Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded Woodlands
Tree density is an important parameter affecting ecosystems functions and management decisions, while tree distribution patterns affect sampling design. Pittosporum undulatum stands in the Azores are being targeted with a biomass valorization program, for which efficient tree density estimators are...
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| Format: | Article |
| Language: | English |
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Wiley
2017-01-01
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| Series: | International Journal of Forestry Research |
| Online Access: | http://dx.doi.org/10.1155/2017/2818132 |
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| _version_ | 1841524546705817600 |
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| author | Lurdes Borges Silva Mário Alves Rui Bento Elias Luís Silva |
| author_facet | Lurdes Borges Silva Mário Alves Rui Bento Elias Luís Silva |
| author_sort | Lurdes Borges Silva |
| collection | DOAJ |
| description | Tree density is an important parameter affecting ecosystems functions and management decisions, while tree distribution patterns affect sampling design. Pittosporum undulatum stands in the Azores are being targeted with a biomass valorization program, for which efficient tree density estimators are required. We compared T-Square sampling, Point Centered Quarter Method (PCQM), and N-tree sampling with benchmark quadrat (QD) sampling in six 900 m2 plots established at P. undulatum stands in São Miguel Island. A total of 15 estimators were tested using a data resampling approach. The estimated density range (344–5056 trees/ha) was found to agree with previous studies using PCQM only. Although with a tendency to underestimate tree density (in comparison with QD), overall, T-Square sampling appeared to be the most accurate and precise method, followed by PCQM. Tree distribution pattern was found to be slightly aggregated in 4 of the 6 stands. Considering (1) the low level of bias and high precision, (2) the consistency among three estimators, (3) the possibility of use with aggregated patterns, and (4) the possibility of obtaining a larger number of independent tree parameter estimates, we recommend the use of T-Square sampling in P. undulatum stands within the framework of a biomass valorization program. |
| format | Article |
| id | doaj-art-65c966210f7b4b47b1db73a901133c4d |
| institution | Kabale University |
| issn | 1687-9368 1687-9376 |
| language | English |
| publishDate | 2017-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | International Journal of Forestry Research |
| spelling | doaj-art-65c966210f7b4b47b1db73a901133c4d2025-02-03T05:52:53ZengWileyInternational Journal of Forestry Research1687-93681687-93762017-01-01201710.1155/2017/28181322818132Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded WoodlandsLurdes Borges Silva0Mário Alves1Rui Bento Elias2Luís Silva3InBIO, Rede de Investigação em Biodiversidade e Biologia Evolutiva, Laboratório Associado, CIBIO-Açores, Universidade dos Açores, Açores, 9501-801 Ponta Delgada, PortugalNATURALREASON, LDA, Caminho do Meio Velho, 5-B, Açores, 9760-114 Cabo da Praia, PortugalCentre for Ecology, Evolution and Environmental Changes (CE3C), Azorean Biodiversity Group and Universidade dos Açores, Faculdade de Ciências Agrárias e do Ambiente, Açores, 9700-042 Angra do Heroísmo, PortugalInBIO, Rede de Investigação em Biodiversidade e Biologia Evolutiva, Laboratório Associado, CIBIO-Açores, Universidade dos Açores, Açores, 9501-801 Ponta Delgada, PortugalTree density is an important parameter affecting ecosystems functions and management decisions, while tree distribution patterns affect sampling design. Pittosporum undulatum stands in the Azores are being targeted with a biomass valorization program, for which efficient tree density estimators are required. We compared T-Square sampling, Point Centered Quarter Method (PCQM), and N-tree sampling with benchmark quadrat (QD) sampling in six 900 m2 plots established at P. undulatum stands in São Miguel Island. A total of 15 estimators were tested using a data resampling approach. The estimated density range (344–5056 trees/ha) was found to agree with previous studies using PCQM only. Although with a tendency to underestimate tree density (in comparison with QD), overall, T-Square sampling appeared to be the most accurate and precise method, followed by PCQM. Tree distribution pattern was found to be slightly aggregated in 4 of the 6 stands. Considering (1) the low level of bias and high precision, (2) the consistency among three estimators, (3) the possibility of use with aggregated patterns, and (4) the possibility of obtaining a larger number of independent tree parameter estimates, we recommend the use of T-Square sampling in P. undulatum stands within the framework of a biomass valorization program.http://dx.doi.org/10.1155/2017/2818132 |
| spellingShingle | Lurdes Borges Silva Mário Alves Rui Bento Elias Luís Silva Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded Woodlands International Journal of Forestry Research |
| title | Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded Woodlands |
| title_full | Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded Woodlands |
| title_fullStr | Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded Woodlands |
| title_full_unstemmed | Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded Woodlands |
| title_short | Comparison of T-Square, Point Centered Quarter, and N-Tree Sampling Methods in Pittosporum undulatum Invaded Woodlands |
| title_sort | comparison of t square point centered quarter and n tree sampling methods in pittosporum undulatum invaded woodlands |
| url | http://dx.doi.org/10.1155/2017/2818132 |
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