Editorial

3 pages, 642 KiB

Open AccessEditorial

Simulation Models of the Dynamics of Forest Ecosystems

by Guy R. Larocque

Forests 2022, 13(5), 705; https://doi.org/10.3390/f13050705 - 30 Apr 2022

Cited by 2 | Viewed by 2054

The development of simulation models of the dynamics of forest ecosystems has been an active area of research [...] Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

Research

Jump to: Editorial, Review

19 pages, 7130 KiB

Open AccessArticle

Maxent Modeling for Identifying the Nature Reserve of Cistanche deserticola Ma under Effects of the Host (Haloxylon Bunge) Forest and Climate Changes in Xinjiang, China

by Minghao Shao, Lei Wang, Bingwen Li, Shengyu Li, Jinglong Fan and Congjuan Li

Forests 2022, 13(2), 189; https://doi.org/10.3390/f13020189 - 26 Jan 2022

Cited by 11 | Viewed by 2665

Abstract

Cistanche deserticola Ma is a traditional Chinese medicinal plant exclusively parasitizing on the roots of Haloxylon ammodendron (C. A. Mey.) Bunge and H. Persicum Bunge ex Boiss and the primary cultivated crop of the desert economy. Its wild resources became scarce due to [...] Read more.

Cistanche deserticola Ma is a traditional Chinese medicinal plant exclusively parasitizing on the roots of Haloxylon ammodendron (C. A. Mey.) Bunge and H. Persicum Bunge ex Boiss and the primary cultivated crop of the desert economy. Its wild resources became scarce due to over-exploitation and poaching for economic benefits. To protect the biological diversity of the desert Haloxylon–Cistanche community forest, the optimal combination of desert ecology and economy industry, and their future survival, this paper examines the conservation areas of wild C. deserticola from the perspective of hosts’ effects and climate changes. To identify conservation areas, the potential distributions generated by MaxEnt in two strategies (AH: abiotic and hosts factors; HO: hosts factors only) compare the model’s performance, the niche range overlap, and the changing trend in climate changes. The results show the following: (1) The HO strategy is more suitable for prediction and identifying the core conservation areas in hosts and climate changes (indirectly affected by host distributions) for C. deserticola. (2) The low-suitable habitat and the medium-suitable habitat are both sensitive to the climate changes; the reduction reaches 48.2% (SSP585, 2081–2100) and 26.6%(SSP370, 2081–2100), respectively. The highly suitable habitat is always in growth, with growth reaching 27.3% (SSP585, 2081–2100). (3) Core conservation areas and agriculture and education areas are 317,315.118 km² and 319,489.874 km², respectively. This study developed a predictive model for Maxent under climate change scenarios by limiting host and abiotic factors and inverted the natural habitat of C. deserticola to provide scientific zoning for biodiversity conservation in desert Haloxylon–Cistanche community forests systems, providing an effective reference for decision makers. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

17 pages, 2730 KiB

Open AccessArticle

Nitrate Uptake from an Aquifer by Two Plantation Forests: Plausibility Strengthened by Process-Based Modelling

by Philip J. Smethurst, Tim R. McVicar, Neil I. Huth, Ben P. Bradshaw, Stephen B. Stewart, Thomas G. Baker, Richard G. Benyon, John F. McGrath and Thomas G. Van Niel

Forests 2022, 13(2), 184; https://doi.org/10.3390/f13020184 - 26 Jan 2022

Cited by 5 | Viewed by 2171

Abstract

Forest plantations can access water from some unconfined aquifers that also contain nitrate at concentrations that could support hydroponic culture, but the separate effects of such additional water and nitrogen availability on tree growth have not hitherto been quantified. We demonstrate these effects [...] Read more.

