Density and diversity of lianas along a chronosequence in a central Panamanian lowland forest

2000 ◽  
Vol 16 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Saara J. Dewalt ◽  
Stefan A. Schnitzer ◽  
Julie S. Denslow
Keyword(s):  
Tropical Forest ◽  
Tropical Forests ◽  
Relative Abundance ◽  
Light Availability ◽  
Basal Area ◽  
Stand Age ◽  
Old Growth ◽  
Lowland Forest ◽  
Abundance And Diversity

The abundance and diversity of lianas were examined along a tropical forest chronosequence at the Barro Colorado Nature Monument, Panama. Lianas ≥0.5 cm diameter were sampled along transects in two replicated stands in secondary (20, 40, 70 and 100 y after abandonment) and old-growth (>500 y) forests. Ordination of stands based on relative abundance, but not presence-absence, showed a significant separation of stands by age. Lianas were significantly more abundant and diverse (Fisher's α) in younger forests (20 and 40 y) than in older forests (70 and 100 y, and old-growth). The decline in liana abundance with stand age was offset by increased mean basal area per individual, resulting in a relatively constant total basal area and estimated biomass across stand age. The proportions of tendril climbers decreased and stem twiners increased over stand age. Decline in liana abundance and changes in liana composition may be related to changes in support and light availability. Although lianas are recognized as playing an important role in the early secondary sucession of many tropical forests, these results have shown that their important contribution to total basal area and biomass can continue as the forest matures, even as the numbers of established lianas declines.

Small understorey trees have greater capacity than canopy trees to adjust hydraulic traits following prolonged experimental drought in a tropical forest

2021 ◽  
Author(s):  
A L Giles ◽  
L Rowland ◽  
P R L Bittencourt ◽  
D C Bartholomew ◽  
I Coughlin ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Light Availability ◽  
Future Climate Change ◽  
Hydraulic Systems ◽  
Exclusion Experiment ◽  
Canopy Trees ◽  
Large Trees ◽  
Throughfall Exclusion

Abstract Future climate change predictions for tropical forests highlight increased frequency and intensity of extreme drought events. However, it remains unclear whether large and small trees have differential strategies to tolerate drought due to the different niches they occupy. The future of tropical forests is ultimately dependent on the capacity of small trees (<10 cm in diameter) to adjust their hydraulic system to tolerate drought. To address this question, we evaluated whether the drought tolerance of neotropical small trees can adjust to experimental water stress and was different from tall trees. We measured multiple drought resistance-related hydraulic traits across nine common neotropical genera at the world’s longest-running tropical forest throughfall-exclusion experiment and compared their responses with surviving large canopy trees. Small understorey trees in both the Control and the throughfall exclusion treatment (TFE) had lower minimum stomatal conductance and maximum hydraulic leaf-specific conductivity relative to large trees of the same genera, as well as greater hydraulic safety margin (HSM), percentage loss of conductivity (PLC) and embolism resistance, demonstrating they occupy a distinct hydraulic niche. Surprisingly, in response to the drought treatment, small trees increased specific hydraulic conductivity by 56.3% and leaf:sapwood area ratio by 45.6%. The greater HSM of small understorey trees relative to large canopy trees likely enabled them to adjust other aspects of their hydraulic systems to increase hydraulic conductivity and take advantage of increases in light availability in the understorey resulting from the drought-induced mortality of canopy trees. Our results demonstrate that differences in hydraulic strategies between small understorey and large canopy trees drive hydraulic niche segregation. Small understorey trees can adjust their hydraulic systems in response to changes in water and light availability indicating natural regeneration of tropical forests following long-term drought may be possible.

Effects of light availability and rainfall on leaf production in a moist tropical forest in central Panama

1998 ◽  
Vol 14 (3) ◽  
pp. 309-321 ◽  
Author(s):  
JOHN A. BARONE
Keyword(s):  
Tropical Forest ◽  
Tropical Forests ◽  
Light Availability ◽  
Dry Season ◽  
Wet Season ◽  
Leaf Production ◽  
Active Radiation ◽  
One Year ◽  
The Relationship ◽  
Central Panama

