy woodlands have been extensively cleared for agricultural land uses; land managers need to know whether restoration of biodiversity on such sites requires further interventions beyond simply stopping agricultural land use. Cumberland Plain Woodland occurs on shale‐derived soils in western Sydney; former Cumberland Plain Woodland sites can range from grasslands cleared for agricultural use to regenerated woodlands. An experiment was established in Scheyville National Park to determine what effect repeated burning would have in this system. Four blocks were established (three in grassy areas, one in woodland) and plots in each block were either burnt in 2001 and 2005 or left unburnt. Native plant species richness was initially lower in the grassy blocks than in the woodland, and this ranking remained on unburnt plots over time. The first fire increased species richness of both natives and exotics on the grassy blocks, with the largest increases observed for native and exotic forbs, and lesser increases for grasses (native only), gramminoids and shrubs. Native species richness changed very little with burning in the woodland. Fire effects on species richness were still apparent 3 years later on the grassy blocks; the difference between the grassy blocks and the woodland was not significant on burnt plots at this stage. Changes in native species richness were far less after the second fire on the grassy blocks, with grasses and gramminoids showing increases; native species richness remained higher in the burnt treatment. The first fire reduced the initial differences in native species richness between the grassy blocks and the woodland, and the second fire maintained the benefit through time. Fire also increased exotic species richness; the proportion of total species as natives was not altered by the two fires. On unburnt grassy plots, native species richness and prior cumulative rainfall were positively related; a decline in native species richness on unburnt plots corresponded to increasingly drier conditions over the study.  相似文献   

3.
Summary   Moths and butterflies are strongly associated with vegetation structure and composition, which makes them a suitable indicator taxon for various ecological studies. Despite a good knowledge of many Australian lepidopteran taxa, they have rarely been used for restoration assessment. To explore the feasibility of using Lepidoptera as an indicator taxon for restoration monitoring in Australia, we used it to evaluate the success of a large-scale revegetation program in western Sydney. We compared moth and butterfly assemblages sampled with relatively low intensity in unrestored pastures, revegetated pastures and remnants of endangered Cumberland Plain Woodland (restoration aim). A light-trap survey of moth assemblages showed no significant differences in moth species richness and composition between any of the treatments with traps in revegetated areas producing most species rich samples. Butterfly surveys conducted over a 1-year period showed a considerable increase in butterfly species richness in revegetated areas compared to pastures, while forest remnants still had twice as many butterfly species compared to revegetated areas. Current revegetation practices employed to restore Cumberland Plain Woodland increased the diversity of lepidopteran assemblages, however, it is not clear whether they are on a trajectory towards the reference assemblages of forest remnants. Our study demonstrates that Lepidoptera, particularly butterflies, has a potential for broader application as an indicator group in restoration monitoring in Australia.  相似文献   

4.
    
Abstract Soil was investigated in a Cumberland Plain Woodland community to determine the presence of a soil seed‐bank and whether species richness and abundance of plants germinating from it were affected by heating such as that experienced in a fire. Soil samples were taken from the Holsworthy Military Area, in the south‐eastern region of the Sydney Basin, New South Wales, Australia, and one of four treatments was applied; soil was heated to 80°C, 40°C, unheated or unheated with litter not removed. Sixty‐eight species, representing 26 families including 11 exotic and 57 native species germinated from the soil. Herbs and grasses dominated and were in similar proportions to those surveyed in the above‐ground vegetation, suggesting that the soil seed‐bank reflected the current structure of the vegetation, although species composition differed. Species responded differently to heating. The seeds of some species germinated when heated at a higher temperature (80°C), particularly those from the family Fabaceae, whereas other species were more common in unheated or lightly heated samples (40°C). This suggests that fire is likely to change the species composition of the above‐ground vegetation and indicates that management must ensure that species that do not germinate when heated are maintained, as well as those species that germinate following heating. A large proportion of soil seed‐bank species showed low germination rates in the trials, and 112 above‐ground species did not germinate in the soil samples. We do not understand whether species of these two sets do not produce a soil‐stored seed‐bank or whether the seed‐bank has been depleted by past practices at Holsworthy. Further research is needed.  相似文献   

