Skip to main content

Advertisement

Log in

Landscape history, time lags and drivers of change: urban natural grassland remnants in Potchefstroom, South Africa

  • Research Article
  • Published:
Landscape Ecology Aims and scope Submit manuscript

Abstract

Context

The history of the landscape directly affects biotic assemblages, resulting in time lags in species response to disturbances. In highly fragmented environments, this phenomenon often causes extinction debts. However, few studies have been carried out in urban settings.

Objectives

To determine if there are time lags in the response of temperate natural grasslands to urbanization. Does it differ for indigenous species and for species indicative of disturbance and between woody and open grasslands? Do these time lags change over time? What are the potential landscape factors driving these changes? What are the corresponding vegetation changes?

Methods

In 1995 and 2012 vegetation sampling was carried out in 43 urban grassland sites. We calculated six urbanization and landscape measures in a 500 m buffer area surrounding each site for 1938, 1961, 1970, 1994, 1999, 2006, and 2010. We used generalized linear models and model selection to determine which time period best predicted the contemporary species richness patterns.

Results

Woody grasslands showed time lags of 20–40 years. Contemporary open grassland communities were, generally, associated with more contemporary landscapes. Altitude and road network density of natural areas were the most frequent predictors of species richness. The importance of the predictors changed between the different models. Species richness, specifically, indigenous herbaceous species, declined from 1995 to 2012.

Conclusions

The history of urbanization affects contemporary urban vegetation assemblages. This indicates potential extinction debts, which have important consequences for biodiversity conservation planning and sustainable future scenarios.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

References

  • Adriaens D, Honnay O, Hermy M (2006) No evidence of a plant extinction debt in highly fragmented calcareous grasslands in Belgium. Biol Conserv 133(2):212–224

    Article  Google Scholar 

  • Anderson JE, Inouye RS (2001) Landscape-scale changes in plant species abundance and biodiversity of a sagebrush steppe over 45 years. Ecol Monogr 71(4):531–556

    Article  Google Scholar 

  • Andersson E, Ahrné K, Pyykönen M, Elmqvist T (2009) Patterns and scale relations among urbanization measures in Stockholm, Sweden. Landscape Ecol 24(10):1331–1339

    Article  Google Scholar 

  • Beyer HL (2006) Hawth’s analysis tools version 3.27

  • Bezuidenhout H, Bredenkamp GJ (1990) A reconnaissance survey of the vegetation of the dolomitic region in the Potchefstroom-Ventersdorp-Randfontein area, South Africa. Phytocoenologia 18:387–403

    Article  Google Scholar 

  • Bezuidenhout H, Bredenkamp GJ (1991) The vegetation of the Bc land type in the western Transvaal Grassland, South Africa. Phytocoenologia 19:497–518

    Article  Google Scholar 

  • Bezuidenhout H, Bredenkamp GJ, Theron GK (1994a) A classification of the vegetation of the western Transvaal dolomite and chert grassland, South Africa. S Afr J Bot 60(3):152–161

    Article  Google Scholar 

  • Bezuidenhout H, Bredenkamp GJ, Theron GK (1994b) Syntaxonomy of the vegetation of the Fb land type in the western Transvaal grassland, South Africa. S Afr J Bot 60(1):72–81

    Article  Google Scholar 

  • Boone CG, Cadenasso ML, Grove JM, Schwarz K, Buckley GL (2009) Landscape, vegetation characteristics, and group identity in an urban and suburban watershed: why the 60 s matter. Urban Ecosyst 13(3):255–271

    Article  Google Scholar 

  • Bredenkamp GJ, Theron GK (1978) A synecological account of the Suikerbosrand Nature Reserve 1. The phytosociology of the Witwatersrand geological system. Bothalia 12:513–529

    Article  Google Scholar 

  • Bredenkamp GJ, Bezuidenhout H, Naude C, Joubert H (1994) The vegetation of the Boskop Dam Nature Reserve, Potchefstroom. Koedoe 37(1):19–33

    Article  Google Scholar 

  • Bredenkamp GJ, Joubert AF, Bezuidenhout H (1989) A reconnaissance survey of the plains of the Potchefstroom-Parys-Fochville area. S Afr J Bot 55:199–206

