scholarly journals Principal Factors Influencing Tree Growth in Low-Lying Mid Atlantic Coastal Forests

Forests ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1351
Author(s):  
LeeAnn Haaf ◽  
Salli F. Dymond ◽  
Danielle A. Kreeger

Flood frequencies in coastal forests are increasing as sea level rise accelerates from 3–4 mm year−1 to possibly more than 10 mm year−1 by the end of this century. As flooding increases, coastal forests retreat, ghost forests form, and coastal marshes migrate inland. The existence of ghost forests makes the mechanism of forest retreat clear: low-lying trees become more exposed to coastal flooding until they ultimately die. Variability in these retreat rates, however, makes it difficult to predict where and when retreat will continue to occur. Understanding tree growth responses to tidal water levels relative to other environmental factors is a critical step in elucidating the factors that influence retreat variability. Here, dendrochronology was used to study factors that contribute to variations in growth patterns in four coastal forests fringing the Delaware and Barnegat Bays. Species chosen for study included loblolly pine (Pinus taeda), pitch pine (Pinus rigida), and American holly (Ilex opaca). Pearson’s and partial correlation tests showed that growth relationships with monthly environmental conditions varied across sites and were moderate in strength (generally R < 0.5), but each site had at least one significant growth-water level correlation. As coastal flooding exposure is spatially dependent, tree chronologies were also separated into high and low elevation groups. Pearson’s and partial correlation tests of the mean differences between elevation groups showed that at some sites, low elevation trees grew less than high elevation trees when water levels were high, as might be expected. At one site, however, lower elevation trees grew more when water levels were higher, which suggests that other interacting factors—regardless of current flood exposure—potentially have positive, yet likely temporary, influence over tree growth in these low-lying areas.

2021 ◽  
Vol 12 ◽  
Author(s):  
Joana Vieira ◽  
Cristina Nabais ◽  
Filipe Campelo

Tree rings are valuable proxies of past climate that allow inferring past growth responses to climate variability and extreme events, which is only possible considering that the relationship between tree growth and environmental conditions is linear and stable over time. However, in the last decades, divergent growth patterns have been observed in trees from the same forest stand, while unprecedented growth convergence was observed between trees from distant locations. Here, we use a new approach that considers convergent and divergent event years in two populations of Pinus pinaster Aiton in an altitudinal and oceanic-continental gradient to investigate what is triggering divergence and convergence in tree growth. The two study sites are Tocha (TCH), a plantation on sand dunes at low altitude near the ocean, and Serra da Estrela (SdE), a mountain plantation located at 1,100 m altitude, 100 km away from the ocean. The analysis of the climatic conditions in convergent growth years revealed that positive convergent growth was related to above average precipitation in previous winter and that negative convergent growth was related to below average precipitation during the growing season. Divergent growth revealed a temperature signal with warmer temperatures in spring promoting growth in SdE and growth reduction in TCH. Convergent growth was associated with a regional climatic signal, reinforcing the importance of precipitation in the Mediterranean region, and divergent growth to site conditions, revealing local adaptation. The information gathered in this study gives valuable insights on the response of P. pinaster to extreme climatic events, allowing for more adjusted management strategies of Mediterranean pine forests.


Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1133 ◽  
Author(s):  
Lei Zhang ◽  
Hao Shi ◽  
Pengtao Yu ◽  
Yanhui Wang ◽  
Shufen Pan ◽  
...  

Dryland montane forests conserve water for people living in the fluvial plains. The fate of these forests under climate warming is strongly affected by local environmental factors. The question remains of how internal factors contribute to climate change impacts on forest growth in these regions. Here, we investigated tree ring records for similar-aged stand-grown trees and their neighboring open-grown trees at elevation in a dryland montane forest (Picea crassifolia Kom.) in northwestern China. The growth rate of open-grown trees is much higher than their neighboring stand-grown trees across the entire elevation gradient, and the lower the altitude, the greater the difference. Open-grown trees at different elevations showed similar growth patterns, as tree growth at all sites was accelerated over time. In contrast, growth patterns of stand-grown trees were divergent at different altitudes, as growth at high elevations (3100–3300 m a.s.l.) was accelerated, whereas growth at low elevations (2700–2900 m a.s.l.) became stable after the year 1990. Analysis of growth–climate relationships indicated that warming promoted open-grown tree growth across the entire altitude gradient, and also stand-grown tree growth at high elevations, but negatively affected the growth of stand-grown trees at low elevations. Water scarcity can be exacerbated by competition within forests, inhibiting the warming-induced benefits on tree growth. Moving window correlation analysis suggested the negative effect of warming on tree growth at low elevations was diminished after the late 1990s, as the drought stress was alleviated. Our research shows the divergent growth responses to warming of stand-grown and open-grown trees along elevation. It reveals effects of internal factors in determining tree growth response to warming and holds the potential to aid forest management and ecosystem models in responding to climate change.


