A reconstruction of Atlantic Central African biomes and forest  succession stages derived from modern pollen data and plant functional  types

Abstract. New detailed vegetation reconstructions are proposed in Atlantic Central Africa from a modern pollen data set derived from 199 sites (Cameroon, Gabon and Congo) including 131 new sites. In this study, the concept of plant functional classification is improved with new and more detailed plant functional types (PFTs) and new aggregations of pollen taxa. Using the biomisation method, we reconstructed (1) modern potential biomes and (2) potential succession stages of forest regeneration, a new approach in Atlantic Central African vegetation dynamics and ecosystem functioning reconstruction. When compared to local vegetation, potential biomes are correctly reconstructed (97.5% of the sites) and tropical evergreen to semi-evergreen forest (TRFO biome) is well identified from semi-deciduous forest (TSFO biome). When the potential biomes are superimposed on the White's vegetation map, only 76.4% of the sites are correctly reconstructed. But using botanical data, correspondence and cluster analyses, the 43 sites from Congo (Mayombe) evidence more affinities with those of central Gabon and so they can also be considered as correctly reconstructed as TRFO biome and White's map must be revised. In terms of potential succession stages of forest regeneration, the mature forest (TMFO) is well differentiated from the secondary forest (TSFE), but inside this latter group, the young and the pioneer stages are not clearly identified due probably to their low sampling representation. Moreover, linked to their progressive and mosaic character, the boundaries between two forest biomes or two forest stages are not clearly detected and need also a more intensive sampling in such transitions.

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Central African biomes and forest succession stages derived from modern pollen data and plant functional types

Climate of the Past ◽

10.5194/cp-5-403-2009 ◽

2009 ◽

Vol 5 (3) ◽

pp. 403-429 ◽

Cited By ~ 22

Author(s):

J. Lebamba ◽

A. Ngomanda ◽

A. Vincens ◽

D. Jolly ◽

C. Favier ◽

...

Keyword(s):

Forest Regeneration ◽

Forest Succession ◽

Secondary Forest ◽

Central Africa ◽

Plant Functional Types ◽

Pollen Data ◽

Data Set ◽

Modern Pollen ◽

Functional Types ◽

Well Differentiated

Abstract. New detailed vegetation reconstructions are proposed in Atlantic Central Africa from a modern pollen data set derived from 199 sites (Cameroon, Gabon and Congo) including 131 new sites. In this study, the concept of plant functional classification is improved with new and more detailed plant functional types (PFTs) and new aggregations of pollen taxa. Using the biomisation method, we reconstructed (1) modern potential biomes and (2) potential succession stages of forest regeneration, a new approach in Atlantic Central African vegetation dynamics and ecosystem functioning reconstruction. When compared to local vegetation, potential biomes are correctly reconstructed (97.5% of the sites) and tropical rain forest (TRFO biome) is well identified from tropical seasonal forest (TSFO biome). When the potential biomes are superimposed on the White's vegetation map, only 76.4% of the sites are correctly reconstructed. But using botanical data, correspondence and cluster analyses, the 43 sites from Congo (Mayombe) evidence more affinities with those of central Gabon and so they can also be considered as correctly reconstructed as TRFO biome and White's map should be revised. In terms of potential succession stages of forest regeneration, the mature forest (TMFO) is well differentiated from the secondary forest (TSFE), but inside this latter group, the young and the pioneer stages are not clearly identified due probably to their low sampling representation. Moreover, linked to their progressive and mosaic character, the boundaries between two forest biomes or two forest stages are not clearly detected and need also a more intensive sampling in such transitions.

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A model for the importance of large arborescent palms in the dynamics of seasonally-dry amazonian forests

Biota Neotropica ◽

10.1590/s1676-06032005000300011 ◽

2005 ◽

Vol 5 (2) ◽

pp. 151-156 ◽

Cited By ~ 5

Author(s):

Rodolfo Salm ◽

Euphly Jalles-Filho ◽

Cynthia Schuck-Paim

Keyword(s):

