Determinants of tree mortality in mixed old-growth Nothofagus forest

Hurst, Jennifer M.; Stewart, Glenn H.; Perry, George L.; Wiser, Susan K.; Norton, David A.

doi:10.1016/j.foreco.2012.01.029

Cited by 20 publications

(11 citation statements)

References 86 publications

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“…These opposing forms of density dependence reflect the importance of competition as a primary determinant of mortality for small‐diameter trees (Das et al 2008, 2011, Lutz et al 2014), and the importance of external factors (i.e., pests, pathogens, and physical damage) that compose the mortality complexes responsible for medium‐ and large‐diameter tree mortality (Franklin et al 1987, Das et al 2011, 2016). These results are consistent with the expectation that background mortality transitions from strongly density‐dependent within young forests to density‐independent among mature trees in old‐growth forests (He and Duncan 2000, Gray and He 2009, Yu et al 2009, Aakala et al 2012, Hurst et al 2012, Johnson et al 2014, Larson et al 2015), and they provide a more nuanced understanding of this transition by demonstrating that density dependence can continue to regulate mortality among small‐diameter stems even within a structurally complex, old‐growth forest.…”

Section: Discussionsupporting

confidence: 90%

Wildfire and drought moderate the spatial elements of tree mortality

et al. 2020

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Background tree mortality is a complex process that requires large sample sizes and long timescales to disentangle the suite of ecological factors that collectively contribute to tree stress, decline, and eventual mortality. Tree mortality associated with acute disturbance events, in contrast, is conspicuous and frequently studied, but there remains a lack of research regarding the role of background mortality processes in mediating the severity and delayed effects of disturbance. We conducted an empirical study by measuring the rates, causes, and spatial pattern of mortality annually among 32,989 individual trees within a large forest demography plot in the Sierra Nevada. We characterized the relationships between background mortality, compound disturbances (fire and drought), and forest spatial structure, and we integrated our findings with a synthesis of the existing literature from around the world to develop a conceptual framework describing the spatio‐temporal signatures of background and disturbance‐related tree mortality. The interactive effects of fire, drought, and background mortality processes altered the rate, spatial structuring, and ecological consequences of mortality. Before fire, spatially non‐random mortality was only evident among small (1 < cm DBH ≤ 10)‐ and medium (10 < cm DBH ≤ 60)‐diameter classes; mortality rates were low (1.7% per yr), and mortality was density‐dependent among small‐diameter trees. Direct fire damage caused the greatest number of moralities (70% of stems ≥1 cm DBH), but the more enduring effects of this disturbance on the demography and spatial pattern of large‐diameter trees occurred during the post‐fire mortality regime. The combined effects of disturbance and biotic mortality agents provoked density‐dependent mortality among large‐diameter (≥60 cm DBH) trees, eliciting a distinct post‐disturbance mortality regime that did not resemble the pattern of either pre‐fire mortality or direct fire effects. The disproportionate ecological significance of the largest trees renders this mortality regime acutely consequential to the long‐term structure and function of forests.

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Section: Discussionsupporting

confidence: 90%

Wildfire and drought moderate the spatial elements of tree mortality

et al. 2020

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“…Mortality, growth and recruitment of tree species are key factors influencing the structure, composition and succession of forest communities 7 . Tree mortality is recognized as one of the most important processes in forest dynamics and is influenced by many factors 7 . It can facilitate turnover in species composition, affect community structure, and alter rates of nutrient cycling or biomass accumulation 8 .…”

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confidence: 99%

“…Dispersal limitation is another mechanism driving of species diversity. Dispersal limitation refers to the phenomenon of declining seed density with increasing distance from the maternal tree 7 . Seeds of superior competitors may fail to arrive at suitable micro-sites and less competitive species will have more chances to take their places, thus, slowing competitive exclusion and promoting species coexistence 23 .…”

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Forest dynamics and its driving forces of sub-tropical forest in South China

