Publications

Assessing differences in competitive effects among tree species in central British Columbia, Canada.

sbritwum — Wed, 07 Feb 2024 13:11:29 +0000

Assessing differences in competitive effects among tree species in central British Columbia, Canada.

Description

Research Highlights: We investigated the competitive interactions among three tree species (interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), interior spruce (Picea glauca [Moench] Voss × Picea engelmannii Engelm.), and lodgepole pine (Pinus contorta Dougl. Ex Loud. var. latifolia Englem.)) in multi-aged stands in central British Columbia, Canada. Background and Objectives: Understanding competitive interactions among tree species in mixed-species stands is fundamental to supporting silvicultural decision-making in such stands. Using the periodic annual basal area increment for single trees as our dependent variable, we investigated whether neighboring trees competed with subject trees independently of species identity. We also examined the differences in single-tree basal area growth among the three conifer species over time under different levels of competition. Materials and Methods: We developed several spatially explicit, single-tree basal area growth models for interior Douglas-fir, interior spruce, and lodgepole pine using data from 16 plots in two blocks of a long-term study (five measurements over a 21-year period) on the response to pre-commercial thinning. We compared these equations to assess whether intraspecific or interspecific competition predominated. We also examined the differences in basal area growth among the three conifer species over time under different levels of competition. Results: We found asymmetrical relationships between the conifer trees and their neighbors for all species, indicating that the main driver limiting growth in these stands is aboveground competition for light. There was evidence of higher intraspecific competition for small (<10.0 cm DBH) interior Douglas-fir in one block. However, there was no general pattern among larger subject trees with respect to the identity of neighborhood competitive effects and the equivalence of neighbors. We observed a higher level of basal area growth over time for interior Douglas-fir than for lodgepole pine and interior spruce, irrespective of the competition intensity and, not surprisingly, the growth rate declined with increasing competition levels for the three species. Conclusions: Our results provide an understanding of how interior Douglas-fir stands will develop over time and information on species interactions that could help forest managers explore different silvicultural options and their effects on individual tree growth in these complex stands

sbritwum Wed, 02/07/2024 - 07:11

Citation

Acquah, S.B., and Marshall, P.L. (2020). Assessing differences in competitive effects among tree species in central British Columbia, Canada. Forests, 11(2), 167. doi:10.3390/f11020167

Responsible party

Faculty of Forestry, University of British Columbia and CSIR-Forestry Research Institute of Ghana

Language

Author

Acquah, S.B., and Marshall, P.L

Forests and Climate Change competition; mixed-species forests; neighborhood effects; basal area increment

Changes in size inequality and growth dominance in thinned and unthinned uneven-aged interior Douglas-fir dominated stands

sbritwum — Wed, 07 Feb 2024 13:07:27 +0000

Changes in size inequality and growth dominance in thinned and unthinned uneven-aged interior Douglas-fir dominated stands

Description

This study sought to gain insight into the impact of thinning treatments on stand structure dynamics in uneven-aged interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) dominated stands in central British Columbia (BC), Canada. We applied the Gini coefficient (GC) and the growth dominance coefficient (GDc) to determine how size inequality and growth dominance changed through time in both pre-commercially thinned (PCT) and unthinned stands across a moisture gradient. We used data from 24 plots in three blocks of a long-term study on the response to PCT, comprising five measurements over a 21-year period. The stand structures of each of the thinned plots were not identical before thinning. Therefore, the GC of the post-thinning measurements was expressed as a ratio relative to the pre-thinning treatment GC, referred to as the Gini coefficient ratio (GCr), to compare changes in size inequality through time across the PCT treatments. Three PCT treatments were applied, which differed in intensity and spatial pattern. All PCT treatments were applied in such a way that size inequality was reduced immediately after thinning. Size inequality did not decrease with increasing thinning intensity. There was a non-constant decrease in GCr in the unthinned plots, but an increase in the more heavily thinned plots over time. GDc decreased with increasing thinning intensity, where smaller trees were relatively more productive as the thinning intensity increased. Over time, thinned plots on the site with limited soil moisture and the moistest site shifted from negative to zero to positive growth dominance, while the GDc in the thinned plots with moderate soil moisture remained negative. These results suggest that site characteristics impact the response to PCT in these stands, and consequently should be considered in the design of the thinning treatments.

sbritwum Wed, 02/07/2024 - 07:07

Citation

Acquah, S.B., Marshall, P.L., Eskelson, B.N.I., Moss, I., and Barbeito, I. (2022). Changes in size inequality and growth dominance in thinned and unthinned uneven-aged interior Douglas-fir dominated stands. Forest Ecology and Management, 524, 120517. doi:10.1016/j.foreco.2022.120517

Responsible party

Faculty of Forestry, University of British Columbia and CSIR-Forestry Research Institute of Ghana

Language

Author

Acquah, S.B., Marshall, P.L., Eskelson, B.N.I., Moss, I., and Barbeito, I.

