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Lee BR, Schaffer-Morrison S. Forests of the future: The importance of tree seedling research in understanding forest response to anthropogenic climate change. Tree Physiol 2024:tpae039. [PMID: 38598325 DOI: 10.1093/treephys/tpae039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/19/2024] [Accepted: 04/03/2024] [Indexed: 04/12/2024]
Affiliation(s)
- Benjamin R Lee
- University of Michigan Institute for Global Change Biology, 440 Church St., Ann Arbor, MI, USA
- Carnegie Museum of Natural History, 4400 Forbes Ave., Pittsburgh, PA, USA
| | - Samuel Schaffer-Morrison
- University of Michigan Dept. of Ecology and Evolutionary Biology, 1105 N. University Ave, Ann Arbor, MI, USA
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2
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Galuszynski NC. Regeneration dynamics of Portulacaria afra in restored succulent thicket of South Africa. PeerJ 2023; 11:e15081. [PMID: 37151286 PMCID: PMC10158758 DOI: 10.7717/peerj.15081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 02/25/2023] [Indexed: 05/09/2023] Open
Abstract
Introduction Over-grazing by livestock has resulted in the widespread degradation of South Africa's succulent thicket ecosystems. This is characterised by a significant reduction in the cover of the dominant succulent shrub, Portulacaria afra. Because this species is unable to regenerate naturally in degraded habitat, active reintroduction is required to restore ecosystem function. However, reintroduction success is relatively low, and the recruitment barriers for this species are poorly understood. Methods By conducting pairwise plot surveys in actively restored and adjacent degraded succulent thicket habitats, the extent of P. afra seedling abundance in these contrasting ecosystem conditions is quantified. Results Seedling abundance was significantly greater in restored ecosystems (W = 23, p = 0.03225). Additionally, seedlings found in restored habitats were strongly associated with open habitat, whereas seedlings in degraded ecosystems were more restricted to nurse sites (X2 = 122.84, df = 2, p-value < 2.2e-16). A weak (R2 = 0,237), but significant (p = 0, 0295) correlation between P. afra cover and seedling abundance was recorded. Conclusion Active restoration of succulent thicket habitat through P. afra reintroduction appears to overcome recruitment barriers. This may suggest that, despite the poor survival of introduced individuals, natural recruitment could contribute to the regeneration of restored succulent thicket ecosystems.
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Affiliation(s)
- Nicholas C. Galuszynski
- Spekboom Thicket research group, Botany Department, Nelson Mandela University, Gqeberha, South Africa
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Benjankar R, Tranmer AW, Vidergar D, Tonina D. Riparian vegetation model to predict seedling recruitment and restoration alternatives. J Environ Manage 2020; 276:111339. [PMID: 32920462 DOI: 10.1016/j.jenvman.2020.111339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/13/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Native riparian vegetation communities have declined downstream of large water infrastructure like dams and diversions, owing to water management operations that prevent successful seedling colonization and recruitment. Altered timing and magnitude of reservoir releases to fulfill competing water demands often lead to reduced peak discharges and flow recession rates that do not support native riparian reproduction processes. To achieve short-term ecosystem function in highly regulated rivers an alternative method might be restoration planting, whereby success depends on identifying appropriate planting location and spatial extents. This study aims to provide a methodology to inform resource managers about the extent of possible natural seedling recruitment under average and wet hydrologic conditions, as well as constrain restoration planting operational uncertainties. Results from field surveys and simulations showed limited favorable areas for successful riparian seedling recruitment under regulated flows, regardless of hydrologic conditions in the basin. However, wet (11.4 ha) hydrologic conditions were more (approximately 11 times) favorable than average (1 ha) conditions for seedling recruitment. Furthermore, model results identified the location and spatial extent (25.6 ha) of favorable restoration planting areas during average flow. This extent is approximately 25 times larger than natural recruitment during an average (hydrological) year and even twice that for natural recruitment for a wet year. This suggests that ground operational activities guided by numerical modeling may effectively constrain planting uncertainties.