Forest Regeneration ◽

Forest Canopy ◽

Forest Succession ◽

Secondary Forest ◽

Forest Disturbance ◽

Dry Forest ◽

Forest Patch ◽

Seasonally Dry ◽

Palm Trees ◽

Amazonian Forests

In this study we propose a model that represents the importance of large arborescent palms in the dynamics of seasonally-dry Amazonian forests. Specifically, the model is aimed at guiding the investigation of the role of large arborescent palms on forest regeneration and succession. Following disturbance, the high level of luminosity reaching recently formed forest gaps favors the quick proliferation of shade-intolerant lianas that, by casting shade on the crowns of mature forest trees and increasing tree-fall probability, suppress forest succession. Due to their columnar architecture palm trees are, however, not severely affected by vines. As the palms grow, the canopy at the gaps becomes gradually higher and denser, progressively obstructing the passage of light, thus hindering the growth of shade-intolerant lianas and enabling late-successional tree development and forest regeneration. Owing to the long time associated with forest regeneration, the model cannot be tested directly, but aspects of it were examined with field data collected at an Attalea maripa-rich secondary forest patch within a matrix of well-preserved seasonally-dry forest in the Southeastern Amazon. The results indicate that (1) forest disturbance is important for the recruitment of large arborescent palms species, (2) these palms can grow rapidly after an event of disturbance, restoring forest canopy height and density, and (3) secondary forest dominated by palm trees species may be floristically similar to nearby undisturbed forests, supporting the hypothesis that the former has undergone regeneration, as purported in the model.

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Germination and development of sown mahogany (Swietenia macrophylla King) in secondary tropical dry forest habitats in Costa Rica

Journal of Tropical Ecology ◽

10.1017/s0266467400009457 ◽

1996 ◽

Vol 12 (2) ◽

pp. 275-289 ◽

Cited By ~ 27

Author(s):

Karin Gerhardt

Keyword(s):

Costa Rica ◽

Seedling Establishment ◽

Rainy Season ◽

Deciduous Forest ◽

Secondary Forest ◽

Dry Forest ◽

Root Competition ◽

Evergreen Forest ◽

Swietenia Macrophylla ◽

Seedling Mortality

ABSTRACTEffects of irradiance, root competition and water availability on germination and seedling establishment of Swietenia macrophylla King were investigated in tropical secondary dry forests in the Guanacaste Conservation Area, Costa Rica. The fate of seeds sown in the beginning and the middle of the rainy season was studied in abandoned pasture, and in deciduous and semi-evergreen secondary forest. In the pasture, experimental treatments were mown and unmown grass. In the forest sites, thinning to increase light and trenching to reduce root competition were combined in a factorial design. Effects of moisture availability on germination were tested by supplementing natural rainfall in the initial rainy month. Germination at the beginning of the rainy season was not influenced by the supplementary water and was higher in the semi-evergreen forest than in the deciduous forest and pasture. In the forests, germination was little affected by irradiance or root competition. More seeds germinated in unmown than in mown pasture during the initial rains, but were not influenced by mowing when sown in the peak of the rainy season. Seedling mortality was low (>10%) during the initial months, but increased greatly in the dry season. Seedlings germinating early in the rainy season had a higher survival than those germinating later. The relatively slight effects of the different treatments and habitats on seedling establishment suggest that this species is rather insensitive to the large microsite variation in secondary vegetation.

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Consequences of a Reduced Number of Plant Functional Types for the Simulation of Forest Productivity

Forests ◽

10.3390/f9080460 ◽

2018 ◽

Vol 9 (8) ◽

pp. 460 ◽

Cited By ~ 4

Author(s):

Rico Fischer ◽

Edna Rödig ◽

Andreas Huth

Keyword(s):

Tropical Forests ◽

Tree Species ◽

Forest Succession ◽

Carbon Fluxes ◽

Forest Growth ◽

Plant Functional Types ◽

Pioneer Tree Species ◽

Old Growth Forest ◽

Pioneer Tree ◽

Functional Types

Tropical forests represent an important pool in the global carbon cycle. Their biomass stocks and carbon fluxes are variable in space and time, which is a challenge for accurate measurements. Forest models are therefore used to investigate these complex forest dynamics. The challenge of considering the high species diversity of tropical forests is often addressed by grouping species into plant functional types (PFTs). We investigated how reduced numbers of PFTs affect the prediction of productivity (GPP, NPP) and other carbon fluxes derived from forest simulations. We therefore parameterized a forest gap model for a specific study site with just one PFT (comparable to global vegetation models) on the one hand, and two versions with a higher amount of PFTs, on the other hand. For an old-growth forest, aboveground biomass and basal area can be reproduced very well with all parameterizations. However, the absence of pioneer tree species in the parameterizations with just one PFT leads to a reduction in estimated gross primary production by 60% and an increase of estimated net ecosystem exchange by 50%. These findings may have consequences for productivity estimates of forests at regional and continental scales. Models with a reduced number of PFTs are limited in simulating forest succession, in particular regarding the forest growth after disturbances or transient dynamics. We conclude that a higher amount of species groups increases the accuracy of forest succession simulations. We suggest using at a minimum three PFTs with at least one species group representing pioneer tree species.