2021 ◽  
Vol 7 (22) ◽  
pp. eabb7572
Author(s):  
Paulo Quadri ◽  
Lucas C. R. Silva ◽  
Erika S. Zavaleta

Globally, cold-limited trees and forests are expected to experience growth acceleration as a direct response to warming temperatures. However, thresholds of temperature limitation may vary substantially with local environmental conditions, leading to heterogeneous responses in tree ecophysiology. We used dendroecological and isotopic methods to quantify shifting tree growth and resource use over the past 143 years across topographic aspects in a high-elevation forest of central Mexico. Trees on south-facing slopes (SFS) grew faster than those on north-facing slopes (NFS) until the mid-20th century, when this pattern reversed notably with marked growth rate declines on SFS and increases on NFS. Stable isotopes of carbon, oxygen, and carbon-to-nitrogen ratios suggest that this reversal is linked to interactions between CO2 stimulation of photosynthesis and water or nitrogen limitation. Our findings highlight the importance of incorporating landscape processes and habitat heterogeneity in predictions of tree growth responses to global environmental change.


Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1015
Author(s):  
Xuan Wu ◽  
Liang Jiao ◽  
Dashi Du ◽  
Changliang Qi ◽  
Ruhong Xue

It is important to explore the responses of radial tree growth in different regions to understand growth patterns and to enhance forest management and protection with climate change. We constructed tree ring width chronologies of Picea crassifolia from different regions of the Qilian Mountains of northwest China. We used Pearson correlation and moving correlation to analyze the main climate factors limiting radial growth of trees and the temporal stability of the growth–climate relationship, while spatial correlation is the result of further testing the first two terms in space. The conclusions were as follows: (1) Radial growth had different trends, showing an increasing followed by a decreasing trend in the central region, a continuously increasing trend in the eastern region, and a gradually decreasing trend in the isolated mountain. (2) Radial tree growth in the central region and isolated mountains was constrained by drought stress, and tree growth in the central region was significantly negatively correlated with growing season temperature. Isolated mountains showed a significant negative correlation with mean minimum of growing season and a significant positive correlation with total precipitation. (3) Temporal dynamic responses of radial growth in the central region to the temperatures and SPEI (the standardized precipitation evapotranspiration index) in the growing season were unstable, the isolated mountains to total precipitation was unstable, and that to SPEI was stable. The results of this study suggest that scientific management and maintenance plans of the forest ecosystem should be developed according to the response and growth patterns of the Qinghai spruce to climate change in different regions of the Qilian Mountains.


1997 ◽  
Vol 21 (2) ◽  
pp. 84-89 ◽  
Author(s):  
Steven E. McKeand ◽  
Robert P. Crook ◽  
H. Lee Allen

Abstract The lack of rank change in growth characteristics when open-pollinated families of loblolly pine (Pinus taeda L.) are planted on different sites in the Southeast has greatly simplified breeding for superior genotypes. Although family rank does not usually change, genotype by environment interactions (GxE) may be very important in operational deployment of families in regeneration programs. Using data from GxE trials and two site preparation-fertilization-herbicide trials, we estimated the growth that different families should achieve following application of these silvicultural practices. Better performing families tend to be most responsive to site changes (i.e. genetically unstable). Growth responses to silvicultural treatment will be overestimated if only the most responsive families are used in silvicultural research trials. Similarly, genetic gains will be overestimated if gain trials are planted on only the best sites or receive intensive culture. South. J. Appl. For. 21(2):84-89.


Fractals ◽  
1994 ◽  
Vol 02 (02) ◽  
pp. 297-301
Author(s):  
B. DUBUC ◽  
S. W. ZUCKER ◽  
M. P. STRYKER

A central issue in characterizing neuronal growth patterns is whether their arbors form clusters. Formal definitions of clusters have been elusive, although intuitively they appear to be related to the complexity of branching. Standard notions of complexity have been developed for point sets, but neurons are specialized "curve-like" objects. Thus we consider the problem of characterizing the local complexity of a "curve-like" measurable set. We propose an index of complexity suitable for defining clusters in such objects, together with an algorithm that produces a complexity map which gives, at each point on the set, precisely this index of complexity. Our index is closely related to the classical notions of fractal dimension, since it consists in determining the rate of growth of the area of a dilated set at a given scale, but it differs in two significant ways. First, the dilation is done normal to the local structure of the set, instead of being done isotropically. Second, the rate of growth of the area of this new set, which we named "normal complexity", is taken at a fixed (given) scale instead instead of around zero. The results will be key in choosing the appropriate representation when integrating local information in low level computer vision. As an application, they lead to the quantification of axonal and dendritic tree growth in neurons.


Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 545
Author(s):  
Alexis K. Mills ◽  
Peter Ruggiero ◽  
John P. Bolte ◽  
Katherine A. Serafin ◽  
Eva Lipiec

Coastal communities face heightened risk to coastal flooding and erosion hazards due to sea-level rise, changing storminess patterns, and evolving human development pressures. Incorporating uncertainty associated with both climate change and the range of possible adaptation measures is essential for projecting the evolving exposure to coastal flooding and erosion, as well as associated community vulnerability through time. A spatially explicit agent-based modeling platform, that provides a scenario-based framework for examining interactions between human and natural systems across a landscape, was used in Tillamook County, OR (USA) to explore strategies that may reduce exposure to coastal hazards within the context of climate change. Probabilistic simulations of extreme water levels were used to assess the impacts of variable projections of sea-level rise and storminess both as individual climate drivers and under a range of integrated climate change scenarios through the end of the century. Additionally, policy drivers, modeled both as individual management decisions and as policies integrated within adaptation scenarios, captured variability in possible human response to increased hazards risk. The relative contribution of variability and uncertainty from both climate change and policy decisions was quantified using three stakeholder relevant landscape performance metrics related to flooding, erosion, and recreational beach accessibility. In general, policy decisions introduced greater variability and uncertainty to the impacts of coastal hazards than climate change uncertainty. Quantifying uncertainty across a suite of coproduced performance metrics can help determine the relative impact of management decisions on the adaptive capacity of communities under future climate scenarios.


2018 ◽  
Vol 18 (4) ◽  
pp. 1247-1260 ◽  
Author(s):  
Gemma L. Franklin ◽  
Alec Torres-Freyermuth ◽  
Gabriela Medellin ◽  
María Eugenia Allende-Arandia ◽  
Christian M. Appendini

Abstract. Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef–dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH). Wave hindcast information, tidal level, and a measured beach profile of the reef–dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore reef slope) is warranted.


Author(s):  
Peng Bun Ngor ◽  
Ratha Sor ◽  
Leang Hour Prak ◽  
Nam So ◽  
Zeb S. Hogan ◽  
...  

Molluscs are important for ecological function, livelihoods and fisheries, but are often forgotten in research and management. Here, we investigated intra-annual variation in the landing and growth patterns of three mollusc species, i.e., Corbicula moreletiana, Pila virescens and Pila ampullacea, using one-year daily data on landing catches and values, recorded in Kampong Chhnang province of Tonle Sap (TS) Lake. Overall, 8330 tonnes with a first sale landing value of US$ 1.4 million for the three species were reported. Also, we found that C. moreletiana was abundant during the dry season with high temperature and less precipitation. By contrast, the two Pila species were abundant from the early rainy to early dry seasons when precipitation and water levels increase. The length–weight relationship analysis indicated that a faster growth in weight of Pila species occurred in the rainy season, and a general negative allometric growth was observed for the three species. This implies that their populations were intensively fished. Our preliminary results suggest that molluscs in the TS Lake (i) are important resources in support of people's livelihoods, (ii) respond differently to intra-annual variation in temperature, precipitation and hydrology and (iii) are being intensively exploited with significant reduction in growth rate. Therefore, it is necessary to conduct further comprehensive research describing status of mollusc stocks and their ecology to support long-term management and conservation of this important aquatic fauna. Our study contributes to establishing the first important baseline data and information on key mollusc species for the TS.


1996 ◽  
Vol 26 (4) ◽  
pp. 670-681 ◽  
Author(s):  
S.B. McLaughlin ◽  
D.J. Downing

Seasonal growth patterns of mature loblolly pine (Pinustaeda L.) trees over the interval 1988–1993 have been analyzed to evaluate the effects of ambient ozone on growth of large forest trees. Patterns of stem expansion and contraction of 34 trees were examined using serial measurements with sensitive dendrometer band systems. Study sites, located in eastern Tennessee, varied significantly in soil moisture, soil fertility, and stand density. Levels of ozone, rainfall, and temperature varied widely over the 6-year study interval. Regression analysis identified statistically significant influences of ozone on stem growth patterns, with responses differing widely among trees and across years. Ozone interacted with both soil moisture stress and high temperatures, explaining 63% of the high frequency, climatic variance in stem expansion identified by stepwise regression of the 5-year data set. Observed responses to ozone were rapid, typically occurring within 1–3 days of exposure to ozone at ≥40 ppb and were significantly amplified by low soil moisture and high air temperatures. Both short-term responses, apparently tied to ozone-induced increases in whole-tree water stress, and longer term cumulative responses were identified. These data indicate that relatively low levels of ambient ozone can significantly reduce growth of mature forest trees and that interactions between ambient ozone and climate are likely to be important modifiers of future forest growth and function. Additional studies of mechanisms of short-term response and interspecies comparisons are clearly needed.


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