New leaf production in seasonal tropical forests may result from changes in water or light availability. In this study, the relationship between leaf flushing, photosynthetically active radiation (PAR) and rainfall was examined for understorey saplings in a moist tropical forest over one year. During the wet season, weeks with greater PAR were correlated with a greater proportion of saplings flushing new leaves during subsequent weeks in nine out of ten species. Rainfall was negatively correlated with subsequent leafing during the wet season for six of ten species. However, during the dry season, rainfall was positively correlated with leafing during the following weeks for six species, but the relationship was much weaker. PAR in the dry season was negatively correlated with flushing in eight species. These results support the hypothesis that under well-watered conditions, light limits leaf production, and peaks in insolation result in greater leaf production.

scholarly journals Deadwood Characteristics in Mature and Old-Growth Birch Stands and Their Implications for Carbon Storage

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 536 ◽  
Author(s):  
Silva Šēnhofa ◽  
Ieva Jaunslaviete ◽  
Guntars Šņepsts ◽  
Jurģis Jansons ◽  
Līga Liepa ◽  
...  
Keyword(s):  
Basal Area ◽  
High Volume ◽  
Stand Age ◽  
Old Growth ◽  
Stand Productivity ◽  
Stand Type ◽  
The Difference ◽  
Mineral Soils ◽  
Stand Height ◽  
Mature Stands

As one of the most abundant tree species in the hemiboreal zone, birch is important from both commercial and biodiversity perspectives. While old-growth deciduous stands are important for biodiversity conservation with an emphasis on deadwood availability, the role that deadwood in these stands plays in carbon sequestration remains unclear. We studied mature (71–110 years old) and old-growth (121–150 years old) birch stands on fertile mineral soils. The marginal mean deadwood volume was 43.5 ± 6.4 m3 ha−1 in all mature stands, 51.3 ± 7.1 m3 ha−1 in recently unmanaged mature stands, and 54.4 ± 4.4 m3 ha−1 in old-growth stands; the marginal mean deadwood carbon pool for each stand type was 5.4 ± 0.8 t·ha−1, 6.3 ± 0.9 t·ha−1, and 7.9 ± 0.6 t·ha−1, respectively. Deadwood volume was not related to stand productivity in terms of stand basal area, stand height, or stand age. The difference between mature and old-growth stands remained non-significant (p < 0.05). A high volume of deadwood was almost continuously present throughout the landscape in assessed unmanaged sites; moreover, 88% of sample plots in old-growth stands and 63% of sample plots in mature stands had a deadwood volume higher than 20 m3·ha−1. Old-growth stands had a slightly greater volume of large deadwood than unmanaged mature stands; in both, almost half of the deadwood was more than 30 cm in diameter and approximately one-fifth had a diameter greater than 40 cm. Both groups of stands had similar proportions of coniferous and deciduous deadwood and lying and standing deadwood. Old-growth stands had a higher volume of recently and weakly decayed wood, indicating increased dieback during recent years.

Evidence for arrested succession within a tropical forest fragment in Singapore

2011 ◽  
Vol 27 (03) ◽  
pp. 323-326 ◽  
Author(s):  
Gregory R. Goldsmith ◽  
Liza S. Comita ◽  
Siew Chin Chua
Keyword(s):  
Ecosystem Services ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Secondary Forests ◽  
Forest Fragment ◽  
Landscape Mosaic ◽  
Old Growth ◽  
Arrested Succession ◽  
Old Growth Forests ◽  
Tropical Landscape

Secondary forests occupy a growing portion of the tropical landscape mosaic due to regeneration on abandoned pastures and other disturbed sites (Asneret al. 2009). Tropical secondary forests and degraded old-growth forests now account for more than half of the world's tropical forests (Chazdon 2003), and provide critical ecosystem services (Brown &amp; Lugo 1990, Guariguata &amp; Ostertag 2001).

scholarly journals Detecting tropical forest biomass dynamics from repeated airborne lidar measurements

2013 ◽  
Vol 10 (8) ◽  
pp. 5421-5438 ◽  
Author(s):  
V. Meyer ◽  
S. S. Saatchi ◽  
J. Chave ◽  
J. W. Dalling ◽  
S. Bohlman ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Spatial Scale ◽  
Tropical Forests ◽  
Spatial Scales ◽  
Forest Biomass ◽  
Airborne Lidar ◽  
Barro Colorado Island ◽  
Accurate Estimation ◽  
Old Growth ◽  
Lidar Measurements

