Cavity characteristics explain the differences in realized nest niches among tree cavity-nesting birds in a lowland tropical forest in Luzon Island, Philippines

Experimental evidence for limitation of net primary productivity (NPP) by nitrogen (N) or phosphorus (P) in lowland tropical forests is rare, and the results from the few existing studies have been inconclusive. To directly test if N or P limit NPP in a lowland tropical wet forest in Costa Rica, we conducted a full factorial fertilization experiment (4 treatments x 6 replicates in 30 x 30 m plots). We focused on the influence of tree size and taxa on nutrient limitation, because in these forests a wide variety of tree functional traits related to nutrient acquisition and use are likely to regulate biogeochemical processes. After 2.7 years, a higher percentage of trees per plot increased basal area (BA) with P additions (66.45% +/- 3.28% without P vs. 76.88% +/- 3.28% with P), but there were no other community-level responses to N or P additions on BA increase, litterfall productivity, or root growth. Phosphorus additions resulted in doubled stem growth rates in small trees (5-10 cm diameter at breast height (dbh); [P < or = 0.01]) but had no effect on intermediate (10-30 cm dbh) or large trees (> 30 cm dbh). Phosphorus additions also increased the percentage of seedling survival from 59% to 78% (P < 0.01), as well as the percentage of seedlings that grew (P = 0.03), and increased leaf number (P = 0.02). Trees from Pentaclethra macroloba, the most abundant species, did not increase growth rates with fertilization (P = 0.40). In contrast, the most abundant palms (Socratea exorrhiza) had more than two times higher stem growth rates with P additions (P = 0.01). Our experiment reiterates that P availability is a significant driver of plant processes in these systems, but highlights the importance of considering different aspects of the plant community when making predictions concerning nutrient limitation. We postulate that in diverse, lowland tropical forests "heterogeneous nutrient limitation" occurs, not only driven by variability in nutrient responses among taxa, but also among size classes and potential functional groups. Heterogeneous responses to nutrient additions could lead to changes in forest structure or even diversity in the long-term, affecting rates of NPP and thus carbon cycling.

Many studies analyzing the relative contribution of soil properties versus distance‐related processes on plant species composition have focused on lowland tropical forests. Very few have investigated two forest types simultaneously, to contrast ecological processes that assemble the communities. This study analyses—at the landscape scale—the relative contribution of soil and distance on lowland and submontane tropical forests, which co‐occur in two reserves of the Azuero peninsula (Panama). Floristic inventories and soil sampling were conducted in 81 0.1‐ha plots clustered in 27 sites, and data were analyzed using Mantel tests, variance partitioning and non‐metric multidimensional scaling. The largest differences in floristic composition occurred between reserves in both forest types. Soil variation and geographic distance were important determinants of floristic composition, but their effects were highly correlated; together they explained 7–25 percent and 46–50 percent of the variation in lowland and submontane forests, respectively. Soil variables that had the best correlations with floristic composition were iron, zinc, and silt content in lowland, and calcium, copper, iron, potassium, magnesium, phosphorus, zinc, and sand content in submontane forests. The studied forests showed a high beta diversity that seems to be related primarily with soils and, secondarily, with dispersal limitation and stochastic events. The results reveal a response of tree assemblages to environmental gradients, which are particularly conspicuous in Panama. The effects of limited dispersal seem to be more important in submontane than in lowland forests, probably as a result of higher isolation.

Tropical forests are a significant global source of the greenhouse gas nitrous oxide (N2O). Predicted environmental changes for this biome highlight the need to understand how simultaneous changes in precipitation and labile carbon (C) availability may affect soil N2O production. We conducted a small‐scale throughfall and leaf litter manipulation in a lowland tropical forest in southwestern Costa Rica to test how potential changes in both water and litter derived labile C inputs to soils may alter N2O emissions. Experimentally reducing throughfall in this wet tropical forest significantly increased soil emissions of N2O, and our data suggest that at least part of this response was driven by an increase in the concentration of dissolved organic carbon [DOC] inputs delivered from litter to soil under the drier conditions. Furthermore, [DOC] was significantly correlated with N2O emissions across both throughfall and litterfall manipulation plots, despite the fact that native NO3− pools in this site were generally small. Our results highlight the importance of understanding not only the potential direct effects of changing precipitation on soil biogeochemistry, but also the indirect effects resulting from interactions between the hydrologic, C and N cycles. Finally, over all sampling events we observed lower mean N2O emissions (&lt;1 ng N2O‐N cm−2 h−1) than reported for many other lowland tropical forests, perhaps reflecting a more general pattern of increasing relative N constraints to biological activity as one moves from drier to wetter portions of the lowland tropical forest biome.

