Belinho 1 Shipwreck by Peter Groenendijk
Within the past four years, a multidisciplinary and innovative investigation focusing on the reco... more Within the past four years, a multidisciplinary and innovative investigation focusing on the recording and analysis of ship timbers` parent trees has led to significant advances in archaeological research methods. The 3D digital reconstruction of ship timbers` parent trees
facilitates a better understanding of the timber requirements, and related forestry practices, of the shipbuilding industry during the Iberian Age of Discovery.
An aggressive Iberian expansionist policy increased the demand for timber and led to the implementation of forest regulations and the imposition of programs for tree planting. Forest regeneration became threatened by the increased exploitation of timber for not only
shipbuilding but also agricultural intensification and urban growth. In Iberia, a perceived lack of appropriate local timber led to increases in timber importation, arguably leading to the interruption of the shipyards carpenter`s intimate relation with the woodlands.
The increasing pressure to build larger ships imposed by the crown and merchantmen changed the paradigm in Iberian shipbuilding from the 15th -century onwards. The “perfect timber log” was no longer available in the shipyards. Therefore, it became crucial to investigate potential shifts in shipbuilding technology and technique by analysing the growth pattern, wood morphologies and growth patterns of the shipwrecks surviving timbers. By adopting a dendroarchaeological approach, a multidisciplinary team aimed to analyse detailed information collected from a selection of Iberian shipwrecks. A 3D digital record was produced for the surviving timbers of three early Iberian ships: Belinho 1, Cais do Sodre and Corpo Santo. The species, morphologies and growth patterns of individual timbers were recorded and combined with data collected about their shapes, tool marks and other shipbuilding features allowed to reconstruct individual parent trees and pointed to the reconstruction of the ships` hull.
This paper will present the results from the investigation undertaken on the ships timber and parent tree`s morphologies employed in the construction of the vessels mentioned above.
Preliminary catalog of the Belinho 1 Shipwreck timbers analyzed in the summer of 2015.
Papers by Peter Groenendijk
Dry-season climate drives interannual variability in tropical tree growth
<p>Tropical and subtropical ecosystems are ... more <p>Tropical and subtropical ecosystems are primarily responsible for the large inter-annual variability (IAV) in the global carbon land sink. The response of tropical vegetation productivity to climatic variation likely drives this IAV, but the climate sensitivity of key productivity components are poorly understood. Tree-ring analysis can help fill this knowledge gap by estimating IAV in woody biomass growth, the major carbon accumulation process in tropical vegetation.</p><p> </p><p>Here, we evaluate the climate responses of woody biomass growth throughout the global tropics. Using an unprecedented compilation of tropical tree-ring data, we test hypotheses that (1) precipitation (P) and maximum temperature (T<sub>max</sub>) have opposite and additive effects on annual tree growth, (2) these climate responses amplify with increasing aridity and (3) wet-season climate is a more important driver of growth than dry-season climate.</p><p> </p><p>We established a network of 347 tree-ring width chronologies compiled from (sub-)tropical latitudes, representing 99 tree species on five continents and obtained from contributors (n=112) and the International Tree-Ring Data Bank (ITRDB; n=235). Our network is climatologically representative for 66% of the pantropical land area with woody vegetation.</p><p> </p><p>To test hypotheses we re-developed standardized ring-width index (RWI) chronologies and assessed climate responses using SOM cluster analysis (monthly P and T<sub>max</sub>) and multiple regression analysis (seasonal P and T<sub>max</sub>). Our results were consistent with hypothesis 1: effects of monthly or seasonal P and T<sub>max</sub> on tree growth were indeed additive and opposite, suggesting water availability to be the primary driver of tropical tree growth. In accordance with hypothesis 2, these climate responses were stronger at sites with lower mean annual precipitation or a larger annual water deficit. However, our results contrast those expected under hypothesis 3. Three of the four clusters show a dominant role of dry-season climate on annual tree growth and regression analyses confirmed this strong dry-season role.</p><p> </p><p>The strong dry-season effect on tropical tree growth seemingly contrasts the general notion that tropical vegetation productivity peaks during the wet season but is consistent with studies showing that climatologically benign dry seasons increase reserve storage and xylem growth. We posit that dry-season climate constrains the magnitude of woody biomass growth that takes place during the following wet season, and thus contributes to IAV in tree growth.</p><p> </p><p>By providing field-based insights on climate sensitivity of tropical vegetation productivity, our study contributes to the major task in Earth system science of quantifying, understanding, and predicting the IAV of the carbon land sink.</p>
