Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in Kenya
Background The minimum set of sub-models for simulating stand dynamics on an individual-tree basis consists of tree-level models for diameter increment and survival. Ingrowth model is a necessary third component in uneven-aged management. The development of this type of model set needs data from pe...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
KeAi Communications Co., Ltd.
2014-08-01
|
| Series: | Forest Ecosystems |
| Online Access: | http://www.forestecosyst.com/content/1/1/14 |
| _version_ | 1797967987850870784 |
|---|---|
| author | Rita Juma Timo Pukkala Sergio de-Miguel Mbae Muchiri |
| author_facet | Rita Juma Timo Pukkala Sergio de-Miguel Mbae Muchiri |
| author_sort | Rita Juma |
| collection | DOAJ |
| description | Background
The minimum set of sub-models for simulating stand dynamics on an individual-tree basis consists of tree-level models for diameter increment and survival. Ingrowth model is a necessary third component in uneven-aged management. The development of this type of model set needs data from permanent plots, in which all trees have been numbered and measured at regular intervals for diameter and survival. New trees passing the ingrowth limit should also be numbered and measured. Unfortunately, few datasets meet all these requirements. The trees may not have numbers or the length of the measurement interval varies. Ingrowth trees may not have been measured, or the number tags may have disappeared causing errors in tree identification.
Methods
This article discussed and demonstrated the use of an optimization-based approach to individual-tree growth modelling, which makes it possible to utilize data sets having one or several of the above deficiencies. The idea is to estimate all parameters of the sub-models of a growth simulator simultaneously in such a way that, when simulation begins from the diameter distribution at the first measurement occasion, it yields a similar ending diameter distribution as measured in the second measurement occasion. The method was applied to Pinus patula permanent sample plot data from Kenya. In this dataset, trees were correctly numbered and identified but measurement interval varied from 1 to 13 years. Two simple regression approaches were used and compared to the optimization-based model recovery approach.
Results
The optimization-based approach resulted in far more accurate simulations of stand basal area and number of surviving trees than the equations fitted through regression analysis.
Conclusions
The optimization-based modelling approach can be recommended for growth modelling when the modelling data have been collected at irregular measurement intervals. |
| first_indexed | 2024-04-11T02:39:57Z |
| format | Article |
| id | doaj.art-5cfa1d9f0cec45d1a64c06d90ed62021 |
| institution | Directory Open Access Journal |
| issn | 2095-6355 2197-5620 |
| language | English |
| last_indexed | 2024-04-11T02:39:57Z |
| publishDate | 2014-08-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Forest Ecosystems |
| spelling | doaj.art-5cfa1d9f0cec45d1a64c06d90ed620212023-01-02T19:22:49ZengKeAi Communications Co., Ltd.Forest Ecosystems2095-63552197-56202014-08-01110.1186/s40663-014-0014-3Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in KenyaRita Juma0Timo Pukkala1Sergio de-Miguel2Mbae Muchiri3University of Eastern Finland, Joensuu 80101, Finland University of Eastern Finland, Joensuu 80101, Finland University of Eastern Finland, Joensuu 80101, Finland Kenya Forest Research Institute, Nairobi 00200, KenyaBackground The minimum set of sub-models for simulating stand dynamics on an individual-tree basis consists of tree-level models for diameter increment and survival. Ingrowth model is a necessary third component in uneven-aged management. The development of this type of model set needs data from permanent plots, in which all trees have been numbered and measured at regular intervals for diameter and survival. New trees passing the ingrowth limit should also be numbered and measured. Unfortunately, few datasets meet all these requirements. The trees may not have numbers or the length of the measurement interval varies. Ingrowth trees may not have been measured, or the number tags may have disappeared causing errors in tree identification. Methods This article discussed and demonstrated the use of an optimization-based approach to individual-tree growth modelling, which makes it possible to utilize data sets having one or several of the above deficiencies. The idea is to estimate all parameters of the sub-models of a growth simulator simultaneously in such a way that, when simulation begins from the diameter distribution at the first measurement occasion, it yields a similar ending diameter distribution as measured in the second measurement occasion. The method was applied to Pinus patula permanent sample plot data from Kenya. In this dataset, trees were correctly numbered and identified but measurement interval varied from 1 to 13 years. Two simple regression approaches were used and compared to the optimization-based model recovery approach. Results The optimization-based approach resulted in far more accurate simulations of stand basal area and number of surviving trees than the equations fitted through regression analysis. Conclusions The optimization-based modelling approach can be recommended for growth modelling when the modelling data have been collected at irregular measurement intervals.http://www.forestecosyst.com/content/1/1/14 |
| spellingShingle | Rita Juma Timo Pukkala Sergio de-Miguel Mbae Muchiri Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in Kenya Forest Ecosystems |
| title | Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in Kenya |
| title_full | Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in Kenya |
| title_fullStr | Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in Kenya |
| title_full_unstemmed | Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in Kenya |
| title_short | Evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals – a case study for Pinus patula in Kenya |
| title_sort | evaluation of different approaches to individual tree growth and survival modelling using data collected at irregular intervals a case study for pinus patula in kenya |
| url | http://www.forestecosyst.com/content/1/1/14 |
| work_keys_str_mv | AT ritajuma evaluationofdifferentapproachestoindividualtreegrowthandsurvivalmodellingusingdatacollectedatirregularintervalsacasestudyforpinuspatulainkenya AT timopukkala evaluationofdifferentapproachestoindividualtreegrowthandsurvivalmodellingusingdatacollectedatirregularintervalsacasestudyforpinuspatulainkenya AT sergiodemiguel evaluationofdifferentapproachestoindividualtreegrowthandsurvivalmodellingusingdatacollectedatirregularintervalsacasestudyforpinuspatulainkenya AT mbaemuchiri evaluationofdifferentapproachestoindividualtreegrowthandsurvivalmodellingusingdatacollectedatirregularintervalsacasestudyforpinuspatulainkenya |