Forests and Climate Change Growth dominance coefficient / Size variability / Forest stand structure / Site quality

Temporal changes in tree spatial patterns in uneven-aged interior Douglas-fir dominated stands managed under different thinning treatments

sbritwum — Wed, 07 Feb 2024 13:02:58 +0000

Temporal changes in tree spatial patterns in uneven-aged interior Douglas-fir dominated stands managed under different thinning treatments

Description

Understanding the spatial patterns of trees and their interactions can reveal the ecological processes driving forest stand structure and stand development over time. We assessed temporal changes in tree spatial patterns in uneven-aged interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) dominated stands in central British Columbia, Canada. Data were available on 24 plots in three blocks over 21 years, 18 of which had received pre-commercial thinning (PCT) treatments of varying intensity. We first applied the Clark and Evans aggregation index and the L function, a transformation of Ripley’s K function, to describe the spatial pattern of live trees in thinned and unthinned plots over time. Second, we analysed the spatial correlations between live tree diameters using the mark correlation function and the mark variogram. Third, the spatial pattern of dead trees in the unthinned plots after 21 years was analysed. Lastly, we tested the spatial relationship between dead and surviving trees in the unthinned plots. In all three blocks, the spatial patterns of live trees in the unthinned plots were clustered through time. The moderate thinning treatments had random or regular spatial patterns that remained unchanged through time, because of reduced mortality rates and low levels of ingrowth. The heavier thinning initially retained a clustered pattern at small inter-tree distances; however, this changed to a random pattern with increasing distance 15 years post-thinning and remained as such until the end of the study period. Tree diameters were not spatially autocorrelated in the thinned plots, although there was positive spatial correlation of tree diameters in the unthinned plots, probably due to competitive growth inhibition among neighbouring trees. Dead trees were primarily smaller in size and were significantly clustered at all spatial scales. The lack of spatial relationship between dead and surviving trees indicated that mortality was a random process. Our study contributes to a better understanding of how spatial patterns of trees change over time in these stands, which could help in the design of silvicultural regimes that mimic natural processes.

sbritwum Wed, 02/07/2024 - 07:02

Citation

Acquah, S.B., Marshall, P.L., Eskelson, B.N.I., and Barbeito, I. (2023). Temporal changes in tree spatial patterns in uneven-aged interior Douglas-fir dominated stands managed under different thinning treatments. Forest Ecology and Management, 528, 120640. doi: 10.1016/j.foreco.2022.120640

Responsible party

Faculty of Forestry, University of British Columbia and CSIR-Forestry Research Institute of Ghana

Language

Author

Acquah, S.B., Marshall, P.L., Eskelson, B.N.I., and Barbeito, I.

Forests and Climate Change Spatial point pattern / Tree-to-tree interactions / pre-commercial thinning / Mortality patterns

Growth responses to thinning from below in uneven-aged interior Douglas-fir dominated stands

sbritwum — Wed, 07 Feb 2024 12:55:32 +0000

Growth responses to thinning from below in uneven-aged interior Douglas-fir dominated stands

Description

We assessed the impacts of three approaches to thinning from below with varying spatial patterns on several stand and individual tree variables for interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), interior spruce (Picea glauca (Moench) Voss × Picea engelmannii Engelm.), and lodgepole pine (Pinus contorta Dougl. Ex Loud. var. latifolia Englem.) in central British Columbia, Canada. The three thinning treatments were two experimental “clumped” treatments (3 m Clumped and 5 m Clumped) and the Standard (more uniform spacing) thinning treatment that was employed operationally at that time. We used long-term data from 24 plots measured five times over 21 years. Thinning increased stand basal area increment, with the plots that received the 5 m Clumped treatment having significantly higher periodic annual relative basal area increment than the unthinned Control plots. The responses for the two clumped treatments were not any lower than the Standard. The 3 m Clumped treatment was best if one is concerned about fast recovery of the growing space; however, the 5 m Clumped spacing treatment may be preferable if higher individual tree vigour is needed for resistance and resilience to fire, insects, and disease.