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Diversity of leaf phenology in a tropical deciduous forest in India

Journal of Tropical Ecology ◽

10.1017/s0266467404002032 ◽

2005 ◽

Vol 21 (1) ◽

pp. 47-56 ◽

Cited By ~ 33

Author(s):

C. P. Kushwaha ◽

K. P. Singh

Keyword(s):

Tree Species ◽

Deciduous Forest ◽

Plant Functional Types ◽

Deciduous Tree ◽

Tropical Deciduous Forest ◽

Leaf Fall ◽

Evergreen Species ◽

Functional Types ◽

Leaf Flush ◽

Strategy Index

Patterns of leaf phenological diversity were documented in nine key tree species of a tropical deciduous forest in the Vindhyan region of India. Monthly leaf counts on 160 tagged twigs on ten individuals of each species were made through two annual cycles. Tree species exhibited a gradient of deciduousness (∼leafless duration), ranging from semi-evergreen species (entire population never becoming leafless) to 7-mo-deciduous species. The semi-evergreen species initiated leaf flush (bud break of vegetative bud) earlier around the spring equinox. In all deciduous tree species synchronous leaf-flush initiation, with low inter-annual variability, occurred during the hot dry summer (May–June, day temperature >40 °C), prior to the onset of the rainy season. Based on the quantification of leafless period, leaf-flush duration, and leaf strategy index (leaf-flush rate/leaf-fall rate, proposed in this study) in different species, four plant functional types were recognized: (a) semi-evergreen, spring flushing, showing leaf exchange, with mean leafless period 8 d, leaf-flush duration 6–7 mo and leaf strategy index <0.5 (Shorea robusta); (b) <2-mo-deciduous, summer flushing, leafless period 3–8 wk, leaf-flush duration 5–6 mo, and leaf strategy index >0.5−<0.7 (Anogeissus latifolia, Diospyros melanoxylon and Hardwickia binata); (c) 2–4-mo-deciduous, summer flushing, leafless period 2–3 mo, leaf-flush duration 4–5 mo, and leaf strategy index >0.8−<1.0 (Acacia catechu, Lagerstroemia parviflora and Terminalia tomentosa); and (d) >4-mo-deciduous, summer flushing, leafless period >4–7 mo, leaf-flush duration 3–4 mo, and leaf strategy index 1.0 (Boswellia serrata and Lannea coromandelica). Conspecific trees showed asynchrony with respect to leaf-flush completion, initiation and completion of leaf-fall, and extent of leafless period. Leaf strategy index (indicating rate of resource use and conservation) was strongly related with the leafless period in different species (r=0.82) and can serve as a useful index in leaf phenological studies and classification of plant functional types.

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Global Vegetation Photosynthetic Phenology Products Based on MODIS Vegetation Greenness and Temperature: Modeling and Evaluation

Remote Sensing ◽

10.3390/rs13245080 ◽

2021 ◽

Vol 13 (24) ◽

pp. 5080

Author(s):

Xiaojun Xu ◽

Yan Tang ◽

Yiling Qu ◽

Zhongsheng Zhou ◽

Junguo Hu

Keyword(s):

Land Surface ◽

Vegetation Index ◽

Deciduous Forest ◽

Forest Type ◽

Gross Primary Production ◽

Plant Functional Types ◽

Linear Regression Models ◽

Climatic Regions ◽

Functional Types ◽

Global Vegetation

Land surface phenology (LSP) products that are derived from different data sources have different definitions and biophysical meanings. Discrepancies among these products and their linkages with carbon fluxes across plant functional types and climatic regions remain somewhat unclear. In this study, to differentiate LSP related to gross primary production (GPP) from LSP related to remote sensing data, we defined the former as vegetation photosynthetic phenology (VPP), including the starting and ending days of GPP (SOG and EOG, respectively). Specifically, we estimated VPP based on a combination of observed VPP from 145 flux-measured GPP sites together with the vegetation index and temperature data from MODIS products using multiple linear regression models. We then compared VPP estimates with MODIS LSP on a global scale. Our results show that the VPP provided better estimates of SOG and EOG than MODIS LSP, with a root mean square error (RMSE) for SOG of 12.7 days and a RMSE for EOG of 10.5 days. The RMSE was approximately three weeks for both SOG and EOG estimates of the non-forest type. Discrepancies between VPP and LSP estimates varied across plant functional types (PFTs) and climatic regions. A high correlation was observed between VPP and LSP estimates for deciduous forest. For most PFTs, using VPP estimates rather than LSP improved the estimation of GPP. This study presents a useful method for modeling global VPP, investigates in detail the discrepancies between VPP and LSP, and provides a more effective global vegetation phenology product for carbon cycle modeling than the existing ones.

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Simulated effects of a seasonal precipitation change on the vegetation in tropical Africa

Climate of the Past ◽

10.5194/cp-6-169-2010 ◽

2010 ◽

Vol 6 (2) ◽

pp. 169-178 ◽

Cited By ~ 17

Author(s):

E. S. Gritti ◽

C. Cassignat ◽

O. Flores ◽

R. Bonnefille ◽

F. Chalié ◽

...