Implementing sustainable forest management requires basic information on growth, ages, reproducti... more Implementing sustainable forest management requires basic information on growth, ages, reproduction and survival of exploited tree species. This information is generally derived from permanent sample plots in which individual trees are monitored. Accurately estimating growth rates and especially tree ages from plots is however challenging, as plots often contain only few individuals of the exploited species and monitoring periods cover only a fraction of the lifespan of most trees. Alternatively, tree-ring analysis is increasingly used to obtain accurate age estimates and growth rates for tropical tree species, especially in regions with seasonally harsh conditions. However, for species from wet tropical forests (>4000 mm yr-1 rainfall) few tree-ring studies exist. Under persistent high levels of rainfall, formation of distinct tree rings is uncertain due to the lack of strong seasonal variation in climate factors. Here we evaluated the potential of applying tree-ring analysis on commercial tree species in a wet tropical forest in Central-Africa. For this purpose we screened the wood anatomy of 22 tree species for the presence of tree-ring structures and, on a subset of five species, we assessed crossdating potential and evaluated the annual character of treering formation by radiocarbon dating. A total of 14 of the 22 tree species showed distinct tree-ring boundaries. Radiocarbon proved annual tree-ring formation in four of the five tested species. Crossdating between trees was problematic for all species and prohibited to exactly date each detected ring and build tree-ring chronologies. We also show that diameter growth rates vary strongly between and among species, with important consequences for the calculation of future timber yields. Tree-ring analysis can thus be applied on tree species growing in wet tropical forests to obtain growth rates. We argue that tree-ring analysis should actually be applied on more tree species from different areas to obtain accurate, site specific growth data. This data is urgently required to design and improve sustainable forest management practices.
Tropical forests and climate change: understanding links to prodict future responses
Dendrochronologia, Feb 1, 2022
This publication is made publicly available in the institutional repository of Wageningen Univers... more This publication is made publicly available in the institutional repository of Wageningen University and Research, under the terms of article 25fa of the Dutch Copyright Act, also known as the Amendment Taverne. This has been done with explicit consent by the author. Article 25fa states that the author of a short scientific work funded either wholly or partially by Dutch public funds is entitled to make that work publicly available for no consideration following a reasonable period of time after the work was first published, provided that clear reference is made to the source of the first publication of the work. This publication is distributed under The Association of Universities in the Netherlands (VSNU) 'Article 25fa implementation' project. In this project research outputs of researchers employed by Dutch Universities that comply with the legal requirements of Article 25fa of the Dutch Copyright Act are distributed online and free of cost or other barriers in institutional repositories. Research outputs are distributed six months after their first online publication in the original published version and with proper attribution to the source of the original publication. You are permitted to download and use the publication for personal purposes. All rights remain with the author(s) and / or copyright owner(s) of this work. Any use of the publication or parts of it other than authorised under article 25fa of the Dutch Copyright act is prohibited. Wageningen University & Research and the author(s) of this publication shall not be held responsible or liable for any damages resulting from your (re)use of this publication.