Forest plantations can access water from some unconfined aquifers that also contain nitrate at concentrations that could support hydroponic culture, but the separate effects of such additional water and nitrogen availability on tree growth have not hitherto been quantified. We demonstrate these effects using simulation modelling at two contrasting sites supporting Eucalyptus globulus Labill. or Pinus radiata D.Don plantations. The APSIM Eucalyptus and Pinus models simulated plantation growth within 2% of observed growth where the water table was at 4 m depth for eucalypts (height 28 m, MAI 32 m³ ha⁻¹ year⁻¹) and at 23 m for pines (height 37 m, MAI 20 m³ ha⁻¹ year⁻¹). In simulations without an aquifer, observed growth could only be matched using unrealistically high surface soil nitrogen (N) supply, suggesting this is an unlikely mechanism. Simulated aquifer N concentrations, evapotranspiration, and net N mineralization and leaching (emergent properties of modelling) were similar to measured values. These results strengthen the plausibility that aquifer N uptake by plantations could be contributing to tree growth. This hypothesis warrants further research that quantifies these processes at multiple sites. Simulations included growth of herbaceous and tree weed species, and pasture, which demonstrated the utility of the process-based APSIM modelling framework for dynamically simulating carbon, water and N of plantations and other mixed-species systems. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

12 pages, 2236 KiB

Open AccessArticle

Predicting Potential Habitat of a Plant Species with Small Populations under Climate Change: Ostryarehderiana

by Lei Feng, Jiejie Sun, Yousry A. El-Kassaby, Xianyu Yang, Xiangni Tian and Tongli Wang

Forests 2022, 13(1), 129; https://doi.org/10.3390/f13010129 - 17 Jan 2022

Cited by 11 | Viewed by 2089

Abstract

Ostrya rehderiana is a famous plant species with extremely small populations. With ongoing global climate change, the extremely small populations would face more uncertainties and risks, including the loss of genetic diversity and extirpation. Thus, assessing the impact of climate change on suitable [...] Read more.

Ostrya rehderiana is a famous plant species with extremely small populations. With ongoing global climate change, the extremely small populations would face more uncertainties and risks, including the loss of genetic diversity and extirpation. Thus, assessing the impact of climate change on suitable habitat of O. rehderiana is particularly important for its conservation and restoration. Here, we built niche models with climate variables and soil and human footprint variables. Furthermore, new methods were applied to avoid confounding effects between climate and soil and human footprint variables to simulate the potential habitats of O. rehderiana in current and future climates. We found that the Hargreaves climatic moisture deficit, degree-days below 0 °C, chilling degree-days, and the temperature difference between mean warmest month temperature and mean coldest month temperature, or continentality, were the most important climate factors. The topsoil USDA texture classification, topsoil cation exchange capacity of (clay), and topsoil sodicity (ESP) were the key soil factors determining the suitable distribution of O. rehderiana. Compared with soil factors, human footprint has less influence on the suitable distribution of O. rehderiana. The niche range of this species was projected to expand and shift to north in the Representative Concentration Pathway (RCP) 4.5 scenario for the 2050s. Our study results could be referenced in further extremely small populations ecological restoration studies and provide the scientific strategies for the conservation and restoration of O. rehderiana. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

14 pages, 1820 KiB

Open AccessArticle

Model-Based Growth Comparisons between Loblolly and Slash Pine and between Silvicultural Intensities in East Texas

by Yuhui Weng, Jason Grogan, Bilawal Cheema, Jing Tao, Xiongwei Lou and Harold Burkhart

Forests 2021, 12(12), 1611; https://doi.org/10.3390/f12121611 - 23 Nov 2021

Cited by 2 | Viewed by 1428

Abstract

Growth differences between key commercial species and between silvicultural intensities (phases) within a species in a region are of great interest to foresters. This study used modeling methods to investigate these differences in east Texas. Datasets collected from loblolly and slash pine plots [...] Read more.