    Article  Google Scholar 

  • Brooks TM, Pimm SL, Oyugi JO (1999) Time lag between deforestation and bird extinction in tropical foreat fragments. Conserv Biol 13(5):1140–1150

    Article  Google Scholar 

  • Burel F (1993) Time lags between spatial pattern changes and species distribution changes in dynamic landscapes. Landscape Urban Plan 24:161–166

    Article  Google Scholar 

  • Chapin FS III, Starfield AM (1997) Time lags and novel ecosystems in response to transient climatic change in arctic Alaska. Clim Change 35:449–461

    Article  Google Scholar 

  • Chiba S, Okochi I, Ohbayashi T, Miura D, Mori H, Kimura K, Wada S (2009) Effects of habitat history and extinction selectivity on species-richness patterns of an island land snail fauna. J Biogeogr 36(10):1913–1922

    Article  Google Scholar 

  • Chocholoušková Z, Pyšek P (2003) Changes in composition and structure of urban flora over 120 years: a case study of the city of Plzeň. Flora 198(5):366–376

    Article  Google Scholar 

  • Cilliers SS, Bredenkamp GJ (1998) Vegetation analysis of railway reserves in the Potchefstroom municipal area, North West Province, South Africa. S Afr J Bot 64(5):271–280

    Article  Google Scholar 

  • Cilliers SS, Bredenkamp GJ (1999) Ruderal and degraded natural vegetation on vacant lots in the Potchefstroom Municipal Area, North West Province, South Africa. S Afr J Bot 65(2):163–173

    Article  Google Scholar 

  • Cilliers SS, Bredenkamp GJ (2000) Vegetation of road verges on an urbanisation gradient in Potchefstroom, South Africa. Landscape Urban Plan 46:217–239

    Article  Google Scholar 

  • Cilliers S, Schoeman L, Bredenkamp G (1998) Wetland plant communities in the Potchefstroom Municipal area, North-west, South Africa. Bothalia 28(2):213–229

    Article  Google Scholar 

  • Cilliers SS, Van Wyk E, Bredenkamp GJ (1999) Urban nature conservation: vegetation of natural areas in the Potchefstroom municipal area, North West Province, South Africa. Koedoe 42(1):1–30

    Article  Google Scholar 

  • Cilliers SS, Williams NSG, Barnard FJ (2008) Patterns of exotic plant invasions in fragmented urban and rural grasslands across continents. Landscape Ecol 23(10):1243–1256

    Article  Google Scholar 

  • Clarke KR, Gorley RN (2006) PRIMER v6: user manual/tutorial. PRIMER-E, Plymouth

    Google Scholar 

  • Crooks JA (2005) Lag times and exotic species: the ecology and management of biological invasions in slow-motion. Ecoscience 12(3):316–329

    Article  Google Scholar 

  • Daehler CC (2009) Short lag times for invasive tropical plants: evidence from experimental plantings in Hawai’i. PLoS One 4(2):e4462

    Article  PubMed  PubMed Central  Google Scholar 

  • Dauber J, Hirsch M, Simmering D, Waldhardt R, Otte A, Wolters V (2003) Landscape structure as an indicator of biodiversity: matrix effects on species richness. Agric Ecosyst Environ 98(1–3):321–329

    Article  Google Scholar 

  • Davis MB (1986) Climatic instability, time lags, and community disequilibrium. In: Diamond J, Case TJ (eds) Community ecology. Harper & Row, New York, pp 269–284

    Google Scholar 

  • Deng X, Huang J, Huang Q, Rozelle S, Gibson J (2011) Do roads lead to grassland degradation or restoration? A case study in Inner Mongolia, China. Environ Dev Econ 16(06):751–773

    Article  Google Scholar 

  • du Toit MJ (2009) Grassland ecology along an urban–rural gradient using GIS techniques in Klerksdorp, South Africa. North-West University, Potchefstroom. http://hdl.handle.net/10394/4197

  • du Toit MJ, Cilliers SS (2011) Aspects influencing the selection of representative urbanization measures to quantify urban–rural gradients. Landscape Ecol 26(2):169–181

