NECROMASS PRODUCTION: STUDIES IN UNDISTURBED AND LOGGED AMAZON FORESTS

Necromass stocks account for up to 20% of carbon stored in tropical forests and have been estimated to be 14–19% of the annual aboveground carbon flux. Both stocks and fluxes of necromass are infrequently measured. In this study, we directly measured the production of fallen coarse necromass (≥2 cm diameter) during 4.5 years using repeated surveys in undisturbed forest areas and in forests subjected to reduced‐impact logging at the Tapajos National Forest, Belterra, Brazil (3.08° S, 54.94° W). We also measured fallen coarse necromass and standing dead stocks at two times during our study. The mean (SE) annual flux into the fallen coarse necromass pool in undisturbed forest of 6.7 (0.8) Mg·ha−1·yr−1 was not significantly different from the flux under a reduced‐impact logging of 8.5 (1.3) Mg·ha−1·yr−1. With the assumption of steady state, the instantaneous decomposition constants for fallen necromass in undisturbed forests were 0.12 yr−1 for large, 0.33 yr−1 for medium, and 0.47 yr−1 for small size classes. The mass weighted decomposition constant was 0.15 yr−1 for all fallen coarse necromass. Standing dead wood had a residence time of 4.2 years, and ∼0.9 Mg·ha−1·yr−1 of this pool was respired annually to the atmosphere through decomposition. Coarse necromass decomposition at our study site accounted for 12% of total carbon re‐mineralization, and total aboveground coarse necromass was 14% of the aboveground biomass. Use of mortality rates to calculate production of coarse necromass leads to an underestimation of coarse necromass production by 45%, suggesting that nonlethal disturbance such as branch fall contributes significantly to this flux. Coarse necromass production is an important component of the tropical forest carbon cycle that has been neglected in most previous studies or erroneously estimated

Necromass in forests of Madre de Dios, Peru: A comparison between terra firme and lowland forests

This is the final version of the article. Available from Universidad Nacional Mayor de San Marcos, Facultad de Ciencias Biológicas via the DOI in this record.Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of “terra firme” and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing

Microbial carbon use efficiency: accounting for population, community, and ecosystem-scale controls over the fate of metabolized organic matter

Microbial carbon use efficiency (CUE) is a critical regulator of soil organic matter dynamics and terrestrial carbon fluxes, with strong implications for soil biogeochemistry models. While ecologists increasingly appreciate the importance of CUE, its core concepts remain ambiguous: terminology is inconsistent and confusing, methods capture variable temporal and spatial scales, and the significance of many fundamental drivers remains inconclusive. Here we outline the processes underlying microbial efficiency and propose a conceptual framework that structures the definition of CUE according to increasingly broad temporal and spatial drivers where (1) CUEP reflects population-scale carbon use efficiency of microbes governed by species-specific metabolic and thermodynamic constraints, (2) CUEC defines community-scale microbial efficiency as gross biomass production per unit substrate taken up over short time scales, largely excluding recycling of microbial necromass and exudates, and (3) CUEE reflects the ecosystem-scale efficiency of net microbial biomass production (growth) per unit substrate taken up as iterative breakdown and recycling of microbial products occurs. CUEE integrates all internal and extracellular constraints on CUE and hence embodies an ecosystem perspective that fully captures all drivers of microbial biomass synthesis and decay. These three definitions are distinct yet complementary, capturing the capacity for carbon storage in microbial biomass across different ecological scales. By unifying the existing concepts and terminology underlying microbial efficiency, our framework enhances data interpretation and theoretical advances

Carbon Sinks of Morphologic Tree Stands in Bandung City Green Space: Case Study Taman Balai Kota, KebunBinatang, and Taman LaluLintas Ade Irma Suryani

One of the greenhouse gases which have a big contribution at global warming issues is carbon dioxide gas (CO2). Open green spaces in Bandung city are urban forest that can sequester carbon dioxide gases and store it into biomass at stems, branches, or roots. The research was conducted from June to July 2015 at green spaces that the carbon sinks haven not been examined. The purpose of this research was to count the tree stands (DBH >5 cm) ability at Bandung green spaces in sequestrating carbon with quantitative approached. The carbon sequestration was estimated by allometric equations at RaCSA (Rapid Carbon Assessment) [1]. The research has been conducted in Kebun Binatang (KB), we found 35 families with 95 species. Taman Lalu Lintas (TLL) with 22 familiesand 47 species. Taman Balai Kota (TBK) has 19 families and 35 species. From the examined green spaces, there was structure differences which shown by the ISs of KB-TLL and TBK-TLL in the amount of 52.11% and 51.22%. It’s different with KB-TBK’s ISs index is 43.08 %. Based on the stands structure (amount of individual, DBH size, and height average), it shows the difference among KB (745 individual, DBH 60 cm, and 11.3 m height), TLL (321 individual, DBH 14.97 cm, and 6.76 m height), while TBK (145 individual, DBH 25 cm, and 6.74 m height). Those stands structure also made different biomass density at KB (85.63 ton/Ha), TBK (36.64 ton/Ha), and TLL (33.04 ton/Ha). From the biomass density, the green space’s carbon and CO2 sequestration can be estimated at KB (41.81 tonC/Ha and 309.42 tonCO2/Ha), TBK (18.32 tonC/Ha and 135.57 tonCO2/Ha), and TLL (16.52 tonC/Ha with 122.24 tonCO2/Ha). The analysis shows that the carbon sequestration difference caused by the variance of stands ages, size of tree (DBH), and stands structure value (amount of species and individual)

Necromass in forests of Madre de Dios, Peru: a comparison between terra firme and lowland forests

Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of "terra firme" and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing

