Projects per year
Abstract
Tropical montane forests are important reservoirs of carbon and biodiversity and have a central role in the hydrological cycle. They are, however, very fragmented and degraded, leaving isolated remnants across the landscape. These montane forest remnants have considerable differences in forest structure, depending on factors such as tree species composition and degree of forest degradation. Our objectives were (1) to analyse the reliability of airborne laser scanning (ALS) in modelling forest structural heterogeneity, as described by the Gini coefficient (GC) of tree size inequality; (2) to determine whether models are improved by including tree species-sensitive spectral-temporal metrics from the Landsat time series (LTS); and (3) to evaluate differences between three forest remnants and different forest types using the resulting maps of predicted GC. The study area was situated in Taita Hills, Kenya, where indigenous montane forests have been partly replaced by single-species plantations. The data included field measurements from 85 sample plots and two ALS data sets with different pulse densities (9.6 and 3.1 pulses m(-2)). GC was modeled using beta regression. We found that GC was predicted more accurately by the ALS data set with a higher point density (a cross-validated relative root mean squared error (rRMSE(CV)) 13.9%) compared to ALS data set with lower point density (rRMSE(CV) 15.1%). Furthermore, important synergies exist between ALS and LTS metrics. When combining ALS and LTS metrics, rRMSE(CV) was improved to 12.5% and 13.0%, respectively. Therefore, if the LTS metrics are included in models, ALS data with lower pulse density are sufficient to yield similar accuracy to more expensive, higher pulse density data acquired from the lower altitude. In Ngangao and Yale, forest canopy has multiple layers of variable tree sizes, whereas elfin forests in Vuria are of more equal tree size, and the GC value ranges of the indigenous forests are 0.42-0.71, 0.20-0.74, and 0.17-0.76, respectively. The single-species plantations of cypress and pine showed lower values of GC than indigenous forests located in the same remnants in Yale, whereas Eucalyptus plantations showed GC values more similar to the indigenous forests. These results show the usefulness of GC maps for identifying and separating forest types as well as for assessing their distinctive ecologies.
Original language | English |
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Article number | 105739 |
Journal | Ecological Indicators |
Volume | 108 |
Number of pages | 16 |
ISSN | 1470-160X |
DOIs | |
Publication status | Published - Jan 2020 |
MoE publication type | A1 Journal article-refereed |
Fields of Science
- 4112 Forestry
- Forest structure
- Gini coefficient
- Spectral-temporal metrics
- LiDAR
- Africa
- EASTERN ARC MOUNTAINS
- TOPOGRAPHIC NORMALIZATION
- SPECIES-DIVERSITY
- GINI COEFFICIENT
- BOREAL FORESTS
- COVER CHANGE
- LIDAR
- MANAGEMENT
- INDEX
- BIODIVERSITY
Projects
- 4 Finished
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TAITASMART: Environmental sensing of ecosystem services for developing climate smart landscape framework to improve food security in East Africa
Pellikka, P. (Principal Investigator), Alakukku, L. (Principal Investigator), Vesala, T. (Principal Investigator), Johansson, T. (Participant), Heiskanen, J. (Participant), Räsänen, M. (Participant), Tuure, J. (Participant), Adhikari, H. (Participant), Piiroinen, R. (Participant), Abera, T. (Participant), Tang, Z. (Participant), Wachiye, S. A. (Participant), Mäkelä, P. (Participant), Karhu, K. (Participant), Di Minin, E. (Participant) & Autio, A. (Participant)
European Commission, DG International Cooperation and Development
01/03/2018 → 01/03/2022
Project: Research project
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The Ecological Context of Human Origins and its Evolutionary Significance (ECHOES):Six Million Years of Changing Herbivore Resource Use in the Turkana Basin
Fortelius, M. (Project manager)
01/09/2014 → 31/08/2018
Project: Research project
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TAITAWATER: Integrated land cover-climate-ecosystem process study for water management in East African highlands (TAITAWATER)
Pellikka, P. (Project manager), Rikkinen, J. (Participant), Minoia, P. (Participant), Hohenthal, J. (Participant), Rinne, J. (Participant) & Starr, M. (Participant)
01/09/2012 → 31/08/2016
Project: Research project