Forest Ecology and Management, Sep 1, 2017
Worldwide, over 400 million hectares of tropical forests are set aside for timber production. Sev... more Worldwide, over 400 million hectares of tropical forests are set aside for timber production. Several certification schemes exist to ensure more sustainable exploitation and large areas of production forests are currently certified. Under such schemes, logging companies are required to evaluate whether species are not overexploited and, if necessary, adapt their logging activities. However, the data needed to project exploitation intensities-growth, mortality and regeneration rates of trees-are scarce or nonexistent. Tree-ring analysis provides lifetime species-specific growth data that can be used to allow or improve the projections of timber availability during following logging cycles. In this study, we integrated growth data from tree rings with logging inventory data to forecast timber yields in the next harvest round for four timber species in Cameroon. We compared projections using tree-ring data with projections using fixed growth rates, as set by law and customarily applied in Cameroon. Additionally, we assessed the effect of increasing logging cycles and of using filed-based species-specific logging intensities on the next cycle's yield projections. Under current logging practices, timber volumes available at next logging cycles are projected to be 21-36% of the volumes obtained at first harvest. Simulations using fixed rates often resulted in lower yields with lower volume ingrowth from trees that were below minimum cutting diameters in the first harvest. Lengthening the logging cycle increased yield predictions during the next harvests, but yields were still not sustained over time. This problem can be resolved by using species-specific logging intensities, which led to projected yields of up to 73% of the initial harvested volume. The growth data provided by tree-ring analysis allows conducting such species-specific projections and thus helps to provide the knowledge base necessary for sustainable forest management. Yet, the low overall yields are a concern to forest conservation, as loss of economic value may lead to conversion of forests to other land uses.
Potential of tree-ring analysis in a wet tropical forest: A case study on 22 commercial tree species in Central Africa
Forest Ecology and Management, Jul 1, 2014
ABSTRACT Implementing sustainable forest management requires basic information on growth, ages, r... more ABSTRACT Implementing sustainable forest management requires basic information on growth, ages, reproduction and survival of exploited tree species. This information is generally derived from permanent sample plots where individual trees are monitored. Accurately estimating growth rates and especially tree ages from plots is however challenging, as plots often contain only few individuals of the exploited species and monitoring periods cover only a fraction of the life-span of most trees. Alternatively, tree-ring analysis is increasingly used to obtain accurate age estimates and growth rates for tropical tree species, especially in regions with seasonally harsh conditions. However, for species from wet tropical forests (>4000 mm year−1 rainfall) few tree-ring studies exist. Under persistent high levels of rainfall, formation of distinct tree rings is uncertain due to the lack of strong seasonal variation in climate factors. Here we evaluated the potential of applying tree-ring analysis on commercial tree species in a wet tropical forest in Central-Africa. For this purpose we screened the wood anatomy of 22 tree species for the presence of tree-ring structures and, on a subset of five species, we assessed crossdating potential and evaluated the annual character of tree-ring formation by radiocarbon dating. A total of 14 of the 22 tree species showed distinct tree-ring boundaries. Radiocarbon proved annual tree-ring formation in four of the five tested species. Crossdating between trees was problematic for all species and impeded exactly dating each detected ring and building tree-ring chronologies. We also show that diameter growth rates vary strongly between and among species, with important consequences for the calculation of future timber yields. Tree-ring analysis can thus be applied on tree species growing in wet tropical forests to obtain growth rates. We argue that tree-ring analysis should actually be applied on more tree species from different areas to obtain accurate, site specific growth data. This data is urgently required to design and improve sustainable forest management practices.