Abstract. Aboveground primary productivity is widely considered to be limited by phosphorus (P) availability in lowland tropical forests and by nitrogen (N) availability in montane tropical forests. However, the extent to which this paradigm applies to belowground processes remains unresolved. We measured indices of soil microbial nutrient status in lowland, sub-montane and montane tropical forests along a natural gradient spanning 3400 m in elevation in the Peruvian Andes. With increasing elevation there were marked increases in soil concentrations of total N, total P, and readily exchangeable P, but a decrease in N mineralization determined by in situ resin bags. Microbial carbon (C) and N increased with increasing elevation, but microbial C : N : P ratios were relatively constant, suggesting homeostasis. The activity of hydrolytic enzymes, which are rich in N, decreased with increasing elevation, while the ratio of enzymes involved in the acquisition of N and P increased with increasing elevation, further indicating an increase in the relative demand for N compared to P with increasing elevation. We conclude that soil microorganisms shift investment in nutrient acquisition from P to N between lowland and montane tropical forests, suggesting that different nutrients regulate soil microbial metabolism and the soil carbon balance in these ecosystems.

Nutrient availability is widely considered to constrain primary productivity in lowland tropical forests, yet there is little comparable information for the soil microbial biomass. We assessed microbial nutrient limitation by quantifying soil microbial biomass and hydrolytic enzyme activities in a long-term nutrient addition experiment in lowland tropical rain forest in central Panama. Multiple measurements were made over an annual cycle in plots that had received a decade of nitrogen, phosphorus, potassium, and micronutrient addition. Phosphorus addition increased soil microbial carbon (13 %), nitrogen (21 %), and phosphorus (49 %), decreased phosphatase activity by ~65 % and N-acetyl β-glucosaminidase activity by 24 %, but did not affect β-glucosidase activity. In contrast, addition of nitrogen, potassium, or micronutrients did not significantly affect microbial biomass or the activity of any enzyme. Microbial nutrients and hydrolytic enzyme activities all declined markedly in the dry season, with the change in microbial biomass equivalent to or greater than the annual nutrient flux in fine litter fall. Although multiple nutrients limit tree productivity at this site, we conclude that phosphorus limits microbial biomass in this strongly-weathered lowland tropical forest soil. This finding indicates that efforts to include enzymes in biogeochemical models must account for the disproportionate microbial investment in phosphorus acquisition in strongly-weathered soils.

&lt;p&gt;The lichen flora of tropical areas is still much underworked Java in general and Alas Purwo in East Java for specially is no exception. Alas Purwo National Park is representative of a typical lowland tropical rain forest ecosystem in Java. . It is famous with peculiar and endemic species of plant include sawo kecik (Manilkara kauki) and manggong bamboo (Gigantochloa manggong). , beside among the other plants also ketapang (Terminalia cattapa), nyamplung (Calophyllum inophyllum), kepuh (Sterculia foetida), and keben (Barringtonia asiatica). Moreover, in lowland tropical rain forest ecosystem have reported the lichens species diversity is very high and may include over 200 species in 1 ha. There is no reported have found concerning the lichens richness in Alas Purwo. Recently preliminary study of Lichens diversity have been done at triangulation Zone Alas Purwo National Park , East Java. The lichens of the study area have not been treated comprehensively. We explored the lichenological characteristics of putative”tropical lowland cloud forest” (LCF) in a lowland area (0–20ma.s.l.) near Triangulation using macrolichens (cortocoulous species) as indicator taxa We analyzed lichen diversity on 20 trees in two 0,25 ha plots. In tropical lowland forests, corticolous green algal lichens are abundant and highly diverse. This may be related to adaptation to prevailing microenvironmental conditions including, for example, high precipitation and low light intensities. In the understory of a tropical lowland rain forest in Alas Purwo , we studied the morphology and anatomy of corticolous lichens and microcristal test. We found that from Tetrasigma sp , Serbella otodans, Hemandia feltata Baringtonia aciatika Pandanaceae Manilcara cauci Swetinia mahagoni trees there are 30 species of lichens, dominated by Dyorigma sp Graphis and Glyphis from familia of Graphidaceae and Dirinaria Physcia Pyxine Ramalina from familia of Parmeliaceae. The thallus calour was variety from Green-grey, Green-bllue, green, light green, grey, brown, dark green to orange. They have vegetative as wel as generative reproduction such as isidia, soralia, soredia, chypellae, histerothecia, perithecia,and apothecia. The lichenic acids contain such as gyrophoric acid, barbatic acid, usnic acid, atranorin, acid, divaricatic acid and lecanoric acid, &lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords&lt;/strong&gt;: Alas Purwo, lichens and lichenic acid.&lt;/p&gt;