5.
Planning for the restoration of degraded ecosystems has a strong basis in facilitation successional theory, which, as applied in restoration practice, states that planting of structurally dominant tree species will assist the entry of other native species into a restored community. In Australia, tree planting has been widely applied in restoration of grassy woodland ecosystems. Trees have been postulated to reduce the cover and diversity of weed species, thus facilitating recolonization of native woodland species (indirect facilitation). The expected outcomes of this process include reduced species richness and abundance of exotic plant species and increased species richness and abundance/dominance of natives in areas beneath tree canopies, with these trends strengthening with time. To assess whether this was occurring, we carried out a comparative analysis of species assemblages found underneath and outside of planted tree canopies in sites replanted with juvenile canopy tree species 3–5 or 8–10 years previously. We sampled revegetated stands of Cumberland Plain Woodland, an endangered ecological community in Western Sydney, Australia. We found that neither the number nor abundance of native ground layer species beneath canopies increased as a result of trees being planted at sites of both ages. Where seed is limited, we predicted an increase in abundance of existing native species under planted tree canopies. On this point, the results were mixed and showed some natives with an increased abundance while others decreased. Exotic species richness showed the reverse of the expected pattern, being greater under tree canopies. These findings lend no support to the theory of indirect facilitation. We conclude that simple facilitation models may be inadequate to support planning of grassy woodland restoration and that those models incorporating successional time lags and restoration barriers are likely to be more informative about the development of communities initiated by tree planting.  相似文献   

6.
7.
    
There is growing interest in the potential for reforestation to assist the recovery of rainforest biodiversity. There is also a need to identify taxonomically tractable groups for use as cost‐effective indicators when monitoring the status of biodiversity within reforested sites. Insects are an important component of terrestrial biodiversity but often require considerable resources to sample at species level. Ant genera and generic‐based functional groups have been suggested as possible indicators of environmental disturbance. Here we ask to what extent the development of biodiversity is indicated by epigaeic ant genera and functional groups, across different types of reforestation in tropical and subtropical Australia. In each region, we used pitfall traps to sample the ants in replicate sites of: unmanaged regrowth, monoculture and mixed species plantations and ‘ecological restoration’ plantings, together with reference sites in pasture and rainforest. We recorded 35 epigaeic ant genera (and 4623 individuals) from 50 tropical sites, and 39 genera (and 9904 individuals) from 54 subtropical sites, with 47 genera overall. Community composition of both genera and functional groups differed between pasture and rainforest, although many genera were widespread in both. Reforested sites were intermediate between pasture and rainforest in both regions, and showed a gradient associated with decreasing grass and increasing tree and litter cover. Older monoculture plantations and ecological restoration plantings had the most rainforest‐like ant assemblages, and mixed‐species cabinet timber plots the least, of the reforested sites. We conclude that ground‐active ant genera and functional groups sampled in rapid surveys by pitfall‐trapping showed only a modest ability to discriminate among different types of reforestation. Species‐level identification, perhaps together with expanded sampling effort, could be more informative, but would require resourcing beyond the scope of rapid assessments.  相似文献   

8.
    
A restoration trial of grassy woodland on former agricultural land applied carbon at a standard rate (840 g C/m2/year) and at a high rate (4,200 g C/m2/year), to test whether further benefits to native plants and suppression of exotics would emerge. Carbon addition at the high rate reduced plant cover further than the standard rate but led to severe loss of plant species; it also reduced soil pH. Soil Al, Fe and Mn levels increased across the gradient of C addition, which would be consistent with the reduction in soil pH for Al and Mn, and a decrease in soil redox potential for Mn and Fe. Nutrient analysis of leaf tissue confirmed that uptake of Fe and Mn increased over the range of C addition, with the concentration of Mn in the high carbon treatment exceeding the threshold for toxicity for a range of species. The soil and plant tissue data are consistent with the induction of increased soil acidity and of stronger reducing conditions in the soil by high level of carbon addition and localised soil flooding. Plant uptake of Mn to toxic levels occurred subsequently, leading to negative effects on plants; aluminium phytotoxicity may also have occurred.  相似文献   

