QUESTIONS: Natural hazards can wreak catastrophic damage to forest ecosystems. Here, the effects of typhoon disturbance on forest structure and demography of the 16‐ha Palanan Forest Dynamics Plot in ...the northeast Philippines were examined by comparing census intervals with (1998–2004) and without (2004–2010) a strong typhoon. Category 4 Typhoon Imbudo, with wind gusts exceeding 210 kph, hit Palanan in July 2003. In this study, we ask: (1) was there an effect of the typhoon on stand structure and biomass; (2) was there an impact on species diversity; (3) did annual mortality, growth and recruitment change significantly between typhoon and non‐typhoon periods; and (4) did the typhoon's impact vary with local topography, from leeward to windward sides of a ridge? LOCATION: Lowland mixed dipterocarp forest, Palanan, Isabela, Philippines. METHODS: Census data from 1998, 2004 and 2010 for all trees ≥1 cm DBH in a 16‐ha permanent plot in Palanan, Isabela, were used to assess tree demography. Recorded in the census were species identification and measurements of DBH and tree locations. Biomass was calculated from published allometry. RESULTS: Species diversity and stand structure remained stable, except for an increase in small‐sized trees (1–2 cm) recorded in the census conducted within a year of the typhoon disturbance. Tree mortality was significantly higher during the typhoon interval at 2.27%·yr⁻¹ and more so in windward than leeward habitats. Above‐ground biomass loss in the typhoon interval was minimal (2.64%) and biomass exceeded pre‐typhoon levels after 6 yrs. Recruitment rate during the typhoon interval was almost four times the rate in the non‐typhoon interval that followed, attributed to the rapid growth of seeds and seedlings of pioneer species due to the open, defoliated canopy. Negative population growth was recorded for the early successional species in the non‐typhoon interval. Significantly higher growth rates of trees in the non‐typhoon interval also contributed to biomass gain. CONCLUSIONS: Mortality, recruitment and growth rates vary across a heterogeneous landscape and are related to typhoon disturbances. The relatively low mortality and fast recovery of the Palanan forest demonstrates the resistance and resilience of the forest to intense episodic typhoon disturbances.
A new filamentous bangialean alga, Pseudobangia corderoi sp. nov., is described from the northern Philippines. Locally known as a sea vegetable, this species was previously identified as 'Bangia ...fuscopurpurea'. Inferred combined analyses of the nucleus-encoded SSU rDNA and the plastid-encoded RubisCO LSU (rbcL) gene indicate that P. corderoi is sister to another unidentified species of Pseudobangia (originally referred to also as 'Bangia fuscopurpurea') from Taiwan. Together, these two taxa formed the closest diverging lineage from Pseudobangia kaycoleae (generitype). Current molecular phylogenies have also yielded monophyly of Pseudobangia and strong support for a sister relationship with the 'Bangia 2' lineage. Molecular and geographic analyses clearly differentiate P. corderoi from other filamentous Bangiales, whereas morpho-anatomical analysis identified only one distinguishing character, i.e. larger dimensions of the thalli.
1. The relationship between species richness and ecosystem function, as measured by productivity or biomass, is of long-standing theoretical and practical interest in ecology. This is especially true ...for forests, which represent a majority of global biomass, productivity and biodiversity. 2. Here, we conduct an analysis of relationships between tree species richness, biomass and productivity in 25 forest plots of area 8-50 ha from across the world. The data were collected using standardized protocols, obviating the need to correct for methodological differences that plague many studies on this topic. 3. We found that at very small spatial grains (0.04 ha) species richness was generally positively related to productivity and biomass within plots, with a doubling of species richness corresponding to an average 48% increase in productivity and 53% increase in biomass. At larger spatial grains (0.25 ha, 1 ha), results were mixed, with negative relationships becoming more common. The results were qualitatively similar but much weaker when we controlled for stem density: at the 0.04 ha spatial grain, a doubling of species richness corresponded to a 5% increase in productivity and 7% increase in biomass. Productivity and biomass were themselves almost always positively related at all spatial grains. 4. Synthesis. This is the first cross-site study of the effect of tree species richness on forest biomass and productivity that systematically varies spatial grain within a controlled methodology. The scale-dependent results are consistent with theoretical models in which sampling effects and niche complementarity dominate at small scales, while environmental gradients drive patterns at large scales. Our study shows that the relationship of tree species richness with biomass and productivity changes qualitatively when moving from scales typical of forest surveys (0.04 ha) to slightly larger scales (0.25 and 1 ha). This needs to be recognized in forest conservation policy and management.
Species packing and the latitudinal gradient in beta-diversity Cao, Ke; Condit, Richard; Mi, Xiangcheng ...