Canopy level fog occurrence in a tropical lowland forest of French Guiana as a prerequisite for high epiphyte diversity

The “hierarchy of factors” hypothesis states that decomposition rates are controlled primarily by climatic, followed by biological and soil variables. Tropical montane forests (TMF) are globally important ecosystems, yet there have been limited efforts to provide a biome‐scale characterization of litter decomposition. We designed a common litter decomposition experiment replicated in 23 tropical montane sites across the Americas, Asia, and Africa and combined these results with a previous study of 23 sites in tropical lowland forests (TLF). Specifically, we investigated (1) spatial heterogeneity in decomposition, (2) the relative importance of biological factors that affect leaf and wood decomposition in TMF, and (3) the role of climate in determining leaf litter decomposition rates within and across the TMF and TLF biomes. Litterbags of two mesh sizes containingLaurus nobilisleaves or birchwood popsicle sticks were spatially dispersed and incubated in TMF sites, for 3 and 7 months on the soil surface and at 10–15 cm depth. The within‐site replication demonstrated spatial variability in mass loss. Within TMF, litter type was the predominant biological factor influencing decomposition (leaves &gt; wood), with mesh and burial effects playing a minor role. When comparing across TMF and TLF, climate was the predominant control over decomposition, but the Yasso07 global model (based on mean annual temperature and precipitation) only modestly predicted decomposition rate. Differences in controlling factors between biomes suggest that TMF, with their high rates of carbon storage, must be explicitly considered when developing theory and models to elucidate carbon cycling rates in the tropics.Abstract in Spanish is available with online material.