Keyword(s):

Transfer Functions ◽

Deciduous Forest ◽

Potential Effect ◽

Dry Season ◽

Mean Annual Precipitation ◽

Pollen Data ◽

Modern Pollen ◽

Precipitation Regimes ◽

Precipitation Seasonality ◽

Annual Amount

Abstract. Pollen data collected in Africa at high (Kuruyange, valley swamp, Burundi) and low altitude (Victoria, lake, Uganda; Ngamakala, pond, Congo) showed that after 6 ky before present (BP), pollen of deciduous trees increase their relative percentage, suggesting thus the reduction of the annual amount of precipitation and/or an increase of in the length of the dry season. Until now, pollen-climate transfer functions only investigated mean annual precipitation, due to the absence of modern pollen-assemblage analogs under diversified precipitation regimes. Hence these functions omit the potential effect of a change in precipitation seasonality modifying thus the length of the dry season. In the present study, we use an equilibrium biosphere model (i.e. BIOME3.5) to estimate the sensitivity of equatorial African vegetation, at specific sites, to such changes. Climatic scenarios, differing only in the monthly distribution of the current annual amount of precipitation, are examined at the above three locations in equatorial Africa. Soil characteristics, monthly temperatures and cloudiness are kept constant at their present-day values. Good agreement is shown between model simulations and current biomes assemblages, as inferred from pollen data. To date, the increase of the deciduous forest component in the palaeodata around 6 ky BP has been interpreted as the beginning of a drier climate period. However, our results demonstrate that a change in the seasonal distribution of precipitation could also induce the observed changes in vegetation types. This study confirms the importance of taking into account seasonal changes in the hydrological balance. Palaeoecologists can greatly benefit from the use of dynamic process based vegetation models to acccount for modification of the length of the dry season when they wish to reconstruct vegetation composition or to infer quantitative climate parameters, such as temperature and precipitation, from pollen or vegetation proxy.

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Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information

Geoscientific Model Development ◽

10.5194/gmd-9-2415-2016 ◽

2016 ◽

Vol 9 (7) ◽

pp. 2415-2440 ◽

Cited By ~ 59

Author(s):

Anna B. Harper ◽

Peter M. Cox ◽

Pierre Friedlingstein ◽

Andy J. Wiltshire ◽

Chris D. Jones ◽

...

Keyword(s):

Climate Change ◽

Net Primary Productivity ◽

Leaf Nitrogen ◽

Plant Functional Types ◽

Deciduous Trees ◽

Leaf Life Span ◽

C4 Grasses ◽

Data Set ◽

Functional Types ◽

C3 And C4 Grasses

Abstract. Dynamic global vegetation models are used to predict the response of vegetation to climate change. They are essential for planning ecosystem management, understanding carbon cycle–climate feedbacks, and evaluating the potential impacts of climate change on global ecosystems. JULES (the Joint UK Land Environment Simulator) represents terrestrial processes in the UK Hadley Centre family of models and in the first generation UK Earth System Model. Previously, JULES represented five plant functional types (PFTs): broadleaf trees, needle-leaf trees, C3 and C4 grasses, and shrubs. This study addresses three developments in JULES. First, trees and shrubs were split into deciduous and evergreen PFTs to better represent the range of leaf life spans and metabolic capacities that exists in nature. Second, we distinguished between temperate and tropical broadleaf evergreen trees. These first two changes result in a new set of nine PFTs: tropical and temperate broadleaf evergreen trees, broadleaf deciduous trees, needle-leaf evergreen and deciduous trees, C3 and C4 grasses, and evergreen and deciduous shrubs. Third, using data from the TRY database, we updated the relationship between leaf nitrogen and the maximum rate of carboxylation of Rubisco (Vcmax), and updated the leaf turnover and growth rates to include a trade-off between leaf life span and leaf mass per unit area.Overall, the simulation of gross and net primary productivity (GPP and NPP, respectively) is improved with the nine PFTs when compared to FLUXNET sites, a global GPP data set based on FLUXNET, and MODIS NPP. Compared to the standard five PFTs, the new nine PFTs simulate a higher GPP and NPP, with the exception of C3 grasses in cold environments and C4 grasses that were previously over-productive. On a biome scale, GPP is improved for all eight biomes evaluated and NPP is improved for most biomes – the exceptions being the tropical forests, savannahs, and extratropical mixed forests where simulated NPP is too high. With the new PFTs, the global present-day GPP and NPP are 128 and 62 Pg C year−1, respectively. We conclude that the inclusion of trait-based data and the evergreen/deciduous distinction has substantially improved productivity fluxes in JULES, in particular the representation of GPP. These developments increase the realism of JULES, enabling higher confidence in simulations of vegetation dynamics and carbon storage.

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