sbritwum Wed, 02/07/2024 - 06:55

Citation

Acquah, S.B., Marshall, P.L., Eskelson, B.N.I., and Barbeito, I. (2023). Growth responses to thinning from below in uneven-aged interior Douglas-fir dominated stands. Canadian Journal of Forest Research, 00:1-14. doi:10.1139/cjfr-2023-0154

Responsible party

Faculty of Forestry, University of British Columbia and CSIR-Forestry Research Institute of Ghana

Language

Author

Acquah, S.B., Marshall, P.L., Eskelson, B.N.I., and Barbeito, I.

Forests and Climate Change pre-commercial thinning / long-term silviculture study / stand density / complex stands / uneven-aged

Traditional Knowledge and Consumption of Forest Plant Foods in Ghana

sbritwum — Thu, 25 Apr 2019 20:27:22 +0000

Traditional Knowledge and Consumption of Forest Plant Foods in Ghana

Description

Promoting the consumption of forest plant foods is a sustainable way of ensuring good nutrition and food security. This study assessed traditional knowledge on and use of forest plant foods in three administrative districts of Ghana and evaluated their potentials for domestication and processing. A total of 606 households were randomly selected and interviewed using enumerator-administered questionnaires. Validation workshops with 30 participants were held in each district to help identify the species mentioned. In all, 83 species belonging to 45 families were documented. Knowledge of forest plant foods was found to be higher among older respondents than younger ones, indicating an urgent need to document traditional knowledge on forest plant foods before it disappears along with the older generation. Artocarpus altilis (Parkinson) Fosberg and Tetrapleura tetraptera (Schumach. & Thonn.) Taub. were identified as potential species for domestication and processing. Domestication and processing of forest plant foods on a larger scale presents opportunity for economic development, sustainability benefits and food security.

sbritwum Thu, 04/25/2019 - 15:27

Citation

Acquah, S.B., Sraku-Lartey, M., Samar, S.B., Djagbletey, G.D. 2018. Traditional knowledge and consumption of forest plant foods in Ghana. Ghana Journal of Forestry 34(1) 49-70

Responsible party

CSIR-Forestry Research Institute of Ghana

Funding bodies

Elsevier Foundation

Attachment	Size
TK_forestplant_foods_Ghana.pdf	1.11 MB

Language

Author

Acquah, S.B., Sraku-Lartey, M., Samar, S.B., Djagbletey, G.D

Forests and People / Biodiversity, Ecosystem Services and Biological Invasions / Other Information

Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities. A Global Assessment Report. IUFRO World Series Volum 38

rprueller — Mon, 26 Nov 2018 10:17:34 +0000

Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities. A Global Assessment Report. IUFRO World Series Volum 38

Description

This report entitled "Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities" presents the outcomes of the sixth global scientific assessment undertaken in the framework of GFEP. The report reflects the importance of integrated action towards ensuring access to water for all and sustaining life on land. The provision of clean water is the most basic ecosystem service necessary for life on earth. Yet, growing demand for water caused by an increasing human population, combined with adverse effects of climate change, are creating unprecedented challenges for sustainable development.

rprueller Mon, 11/26/2018 - 04:17

Responsible party

IUFRO

Language

Author

Irena F. Creed and Meine van Noordwijk (eds.)

Forests and Forest-based Products for a Greener Future / Forests and Climate Change

The contribution of forests to national income in Ethiopia and linkages with REDD+

rprueller — Fri, 16 Mar 2018 10:51:15 +0000

The contribution of forests to national income in Ethiopia and linkages with REDD+

Description

In 2014, the Government of Ethiopia requested the UN-REDD Programme to support the country in assessing the contribution of forest ecosystems to national income in the context of the national REDD+ process. The contribution of forest ecosystems to national income is seen as a vital element of the case for forest conservation in Ethiopia. Prior to this study, no full assessment of the income derived from forest-derived goods and services had been. By assessing the full contribution of forests to market and non-market income, a more complete picture of their economic importance emerged.