9.
C addition has been used successfully in grassland restoration in Australia, generally as sucrose at a standard rate of 840 g C/m2/year. Previous experiments that have varied the rate of soil carbon application to reduce nitrate to favour native over nitrophilous exotic species have found that the benefits can increase over the whole range used for some native species, but only appear above particular rates of C addition for others. A restoration trial of degraded grassy woodland on former agricultural land in western Sydney combined burning and slashing to remove biomass with C addition at the standard rate, and a high rate, to reduce soil nitrate on the burnt or slashed plots. Soil was sampled for extractable nitrate, ammonium and phosphorus, and plant root simulator probes were used to measure nitrate and ammonium supply. Both extractable nitrate and nitrate supply were periodically high in the controls, at which times C addition at the standard rate significantly reduced extractable nitrate with an even greater reduction at the high rate, and resulted in negative relationships between nitrate supply and added C. Effects of added C on extractable nitrate or nitrate supply were not detectable in non‐peak periods. Extractable ammonium and ammonium supply were either unaffected or increased with added C. Colwell phosphorus showed temporal variation but was unresponsive to added C. Of the three nutrients, only the decline in nitrate matched the decline in plant cover which was lowest in value at the high carbon rate (Morris & Gibson‐Roy 2018). In the absence of added C, extractable nitrate was less than control values in the fire and slash treatments 1 year after treatment application but was similar to control values at other times.  相似文献   

10.
种子库是湿地植被恢复的重要途径之一,不同时期的耕作土壤中残留的种子对开垦湿地恢复具有重要的作用.本文采用温室萌发法在两种水分条件下对三江平原天然湿地、不同开垦年限湿地种子库结构和规模进行了研究,以了解不同开垦年限湿地种子库特征及其在湿地植被恢复中的潜力.本次实验共萌发物种50种,随着开垦年限增加,萌发物种逐渐减少,天然湿地、开垦1年、3年、10年、20年的湿地分别为34种、31种、21种、21种和8种,萌发物种数与种子库规模均表现出极显著差异(F1=8.32,F2=5.946,P<0.001).种子库密度以天然湿地和开垦1年湿地最大,分别为7624粒/m2,9836粒/m2.随着开垦年限增加,种子库规模逐渐减小,开垦3年、10年种子库密度为4336粒/m2,4872粒/m2.开垦20 a后,显著减少为432粒/m2.湿润条件下萌发物种数及种子密度显著高于淹水处理,种子库具有明显的分层现象,0-5 cm土层种子库规模显著高于5-10 cm.小叶章(Calamagrostis angustifolia)作为该地区优势物种,由最初的1192粒/m2,经过20 a开垦后在种子库中消失.研究表明,在一定的开垦年限范围内,开垦湿地土壤中仍然保留大量的湿地物种种子,在湿地恢复中具有重要的作用.  相似文献   

11.
    
Aim The distribution of genetic variation in the Australian dry sclerophyll plant Hardenbergia violacea (Fabaceae) is examined in the context of Pleistocene climate change in order to identify likely refugia. Particular consideration is given to the origin of range disjunctions in South Australia and Tasmania, and to determining whether the Tasmanian population is indigenous or recently introduced from mainland Australia. Location Southeastern Australian mainland and Tasmania. Methods A combination of chloroplast polymerase chain reaction–restriction fragment length polymorphism and genomic amplified fragment length polymorphism (AFLP) marker systems was used to examine the genetic structure of 292 individuals from 13 populations across the range of H. violacea in southeastern Australia. Results Hardenbergia violacea populations in Tasmania and southern Victoria were characterized by low, almost monotypic chloroplast diversity. New South Wales showed higher haplotype diversity and haplotype sharing among widely distributed populations. Principal coordinates analysis (PCoA) of the AFLP data found a strong latitudinal cline in AFLP variation from northern New South Wales south to Tasmania. The Tasmanian population formed an isolated and somewhat disjunct genetic cluster at one end of this cline. However, the South Australian population was an exception to the clinal variation shown by all other populations, forming a highly disjunct cluster in the PCoA. Within‐population genetic diversity was low in both disjunct populations. Main conclusions The genetic evidence indicates that the Tasmanian population is likely to be indigenous and probably the product of vicariance, which was followed by range contraction at the Last Glacial Maximum or an earlier glacial event. The deep phylogenetic disjunction in South Australia is evidence of a much earlier separation on mainland Australia. The chloroplast structure indicates that, during the Pleistocene, H. violacea underwent broad‐scale recolonization in southern Victoria and Tasmania, possibly from a large continental refugium in eastern New South Wales. We conclude that H. violacea, and presumably the sclerophyll communities in which it occurs, have undergone multiple range contractions to large continental refugia during different Pleistocene glaciations in southeastern Australia.  相似文献   

12.
    
