Influences of gap microheterogeneity on the regeneration of Nothofagus pumilio in a xeric old-growth forest of northwestern Patagonia, Argentina

2000 ◽  
Vol 30 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Karin Heinemann ◽  
Thomas Kitzberger ◽  
Thomas T. Veblen
2014 ◽  
Vol 44 (10) ◽  
pp. 1265-1273 ◽  
Author(s):  
Valeria Ojeda ◽  
Laura Chazarreta

The Magellanic Woodpecker (Campephilus magellanicus (King, 1827)) is a large, vulnerable species exhibiting geographic range retraction. We analyzed the size and location of forest areas used by these woodpeckers in consecutive years (2010–2012), as related to habitat characteristics, in an old-growth lenga (Nothofagus pumilio (Poepp et Endl.) Krasser) forest of Argentine Patagonia. Woodpeckers were tracked during the postbreeding season, and forest features were evaluated in plots within territories. Woodpecker density was 1.01 territories·100 ha–1. The resident population apparently saturates the forest available in the study site; hence, territorial disputes were frequent between all pairs of adjacent families. Families used 39.3 ± 13.6 ha during the postreproductive season and 63.2 ± 12.3 ha across the three seasons, with interannual variability in both location and size of the areas used. Abundances of large live trees and of coarse woody debris were correlated with smaller, presumably high-quality, home ranges. Other forest attributes that are often important in woodpecker habitat (e.g., snag density) had little relationship with home-range size, but the high availability of resources in old-growth forests may mask their potential importance in a poorer quality habitat. Our results show that Magellanic Woodpecker family groups require a minimum of 100 ha in old-growth forest habitat; thus, forest patches in less favourable forest conditions (e.g., younger, managed, fragmented, mixed forests) should probably be much larger to support a resident pair or family. This habitat size would be a provisional minimum threshold to be used in management decisions involving the forests of Patagonia until alternative figures are derived from studies across multiple forest types.


2000 ◽  
Vol 30 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Karin Heinemann ◽  
Thomas Kitzberger ◽  
Thomas T Veblen

We experimentally examined the influences of within-gap environmental heterogeneity on regeneration patterns of Nothofagus pumilio (Poepp. & Endl.) Krasser near the xeric limit of its distribution in northern Patagonia, Argentina. Results from this xeric old-growth forest are compared with patterns previously described for the same species in mesic forests. Survival of N. pumilio seedlings beneath tree-fall gaps in this relatively xeric forest appears to be strongly influenced by moisture availability. Seedlings and saplings that have survived this demographic bottleneck are found at microsites where soil water potentials are higher, such as in the shady northern edges of tree-fall gaps (Ψ = -0.46 MPa compared with less than -0.6 MPa in other gap positions) and on coarse woody debris (Ψ = -0.29 MPa, compared with -0.51 MPa on the forest floor). Although gap creation in this dry N. pumilio forest is favorable to tree regeneration by releasing light resources, decreased water resources may switch the system from a light- to a water-limited system in some positions of the gap. This may explain the lack of regeneration of N. pumilio often observed after creation of large gaps towards the xeric end of its range and needs to be considered in the management of this important timber species.


2017 ◽  
Vol 7 (1-2) ◽  
pp. 73-107
Author(s):  
Orsolya Perger ◽  
Curtis Rollins ◽  
Marian Weber ◽  
Wiktor Adamowicz ◽  
Peter Boxall

2012 ◽  
Vol 163 (6) ◽  
pp. 240-246 ◽  
Author(s):  
Thomas A. Nagel ◽  
Jurij Diaci ◽  
Dusan Rozenbergar ◽  
Tihomir Rugani ◽  
Dejan Firm

Old-growth forest reserves in Slovenia: the past, present, and future Slovenia has a small number of old-growth forest remnants, as well as many forest reserves approaching old-growth conditions. In this paper, we describe some of the basic characteristics of these old-growth remnants and the history of their protection in Slovenia. We then trace the long-term development of research in these old-growth remnants, with a focus on methodological changes. We also review some of the recent findings from old-growth research in Slovenia and discuss future research needs. The conceptual understanding of how these forests work has slowly evolved, from thinking of them in terms of stable systems to more dynamic and unpredictable ones due to the influence of natural disturbances and indirect human influences. In accordance with this thinking, the methods used to study old-growth forests have changed from descriptions of stand structure to studies that address natural processes and ecosystem functions.


Nature ◽  
2021 ◽  
Vol 591 (7851) ◽  
pp. E21-E23
Author(s):  
Per Gundersen ◽  
Emil E. Thybring ◽  
Thomas Nord-Larsen ◽  
Lars Vesterdal ◽  
Knute J. Nadelhoffer ◽  
...  

2016 ◽  
Vol 13 (11) ◽  
pp. 3503-3517 ◽  
Author(s):  
Mianhai Zheng ◽  
Tao Zhang ◽  
Lei Liu ◽  
Weixing Zhu ◽  
Wei Zhang ◽  
...  

Abstract. Nitrogen (N) deposition is generally considered to increase soil nitrous oxide (N2O) emission in N-rich forests. In many tropical forests, however, elevated N deposition has caused soil N enrichment and further phosphorus (P) deficiency, and the interaction of N and P to control soil N2O emission remains poorly understood, particularly in forests with different soil N status. In this study, we examined the effects of N and P additions on soil N2O emission in an N-rich old-growth forest and two N-limited younger forests (a mixed and a pine forest) in southern China to test the following hypotheses: (1) soil N2O emission is the highest in old-growth forest due to the N-rich soil; (2) N addition increases N2O emission more in the old-growth forest than in the two younger forests; (3) P addition decreases N2O emission more in the old-growth forest than in the two younger forests; and (4) P addition alleviates the stimulation of N2O emission by N addition. The following four treatments were established in each forest: Control, N addition (150 kg N ha−1 yr−1), P addition (150 kg P ha−1 yr−1), and NP addition (150 kg N ha−1 yr−1 plus 150 kg P ha−1 yr−1). From February 2007 to October 2009, monthly quantification of soil N2O emission was performed using static chamber and gas chromatography techniques. Mean N2O emission was shown to be significantly higher in the old-growth forest (13.9 ± 0.7 µg N2O-N m−2 h−1) than in the mixed (9.9 ± 0.4 µg N2O-N m−2 h−1) or pine (10.8 ± 0.5 µg N2O-N m−2 h−1) forests, with no significant difference between the latter two. N addition significantly increased N2O emission in the old-growth forest but not in the two younger forests. However, both P and NP addition had no significant effect on N2O emission in all three forests, suggesting that P addition alleviated the stimulation of N2O emission by N addition in the old-growth forest. Although P fertilization may alleviate the stimulated effects of atmospheric N deposition on N2O emission in N-rich forests, this effect may only occur under high N deposition and/or long-term P addition, and we suggest future investigations to definitively assess this management strategy and the importance of P in regulating N cycles from regional to global scales.


1994 ◽  
Vol 24 (7) ◽  
pp. 1354-1368 ◽  
Author(s):  
Franco Biondi ◽  
Donald E. Myers ◽  
Charles C. Avery

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (Pinusponderosa Dougl. ex Laws. var. scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.


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