    Article  Google Scholar 

  • Duguay S, Eigenbrod F, Fahrig L (2006) Effects of surrounding urbanization on non-native flora in small forest patches. Landscape Ecol 22(4):589–599

    Article  Google Scholar 

  • Dullinger S, Essl F, Rabitsch W, Erb K-H, Gingrich S, Haberl H, Hülber K, Jarošík V, Krausmann F, Kühn I, Pergl J, Pyšek P, Hulme PE (2013) Europe’s other debt crisis caused by the long legacy of future extinctions. Proc Natl Acad Sci 110(18):7342–7347

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Dupouey JL, Dambrine E, Laffite JD, Moares C (2002) Irreversible impact of past land use on forest soils and biodiversity. Ecology 83(11):2978–2984

    Article  Google Scholar 

  • Dupré C, Ehrlén J (2002) Habitat configuration, species traits and plant distributions. J Ecol 90(5):796–805

    Article  Google Scholar 

  • Eckhardt H, Van Rooyen N, Bredenkamp G (1993) Use of Braun-Blanquet data for the assessment of veld condition and grazing capacity in grassland. Afr J Range Forage Sci 10(1):41–46

    Article  Google Scholar 

  • ESRI (2010) ArcGIS, version 10.0. Environmental Systems Research Institude, Redlands, CA

  • Ewers RM, Didham RK (2006) Confounding factors in the detection of species responses to habitat fragmentation. Biol Rev Camb Philos Soc 81(1):117–142

    Article  PubMed  Google Scholar 

  • Foster D, Swanson F, Aber J, Burke I, Brokaw N, Tilman D, Knapp A (2003) The importance of land-use legacies to ecology and conservation. Bioscience 53(1):77–88

    Article  Google Scholar 

  • Foster DR (1992) Land-use history (1730–1990) and vegetation dynamics in central New England, USA. J Ecol 80(4):753–771

    Article  Google Scholar 

  • Friedel MH (1987) A preliminary investigation of woody plant increase in the western Transvaal and implications for veld assessment. J Grassl Soc South Afr 4(1):25–30

    Article  Google Scholar 

  • Gelbard JL, Belnap J (2003) Roads as conduits for exotic plant invasions in a semiarid landscape. Conserv Biol 17(2):420–432

    Article  Google Scholar 

  • Godefroid S, Koedam N (2003) Distribution pattern of the flora in a peri-urban forest: an effect of the city–forest ecotone. Landscape Urban Plan 65(4):169–185

    Article  Google Scholar 

  • Grove JM, Locke DH, O’Neil-Dunne JP (2014) An ecology of prestige in New York City: examining the relationships among population density, socio-economic status, group identity, and residential canopy cover. Environ Manag 54(3):402–419

    Article  Google Scholar 

  • Gustavsson E, Lennartsson T, Emanuelsson M (2007) Land use more than 200 years ago explains current grassland plant diversity in a Swedish agricultural landscape. Biol Conserv 138(1–2):47–59

    Article  Google Scholar 

  • Hahs AK, McDonnell MJ (2006) Selecting independent measures to quantify Melbourne’s urban–rural gradient. Landscape Urban Plan 78(4):435–448

    Article  Google Scholar 

  • Hahs AK, McDonnell MJ, McCarthy MA, Vesk PA, Corlett RT, Norton BA, Clemants SE, Duncan RP, Thompson K, Schwartz MW, Williams NS (2009) A global synthesis of plant extinction rates in urban areas. Ecol Lett 12(11):1165–1173

    Article  PubMed  Google Scholar 

  • Hamburg SP, Sanford RL Jr (1986) Disturbance, “Homo Sapiens,” and ecology. Bull Ecol Soc Am 67(2):169–171

    Google Scholar 

  • Hansen MJ, Clevenger AP (2005) The influence of disturbance and habitat on the presence of non-native plant species along transport corridors. Biol Conserv 125(2):249–259

    Article  Google Scholar 

  • Hanski I, Ovaskainen O (2002) Extinction debt at extinction threshold. Conserv Biol 16(3):666–673

    Article  Google Scholar 

  • Hayashida FM (2005) Archaeology, ecological history, and conservation. Annu Rev Anthropol 34:43–65