Lian

Lin

et al. 2016

Sci Rep

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Tree mortality and recruitment are key factors influencing forest dynamics, but the driving mechanisms of these processes remain unclear. To better understand these driving mechanisms, we studied forest dynamics over a 5-year period in a 20-ha sub-tropical forest in the Dinghushan Nature Reserve, South China. The goal was to identify determinants of tree mortality/recruitment at the local scale using neighborhood analyses on some locally dominant tree species. Results show that the study plot was more dynamic than some temperate and tropical forests in a comparison to large, long-term forest dynamics plots. Over the 5-year period, mortality rates ranged from 1.67 to 12.33% per year while recruitment rates ranged from 0 to 20.26% per year. Tree size had the most consistent effect on mortality across species. Recruitment into the ≥1-cm size class consistently occurred where local con-specific density was high. This suggests that recruitment may be limited by seed dispersal. Hetero-specific individuals also influenced recruitment significantly for some species. Canopy species had low recruitment into the ≥1-cm size class over the 5-year period. In conclusion, tree mortality and recruitment for sixteen species in this plot was likely limited by seed dispersal and density-dependence.

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“…Holloway 1954;Wardle 1978Wardle , 1985. The role of species' regeneration niches is also evident at smaller extents, such as in the dynamics of the forests where L. menziesii and Fuscospora co-occur (Hurst et al 2012). The coexistence of these canopy components in dynamic equilibrium (Ogden 1988) can be seen to relate, in part, to the regeneration requirements and characteristics of the different taxa.…”

Section: Discussionmentioning

confidence: 99%

New Zealand forest dynamics: a review of past and present vegetation responses to disturbance, and development of conceptual forest models

Wyse¹,

Wilmshurst²,

Burns³

et al. 2018

NZ J Ecol

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New Zealand forests have been and are shaped by a suite of disturbance types that vary in both their spatial extent and frequency of recurrence. Post-disturbance forest dynamics can be complex, non-linear, and involve multiple potential pathways depending on the nature of a perturbation, site conditions, and history. To capture the full range of spatial and temporal dynamics that shape forest ecosystems in a given area, we need to use and synthesise data sources that collectively capture all the relevant space-time scales. Here we integrate palaeoecological data with contemporary ecological evidence to build conceptual models describing post-disturbance dynamics in New Zealand (NZ) forests, encompassing large temporal and spatial scales. We review NZ forest disturbance regimes, focussing primarily on geological and geomorphic disturbances and weather-related disturbances but also considering the role of anthropogenic disturbance in shaping present-day NZ forests. Combining information from 58 studies of post-disturbance forest succession, we derive conceptual models and describe forest communities and forest change for conifer-angiosperm (including kauri forest), and beech forests (pure and mixed). The methods used in these studies included chronosequences, assessments of stand dynamics, longitudinal studies, palaeoecological reconstructions, and comparisons with historical observations; the temporal range of the studies extended from 15 years to millennia (c. 14 000 years BP). Our models capture the generalities of NZ forest dynamics, and can be used to support modelling and help guide decision-making in areas such as ecosystem restoration. However, this generality limits model resolution, meaning the models do not always portray the specific features of individual sites and successional pathways. There is, therefore, scope for more detailed, site-specific development and refinement of these frameworks. Finally, our models capture successional pathways and native plant communities from the past and present; invasive species, climate change, and exotic plant pathogens are likely to alter future forest dynamics in novel and unpredictable ways. These models, however, provide us with baselines against which to interpret and assess the impacts of such effects on forest composition and processes.

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Determinants of tree mortality in mixed old-growth Nothofagus forest

Cited by 20 publications

References 86 publications

Wildfire and drought moderate the spatial elements of tree mortality

Wildfire and drought moderate the spatial elements of tree mortality

Forest dynamics and its driving forces of sub-tropical forest in South China

New Zealand forest dynamics: a review of past and present vegetation responses to disturbance, and development of conceptual forest models

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