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Affiliation(s)
- Rohan Benjankar
- Department of Civil Engineering, Southern Illinois University Edwardsville, Edwardsville, 62026, IL, USA.
| | - Andrew W Tranmer
- Center for Ecohydraulics Research, University of Idaho, Boise, 83702, ID, USA
| | | | - Daniele Tonina
- Center for Ecohydraulics Research, University of Idaho, Boise, 83702, ID, USA
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Zhang X, Zhou Y, Adams MP, Wang F, Xu S, Wang P, Liu P, Liu X, Yue S. Plant morphology and seed germination responses of seagrass (Zostera japonica) to water depth and light availability in Ailian Bay, northern China. Mar Environ Res 2020; 162:105082. [PMID: 32836011 DOI: 10.1016/j.marenvres.2020.105082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/12/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Poor water quality and light reduction owing to anthropogenic impacts are the most widespread causes behind marine submerged angiosperm (seagrass) declines, worldwide. Seagrasses could respond to sustained environmental stresses, such as increasing water depth and light reduction, through morphological changes, particularly shoot density and/or biomass reductions. The seagrass Zostera japonica Asch. and Graebn. has been introduced to the Pacific Coast of North America, but it is widely threatened in its native northwestern Pacific Coast range alongside the east coast of China. The main aims of this study were to determine: 1) the depth limit of Z. japonica growth in its native range, and 2) how light availability affects the growth and recruitment of Z. japonica. To achieve these aims, we investigated the temporal responses of Z. japonica shoots and seeds from an intertidal donor site, Swan Lake, to light availability at water depths ranging from 1 to 6 m using in situ suspended cultures deployed in the experimental site, Ailian Bay, off the coast of Weihai City, China. The results showed that the transplanted Z. japonica shoots and seeds could survive for the duration of their annual growth cycle, permanently underwater, at a depth ≤2 m. There was a significant inverse relationship between water depth and time to complete shoot loss, despite temporally varying water clarity levels. Due to the local turbidity of the waters in Ailian Bay, a depth of 2 m yielded sufficient light deprivation (5%-37% surface irradiance) to negatively affect the seagrass shoot density. Our results suggest that this intertidal species can potentially persist in shallow subtidal areas following transplantation with shoots and seeds. The findings may also serve as useful information for local seagrass distribution limits, and will facilitate their habitat establishment and restoration efforts.
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Affiliation(s)
- Xiaomei Zhang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; CAS Engineering Laboratory for Marine Ranching, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Yi Zhou
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; CAS Engineering Laboratory for Marine Ranching, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Matthew P Adams
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, 4000, Queensland, Australia; School of Chemical Engineering, The University of Queensland, St Lucia, 4072, Queensland, Australia.
| | - Feng Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shaochun Xu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengmei Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Peng Liu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xujia Liu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shidong Yue
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
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Bateman AM, Erickson TE, Merritt DJ, Muñoz-Rojas M. Inorganic soil amendments alter seedling performance of native plant species in post-mining arid zone rehabilitation. J Environ Manage 2019; 241:179-186. [PMID: 30999267 DOI: 10.1016/j.jenvman.2019.04.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 03/15/2019] [Accepted: 04/07/2019] [Indexed: 06/09/2023]
Abstract
Rehabilitation of degraded drylands is challenged by environmental and anthropogenic constraints, such as limited availability of locally-sourced topsoil and poor quality alternative soil substrates. Current rehabilitation practices, at times, utilise inorganic soil amendments to improve the physicochemical and biological characteristics of reconstructed soil profiles. These approaches may be appropriate for dryland rehabilitation, but there is limited research available regarding the benefits of using these amendments. Here, we present a study in the Pilbara region of Western Australia, an arid landscape subject to intensive mining that currently uses inorganic soil amendments (gypsum and urea) in post-mining rehabilitation. The aim of this study was to assess the effectiveness of these amendments to (1) promote seed germination, seedling emergence and seedling growth across five plant species and, (2) re-instate soil quality in mine waste substrates. A series of glasshouse experiments assessed eight application combinations of these amendments in two alternative substrates and compared these to unamended substrates and topsoil. Soil amendments had a limited influence on seed germination, were detrimental to seedling emergence and resulted in increased seedling mortality. Mortality in the waste ranged from 2 to 61% but increased to 7-92% in amended waste. Seedling growth improved with high doses of amendments in waste, with a 1.3-5.6-fold increase across all plant species. Soil quality was relatively unaffected by amendments with soil nitrogen ranging from 0.01 to 0.08%, organic carbon from 0.01 to 0.12% and soil microbial activity from 2.3 to 2.4 ppm-CO2 in the amended and unamended waste. The use of soil amendments in mine rehabilitation requires consideration of the trade-off between initial reductions in seedling recruitment and enhanced seedling development at later stages. Future rehabilitation should consider the timing of amendment application to avoid detrimental impacts on seedling recruitment and maximise the benefits to seedling growth.