    Article  Google Scholar 

  • Helm A, Hanski I, Partel M (2006) Slow response of plant species richness to habitat loss and fragmentation. Ecol Lett 9(1):72–77

    PubMed  Google Scholar 

  • Janišová M, Michalcová D, Bacaro G, Ghisla A (2014) Landscape effects on diversity of semi-natural grasslands. Agric Ecosyst Environ 182:47–58

    Article  Google Scholar 

  • Jansen van Rensburg JP (2010) Investigation of the microbial diversity and functionality of soil in fragmented South African grasslands along an urbanization gradient. North-West University, Potchefstroom

  • Kark S, van Rensburg BJ (2006) Ecotones: marginal or central areas of transition? Isr J Ecol Evol 52(1):29–53

    Article  Google Scholar 

  • Kissling M, Hegetschweiler KT, Rusterholz H-P, Baur B (2009) Short-term and long-term effects of human trampling on above-ground vegetation, soil density, soil organic matter and soil microbial processes in suburban beech forests. Appl Soil Ecol 42(3):303–314

    Article  Google Scholar 

  • Kleijn D, Kohler F, Baldi A, Batary P, Concepcion ED, Clough Y, Diaz M, Gabriel D, Holzschuh A, Knop E, Kovacs A, Marshall EJ, Tscharntke T, Verhulst J (2009) On the relationship between farmland biodiversity and land-use intensity in Europe. Proc Biol Sci 276(1658):903–909

    Article  CAS  PubMed  Google Scholar 

  • Koerner W, Dupouey JL, Dambrine E, Benoit M (1997) Influence of past land use on the vegetation and soils of present day forest in the vosges mountains, France. J Ecol 85(3):351–358

    Article  Google Scholar 

  • Koyanagi T, Kusumoto Y, Yamamoto S, Okubo S, Iwasaki N, Takeuchi K (2012) Grassland plant functional groups exhibit distinct time-lags in response to historical landscape change. Plant Ecol 213(2):327–338

    Article  Google Scholar 

  • Kraaij T, Ward D (2006) Effects of rain, nitrogen, fire and grazing on tree recruitment and early survival in bush-encroached savanna, South Africa. Plant Ecol 186(2):235–246

    Article  Google Scholar 

  • Krauss J, Bommarco R, Guardiola M, Heikkinen RK, Helm A, Kuussaari M, Lindborg R, Ockinger E, Partel M, Pino J, Poyry J, Raatikainen KM, Sang A, Stefanescu C, Teder T, Zobel M, Steffan-Dewenter I (2010) Habitat fragmentation causes immediate and time-delayed biodiversity loss at different trophic levels. Ecol Lett 13(5):597–605

    Article  PubMed  PubMed Central  Google Scholar 

  • Kuussaari M, Bommarco R, Heikkinen RK, Helm A, Krauss J, Lindborg R, Ockinger E, Partel M, Pino J, Roda F, Stefanescu C, Teder T, Zobel M, Steffan-Dewenter I (2009) Extinction debt: a challenge for biodiversity conservation. Trends Ecol Evol 24(10):564–571

    Article  PubMed  Google Scholar 

  • Laurance WF (2002) Hyperdynamism in fragmented habitats. J Veg Sci 13(4):595

    Article  Google Scholar 

  • Lawson DM, Lamar CK, Schwartz MW (2008) Quantifying plant population persistence in human-dominated landscapes [Cuantificación de la Persistencia de Poblaciones de Plantas en Paisajes Dominados por Humanos]. Conserv Biol 22(4):922–928

    Article  PubMed  Google Scholar 

  • Lindborg R, Eriksson O (2004) Historical landscape connectivity affects present plant species diversity. Ecology 85(7):1840–1845

    Article  Google Scholar 

  • Lloyd AH (2005) Ecological histories from Alaskan tree lines provide insight into future change. Ecology 86(7):1687–1695

    Article  Google Scholar 

  • Locke DH, Baine G (2014) The good, the bad, and the interested: how historical demographics explain present-day tree canopy, vacant lot and tree request spatial variability in New Haven, CT. Urban Ecosyst 18(2):391–409