Growth differences between key commercial species and between silvicultural intensities (phases) within a species in a region are of great interest to foresters. This study used modeling methods to investigate these differences in east Texas. Datasets collected from loblolly and slash pine plots installed in extensively managed plantations (Phase I) and loblolly pine plots installed in intensively managed plantations (Phase II) were used. Species and silvicultural phase growth differences were determined by comparing their height–age, diameter–age, and height–diameter relationships. Slash and loblolly pine had significantly different parameter estimates for the Chapman and Richards function-based height– and diameter–age models. Slash pine grew faster than loblolly pine, with the superiority in height increasing while that of diameter growth decreased slightly with age. Slash and loblolly pine differed also in all parameter estimates of the exponential function-based height-diameter model. Loblolly pine was taller than the slash for small size (DBH ≤ 18 cm) trees, but thereafter, slash pine outperformed loblolly. While these results may encourage planting slash pine in the region, more studies are needed before definitive conclusions can be made. The differences in the height–age models for loblolly pine Phase I and II plots suggest that intensive management significantly enhanced tree height growth. However, this enhancement did not substantially change the maximum height; instead, trees reached the maximum height younger, thus effectively shortening the rotation age. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

9 pages, 979 KiB

Open AccessArticle

The Significance of Aggregation Methods in Functional Group Modeling

by Huan Zhang, Herman H. Shugart, Bin Wang and Manuel Lerdau

Forests 2021, 12(11), 1560; https://doi.org/10.3390/f12111560 - 11 Nov 2021

Cited by 1 | Viewed by 1572

Abstract

The growth of forests and the feedbacks between forests and environmental changes are central issues in the planetary carbon cycle, global climate change, and basic plant ecology. A challenge to understanding both growth and feedbacks from local to global scales is that many [...] Read more.

The growth of forests and the feedbacks between forests and environmental changes are central issues in the planetary carbon cycle, global climate change, and basic plant ecology. A challenge to understanding both growth and feedbacks from local to global scales is that many critical metabolic processes vary among species. An innovation in solving this challenge is the recognition that species can be lumped into “functional groups” based on metabolic similarity, and these functional groups can then be studied in computational models that simulate ecosystem function. Despite the vast resources devoted to functional group studies and the progress made by them, an important logical and biological question has not been formally addressed, “How do the groupings alter the results of modeling studies?” To what extent do modeling results depend on the choices made in aggregating taxa into functional groups. Here, we consider the effects of using different aggregation strategies in simulating the carbon dynamics of a deciduous forest. Understanding the impacts that aggregation strategy has on efforts to simulate regional-to-global-scale forest dynamics offers insights into both ecosystem regulation and model function and addresses this central problem in the study of carbon dynamics. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

27 pages, 11322 KiB

Open AccessArticle

Evaluation of LandscapeDNDC Model Predictions of CO₂ and N₂O Fluxes from an Oak Forest in SE England

by Shirley M. Cade, Kevin C. Clemitshaw, Saúl Molina-Herrera, Rüdiger Grote, Edwin Haas, Matthew Wilkinson, James I. L. Morison and Sirwan Yamulki

Forests 2021, 12(11), 1517; https://doi.org/10.3390/f12111517 - 03 Nov 2021

Cited by 4 | Viewed by 2550

Abstract

Process-based biogeochemical models are valuable tools to evaluate impacts of environmental or management changes on the greenhouse gas (GHG) balance of forest ecosystems. We evaluated LandscapeDNDC, a process-based model developed to simulate carbon (C), nitrogen (N) and water cycling at ecosystem and regional [...] Read more.