Abstract. Reducing uncertainty of terrestrial carbon cycle depends strongly on the accurate estimation of changes of global forest carbon stock. However, this is a challenging problem from either ground surveys or remote sensing techniques in tropical forests. Here, we examine the feasibility of estimating changes of tropical forest biomass from two airborne lidar measurements of forest height acquired about 10 yr apart over Barro Colorado Island (BCI), Panama. We used the forest inventory data from the 50 ha Center for Tropical Forest Science (CTFS) plot collected every 5 yr during the study period to calibrate the estimation. We compared two approaches for detecting changes in forest aboveground biomass (AGB): (1) relating changes in lidar height metrics from two sensors directly to changes in ground-estimated biomass; and (2) estimating biomass from each lidar sensor and then computing changes in biomass from the difference of two biomass estimates, using two models, namely one model based on five relative height metrics and the other based only on mean canopy height (MCH). We performed the analysis at different spatial scales from 0.04 ha to 10 ha. Method (1) had large uncertainty in directly detecting biomass changes at scales smaller than 10 ha, but provided detailed information about changes of forest structure. The magnitude of error associated with both the mean biomass stock and mean biomass change declined with increasing spatial scales. Method (2) was accurate at the 1 ha scale to estimate AGB stocks (R2 = 0.7 and RMSEmean = 27.6 Mg ha−1). However, to predict biomass changes, errors became comparable to ground estimates only at a spatial scale of about 10 ha or more. Biomass changes were in the same direction at the spatial scale of 1 ha in 60 to 64% of the subplots, corresponding to p values of respectively 0.1 and 0.033. Large errors in estimating biomass changes from lidar data resulted from the uncertainty in detecting changes at 1 ha from ground census data, differences of approximately one year between the ground census and lidar measurements, and differences in sensor characteristics. Our results indicate that the 50 ha BCI plot lost a significant amount of biomass (−0.8 Mg ha−1 yr−1 ± 2.2(SD)) over the past decade (2000–2010). Over the entire island and during the same period, mean AGB change was 0.2 ± 2.4 Mg ha−1 yr−1 with old growth forests losing −0.7 Mg ha−1 yr−1 ± 2.2 (SD), and secondary forests gaining +1.8 Mg ha yr−1 ± 3.4 (SD) biomass. Our analysis suggests that repeated lidar surveys, despite taking measurement with different sensors, can estimate biomass changes in old-growth tropical forests at landscape scales (>10 ha).

scholarly journals Managing forest harvesting to maintain old growth in boreal and sub-boreal forests

1999 ◽  
Vol 75 (4) ◽  
pp. 623-631 ◽  
Author(s):  
Philip J. Burton ◽  
Daniel D. Kneeshaw ◽  
K. David Coates
Keyword(s):  
Basal Area ◽  
Timber Harvest ◽  
Forest Harvesting ◽  
Stand Age ◽  
Forest Age ◽  
Old Growth ◽  
Partial Cutting ◽  
Growth Status ◽  
Age Class ◽  
Old Growth Forest

Old-growth stands can be rare in northern coniferous forests, and hence are worthy of protection and special management. We describe some quantitative guidelines for recognizing old-growth stands and options for maintaining a long-term supply of old-growth values in landscapes managed for timber production. In the Sub-Boreal Spruce forests of central British Columbia, attributes most indicative of old-growth status include stand age, the density of large (> 1.0 m3) snags and downed logs, stand basal area and volume. It is suggested that partial cutting could occur in some old-growth stands, while still maintaining their structural and functional attributes, if large logs, snags and trees are retained at the threshold densities necessary to recognise old-growth status. At the landscape level, the use of extended timber crop rotations is advocated. Planning for a tapered forest age class distribution (with decreasing areas of forest allowed to persist to successively older ages) is suggested as a means of sustainably generating true old-growth, and as an alternative to the use of partial cutting and patch retention. Arithmetic formulas are developed which provide guidelines for the proportion of the forest land base to be kept in each successive age class. This model for regulating human disturbance in commercial forests holds promise as a mechanism for allowing continued timber harvest and even-aged stand management while retaining a near-natural proportion of old-growth forest in northern landscapes. Key words: disturbance regime, even-aged management, extended rotations, forest age class structure, forest management, old-growth attributes, rotation length, silvicultural systems, sub-boreal spruce zone, timber supply planning.

scholarly journals Detecting tropical forest biomass dynamics from repeated airborne Lidar measurements