The role of climate, grazing and tapping on the population dynamics of Boswellia papyrifera, in Ethiopia
Dendrochronologia, Feb 1, 2019
Tropical dry forests (TDF) are highly important tropical forest ecosystems. Yet, these forests ar... more Tropical dry forests (TDF) are highly important tropical forest ecosystems. Yet, these forests are highly threatened, usually neglected and only poorly studied. Understanding the long-term influences of environmental conditions on tree growth in these forests is crucial to understand the functioning, carbon dynamics and potential responses to future climate change of these forests. Dendrochronolgy can be used as a tool to provide these insights but has only scantly been applied in (dry) tropical forests. Here we evaluate the dendrochronological potential of four Caatinga neotropical dry forest tree species-Aspidosperma pyrifolium, Ziziphus joazeiro, Tabebuia aurea, and Libidibia ferreacollected in two locations in northeastern Brazil (Sergipe state). We provide an anatomical characterization of the ring boundaries for the four species and investigate correlations of their growth with local and regional climatic variables. All four species form annual rings and show high inter-correlation (up to 0.806) and sensitivity (up to 0.565). Growth of all species correlated with local precipitation as well as with seasurface temperatures in the tropical Atlantic and/or tropical Pacific oceans. We also show teleconnections between growth and the El Niño South Oscillation. The strong dependence of tree on precipitation is worrisome, considering that climate change scenarios forecast increased drought conditions in the Caatinga dry forest. Including more species and expanding dendrochronological studies to more areas would greatly improve our understanding of tree growth and functioning in TDFs. This type of knowledge is essential to assist the conservation, management and restoration of these critical tropical ecosystems.
Review for "Tree growth periodicity in the ever‐wet tropical forest of the Americas
Trees-structure and Function, Oct 3, 2022
Key message The rate of vessel tapering is highly conserved across a precipitation gradient in tr... more Key message The rate of vessel tapering is highly conserved across a precipitation gradient in tropical trees, pointing to a limit on tree height determined by a maximum basal vessel diameter. Maximum tree height in the tropics decreases strongly with decreasing precipitation. The role of hydraulic architecture in controlling this variation in tree height remains unclear. The widening of conducting xylem vessels from the apex to the base of trees, also known as tapering, is important for maintaining the hydraulic conductivity along the tree stem. If in contrast vessel diameter were constant, then resistance would increase with path length constraining flow rates as tree height increases. Whilst previous research has shown that vessel diameter scales with tree height at a similar rate (similar power law exponent) across biomes and taxa, knowledge on these relationships across precipitation gradients within a single species is incomplete, especially for the tropics. Here we report how vessel density and diameter at the tree base differ for two tropical Cedrela species across four sites varying in precipitation from 1014 to 2585 mm year −1. We find that maximum tree height decreases with decreasing precipitation across sites from 42 to 13 m. Despite the strong differences between sites in maximum tree height and water availability, tapering is indeed remarkably conserved and close to published scaling with height based on multi-species analyses. Thus, for a given tree height, basal vessel diameter does not vary between sites, whilst the maximum basal vessel size is two times smaller at the drier site (with the shortest trees) compared to the wettest site (with the tallest trees). This suggests a possible limitation of tree height determined by a maximum basal vessel diameter that can be sustained, given increasing embolism risk with increasing dryness. Our results show no hydraulic adaptation across this wetness gradient and reveal a clear relationship between maximum tree height and maximum basal vessel size.
Global Change Biology, Feb 17, 2017
Frontiers in Plant Science, Jan 5, 2017
Over the past few decades there has been a growing realization that a large share of apparently '... more Over the past few decades there has been a growing realization that a large share of apparently 'virgin' or 'old-growth' tropical forests carries a legacy of past natural or anthropogenic disturbances that have a substantial effect on present-day forest composition, structure and dynamics. Yet, direct evidence of such disturbances is scarce and comparisons of disturbance dynamics across regions even more so. Here we present a tree-ring based reconstruction of disturbance histories from three tropical forest sites in Bolivia, Cameroon, and Thailand. We studied temporal patterns in tree regeneration of shade-intolerant tree species, because establishment of these trees is indicative for canopy disturbance. In three large areas (140-300 ha), stem disks and increment cores were collected for a total of 1154 trees (>5 cm diameter) from 12 tree species to estimate the age of every tree. Using these age estimates we produced population age distributions, which were analyzed for evidence of past disturbance. Our approach allowed us to reconstruct patterns of tree establishment over a period of around 250 years. In Bolivia, we found continuous regeneration rates of three species and a peaked age distribution of a long-lived pioneer species. In both Cameroon and Thailand we found irregular age distributions, indicating strongly reduced regeneration rates over a period of 10-60 years. Past fires, windthrow events or anthropogenic disturbances all provide plausible explanations for the reported variation in tree age across the three sites. Our results support the recent idea that the long-term dynamics of tropical forests are impacted by large-scale disturbance-recovery cycles, similar to those driving temperate forest dynamics.