Process-based biogeochemical models are valuable tools to evaluate impacts of environmental or management changes on the greenhouse gas (GHG) balance of forest ecosystems. We evaluated LandscapeDNDC, a process-based model developed to simulate carbon (C), nitrogen (N) and water cycling at ecosystem and regional scales, against eddy covariance and soil chamber measurements of CO₂ and N₂O fluxes in an 80-year-old deciduous oak forest. We compared two LandscapeDNDC vegetation modules: PSIM (Physiological Simulation Model), which includes the understorey explicitly, and PnET (Photosynthesis–Evapotranspiration Model), which does not. Species parameters for both modules were adjusted to match local measurements. LandscapeDNDC was able to reproduce daily micro-climatic conditions, which serve as input for the vegetation modules. The PSIM and PnET modules reproduced mean annual net CO₂ uptake to within 1% and 15% of the measured values by balancing gains and losses in seasonal patterns with respect to measurements, although inter-annual variations were not well reproduced. The PSIM module indicated that the understorey contributed up to 21% to CO₂ fluxes. Mean annual soil CO₂ fluxes were underestimated by 32% using PnET and overestimated by 26% with PSIM; both modules simulated annual soil N₂O fluxes within the measured range but with less interannual variation. Including stand structure information improved the model, but further improvements are required for the model to predict forest GHG balances and their inter-annual variability following climatic or management changes. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

11 pages, 3508 KiB

Open AccessArticle

Testing the Performance of Some Competition Indices against Experimental Data and Outputs of Spatially Explicit Simulation Models

by Vladimir Shanin, Hannu Hökkä and Pavel Grabarnik

Forests 2021, 12(10), 1415; https://doi.org/10.3390/f12101415 - 16 Oct 2021

Cited by 2 | Viewed by 2553

Abstract

Three competition indices were tested against experimental data on the growth of individual trees in mapped forest stands and outputs of spatially explicit, process-based models of competition. The comparison showed the fundamental importance of taking into account the spatial structure of stands and, [...] Read more.

Three competition indices were tested against experimental data on the growth of individual trees in mapped forest stands and outputs of spatially explicit, process-based models of competition. The comparison showed the fundamental importance of taking into account the spatial structure of stands and, particularly, the relative spatial locations of individual trees (spatial asymmetry) when calculating the competition between trees. Although none of the competition indices are able to take into account the specific processes affecting the development of individual trees, these indices can be used in forest dynamics modeling as a simplified representation of competition between trees for resources. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

20 pages, 11975 KiB

Open AccessArticle

A Band Model of Cambium Development: Opportunities and Prospects

by Vladimir V. Shishov, Ivan I. Tychkov, Kevin J. Anchukaitis, Grigory K. Zelenov and Eugene A. Vaganov

Forests 2021, 12(10), 1361; https://doi.org/10.3390/f12101361 - 07 Oct 2021

Cited by 14 | Viewed by 2535

Abstract

More than 60% of tree phytomass is concentrated in stem wood, which is the result of periodic activity of the cambium. Nevertheless, there are few attempts to quantitatively describe cambium dynamics. In this study, we develop a state-of-the-art band model of cambium development, [...] Read more.

More than 60% of tree phytomass is concentrated in stem wood, which is the result of periodic activity of the cambium. Nevertheless, there are few attempts to quantitatively describe cambium dynamics. In this study, we develop a state-of-the-art band model of cambium development, based on the kinetic heterogeneity of the cambial zone and the connectivity of the cell structure. The model describes seasonal cambium development based on an exponential function under climate forcing which can be effectively used to estimate the seasonal cell production for individual trees. It was shown that the model is able to simulate different cell production for fast-, middle- and slow-growing trees under the same climate forcing. Based on actual measurements of cell production for two contrasted trees, the model effectively reconstructed long-term cell production variability (up to 75% of explained variance) of both tree-ring characteristics over the period 1937−2012. The new model significantly simplifies the assessment of seasonal cell production for individual trees of a studied forest stand and allows the entire range of individual absolute variability in the ring formation of any tree in the stand to be quantified, which can lead to a better understanding of the anatomy of xylem formation, a key component of the carbon cycle. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

24 pages, 7406 KiB

Open AccessArticle

Comparison between Empirical Models and the CBM-CFS3 Carbon Budget Model to Predict Carbon Stocks and Yields in Nova Scotia Forests

by Jason Heffner, James Steenberg and Brigitte Leblon

Forests 2021, 12(9), 1235; https://doi.org/10.3390/f12091235 - 11 Sep 2021

Cited by 6 | Viewed by 2800

Abstract

In response to the global climate crisis, the Nova Scotia Department of Lands and Forestry is using the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) and associated methodologies to assess the carbon dynamics of the provincial forestry sector. The CBM-CFS3 bases [...] Read more.