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Affiliation(s)
- Amber M Bateman
- The University of Western Australia, School of Biological Sciences, Crawley, 6009, WA, Australia; (b)Kings Park Science, Department of Biodiversity, Conservation and Attractions, Kings Park, 6005, WA, Australia.
| | - Todd E Erickson
- The University of Western Australia, School of Biological Sciences, Crawley, 6009, WA, Australia; (b)Kings Park Science, Department of Biodiversity, Conservation and Attractions, Kings Park, 6005, WA, Australia
| | - David J Merritt
- The University of Western Australia, School of Biological Sciences, Crawley, 6009, WA, Australia; (b)Kings Park Science, Department of Biodiversity, Conservation and Attractions, Kings Park, 6005, WA, Australia
| | - Miriam Muñoz-Rojas
- The University of Western Australia, School of Biological Sciences, Crawley, 6009, WA, Australia; (b)Kings Park Science, Department of Biodiversity, Conservation and Attractions, Kings Park, 6005, WA, Australia; The University of New South Wales, Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, Randwick, 2052, NSW, Australia
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Cui N, Wu J, Dai Y, Li Z, Cheng S. Influence of nitrogen loading and flooding on seedling emergence and recruitment from a seed bank in Chaohu Lake Basin, China. Environ Sci Pollut Res Int 2017; 24:22688-22697. [PMID: 28815432 DOI: 10.1007/s11356-017-9926-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 08/07/2017] [Indexed: 06/07/2023]
Abstract
Vegetation severely degraded and even disappeared in the water bodies of Chaohu Lake basin, which is the fifth largest freshwater lake in the Yangtze flood plain in China, because of water pollution and eutrophication. Vegetation restoration projects have been carried out. However, the influences of water quality and hydrology on vegetation restoration from seed banks have been rarely investigated. This experiment aimed to identify the effect of water level and nitrogen loading (ammonium and nitrate) on seedling emergence and recruitment from the riparian seed bank of the river in this basin. Most of the species in the seed bank germinated under moist conditions. Under flooding conditions, however, the growth of aquatic species, especially Vallisneria natans (Lour.) Hara, was inhibited when the nitrogen concentration increased. At 0.37 mg/L NH4+-N in the water column, the growth of V. natans was inhibited. The results suggested that flooding was a primary limiting factor of seedling emergence. The inhibitory effect of high nitrogen loading on the growth of aquatic species was one of the main driving mechanisms of macrophyte degradation under flooding conditions; nevertheless, competitive advantage might determine the community pattern in moist habitats. Therefore, water level control and water quality improvement should be the key aspects of vegetation restoration in degraded rivers or lakes.
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Affiliation(s)
- Naxin Cui
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Juan Wu
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Yanran Dai
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 Donghu South Road, Wuhan City, Hubei Province, China
| | - Zhu Li
- Institute of Hanjiang, Hubei University of Arts and Science, Xiangyang, 441053, China
| | - Shuiping Cheng
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, 1239 Siping Road, Shanghai, 200092, China.