2013 ◽  
Vol 10 (2) ◽  
pp. 1957-1992 ◽  
Author(s):  
V. Meyer ◽  
S. S. Saatchi ◽  
J. Chave ◽  
J. Dalling ◽  
S. Bohlman ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Tropical Forests ◽  
Spatial Scales ◽  
Forest Biomass ◽  
Airborne Lidar ◽  
Barro Colorado Island ◽  
Accurate Estimation ◽  
Prediction Errors ◽  
Old Growth ◽  
Lidar Measurements

Abstract. Reducing uncertainty of terrestrial carbon cycle depends strongly on the accurate estimation of changes of global forest carbon stock. However, this is a challenging problem from either ground surveys or remote sensing techniques in tropical forests. Here, we examine the feasibility of estimating changes of tropical forest biomass from two airborne Lidar measurements acquired about 10 yr apart over Barro Colorado Island (BCI), Panama from high and medium resolution airborne sensors. The estimation is calibrated with the forest inventory data over 50 ha that was surveyed every 5 yr during the study period. We estimated the aboveground forest biomass and its uncertainty for each time period at different spatial scales (0.04, 0.25, 1.0 ha) and developed a linear regression model between four Lidar height metrics and the aboveground biomass. The uncertainty associated with estimating biomass changes from both ground and Lidar data was quantified by propagating measurement and prediction errors across spatial scales. Errors associated with both the mean biomass stock and mean biomass change declined with increasing spatial scales. Biomass changes derived from Lidar and ground estimates were largely (36 out 50 plots) in the same direction at the spatial scale of 1 ha. Lidar estimation of biomass was accurate at the 1 ha scale (R2 = 0.7 and RMSEmean = 28.6 Mg ha−1). However, to predict biomass changes, errors became comparable to ground estimates only at about 10-ha or more. Our results indicate that the 50-ha BCI plot lost a~significant amount of biomass (−0.8 ± 2.2 Mg ha−1 yr−1) over the past decade (2000–2010). Over the entire island and during the same period, mean AGB change is −0.4 ± 3.7 Mg ha−1 yr−1. Old growth forests lost biomass (−0.7 ± 3.5 Mg ha−1 yr−1), whereas the secondary forests gained biomass (+0.4 ± 3.4 Mg ha−1 yr−1). Our analysis demonstrates that repeated Lidar surveys, even with two different sensors, is able to estimate biomass changes in old-growth tropical forests at landscape scales (>10 ha).

scholarly journals Long-Term Nitrogen Addition Decreases Soil Carbon Mineralization in an N-Rich Primary Tropical Forest

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 734
Author(s):  
Xiankai Lu ◽  
Qinggong Mao ◽  
Zhuohang Wang ◽  
Taiki Mori ◽  
Jiangming Mo ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Organic Carbon ◽  
Tropical Forest ◽  
Soil Carbon ◽  
Tropical Forests ◽  
Carbon Mineralization ◽  
N Deposition ◽  
Soil Carbon Mineralization ◽  
N Additions

Anthropogenic elevated nitrogen (N) deposition has an accelerated terrestrial N cycle, shaping soil carbon dynamics and storage through altering soil organic carbon mineralization processes. However, it remains unclear how long-term high N deposition affects soil carbon mineralization in tropical forests. To address this question, we established a long-term N deposition experiment in an N-rich lowland tropical forest of Southern China with N additions such as NH4NO3 of 0 (Control), 50 (Low-N), 100 (Medium-N) and 150 (High-N) kg N ha−1 yr−1, and laboratory incubation experiment, used to explore the response of soil carbon mineralization to the N additions therein. The results showed that 15 years of N additions significantly decreased soil carbon mineralization rates. During the incubation period from the 14th day to 56th day, the average decreases in soil CO2 emission rates were 18%, 33% and 47% in the low-N, medium-N and high-N treatments, respectively, compared with the Control. These negative effects were primarily aroused by the reduced soil microbial biomass and modified microbial functions (e.g., a decrease in bacteria relative abundance), which could be attributed to N-addition-induced soil acidification and potential phosphorus limitation in this forest. We further found that N additions greatly increased soil-dissolved organic carbon (DOC), and there were significantly negative relationships between microbial biomass and soil DOC, indicating that microbial consumption on soil-soluble carbon pool may decrease. These results suggests that long-term N deposition can increase soil carbon stability and benefit carbon sequestration through decreased carbon mineralization in N-rich tropical forests. This study can help us understand how microbes control soil carbon cycling and carbon sink in the tropics under both elevated N deposition and carbon dioxide in the future.