Proceedings - Royal Society. Biological sciences/Proceedings - Royal Society. Biological Sciences,
04/2021, Volume:
288, Issue:
1948
Journal Article
Peer reviewed
Open access
The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient ...of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogues. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographical heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.
Challenges in morphology come to bear when assigning specific names in foliose Bangiales. Recent studies suggest that the integration of molecular and phenotypic data is essential, particularly in ...setting species boundaries and revealing the true species diversity of a given area. In an attempt to further elucidate the diversity of foliose Bangiales in the Philippines, two new species,
sp. nov. and
sp. nov. are described. Each species differs from other closely related taxa by a combination of morphological and anatomical characters, and nucleotide sequences. Phylogenetic reconstruction based on
L gene sequences supports the sister relationship of
and
, whereas
is recovered as a species allied to
and
. These two previously undescribed species increase the number of confirmed Philippine
species to four. So far,
and
are found only from the Batanes Islands while
and
are known to extend their native distributions across into the Indo-Pacific waters. Questions remain, however, with regard to the true species diversity of foliose Bangiales in the Philippines. A wider sampling effort and the application of molecular methods will make it possible to resolve the remaining gaps in the taxonomy of Philippine foliose Bangiales.
As cyclonic wind storms (hurricanes and typhoons) increase in frequency and intensity with climate change, it is important to understand their effects on the populations and communities of tropical ...trees they impact. Using tree demographic data from four large, tropical forest dynamics plots that differ in cyclonic storm frequency, we compare tree population and community dynamics. Additionally, we assess the effect of cyclonic storms on three functional traits, specific leaf area, wood density, and tree height of the dynamic tree assemblages. Mortality, growth and recruitment rates and the intrinsic rates of population growth of species differed across the plots, and were most dynamic, especially for stems 1-2 cm in diameter, at the plot which had an intermediate level of cyclonic storm frequency. Functional assemblages of species had the greatest degree of temporal variation in relation to disturbance, as measured by the change in functional divergence for the two plots with more intermediate cyclonic storm recurrence. Therefore, cyclonic storms affecting these plots generally have a greater effect on forest composition and dynamism than comparable cyclonic storms do on the plot which experiences cyclonic storms more frequently. Thus, we provide some evidence that community-wide demographic resistance to cyclonic storms is generally lower at an intermediate frequency of storms. While cyclonic storm strength and timing are important determinants of the within forest variation in tree dynamics and functional trait assemblages, we also show that cyclonic storm timing and frequency shapes tropical forest dynamics and functional composition across forests. We conclude that, over a given time interval, sites with intermediate levels of damaging cyclonic wind disturbance express a greater potential for life-history variation in the forest community, when compared to sites with less or more frequent disturbance.
Legumes provide an essential service to ecosystems by capturing nitrogen from the atmosphere and delivering it to the soil, where it may then be available to other plants. However, this facilitation ...by legumes has not been widely studied in global tropical forests. Demographic data from 11 large forest plots (16-60 ha) ranging from 5.25° S to 29.25° N latitude show that within forests, leguminous trees have a larger effect on neighbor diversity than non-legumes. Where soil nitrogen is high, most legume species have higher neighbor diversity than non-legumes. Where soil nitrogen is low, most legumes have lower neighbor diversity than non-legumes. No facilitation effect on neighbor basal area was observed in either high or low soil N conditions. The legume-soil nitrogen positive feedback that promotes tree diversity has both theoretical implications for understanding species coexistence in diverse forests, and practical implications for the utilization of legumes in forest restoration.
The marine algal flora of eastern Sorsogon has been intensively collected and is generally considered as the richest in the Philippines. A trend of species records in the area has been dominated by ...rhodophytes (red algae) with significantly fewer similar studies for other algal groups (green and brown algae). In this study we present an updated catalogue of the green seaweeds (Ulvophyceae) of eastern Sorsogon. A checklist, including notes on taxonomy, is given of the 103 species. Twenty-six species are newly recorded locally of which five represent new records for the Philippines:
,
an unidentified
species,
cf.
, and one taxon new to science. The new species is described as
Verbruggen
Dumilag based on morpho-anatomy and DNA sequence data. The number of ulvophycean species recorded in eastern Sorsogon is found to be the highest in the Philippines. This may be a result of the high collection effort in the region, as well as eastern Sorsogon’s diverse habitats providing favourable conditions for a wide range of seaweed species.
Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and ...climate protection. This review describes an international network of 59 long‐term forest dynamics research sites (CTFS‐ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25 ha), all stems ≥1 cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS‐ForestGEO spans 25°S–61°N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS‐ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 °C), changes in precipitation (up to ±30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8 g N m⁻² yr⁻¹and 3.1 g S m⁻² yr⁻¹), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5 km). The broad suite of measurements made at CTFS‐ForestGEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFS‐ForestGEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change.
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