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Tíscar PA, Candel-Pérez D, Estrany J, Balandier P, Gómez R, Lucas-Borja ME. Regeneration of three pine species in a Mediterranean forest: A study to test predictions from species distribution models under changing climates. Sci Total Environ 2017; 584-585:78-87. [PMID: 28135616 DOI: 10.1016/j.scitotenv.2017.01.150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/21/2017] [Accepted: 01/21/2017] [Indexed: 05/26/2023]
Abstract
The study tested the hypothesis that future changes in the composition of tree communities, as predicted by species distribution models, could already be apparent in the current regeneration patterns of three pine species (Pinus pinaster, P. nigra and P. sylvestris)inhabiting the central-eastern mountains of Spain. We carried out both an observational study and a seed-sowing experiment to analyze, along an altitudinal and latitudinal gradient, whether recent recruitment patterns indicate an expansion of P. pinaster forests to the detriment of P. nigra ones in the low-altitude southern sites of these mountains; or whether P. sylvestris is being replaced by P. nigra in the high-altitude sites from the same area. The observational study gathered data from 561 plots of the Spanish National Forest Inventory. The seed-sowing experiment tested the effects of irrigation and stand basal area on seedling emergence and survival. Data were analyzed by means of Generalized Linear Models and Generalized Linear Mixed Models. Regeneration of the three pine species responded similarly to the explicative factors studied, but the density of tree seedlings and saplings exhibited a wide spatial heterogeneity. This result suggested that a mosaic of site- and species-specific responses to climate change might mislead model projections on the future forest occupancy of tree species. Yet, we found no indications of neither an expansion nor a contraction of the near future forest occupancy of the tree species studied.
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Affiliation(s)
- P A Tíscar
- Centro de Capacitación y Experimentación Forestal, C/Vadillo-Castril s/n, 23470 Cazorla, Jaén, Spain
| | - D Candel-Pérez
- Universidad Pública de Navarra, Campus de Arrosadia, s/n, 31006 Pamplona, Navarra, Spain
| | - J Estrany
- Departamento de Geografía, Universidad de las Islas Baleares, Carr. de Valldemossa, km 7,5, 07122 Palma, Islas Baleares, Spain
| | - P Balandier
- Irstea, Research Unit on Forest Ecosystems (EFNO), Domaine des Barres, 45290 Nogent-Sur-Vernisson, France
| | - R Gómez
- Departamento de Ciencia y Tecnología Agroforestal y Genética, Escuela Técnica Superior de Ingenieros Agrónomos y de Montes, University of Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain
| | - M E Lucas-Borja
- Departamento de Ciencia y Tecnología Agroforestal y Genética, Escuela Técnica Superior de Ingenieros Agrónomos y de Montes, University of Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain..
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Alday JG, Zaldívar P, Torroba-Balmori P, Fernández-Santos B, Martínez-Ruiz C. Natural forest expansion on reclaimed coal mines in Northern Spain: the role of native shrubs as suitable microsites. Environ Sci Pollut Res Int 2016; 23:13606-13616. [PMID: 26517999 DOI: 10.1007/s11356-015-5681-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 10/22/2015] [Indexed: 06/05/2023]
Abstract
The characterization of suitable microsites for tree seedling establishment and growth is one of the most important tasks to achieve the restoration of native forest using natural processes in disturbed sites. For that, we assessed the natural Quercus petraea forest expansion in a 20-year-old reclaimed open-cast mine under sub-Mediterranean climate in northern Spain, monitoring seedling survival, growth, and recruitment during 5 years in three contrasting environments (undisturbed forest, mine edge, and mine center). Seedling density and proportion of dead branches decreased greatly from undisturbed forest towards the center of the mine. There was a positive effect of shrubs on Q. petraea seedling establishment in both mine environments, which increase as the environment undergoes more stress (from the mine edge to the center of the mine), and it was produced by different shrub structural features in each mine environment. Seedling survival reduction through time in three environments did not lead to a density reduction because there was a yearly recruitment of new seedlings. Seedling survival, annual growth, and height through time were greater in mine sites than in the undisturbed forest. The successful colonization patterns and positive neighbor effect of shrubs on natural seedlings establishment found in this study during the first years support the use of shrubs as ecosystem engineers to increase heterogeneity in micro-environmental conditions on reclaimed mine sites, which improves late-successional Quercus species establishment.