The executive summary can be found at http://www.unredd.net/index.php?option=com_docman&view=download&alias=16575-the-contribution-of-forests-to-national-income-in-ethiopia-and-linkages-with-redd-executive-summary&category_slug=studies-reports-and-other-publications-560&Itemid=134

For the full report, go to http://www.unredd.net/index.php?option=com_docman&view=download&alias=16576-the-contribution-of-forests-to-national-income-in-ethiopia-and-linkages-with-redd-full-report&category_slug=studies-and-publications-1145&Itemid=134

rprueller Fri, 03/16/2018 - 05:51

Responsible party

UN-REDD Programme

Language

Forests and Forest-based Products for a Greener Future REDD+

Improving efficiency in forestry operations and forest product processing in Kenya

rprueller — Fri, 16 Mar 2018 10:46:29 +0000

Improving efficiency in forestry operations and forest product processing in Kenya

Description

This publication analyses whether increased efficiency in forestry operations and forest product processing and utilization are interesting REDD+ policies and measures for the Government of Kenya to pursue, with the potential to attract public and/or private investments to enable REDD+ implementation. In particular, the report focuses on the extent to which efficiency improvements could address supply deficiency in the forest sector, thereby reducing pressures on existing forests and related emissions.

You can find the executive summary at http://www.unredd.net/index.php?option=com_docman&view=download&alias=16574-improving-efficiency-in-forestry-operations-and-forest-product-processing-in-kenya-executive-summary&category_slug=studies-reports-and-other-publications-560&Itemid=134

The full report can be found at http://www.unredd.net/index.php?option=com_docman&view=download&alias=16573-improving-efficiency-in-forestry-operations-and-forest-product-processing-in-kenya-a-viable-redd-policy-and-measure-1&category_slug=studies-reports-and-other-publications-560&Itemid=134

rprueller Fri, 03/16/2018 - 05:46

Language

Forests and Forest-based Products for a Greener Future

Données forestières de base pour la REDD+ en Côte d'Ivoire

rprueller — Mon, 13 Nov 2017 15:17:25 +0000

Données forestières de base pour la REDD+ en Côte d'Ivoire

Description

Ce document définit la dynamique forestière en Côte d'Ivoire par télédétection concernant trois années pivot (1986, 2000, 2015) en Côte d'Ivoire. Les résultats de cette étude montrent que la couverture forestière a fortement régressé de 1986 à 2015 (7 850 864 ha en 1986, 5 095 452 ha en 2000 et 3 401 146 ha en 2015). Les taux annuels de déforestation sont de 3,04 % sur la première période et de 2,66% sur la seconde période. Les forêts de la Côte d'Ivoire ont ainsi presque disparues en dehors du Parc National de Tai et la réserve de N'zo.

https://t.co/CeraHO4JOs

rprueller Mon, 11/13/2017 - 09:17

Language

Author

FAO

Forests and Climate Change REDD-plus; Côte d'Ivoire

Vivre et se nourrir de la forêt en Afrique centrale

rprueller — Thu, 18 May 2017 08:06:12 +0000

Vivre et se nourrir de la forêt en Afrique centrale

Description

Ce livre nous emmène au coeur des zones de forêts denses et sahéliennes de l'Afrique centrale, un écosystème précieux et essentiel à la vie quotidienne de ses habitants, représentant l'un des trois principaux ensembles boisés tropicaux de la planète. Dix pays (Burundi, Cameroun, Congo, Gabon, Guinée Equatoriale, République Centrafricaine, République Démocratique du Congo, Rwanda, Sao Tomé & Principe, Tchad) abritent ces forêts et savanes, riches d'importantes ressources naturelles.

http://www.fao.org/documents/card/en/c/77dbd058-8dd4-4295-af77-23f6b28cc683/

Cette publication est l'oeuvre du personnel technique de la FAO, avec la contribution des partenaires internationaux et locaux engagés dans l'évolution des PFNL. Elle est un document précieux consacré au développement des peuples par la promotion des PFNL en Afrique centrale en vue du renforcement de la sécurité alimentaire et la lutte contre la pauvreté.

rprueller Thu, 05/18/2017 - 03:06

Responsible party

FAO, Non-wood forest products working paper no 21, 2016

Language

Author

Ndoye, O.; Vantomme, P.

Forests and Forest-based Products for a Greener Future / Biodiversity, Ecosystem Services and Biological Invasions Afrique centrale