The EGU General Assembly, May 1, 2014
Long-term CO 2 rise has increased photosynthetic efficiency and water use efficiency but did not stimulate diameter growth of tropical trees
2014 AGU Fall Meeting, Dec 16, 2014
Global and Planetary Change, Apr 1, 2015
The availability of instrumental climate data in West and Central Africa is very restricted, both... more The availability of instrumental climate data in West and Central Africa is very restricted, both in space and time. This limits the understanding of the regional climate system and the monitoring of climate change and causes a need for proxies that allow the reconstruction of paleoclimatic variability. Here we show that oxygen isotope values (δ 18 O) in tree rings of Entandrophragma utile from Northwestern Cameroon correlate to precipitation on a regional to sub-continental scale (1930-2009). All found correlations were negative, following the proposed recording of the 'amount effect' by trees in the tropics. The capacity of E. utile to record the variability of regional precipitation is also confirmed by the significant correlation of tree-ring δ 18 O with river discharge data (1944-1983), outgoing longwave radiation (a proxy for cloud cover; 1974-2011) and sea surface salinity in the Gulf of Guinea (1950-2011). Furthermore, the high values in the δ 18 O chronology from 1970 onwards coincide with the Sahel drought period. Given that E. utile presents clear annual growth rings, has a widespread distribution in tropical Africa and is long lived (N 250 years), we argue that the analysis of oxygen isotopes in growth rings of this species is a promising tool for the study of paleoclimatic variability during the last centuries in West and Central Africa.
Long-term growth changes in tropical forests: a Pantropical studyusing tree rings
Tree Physiology, Sep 11, 2021
R (ed.) 2021, 'Small understorey trees have greater capacity than canopy trees to adjust hydrauli... more R (ed.) 2021, 'Small understorey trees have greater capacity than canopy trees to adjust hydraulic traits following prolonged experimental drought in a tropical forest',
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Belinho 1 Shipwreck by Peter Groenendijk
facilitates a better understanding of the timber requirements, and related forestry practices, of the shipbuilding industry during the Iberian Age of Discovery.
An aggressive Iberian expansionist policy increased the demand for timber and led to the implementation of forest regulations and the imposition of programs for tree planting. Forest regeneration became threatened by the increased exploitation of timber for not only
shipbuilding but also agricultural intensification and urban growth. In Iberia, a perceived lack of appropriate local timber led to increases in timber importation, arguably leading to the interruption of the shipyards carpenter`s intimate relation with the woodlands.
The increasing pressure to build larger ships imposed by the crown and merchantmen changed the paradigm in Iberian shipbuilding from the 15th -century onwards. The “perfect timber log” was no longer available in the shipyards. Therefore, it became crucial to investigate potential shifts in shipbuilding technology and technique by analysing the growth pattern, wood morphologies and growth patterns of the shipwrecks surviving timbers. By adopting a dendroarchaeological approach, a multidisciplinary team aimed to analyse detailed information collected from a selection of Iberian shipwrecks. A 3D digital record was produced for the surviving timbers of three early Iberian ships: Belinho 1, Cais do Sodre and Corpo Santo. The species, morphologies and growth patterns of individual timbers were recorded and combined with data collected about their shapes, tool marks and other shipbuilding features allowed to reconstruct individual parent trees and pointed to the reconstruction of the ships` hull.
This paper will present the results from the investigation undertaken on the ships timber and parent tree`s morphologies employed in the construction of the vessels mentioned above.
Papers by Peter Groenendijk