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Affiliation(s)
- Josu G Alday
- School of Environmental Sciences, University of Liverpool, Liverpool, L69 3GP, UK
- Department of Crop and Forest Sciences-AGROTECNIO Center, Universitat de Lleida, 25198, Lleida, Spain
| | - Pilar Zaldívar
- Agroforestry Sciences Department, University of Valladolid, Campus La Yutera, Avda. de Madrid 44, 34071, Palencia, Spain
| | - Paloma Torroba-Balmori
- CIFOR-INIA (Center of Forest Research), Carretera de La Coruña km 7.5, 28040, Madrid, Spain
- Sustainable Forest Management Research Institute UVa-INIA, Campus la Yutera, Avda de Madrid 44, 34071, Palencia, Spain
| | | | - Carolina Martínez-Ruiz
- Agroforestry Sciences Department, University of Valladolid, Campus La Yutera, Avda. de Madrid 44, 34071, Palencia, Spain.
- Sustainable Forest Management Research Institute UVa-INIA, Campus la Yutera, Avda de Madrid 44, 34071, Palencia, Spain.
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Abstract
Whether seed consumers affect plant establishment is an important unresolved question in plant population biology. Seed consumption is ubiquitous; at issue is whether seedling recruitment is limited by safe-sites or seeds. If most seeds inhabit sites unsuitable for germination, post-dispersal seed consumption primarily removes seeds that would otherwise never contribute to the population and granivory has minimal impacts on plant abundance. Alternatively, if most seeds ultimately germinate before they lose viability, there is greater potential for seed consumption to affect plant recruitment. Of the many studies on seed consumption, few ask how seed loss affects seedling recruitment for species with long-lived seed banks. We examined post-dispersal seed predation and seedling emergence in bush lupine (Lupinus arboreus), a woody leguminous shrub of coastal grasslands and dunes in California. We followed the fate of seeds in paired experimental seed plots that were either protected or exposed to rodent granivores in grassland and dune habitats. Significantly more seeds were removed by rodents in dunes than grasslands. In dunes, where rodent granivory was greatest (65% and 86% of seeds removed from plots by rodents in two successive years), there is a sparse seed bank (6.6 seeds m-2), and granivory significantly reduced seedling emergence (in the same two years, 18% and 19.4% fewer seedlings emerged from exposed versus protected plots), suggesting seed rather than safe-site limited seedling recruitment. In contrast, rodents removed an average of 6% and 56% of seeds from grassland plots during the same two years, and the grassland seed bank is 43-fold that of the dunes (288 seeds m-2). Even high seed consumption in the second year of the study only marginally influenced recruitment because seeds that escaped predation remained dormant. Burial of seeds in both habitats significantly reduced the percentage of seeds removed by rodents. Results suggest that granivores exert strong but habitat-dependent effects on lupine seed survival and seedling emergence.