In response to the global climate crisis, the Nova Scotia Department of Lands and Forestry is using the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) and associated methodologies to assess the carbon dynamics of the provincial forestry sector. The CBM-CFS3 bases simulations on a range of studies and national forest inventory plots to predict carbon dynamics using merchantable volume yield curves. Nova Scotia has also maintained thousands of permanent forest sample plots (PSPs) for decades, offering the opportunity to develop empirical, province-specific carbon models. This study used PSP tree measurements and allometric equations to compute plot-level forest carbon models from the PSP dataset and compared their output to that of the CBM-CFS3 model. The PSP-based models were stratified into five forest types and predict the carbon for seven carbon pools as a function of the plot age. Predictions with the PSP- and CBM-CFS3 models were compared to observed PSP data at the plot level and compared against each other at the stand and landscape level. At the plot level, the PSP-derived models predicted carbon closer to the observed data than the CBM-CFS3 model, the extent of over- or under-estimation depending on the carbon pool and forest type. At the stand scale, the CBM-CFS3 model predicted forest carbon to within 3.1–17.6% of the PSP method on average. Differences in predictions between the CBM-CFS3 and PSP models decreased to within 2.4% of the PSP-based models at the landscape level. Thus, the implications of using one method over the other decrease as the prediction scale increases from stand to landscape level, and the implications fluctuate as a function of the forest type and age. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

11 pages, 3534 KiB

Open AccessArticle

Predicting the Potential Habitat of Three Endangered Species of Carpinus Genus under Climate Change and Human Activity

by Jiejie Sun, Lei Feng, Tongli Wang, Xiangni Tian, Xiao He, Hui Xia and Weifeng Wang

Forests 2021, 12(9), 1216; https://doi.org/10.3390/f12091216 - 07 Sep 2021

Cited by 13 | Viewed by 2367

Abstract

The impact of climate change and human activities on endangered plants has been a serious concern in forest ecology. Some Carpinus plants have become extinct. Thus, we need to pay more attention to the Carpinus plants that are not yet extinct but are [...] Read more.

The impact of climate change and human activities on endangered plants has been a serious concern in forest ecology. Some Carpinus plants have become extinct. Thus, we need to pay more attention to the Carpinus plants that are not yet extinct but are endangered. Here, we employed the species distribution model (SDM) considering different climate change scenarios and human footprint to test the potential habitat changes of three Carpinus species (C. oblongifolia, C. tientaiensis, and C. purpurinervis) in the future. Our results showed that the mean diurnal range of temperature (MDRT), isothermality, mean temperature of wettest quarter, and human footprint were the most influential factors determining the distribution of C. oblongifolia. Precipitation seasonality (coefficient of variation), MDRT, and precipitation of driest quarter were the most important climatic factors affecting C. tientaiensis. The minimum temperature of the coldest month was the most important factor in the distribution of C. purpurinervis. Our results also showed that the three species had different adaptability and habitat change trends under the future climate change scenarios, although they belong to the same genus. The potential habitats of C. oblongifolia would expand in the future, while the potential habitats of C. tientaiensis and C. purpurinervis would decrease for the same period. The predicted changes of these three endangered species on temporal and spatial patterns could provide a theoretical basis for their conservation strategies. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

19 pages, 3908 KiB

Open AccessArticle

The Effect of Land Use/Cover Change on Soil Erosion Change by Spatial Regression in Changwu County on the Loess Plateau in China

by Shichuan Yu, Fei Wang, Mei Qu, Binhou Yu and Zhong Zhao

Forests 2021, 12(9), 1209; https://doi.org/10.3390/f12091209 - 06 Sep 2021

Cited by 9 | Viewed by 2002

Abstract

Changwu County is a typical soil and water loss area on the Loess Plateau. Soil erosion is an important ecological process, and the impact of land use/cover change on soil erosion has received much attention. The present study used remote sensing images of [...] Read more.