scholarly journals The relative abundance of wheat Rubisco activase isoforms is post-transcriptionally regulated

2021 ◽  
Author(s):  
Juan Alejandro Perdomo ◽  
Peter Buchner ◽  
Elizabete Carmo-Silva
Keyword(s):  
Relative Abundance ◽  
Light Availability ◽  
Transcript Level ◽  
Rubisco Activase ◽  
Small Subunit ◽  
Diel Cycle ◽  
Diurnal Rhythms ◽  
Crop Species ◽  
Β Protein ◽  
Wheat Leaves

AbstractDiurnal rhythms and light availability affect transcription–translation feedback loops that regulate the synthesis of photosynthetic proteins. The CO2-fixing enzyme Rubisco is the most abundant protein in the leaves of major crop species and its activity depends on interaction with the molecular chaperone Rubisco activase (Rca). In Triticum aestivum L. (wheat), three Rca isoforms are present that differ in their regulatory properties. Here, we tested the hypothesis that the relative abundance of the redox-sensitive and redox-insensitive Rca isoforms could be differentially regulated throughout light–dark diel cycle in wheat. While TaRca1-β expression was consistently negligible throughout the day, transcript levels of both TaRca2-β and TaRca2-α were higher and increased at the start of the day, with peak levels occurring at the middle of the photoperiod. Abundance of TaRca-β protein was maximal 1.5 h after the peak in TaRca2-β expression, but the abundance of TaRca-α remained constant during the entire photoperiod. The redox-sensitive TaRca-α isoform was less abundant, representing 85% of the redox-insensitive TaRca-β at the transcript level and 12.5% at the protein level. Expression of Rubisco large and small subunit genes did not show a consistent pattern throughout the diel cycle, but the abundance of Rubisco decreased by up to 20% during the dark period in fully expanded wheat leaves. These results, combined with a lack of correlation between transcript and protein abundance for both Rca isoforms and Rubisco throughout the entire diel cycle, suggest that the abundance of these photosynthetic enzymes is post-transcriptionally regulated.

scholarly journals Dynamics of Diversity and Abundance of Sulfonamide Resistant Bacteria in a Silt Loam Soil Fertilized by Compost

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 699
Author(s):  
Hui Han ◽  
Mohan Bai ◽  
Yanting Chen ◽  
Yali Gong ◽  
Ming Wu ◽  
...  
Keyword(s):  
High Throughput ◽  
Relative Abundance ◽  
High Throughput Sequencing ◽  
Resistant Bacteria ◽  
Arable Soils ◽  
Soil Bacterial Communities ◽  
Sulfonamide Resistance ◽  
Loam Soil ◽  
Abundance And Diversity ◽  
Sulfonamide Resistance Genes

Although composting is effective in deactivating antibiotic substances in manure, the influence of compost fertilization on the occurrence and dissemination of antibiotic resistance in arable soils remains to be controversial. Herein, the abundance and diversity of two sulfonamide resistance genes (sul1 and sul2) in soil fertilized by compost spiked with two concentrations of sulfadiazine (1 and 10 mg kg−1) were studied intensively by qPCR and high throughput sequencing based on a two-month microcosm experiment. The concentration of sulfadiazine decreased rapidly after spiking from 25% at Day 1 to less than 2.7% at Day 60. Relative abundance of both sul1 and sul2 were significantly higher in soil amended with compost than the non-amended control at Day 1 and slightly decreased with incubation time except for sul2 in the S10 treatment. Soil bacterial communities were transiently shifted by compost fertilization regardless of the presence of sulfadiazine. Relative abundance of genera in three hubs positively interlinked with sul1 and sul2 were significantly higher in compost treated soil than the control at Day 1, 7 and 21, but not at Day 60. High throughput sequencing analyses revealed that most detected (>67% in relative abundance) sul1 and sul2 genotypes sharing >99% similarity with those found in gammaproteobacterial pathogens frequently were commonly present in compost and soil. These results indicated that compost fertilization might increase the abundance rather than diversity of sulfadiazine-resistant populations in soil, which may be facilitated by the presence of sulfadiazine.

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