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Affiliation(s)
- John L Maron
- University of California, Bodega Marine Laboratory, Box 247, Bodega Bay, CA 94923, USA e-mail: ; Fax: 707-875-2089, , , , , , US
| | - Ellen L Simms
- Department of Ecology and Evolution, University of Chicago 1101 East 57 Street, Chicago, IL 60637, USA, , , , , , US
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Abstract
The post-dispersal fate of seeds and fruit (diaspores) of three vertebrate-dispersed trees, Crataegus monogyna, Prunus mahaleb and Taxus baccata, was studied in the Andalusian highlands, south-eastern Spain. Exclosures were used to quantify separately the impact of vertebrates and invertebrates on seed removal in relation to diaspore density and microhabitat. The three plant species showed marked differences in the percentage of diaspores removed, ranging from only 5% for C. monogyna to 87% for T. baccata. Although chaffinches (Fringilla coelebs) fed on diaspores, rodents (Apodemus sylvaticus) were the main vertebrate removers of seed and fruit. Two species of ant (Cataglyphis velox and Aphaenogaster iberica) were the only invertebrates observed to remove diaspores. However, the impact of ants was strongly seasonal and they only removed P. mahaleb fruit to any significant extent. While removal of seed by rodents was equivalent to predation, ants were responsible for secondary dispersal. However, their role was limited to infrequent, small-scale redistribution of fruit in the vicinity of parent trees. Rodents and ants differed in their use of different microhabitats. Rodents foraged mostly beneath trees and low shrubs and avoided open areas while the reverse was true of ants. Thus, patterns of post-dispersal seed removal will be contigent on the relative abundance and distribution of ants and rodents. Studies which neglect to quantify separately the impacts of these two guilds of seed removers may fail to elucidate the mechanisms underlying patterns of post-dispersal seed removal. The coincidence of both increased seed deposition by the main avian dispersers (Turdus spp.) and increased seed predation with increasing vegetation height suggested that selection pressures other than post-dispersal seed predation shape the spatial pattern of seed dispersal. Rather than providing a means of escaping post-dispersal seed predators, dispersal appears to direct seeds to microhabitats most suitable for seedling survival. Nevertheless, the reliance of most vertebrate-dispersed trees on regeneration by seed and the absence of persistent soil seed banks imply that post-dispersal seed predators may exert a strong influence on the demography of the plants whose seeds they consume. Even where microsites are limited, the coincidence of the most suitable microhabitats for seedling establishment with those where seed predation is highest provide a means by which selective seed predators can influence community composition.
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Affiliation(s)
- Philip E Hulme
- Department of Biological Sciences, University of Durham, Science Laboratories, South Road, Durham, DH1 3LE, UK Fax: 0191-374-2417; e-mail: , , , , , , GB
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McKee KL. Seedling recruitment patterns in a Belizean mangrove forest: effects of establishment ability and physico-chemical factors. Oecologia 1995; 101:448-460. [PMID: 28306959 DOI: 10.1007/bf00329423] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/1994] [Accepted: 10/24/1994] [Indexed: 10/26/2022]
Abstract
A field study was conducted to evaluate the relative importance of factors affecting seedling establishment and survival on a mangrove-dominated island in Belize. An examination of spatial patterns of seedling relative densities in relation to reproductive adults and physico-chemical conditions provided correlative information on factors affecting mangrove regeneration patterns. Distance from reproductive adults explained 89-94% of the variation in relative density of Rhizophora mangle seedlings, whereas availability of resources (light and NH4) explained 73-80% of variation in Avicennia germinans seedling relative density. Just after dispersal (December), 89% of the variation in Laguncularia racemosa seedling relative density was attributable to distance from reproductive adults, but 7 months later (July) 74% of the variation was explained by intensity of flooding- and salinity-related stresses. Survivorship (after 2.5 years) of propagules and seedlings of R. mangle and A. germinans transplanted to zones of contrasting physico-chemical conditions demonstrated that: (1) mortality was highest during the establishment phase and major causes were failure to strand before viability was lost, consumption by predators and desiccation; and (2) after establishment, differences in sensitivity to physicochemical stress factors such as flooding (A. germinans) and initial orientation of the seedling axis (R. mangle) exerted a further influence on seedling survival. The results indicate that seedling recruitment in these neotropical forests is strongly influenced by dispersal patterns, differential establishment abilities and effects of physico-chemical factors that vary with elevation and distance from the shoreline.
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Affiliation(s)
- Karen L McKee
- Wetland Biogeochemistry Institute, Center for Coastal, Energy, and Environmental Resources, Louisiana State University, 70803-7511, Baton Rouge, LA, USA
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