Changwu County is a typical soil and water loss area on the Loess Plateau. Soil erosion is an important ecological process, and the impact of land use/cover change on soil erosion has received much attention. The present study used remote sensing images of the study area in 1987, 1997, 2007, and 2017 to analyze the land use/cover change (LULCC), and the RUSLE model was applied to estimate the soil erosion in different times. We exploited the Sankey diagram to visualize the spatiotemporal changes in land use/cover and soil erosion. We planned to obtain the most suitable model by comparing the application of different spatial regression models (Geographically weighted regression model, Spatial lag model, Spatial error model) and Ordinary least squares in LULCC and soil erosion changes. The results revealed that land use/cover has significantly changed in the last 30 years. From 1987 to 1997, cropland expansion came mainly from planted land and orchards, which transformed 68.99 km² and 64.93 km², respectively. In 1997–2007, the planted land increase was mainly through the conversion of cropland. In 2007–2017, the increase in orchard area came mainly from cropland. The forest land increase was mainly from the planted land. Soil erosion in Changwu County was dominated by slight erosion and light erosion, although the area of slight erosion and light erosion continued to decrease. The annual average soil erosion increased, which was estimated at 977.84 ton km⁻² year⁻¹, 1305.17 ton km⁻² year⁻¹, 1310.60 ton km⁻² year⁻¹, and 1891.46 ton km⁻² year⁻¹ in 1987, 1997, 2007, and 2017, respectively. These amounts of transformation mainly occurred when slight erosion was converted to light erosion, light erosion was converted to moderate erosion, and moderate erosion was converted to light and severe erosion. The Spatial lag model and Spatial error model have higher accuracy than the Geographically weighted regression model and Ordinary least squares when fitting the effect of LULCC and soil erosion change, where the accuracy exceeded 0.62 in different periods. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

27 pages, 13159 KiB

Open AccessArticle

Evaluating the Performance of a Forest Succession Model to Predict the Long-Term Dynamics of Tree Species in Mixed Boreal Forests Using Historical Data in Northern Ontario, Canada

by Guy R. Larocque and F. Wayne Bell

Forests 2021, 12(9), 1181; https://doi.org/10.3390/f12091181 - 31 Aug 2021

Cited by 4 | Viewed by 2686

Abstract

Environmental concerns and economic pressures on forest ecosystems have led to the development of sustainable forest management practices. As a consequence, forest managers must evaluate the long-term effects of their management decisions on potential forest successional pathways. As changes in forest ecosystems occur [...] Read more.

Environmental concerns and economic pressures on forest ecosystems have led to the development of sustainable forest management practices. As a consequence, forest managers must evaluate the long-term effects of their management decisions on potential forest successional pathways. As changes in forest ecosystems occur very slowly, simulation models are logical and efficient tools to predict the patterns of forest growth and succession. However, as models are an imperfect representation of reality, it is desirable to evaluate them with historical long-term forest data. Using remeasured tree and stand data from three data sets from two ecoregions in northern Ontario, the succession gap model ZELIG-CFS was evaluated for mixed boreal forests composed of black spruce (Picea mariana [Mill.] B.S.P.), balsam fir (Abies balsamea [L.] Mill.), jack pine (Pinus banksiana L.), white spruce (Picea glauca [Moench] Voss), trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), northern white cedar (Thuja occidentalis L.), American larch (Larix laricina [Du Roi] K. Koch), and balsam poplar (Populus balsamefera L.). The comparison of observed and predicted basal areas and stand densities indicated that ZELIG-CFS predicted the dynamics of most species consistently for periods varying between 5 and 57 simulation years. The patterns of forest succession observed in this study support gap phase dynamics at the plot scale and shade-tolerance complementarity hypotheses at the regional scale. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