Potensi Biomassa Dan Cadangan Karbon Kebun Raya Balikpapan, Kalimantan Timur

Kebun Raya Balikpapan dengan luas area 309,22 ha merupakan sebagian kecil dari 10.000 ha Hutan Lindung Sungai Wain di Kalimantan Timur, Indonesia, yang dialihfungsikan sebagai Kebun Raya. Salah satu peran Kebun Raya Balikpapan adalah penyedia jasa lingkungan diantaranya mengurangi terjadinya pemanasan global melalui penghasil biomassa dan menjaga cadangan karbon. Tujuan dari penelitian ini adalah untuk mengetahui potensi besarnya biomassa dan cadangan karbon di Kebun Raya Balikpapan serta mengetahui persentase komponen hutan dalam menyumbang cadangan karbon. Data utama diambil dari Kebun Raya Balikpapan dengan menggunakan metode kombinasi jalur dan petak, sedangkan teknik penempatan petak contoh dilakukan secara terarah (purposive sampling). Setiap unit contoh diambil data pohon berdiri, necromass, tumbuhan bawah, serasah dan contoh tanah. Pendugaan potensi biomassa dan karbon pada pohon dilakukan dengan menggunakan metode non destruktif, sedangkan tumbuhan bawah dan serasah dilakukan dengan metode destruktif. Kebun Raya Balikpapan mempunyai peran yang besar dalam penyimpanan biomassa dan cadangan karbon. Rata-rata biomassa di Kebun Raya Balikpapan sebesar 203,42 ton/ha dan cadangan karbon sebesar 141,55 ton/ha. Total biomassa Kebun Raya Balikpapan sebesar 58.990,8 ton dan cadangan karbon sebesar 41.049,0 ton. Komponen terbesar penyumbang cadangan karbon adalah pohon hidup (48,50%) dan tanah (28,15%)

Changes in the carbon balance of tropical forest: evidence from long-term plots

The role of the world’s forests as a “sink” for atmospheric carbon dioxide is the subject of active debate. Long-term monitoring of plots in mature humid tropical forests concentrated in South America revealed that biomass gain by tree growth exceeded losses from tree death in 38 out of 50 neotropical sites. These forest plots have accumulated 0.71 + 0.34 tons of carbon per hectare per year in recent decades. The data suggest that neotropical forests may be a significant carbon sink, reducing the rate of increase in atmospheric CO2

Carbon concentration declines with decay class in tropical forest woody debris

Carbon stored in woody debris is a key carbon pool in forest ecosystems. The most widely-used method to convert woody debris volume to carbon is by first multiplying field-measured volume with wood density to obtain necromass, and then assuming that a fixed proportion (often 50%) of the necromass is carbon. However, this crucial assumption is rarely tested directly, especially in the tropics. The aim of this study is to verify the field carbon concentration values of living trees and woody debris in two distinct tropical forests in Taiwan. Wood from living trees and woody debris across five decay classes was sampled to measure density and carbon concentrations. We found that both wood density and carbon concentration (carbon mass/total mass) declined significantly with the decay class of the wood. Mean (±SE) carbon concentration values for living trees were 44.6 ± 0.1%, while for decay classes one to five they were respectively 41.1 ± 1.4%, 41.4 ± 1.0%, 37.7 ± 1.3%, 30.5 ± 2.0%, and 19.6 ± 2.2%. Total necromass carbon stock was low, only 3.33 ± 0.55 Mg C ha−1 in the windward forest (Lanjenchi) and 4.65 ± 1.63 Mg C ha−1 in the lowland forest (Nanjenshan). Applying the conventional 50% necromass carbon fraction value would cause a substantial overestimate of the carbon stocks in woody debris of between 17% and 36%, or about 1 Mg of carbon per hectare. The decline in carbon concentration and the increase of variances in the heavily decayed class suggest that in high-diversity tropical forests there are diverse decomposition trajectories and that assuming a fixed carbon fraction across woody pieces is not justified. Our work reveals the need to consider site-specific and decay class-specific carbon concentrations in order to accurately estimate carbon stocks and fluxes in forest ecosystems. If the marked decline in carbon content with necromass decay is typical of tropical forests, the dead wood carbon pool in the biome needs revision and is likely to be overestimate

Does low soil base saturation affect fine root properties of European beech ( Fagus sylvatica L.)?

It is generally believed that high soil solution Al3+ in acidic soils with low base saturation (BS), negatively influences the properties of fine roots. Fine roots from European beech (Fagus sylvatica L.) trees growing in highly acidic soils with very low BS and potentially high Al3+ concentration in the soil solution were analysed and the dependency of fine root properties on soil BS was measured. The fine roots were sampled down to 1m depth at seven forest sites located on the Swiss Plateau. These sites varied in their BS from 1.4 to 11.4% in the mineral layers. We evaluated relationships between the BS of these mineral layers and fine root properties, such as ratio between bio- and necromass (live/dead ratio), specific root length (SRL), root tip abundance (RTA), root branching abundance (RBA), O2-consumption, and the Ca/Al molar ratio in the fine root tissue. The fine root properties were compared not only with the BS of the soil, but also with the Ca/Al molar ratio in the fine root tissues. Significant relations of fine root properties occurred when the soils of the seven sites were grouped into two BS groups (<5 and 5-10%). The live/dead ratio, the RTA, the RBA, the O2-consumption, and Ca/Al molar ratio were lower in the group of BS <5% than in the group 5-10%. Decreases in the morphological properties and in the O2-consumption were related to decrease in the Ca/Al molar ratio of the fine root tissues. There is evidence that the fine root properties are negatively influenced, nevertheless, fine root systems of mature European beech in their natural ecological environment seem to be able to compensate adverse effects of low B