Ecology Letters (2011) 14: 1313–1317 This is an errata to Cleveland et al. (2011). Figure 1 includes a point in Mexico. However, original data from this lowland forest site were from a secondary (not primary) forest, and thus they were not included in the final lowland forest analysis. In the Methods section, we stated, ‘We also included some data published in previous syntheses (Elser et al. 2007; Townsend et al. 2007; LeBauer & Treseder 2008; Quesada et al. 2009), and examined relevant references cited therein for additional data’. However, the Quesada et al. (2009) citation was incorrectly reported in the references section; the correct reference is included in the list below. We regret this error given the importance of the soil P data reported in Quesada et al. (2010) to the relationships depicted in Fig. 3. We also note that data from the RAINFOR project (http://www.geog.leeds.ac.uk/projects/rainfor) were an important part of this synthesis, and we are grateful to all those involved in the RAINFOR project. A list of all references used to assemble the database is provided below, and all data (including references) are available at: http://knb.ecoinformatics.org/knb/metacat/nceas.964/nceas. Relationships among P cycling variables and ANPP in lowland tropical forests. (a) Foliar P vs. ANPP; (b) total soil P vs. ANPP; (c) total soil P vs. foliar P. In the Abstract and Methods sections, we stated that surface soil P values represented measured concentrations from 0 to 10 cm depths. However, surface soil P concentrations used in the analyses represented concentrations from depths of < 30 cm. In the Results section, we had classified lowland forests as those at a threshold elevation of 1000 m, and that this threshold corresponded to a mean annual temperature (MAT) breakpoint of 20.7 °C. However, in the final analysis, two warm sites (24 °C MAT, elevation 1100 m) were included with ‘lowland forests’, and a cool (19.7 °C MAT) montane forest site at an elevation of 800 m was included with ‘upland forests’. In the process of preparing the database for public distribution, we discovered several data reporting errors, and in a few cases, we were unable to relocate the original sources of the data used in the analyses. While none of these issues affected the overall conclusions of the article, they did lead to subtle changes in the relationships reported in Table 1, 3, 4, and Figure S2 (see Supporting Information), all of which have been reproduced correctly below. Total soil P vs.: (a) decomposition (k); and (b) soil respiration in lowland tropical forest. R-values represent Pearson correlation coefficients. Figure S2 ANPP vs. MAT (A and B) and MAP (C and D) in the upland and lowland forest sites in the database. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer-reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Soil organic matter is an important pool of carbon and nutrients in tropical forests. The majority of this pool is assumed to be relatively stable and to turn over slowly over decades to centuries, although changes in nutrient status can influence soil organic matter on shorter timescales. We measured carbon, nitrogen, and phosphorus concentrations in soil organic matter and leaf litter over an annual cycle in a long-term nutrient addition experiment in lowland tropical rain forest in the Republic of Panama. Total soil carbon was not affected by a decade of factorial combinations of nitrogen, phosphorus, or potassium. Nitrogen addition increased leaf litter nitrogen concentration by 7 % but did not affect total soil nitrogen. Phosphorus addition doubled the leaf litter phosphorus concentration and increased soil organic phosphorus by 50 %. Surprisingly, concentrations of carbon, nitrogen, and phosphorus in soil organic matter declined markedly during the four-month dry season, and then recovered rapidly during the following wet season. Between the end of the wet season and the late dry season, total soil carbon declined by 16 %, total nitrogen by 9 %, and organic phosphorus by between 19 % in control plots and 25 % in phosphorus addition plots. The decline in carbon and nitrogen was too great to be explained by changes in litter fall, bulk density, or the soil microbial biomass. However, a major proportion of the dry-season decline in soil organic phosphorus was explained by a corresponding decline in the soil microbial biomass. These results have important implications for our understanding of the stability and turnover of organic matter in tropical forest soils, because they demonstrate that a considerable fraction of the soil organic matter is seasonally transient, despite the overall pool being relatively insensitive to long-term changes in nutrient status.

Tropical rain forests play a dominant role in global biosphere-atmosphere CO(2) exchange. Although climate and nutrient availability regulate net primary production (NPP) and decomposition in all terrestrial ecosystems, the nature and extent of such controls in tropical forests remain poorly resolved. We conducted a meta-analysis of carbon-nutrient-climate relationships in 113 sites across the tropical forest biome. Our analyses showed that mean annual temperature was the strongest predictor of aboveground NPP (ANPP) across all tropical forests, but this relationship was driven by distinct temperature differences between upland and lowland forests. Within lowland forests (< 1000 m), a regression tree analysis revealed that foliar and soil-based measurements of phosphorus (P) were the only variables that explained a significant proportion of the variation in ANPP, although the relationships were weak. However, foliar P, foliar nitrogen (N), litter decomposition rate (k), soil N and soil respiration were all directly related with total surface (0-10 cm) soil P concentrations. Our analysis provides some evidence that P availability regulates NPP and other ecosystem processes in lowland tropical forests, but more importantly, underscores the need for a series of large-scale nutrient manipulations - especially in lowland forests - to elucidate the most important nutrient interactions and controls.

Abstract. Rohman F, Insani N, Purwanto, Dharmawan A, Fardhani I, Akhsani F. 2023. Short Communication: Vegetation and bird diversity in Pesanggrahan's lowland tropical forest, Malang, Indonesia. Biodiversitas 24: 6169-6176. Universitas Negeri Malang proposes the designation of Pesanggrahan Forest as a Forest Area with a Specific Purpose or Kawasan Hutan dengan Tujuan Khusus (KHDTK). This study investigated plant and bird communities in the lowland tropical forest of Pesanggrahan. We observed 31 tree species, with Teak being the most dominant, with a medium level of diversity (H': 1.67) and an uneven distribution (E: 0.48). There were 104 species of shrubs and forest floor plants with a high diversity (H': 3.45) and an even distribution (E: 0.74) and 49 bird species, with some being protected by the Regulation of the Ministry of Environment and Forestry and listed as "vulnerable" or "near threatened" by International Union for Conservation of Nature (IUCN). These findings highlight the importance of the study site for conserving these species and their habitats. The interaction between plants and birds in Pesanggrahan's lowland tropical forest could be preserved by further investigation. This study can serve as preliminary data for future research on the interaction between the plant and bird species in this forest. Therefore, the designation of the forest as a protected area, or KDTK, would help conserve this habitat as one of the last remaining lowland forests on Java Island.