    Article  Google Scholar 

  • Louw WJ (1951) An ecological account of the vegetation of the Potchefstroom area. Memoirs of the botanical survey of South Africa, no. 24

  • Luck GW, Smallbone LT, O’Brien R (2009) Socio-economics and vegetation change in urban ecosystems: patterns in space and time. Ecosystems 12(4):604–620

    Article  Google Scholar 

  • Madubansi M, Shackleton CM (2007) Changes in fuelwood use and selection following electrification in the Bushbuckridge lowveld, South Africa. J Environ Manag 83(4):416–426

    Article  CAS  Google Scholar 

  • Magnuson JJ (1990) Long-term ecological research and the invisible present. Bioscience 40(7):495–501

    Article  Google Scholar 

  • McDonnell MJ, Hahs AK (2013) The future of urban biodiversity research: moving beyond the ‘low-hanging fruit’. Urban Ecosyst 16(3):397–409

    Article  Google Scholar 

  • Monger C, Sala OE, Duniway MC, Goldfus H, Meir IA, Poch RM, Throop HL, Vivoni ER (2015) Legacy effects in linked ecological–soil–geomorphic systems of drylands. Front Ecol Environ 13(1):13–19

    Article  Google Scholar 

  • Morgan J (1995) Ecological studies of the endangered Rutidosis leptorrhynchoides. II. Patterns of seedling emergence and survival in a native grassland. Aust J Bot 43(1):13–24

    Article  Google Scholar 

  • Morgan JW (1998) Composition and seasonal flux of the soil seed bank of species-rich Themeda triandra grasslands in relation to burning history. J Veg Sci 9:145–156

    Article  Google Scholar 

  • Mucina L, Rutherford MC (eds) (2006) The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria

  • Mueller-Dombois D, Ellenberg H (1974) Aims and methods of plant ecology. Wiley, New York

    Google Scholar 

  • Neser L (1967) Die Kleurlinge van Potchefstroom:’n algemene kultuurbeeld met besondere verwysing na gesinsgebruike. Potchefstroomse Universiteit vir Christelike Hoër Onderwys

  • O’Connor TG (1991) Local extinction in perennial grasslands: a life-history approach. Am Nat 137(6):753–773

    Article  Google Scholar 

  • Pickett ST, Cadenasso ML, Grove JM, Groffman PM, Band LE, Boone CG, Burch WR, Grimmond CSB, Hom J, Jenkins JC (2008) Beyond urban legends: an emerging framework of urban ecology, as illustrated by the Baltimore Ecosystem Study. Bioscience 58(2):139–150

    Article  Google Scholar 

  • Purschke O, Sykes MT, Reitalu T, Poschlod P, Prentice HC (2012) Linking landscape history and dispersal traits in grassland plant communities. Oecologia 168(3):773–783

    Article  PubMed  Google Scholar 

  • R Core Team (2013) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://R-project.org/

  • Ramalho CE, Hobbs RJ (2012) Time for a change: dynamic urban ecology. Trends Ecol Evol 27(3):179–188

    Article  PubMed  Google Scholar 

  • Retief E, Herman PPJ (1997) Plants of the northern provinces of South Africa: keys and diagnostic characters. Strelitzia 6. South African National Biodiversity Institute, Pretoria

  • Rhemtulla JM, Mladenoff DJ, Clayton MK (2009) Legacies of Historical Land Use on Regional Forest Composition and Structure in Wisconsin, USA (Mid-1800s-1930s-2000s). Ecol Appl 19(4):1061–1078

    Article  PubMed  Google Scholar 

  • Risser PG (1995) The status of the science examining ecotones. Bioscience 45(5):318–325

    Article  Google Scholar 

  • Romme WH, Knight DH (1982) Landscape diversity: the concept applied to Yellowstone Park. Bioscience 32(8):664–670

    Article  Google Scholar 

  • Sakai AK, Allendorf FW, Holt JS, Lodge DM, Molofsky J, With KA, Baughman S, Cabin RJ, Cohen JE, Ellstrand NC, McCauley DE, O'Neil P, Parker IM, Thompson JN, Weller SG (2001) The population biology of invasive species. Annu Rev Ecol Syst 32:305–332