With less than half of the world's tropical forests remaining, ecological restoration is urgently needed to halt biodiversity loss. However, the efficacy of different active reforestation methods remains largely untested particularly with respect to the recovery of fauna during the early years of restoration. Here, we present the results of a long-term restoration project in the Australian Wet Tropics after 6 years of planting. Using dung beetles as bioindicators of restoration success, we investigated how the diversity and density of trees in experimental plots influence the recovery of dung beetle diversity and their ecological functions (dung removal and secondary seed dispersal). We found that after only 6 years since planting, a native dung beetle community, representing around 41% of the species found in the adjacent rainforest, has colonized the experimental plots. Plots with the highest diversity of trees (24 species planted) showed higher dung beetle diversity, dung removal, and seed dispersal but only when the density of trees on the plots was low. These plots also have higher species richness, diversity, and abundance of rainforest species, while the opposite trend was found for open-habitat species. Therefore, planting a higher diversity of trees appears to be the best method for the early recovery of rainforest dung beetle communities and their functions. This is particularly crucial at low tree density, which is a common issue in active restoration projects as tree mortality is relatively high in the early years.  相似文献   

13.
    
Restoration practitioners must increasingly incorporate seed procurement models and seed use planning early in project development, despite insufficient guidance about what are reasonable expectations for the sourcing and use of native seeds. This special issue presents a series of articles examining each key step in the native seed supply chain, and provides a framework for the “standards” that need to be applied to native seed batches if the native seed supply chain is to achieve the levels of reliability and transparency required. These Standards provide seed buyers, end users, and funding bodies with a level of confidence and reliability in the sourcing of quality native seeds, and a pathway toward global best practice in native seed use.  相似文献   

14.
Many small‐scale projects in Australia suggest that ground‐layer elements of ecosystems can be restored, but scaling up of grassland and grassy understorey restoration has not occurred to date. Paul Gibson‐Roy recently travelled through the USA, where well‐developed markets for restoration have created a large, financially viable native‐herbaceous seed production and restoration sector. Here, he shares his observations, which show how much about the USA situation can be a model and inspiration for Australian grassy ecosystem restoration.  相似文献   

15.
鸟类栖木在森林植被恢复中的生态意义   总被引:1,自引:0,他引:1       下载免费PDF全文
李新华 《生态学报》2009,29(8):4448-4454
鸟类传播种子对于植物种群自然更新及群落演替具有重要的生态意义,鸟类栖息的树木具有富集种子雨功能,在山体滑坡区及废弃矿区等干扰生境中人工设置鸟类栖木,可以增加鸟类传播的种子雨输入,丰富土壤种子库,尤其食果鸟类可以传播那些处于群落演替中期至后期的乔、灌木树种,能够促进受干扰地区森林植被的演替进程.5·12汶川大地震对地震灾区造成了大面积的山体滑坡和严重的植被破坏,在地震灾区森林植被的生态恢复工作中,一些地区可以采用人工设置鸟类栖木方法,充分利用山体滑坡区周围残余森林的丰富种子源及众多食果鸟类,促进灾区森林植被的自然恢复.  相似文献   

16.
    
Effective seed storage after sourcing (harvesting or purchasing) is critical to restoration practitioners and native seed producers, as it is key to maintaining seed viability. Inadequate seed storage can lead to a waste of both natural and economic resources when seeds of poor quality are sown. When working with native species with unknown storage behavior, general assumptions can be made based on studies on related species, and standard practices may be applied with caution; however, an investigation should be conducted to understand if specific storage requirements are needed and for how long seeds can be stored before they lose significant viability. In this paper of the Special Issue Standards for Native Seeds in Ecological Restoration, we provide an overview of the key concepts in seed storage and the steps to take for effective storage of native seeds for restoration use.  相似文献   

17.
通过幼苗萌发法和样方调查相结合的方法对三江平原不同演替恢复阶段的种子库特征及其与植被的关系进行了研究。将开垦湿地、不同演替恢复阶段湿地以及天然湿地不同土壤层次(0-5、5-10 cm和根茎)的种子库在两种水分条件下(湿润、淹水10 cm)进行萌发处理。结果表明: 随着演替恢复阶段的进行, 种子库的结构和规模逐渐扩大, 地表群落表现出由旱生物种占优势的群落逐渐演变成以小叶章(Calamagrostis angustifolia)占优势的湿生群落的演替趋势。恢复7年湿地、恢复14年湿地、天然湿地土壤种子库萌发物种数分别为24种、29种、39种, 植被物种数为21种、25种、14种。湿地类型、水分条件和土壤层次均显著影响种子库萌发的物种数及幼苗数(p < 0.01)。种子库具有明显的分层现象, 天然湿地0-5 cm土层种子库种子萌发密度是5-10 cm土层的4倍左右, 而恢复湿地仅1.3倍左右, 且土层间萌发物种相似性系数较低。湿润条件下的萌发物种数显著高于淹水条件, 且两种水分条件下萌发物种的生活型不同。由于恢复时间较短, 不同演替恢复阶段的种子库与植被相似性维持在30%以下。湿地中根茎分蘖出大量的湿地物种, 对于小叶章等优势物种的繁殖具有重要作用。研究表明, 在开垦湿地退耕后的次生演替阶段, 种子库能够保持大量的湿地物种, 通过对湿地种子库与植被的关系研究, 能够为三江平原湿地群落演替与湿地恢复提供策略指导。  相似文献   