A new approach to trenching experiments for measuring root–rhizosphere respiration in a lowland tropical forest

Nutrients constrain the soil carbon cycle in tropical forests, but we lack knowledge on how these constraints vary within the soil microbial community. Here, we used in situ fertilization in a montane tropical forest and in two lowland tropical forests on contrasting soil types to test the principal hypothesis that there are different nutrient constraints to different groups of microorganisms during the decomposition of cellulose. We also tested the hypotheses that decomposers shift from nitrogen to phosphorus constraints from montane to lowland forests, respectively, and are further constrained by potassium and sodium deficiency in the western Amazon. Cellulose and nutrients (nitrogen, phosphorus, potassium, sodium, and combined) were added to soils in situ, and microbial growth on cellulose (phospholipid fatty acids and ergosterol) and respiration were measured. Microbial growth on cellulose after single nutrient additions was highest following nitrogen addition for fungi, suggesting nitrogen as the primary limiting nutrient for cellulose decomposition. This was observed at all sites, with no clear shift in nutrient constraints to decomposition between lowland and montane sites. We also observed positive respiration and fungal growth responses to sodium and potassium addition at one of the lowland sites. However, when phosphorus was added, and especially when added in combination with other nutrients, bacterial growth was highest, suggesting that bacteria out-compete fungi for nitrogen where phosphorus is abundant. In summary, nitrogen constrains fungal growth and cellulose decomposition in both lowland and montane tropical forest soils, but additional nutrients may also be of critical importance in determining the balance between fungal and bacterial decomposition of cellulose.

Phosphorus is widely considered to constrain primary productivity in tropical rain forests, yet the chemistry of soil organic phosphorus in such ecosystems remains poorly understood. We assessed the composition of soil organic phosphorus in 19 contrasting soils under lowland tropical forest in the Republic of Panama using NaOH–EDTA extraction and solution 31P nuclear magnetic resonance spectroscopy. The soils spanned a strong rainfall gradient (1730–3404 mm y−1) and contained a wide range of chemical properties (pH 3.3–7.0; total carbon 2.8–10.4%; total phosphorus 74–1650 mg P kg−1). Soil organic phosphorus concentrations ranged between 22 and 494 mg P kg−1 and were correlated positively with total soil phosphorus, pH, and total carbon, but not with annual rainfall. Organic phosphorus constituted 26 ± 1% (mean ± STD error, n = 19) of the total phosphorus, suggesting that this represents a broad emergent property of tropical forest soils. Organic phosphorus occurred mainly as phosphate monoesters (68–96% of total organic phosphorus) with smaller concentrations of phosphate diesters in the form of DNA (4–32% of total organic phosphorus). Phosphonates, which contain a direct carbon–phosphorus bond, were detected in only two soils (3% of the organic phosphorus), while pyrophosphate, an inorganic polyphosphate with a chain length of two, was detected in all soils at concentrations up to 13 mg P kg−1 (3–13% of extracted inorganic phosphorus). Phosphate monoesters were a greater proportion of the total organic phosphorus in neutral soils with high concentrations of phosphorus and organic matter, whereas the proportion of phosphate diesters was greater in very acidic soils low in phosphorus and organic matter. Most soils did not contain detectable concentrations of either myo- or scyllo-inositol hexakisphosphate, which is in marked contrast to many temperate mineral soils that contain abundant inositol phosphates. We conclude that soil properties exert a strong control on the amounts and forms of soil organic phosphorus in tropical rain forests, but that the proportion of the total phosphorus in organic forms is relatively insensitive to variation in climate and soil properties. Further work is now required to assess the contribution of soil organic phosphorus to the nutrition and diversity of plants in these species-rich ecosystems.