    Article  Google Scholar 

  • Shannon CE (1948) A mathematical theory of communication. Bell Syst Tech J 27(379–423):623–656

    Article  Google Scholar 

  • Smit PA (1989) Die ekonomiese ontwikkeling van Potchefstroom vanaf 1902 tot 1945. Potchefstroom University for CHE, Potchefstroom

  • Stehlik I, Caspersen JP, Wirth LEA, Holderegger R (2007) Floral free fall in the Swiss lowlands: environmental determinants of local plant extinction in a peri-urban landscape. J Ecol 95(4):734–744

    Article  Google Scholar 

  • Tait CJ, Daniels CB, Hill RS (2005) Changes in species assemblages within the Adelaide Metropolitan Area, Australia, 1836–2002. Ecol Appl 15(1):346–359

    Article  Google Scholar 

  • Tilman D, Fargione J, Wolff B, D'Antonio C, Dobson A, Howarth R, Schindler D, Schlesinger WH, Simberloff D, Swackhamer D (2001) Forecasting agriculturally driven global environmental change. Science 292(5515):281–284

    Article  CAS  PubMed  Google Scholar 

  • Tilman D, May RM, Lehman CL, Nowak MA (1994) Habitat destruction and the extinction debt. Nature 371:65–66

    Article  Google Scholar 

  • Tlokwe City Council (2015) Business overview. http://www.potch.co.za/cdepstatment.htm. Accessed 25 April 2015

  • Tscharntke T, Klein AM, Kruess A, Steffan-Dewenter I, Thies C (2005) Landscape perspectives on agricultural intensification and biodiversity—ecosystem service management. Ecol Lett 8(8):857–874

    Article  Google Scholar 

  • Vakhlamova T, Rusterholz H-P, Kanibolotskaya Y, Baur B (2014) Changes in plant diversity along an urban–rural gradient in an expanding city in Kazakhstan, Western Siberia. Landscape Urban Plan 132:111–120

    Article  Google Scholar 

  • Van Auken OW (2009) Causes and consequences of woody plant encroachment into western North American grasslands. J Environ Manag 90(10):2931–2942

    Article  Google Scholar 

  • van den Bergh G (1990) Voortrekker plaasbesetting op die Transvaalse Hoëveld: ‘n versteurde beeld. S Afr J Surv Mapp 20( Part 7):301–311

    Google Scholar 

  • van den Bergh G (1992) Die tweede Potchefstroom, opmeting en besetting 1841-60. S Afr J Surv Mapp 21(Part 4):167–178

    Google Scholar 

  • van der Walt L (2013) Landscape functionality and plant diversity of grassland fragments along an urban–rural gradient in the Tlokwe Municipal area, South Africa. North-West University, Potchefstroom. http://hdl.handle.net/10394/9732

  • Ward D (2005) Do we understand the causes of bush encroachment in African savannas? Afr J Range Forage Sci 22(2):101–105

    Article  Google Scholar 

  • Williams NSG, Morgan JW, McCarthy MA, McDonnell MJ (2006) Local extinction of grassland plants: the landscape matrix is more important than patch attributes. Ecology 87(12):3000–3006

    Article  PubMed  Google Scholar 

  • Williams NSG, Morgan JW, McDonnell MJ, McCarthy MA (2005) Plant traits and local extinctions in natural grasslands along an urban–rural gradient. J Ecol 93(6):1203–1213

    Article  Google Scholar 

Download references

Acknowledgments

We would like to thank the South African Weather Service for long-term climate data of Potchefstroom and the National Research Foundation (NRF) for financial assistance towards the studies of MJDT and incentive funding for SSC.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Marié J. du Toit.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary material 1 (DOCX 1892 kb)

Supplementary material 2 (DOCX 49 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

du Toit, M.J., Kotze, D.J. & Cilliers, S.S. Landscape history, time lags and drivers of change: urban natural grassland remnants in Potchefstroom, South Africa. Landscape Ecol 31, 2133–2150 (2016). https://doi.org/10.1007/s10980-016-0386-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10980-016-0386-6

Keywords

Navigation