23 pages, 2628 KiB

Open AccessArticle

A Novel Approach to Modelling Stand-Level Growth of an Even-Aged Forest Using a Volume Productivity Index with Application to New Zealand-Grown Coast Redwood

by Mark O. Kimberley and Michael S. Watt

Forests 2021, 12(9), 1155; https://doi.org/10.3390/f12091155 - 26 Aug 2021

Cited by 11 | Viewed by 4749

Abstract

Empirical growth models are widely used to predict the growth and yield of plantation tree species, and the precise estimation of site quality is an important component of these models. The most commonly used proxy for site quality in growth models is Site [...] Read more.

Empirical growth models are widely used to predict the growth and yield of plantation tree species, and the precise estimation of site quality is an important component of these models. The most commonly used proxy for site quality in growth models is Site Index (SI), which describes the mean height of dominant trees at a specified base age. Although SI is widely used, considerable research shows significant site-dependent variation in height for a given volume, with this latter variable more closely reflecting actual site productivity. Using a national dataset, this study develops and describes a stand-level growth and yield model for even-aged New Zealand-grown coast redwood (Sequoia sempervirens). We used a novel modelling approach that quantifies site quality using SI and a volume-based index termed the 300 Index, defined as the volume mean annual increment at age 30 years for a reference regime of 300 stems ha⁻¹. The growth model includes a number of interrelated components. Mean top height is modelled from age and SI using a polymorphic Korf function. A modified anamorphic Korf function is used to describe tree quadratic mean diameter (D_q) as a function of age, stand density, SI and a diameter site index. As the D_q model includes stand density in its formulation, it can predict tree growth for different stand densities and thinning regimes. The mortality model is based on a simple attritional equation improved through incorporation of the Reineke stand density index to account for competition-induced mortality. Using these components, the model precisely estimates stand-level volume. The developed model will be of considerable value to growers for yield projection and regime evaluation. By more robustly describing the site effect, the growth model provides researchers with an improved framework for quantifying and understanding the causes of spatial and temporal variation in plantation productivity. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

23 pages, 2630 KiB

Open AccessEditor’s ChoiceArticle

Simulating the Effects of Intensifying Silviculture on Desired Species Yields across a Broad Environmental Gradient

by Eric B. Searle, F. Wayne Bell, Guy R. Larocque, Mathieu Fortin, Jennifer Dacosta, Rita Sousa-Silva, Marco Mina and Holly D. Deighton

Forests 2021, 12(6), 755; https://doi.org/10.3390/f12060755 - 08 Jun 2021

Cited by 8 | Viewed by 3432

Abstract

In the past two decades, forest management has undergone major paradigm shifts that are challenging the current forest modelling architecture. New silvicultural systems, guidelines for natural disturbance emulation, a desire to enhance structural complexity, major advances in successional theory, and climate change have [...] Read more.

In the past two decades, forest management has undergone major paradigm shifts that are challenging the current forest modelling architecture. New silvicultural systems, guidelines for natural disturbance emulation, a desire to enhance structural complexity, major advances in successional theory, and climate change have all highlighted the limitations of current empirical models in covering this range of conditions. Mechanistic models, which focus on modelling underlying ecological processes rather than specific forest conditions, have the potential to meet these new paradigm shifts in a consistent framework, thereby streamlining the planning process. Here we use the NEBIE (a silvicultural intervention scale that classifies management intensities as natural, extensive, basic, intensive, and elite) plot network, from across Ontario, Canada, to examine the applicability of a mechanistic model, ZELIG-CFS (a version of the ZELIG tree growth model developed by the Canadian Forest Service), to simulate yields and species compositions. As silvicultural intensity increased, overall yield generally increased. Species compositions met the desired outcomes when specific silvicultural treatments were implemented and otherwise generally moved from more shade-intolerant to more shade-tolerant species through time. Our results indicated that a mechanistic model can simulate complex stands across a range of forest types and silvicultural systems while accounting for climate change. Finally, we highlight the need to improve the modelling of regeneration processes in ZELIG-CFS to better represent regeneration dynamics in plantations. While fine-tuning is needed, mechanistic models present an option to incorporate adaptive complexity into modelling forest management outcomes. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