18.
刘群  彭斌  田长彦  赵振勇  王雷  王守乐 《生态学报》2023,43(17):7284-7293
耐盐植物的选育是盐渍土地生物改良的关键。通过对13个NaCl盐度梯度下,真盐生植物囊果碱蓬、盐地碱蓬、高碱蓬、盐角草、盐爪爪,泌盐植物大叶补血草、耳叶补血草、黄花补血草8种盐生植物的萌发试验,测定其种子发芽率、发芽势、发芽指数和相对盐害率等指标,研究不同NaCl盐度胁迫对其萌发特性的影响。结果表明:低盐度(50 mmol/L)能促进8种盐生植物的萌发;随着盐度的上升,盐角草、盐地碱蓬、囊果碱蓬、高碱蓬表现出较强的萌发耐盐性,发芽势和发芽指数优于其他植物;盐角草的萌发耐盐性最佳,在1000 mmol/L盐度下萌发率仍能达到54.0%。进一步通过S型生长曲线和线性模型分析得出,8种植物为对抗逆境大致分为\"快速型\"和\"缓慢型\"两种萌发策略;随盐度的升高,初始萌发时间和萌发高峰时间均不同程度的向后推迟。盐度≤200 mmol/L时,囊果碱蓬的萌发占据优势,其萌发速率大于其他植物,且差异显著;中盐度400 mmol/L左右时,盐地碱蓬和盐角草萌发最快,二者无显著差异;盐度≥600 mmol/L时,盐角草萌发速率较快,相比其他植物差异显著。泌盐植物的萌发耐盐适宜浓度和耐盐极限浓度均低于真盐生植物。8种植物均有作为氯化物为主盐渍土地区生物改良材料的潜力。  相似文献   

19.
    
A better understanding of seed movement in plant community dynamics is needed, especially in light of disturbance‐driven changes and investments into restoring degraded plant communities. A primary agent of change within the sagebrush‐steppe is wildfire and invasion by non‐native forbs and grasses, primarily cheatgrass (Bromus tectorum). Our objectives were to quantify seed removal and evaluate ecological factors influencing seed removal within degraded sagebrush‐steppe by granivorous Owyhee harvester ants (Pogonomyrmex salinus Olsen). In 2014, we sampled 76 harvester ant nests across 11 plots spanning a gradient of cheatgrass invasion (40%–91% cover) in southwestern Idaho, United States. We presented seeds from four plant species commonly used in postfire restoration at 1.5 and 3.0 m from each nest to quantify seed removal. We evaluated seed selection for presented species, monthly removal, and whether biotic and abiotic factors (e.g., distance to nearest nest, temperature) influenced seed removal. Our top model indicated seed removal was positively correlated with nest height, an indicator of colony size. Distance to seeds and cheatgrass canopy cover reduced seed removal, likely due to increased search and handling time. Harvester ants were selective, removing Indian ricegrass (Achnatherum hymenoides) more than any other species presented. We suspect this was due to ease of seed handling and low weight variability. Nest density influenced monthly seed removal, as we estimated monthly removal of 1,890 seeds for 0.25 ha plots with 1 nest and 29,850 seeds for plots with 15 nests. Applying monthly seed removal to historical restoration treatments across the western United States showed harvester ants can greatly reduce seed availability at degraded sagebrush sites; for instance, fourwing saltbush (Atriplex canescens) seeds could be removed in <2 months. Collectively, these results shed light on seed removal by harvester ants and emphasize their potential influence on postfire restoration within invaded sagebrush communities.  相似文献   

20.
A marriage of ecology with agronomy is proving successful in restoring diverse herbaceous layers ‐ to the extent that some reconstructed grasslands on ex‐agricultural land and rural roadsides have been found eligible for federal protection as threatened ecological communities. Can lessons from this improve our management and expansion of grassy ecosystems more broadly?  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号