Human impacts drive forest structure and diversity. Insights from Mediterranean mountain forest dominated by Abies pinsapo (Boiss.)

2010 ◽  
Vol 130 (4) ◽  
pp. 533-542 ◽  
Author(s):  
J. C. Linares ◽  
J. A. Carreira ◽  
V. Ochoa
Ecosystems ◽  
2021 ◽  
Author(s):  
Dominik Thom ◽  
Rupert Seidl

AbstractClimate change alters forest development pathways, with consequences for ecosystem services and biodiversity. As the rate of warming increases, ecosystem change is expected to accelerate. However, ecosystem dynamics can have many causes unrelated to climate (for example, disturbance and stand development legacies). The compound effects of multiple drivers remain largely unclear. Here, we assessed forest dynamics over 28 years at Berchtesgaden National Park (BGNP), Germany, quantifying the spatiotemporal patterns and unraveling the drivers of forest change. We analyzed high-density forest inventory data, consisting of three consecutive censuses of 3759 permanent sample plots (132,866 tree records in total). We used semi-variograms to analyze spatial patterns of change, and boosted regression trees to quantify the effect of 30 covariates on changes in nine indicators of forest structure and composition. Over the 28 years investigated, the forests of BGNP were becoming denser, structurally more complex, and more species rich. Changes in forest structure were more pronounced and spatially correlated on the landscape than changes in tree species composition. Change rates of all indicators increased over time, signifying an acceleration of forest dynamics since the 1980s. Legacies and climate were the most important drivers of change, but had diverging impacts. Although forest change accelerated with increasing temperature, high legacy levels typical for late development stages dampened it. We here provide evidence for accelerating forest dynamics in mountain forests of the Alps, with potentially far-reaching consequences for biodiversity and ecosystem processes. We highlight that unmanaged forest development toward old-growth conditions could counteract climate-mediated acceleration of forest change.


2008 ◽  
Vol 38 (8) ◽  
pp. 2249-2261 ◽  
Author(s):  
Marc Hanewinkel ◽  
Johannes Breidenbach ◽  
Till Neeff ◽  
Edgar Kublin

We investigated the effects of site properties, forest structure, and time on snow breakage, insect outbreaks, windthrow, and total damage for predominantly planted forests. A time series of forest damage in southwestern Germany spanning 77 years, from 1925 to 2001, was available along with a database on site properties and forest structure. The statistical modeling procedure successively addressed (i) probability of damage occurrence, (ii) timber loss in damaging events, and (iii) interaction among damage agents over time. Logistic and linear regressions were combined with multivariate autoregressive techniques. Natural disturbances were responsible for a total timber loss of 3.0 m3· ha–1· year–1. The distribution of the timber loss values over the years and over sites and stands with different properties was modeled with a standard error of 6.7 m3· ha–1· year–1. Disturbances are more likely to occur in previously damaged stands. Storm events typically provoke subsequent insect outbreaks between 2 and 6 years later. Large windthrow and snow breakage events tend to occur periodically, once every 10th, 11th, or 15th year. Analysis of disturbances as a time series significantly enhances understanding of forest risk processes.


2017 ◽  
pp. 31
Author(s):  
Jorge Meave ◽  
Miguel Angel Soto ◽  
Luz María Calvo-Irabien ◽  
Horacio Paz-Hernández ◽  
Susana Valencia-Avalos

The floristic composition, structure, and texture of 1 ha of mesophytic mountain forest in Omiltemi, Guerrero, is described. With 138 species of vascular plants in the plot, this forest is very rich, with epiphytes, trees and herbs comprising the most diverse growth forms. The geographic affinities of this forest are diverse; many elements are shared with the andean-mesoamerican regions, and others are present in the deciduous forests of eastern United States. The Omiltemi forest is similar to other communities from western Mexico, and many of the endemic elements of this region occur in Omiltemi. This forest is structurally dense, approximately 24 m high, without a well-defined stratification. The canopy is made up mainly by Carpinus caroliniana and Quercus uxoris; Pinus ayacahuite is an emergent tree. The understory is rich in small-statured tree species. The horizontal distributions of the trees were analyzed, and only two understory species had a clumped pattern. Density is 2,096 trees/ha, total basal area is 49.82 m2/ha and cover is 263.8% The most important! species in the forest structure are those reaching the canopy. Two trends in the diametric structures of tree species populations were found: 1) with classes of small sizes having high frequencies, and gradually decreasing towards classes of larger sizes, and 2) with classes of intermediate sizes having lower frequencies than classes of smaller and larger sizes. The internal spatial variation of the forest structure was analyzed using multivariate methods. Tropical species were usually found in more humid places, while species of temperate affinities occurred in more exposed sites. Five floristic groups were recognized, and their associated structural features are described. This forest bears leaves throughout the year, although some of the most abundant species of the canopy are deciduous. The textural characteristics of pollination, dispersal and tree architecture are described. In addition, the mixed character of the mesophytic mountain forest of Omiltemi is discussed and related to its marginal geographic location.


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