24 pages, 3501 KiB

Open AccessArticle

Carbon Sequestration in Mixed Deciduous Forests: The Influence of Tree Size and Species Composition Derived from Model Experiments

by Anne Holtmann, Andreas Huth, Felix Pohl, Corinna Rebmann and Rico Fischer

Forests 2021, 12(6), 726; https://doi.org/10.3390/f12060726 - 02 Jun 2021

Cited by 16 | Viewed by 4755

Abstract

Forests play an important role in climate regulation due to carbon sequestration. However, a deeper understanding of forest carbon flux dynamics is often missing due to a lack of information about forest structure and species composition, especially for non-even-aged and species-mixed forests. In [...] Read more.

Forests play an important role in climate regulation due to carbon sequestration. However, a deeper understanding of forest carbon flux dynamics is often missing due to a lack of information about forest structure and species composition, especially for non-even-aged and species-mixed forests. In this study, we integrated field inventory data of a species-mixed deciduous forest in Germany into an individual-based forest model to investigate daily carbon fluxes and to examine the role of tree size and species composition for stand productivity. This approach enables to reproduce daily carbon fluxes derived from eddy covariance measurements (R² of 0.82 for gross primary productivity and 0.77 for ecosystem respiration). While medium-sized trees (stem diameter 30–60 cm) account for the largest share (66%) of total productivity at the study site, small (0–30 cm) and large trees (>60 cm) contribute less with 8.3% and 25.5% respectively. Simulation experiments indicate that vertical stand structure and shading influence forest productivity more than species composition. Hence, it is important to incorporate small-scale information about forest stand structure into modelling studies to decrease uncertainties of carbon dynamic predictions. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

Review

Jump to: Editorial, Research

25 pages, 3642 KiB

Open AccessReview

Forest Dynamics Models for Conservation, Restoration, and Management of Small Forests

by Dessa L. Benson, Elizabeth G. King and Joseph J. O’Brien

Forests 2022, 13(4), 515; https://doi.org/10.3390/f13040515 - 26 Mar 2022

Cited by 4 | Viewed by 3900

Abstract

Globally, there are myriad situations in which people aim to conserve, restore, or manage forest ecosystems at small spatial scales of 50 ha or less. To inform management, forest dynamics models provide an increasingly diverse and valuable portfolio of tools for projecting forest [...] Read more.

Globally, there are myriad situations in which people aim to conserve, restore, or manage forest ecosystems at small spatial scales of 50 ha or less. To inform management, forest dynamics models provide an increasingly diverse and valuable portfolio of tools for projecting forest change under different management and environmental conditions. Yet, many models may not be appropriate or feasible to use in small forest management because of their design for larger-scale applications, the information needed to initialize models, or discrepancies between model outputs and information relevant for small forest management objectives. This review explores the suitability of 54 existing forest dynamics models to inform the management of small forests. We evaluated the characteristics of each model using five criteria with implications for small forest management: spatial resolution, number of species the model can simulate, inclusion of spatial structure, modeling approach, and mechanistic detail. While numerous models can be suitable under certain conditions, the review criteria led us to conclude that two models offered the broadest versatility and usability for small forest contexts, SORTIE and FORMIND. This review can help orient and guide small forest managers who wish to add modeling to their forest management efforts. Full article

(This article belongs to the Special Issue Simulation Models of the Dynamics of Forest Ecosystems)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Simulation Models of the Dynamics of Forest Ecosystems

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (17 papers)

Editorial

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI