Khe Nuoc Trong forest (KNT) is located in Le Thuy District in Quang Binh Province in north-central Vietnam. KNT covers approximately 20,000 ha of evergreen tropical forests and is part of a larger natural forest network of approximately 500,000 ha ( Department for agri- culture and rural development, 2010 ). Elevation in KNT ranges from 120 m to 1220 m, with the majority of the area (90%) < 700 m altitude on hilly terrain ( Department for agriculture and rural development, 2010 ). Climate conditions are similar to the neighbouring Bac Huong Hoa Nature Reserve, where the area has a tropical monsoon climate with hot summers and relatively cold winters and storms from June to September ( Mahood and Hung, 2008 ; pers. comm. Trai Trong Le, 2019). The hot season is from March to June, when the area receives a hot, dry wind originating from Laos (“Foehn”), with average tempera- tures of 29 °C in June and July and frequent temperatures of 39 °C when the Foehn is blowing ( Mahood and Hung, 2008 ). In December and January, temperatures can drop to 15 °C (> 500 m elevation). Total annual rainfall varies between 2400 and 2800 mm with highest rainfall from August to November. The drier period lasts only for a few months per year, i.e. between December and March ( Mahood and Hung, 2008 ). KNT is a key biodiversity area and one of the last remaining ex- tensive lowlandforests in the Annamese mountain range in Vietnam. A recent study showed that the largest area of deforestation and forest degradation between 2000 and 2010 was found in the north-central region of Vietnam ( Khuc et al., 2018 ). KNT was selectively logged by the state between 1982 and 2007. Since 2007, the forest has been of- ficially protected as a watershed protection forest and logging is for- bidden, but widespread illegal logging still occurs (illegal logging also happened during the state logging period). The forest contains areas with various levels of forest degradation, from relatively undisturbed forests to heavily degraded forests. KNT has not been affected by the defoliants during the Vietnam War.
While SOC stocks in the top 5 cm were mainly influenced by slope and available phosphorus (Table 4-2), the effect of logging was more pronounced in accumulated layer below 5 cm. This result is in line with those found in Guyana where no effect of logging was detected on SOC stocks (van der Sande et al. 2018). In the top layer, the effect of slope outpaced all other variables, suggesting some sort of homogenization on this layer due to the water runoff and litter transport. Organic materials in the soil surface were able to translocate faster by water in a higher slope, and therefore to significantly decrease SOC stocks when, for example, rain happens (Gregorich and Anderson 1985; Tsui, Chen, and Hsieh 2004). The slope influence is related to the rainfall intensity and rainfall was found as the main driver of C concentration at the soil surface (Hobley and Wilson 2016). While organic materials in the surface (0-5 cm) translocate faster in the higher slope, organic materials in the deeper layers (>5 cm) might move downward (Bruun et al. 2007; Dörr and Münnich 1989). Our result, therefore, suggests that the top layer may act as a buffer. Further, available phosphorus might also indirectly affect SOC stocks through the enhanced of above-ground biomass and productivity (Paoli and Curran 2007). Available phosphorus is used as soil fertility indicator and therefore positively affect above-ground biomass (van der Sande et al. 2018) which in turn influencing SOC stocks. We found a positive influence of available phosphorus on SOC stocks for layer 0-5 and 0-15 cm (Figure 4-4) that corroborates the study in tropical lowlandforests of Panama (Dieter, Elsenbeer, and Turner 2010).
, LHP, SKR, and BNS). Previously, it was found that sub-tropical forests in monsoon Asia uptake an exceptionally high amount of carbon regardless of moderate GPP, owing to high nitrogen deposition in the surrounding region ( Yu et al., 2014 ). The forest sites included in this study may reﬂect this regional characteristic; for instance, nitrogen deposition at DHS (25.39 kg N ha −1 yr −1 ) is approximately four times larger than those at temperate and tropical forests such as CBS and BNS (5.27, and 8.89 kg N ha −1 yr −1 , respectively) (Sup- porting information in Yu et al., 2014 ). Additionally, productive young secondary forests constitute a large fraction of sub-tropical and tropical forests in monsoon Asia because of extensive on-going changes in land use ( Achard et al., 2002; Mayaux et al., 2005; Koh and Wilcove, 2007; Carlson et al., 2012 ) and frequent occurrence of large-scale forest ﬁres ( Van Der Werf et al., 2003; Patra et al., 2005 ), and they are represented by QYZ (a plantation forest) and BKS (a regenerated forest after ﬁre) in our dataset. Therefore, QYZ, ALF, DHS, and BKS represent the high carbon-uptake pattern in tropical monsoon Asia, resulting from the potential effects of high nitrogen deposition and disturbance. Those sites are distinct from the low carbon uptake of mature forests, resulting in the negative linear GPP–NEP relationship for the low latitude forests. The variability in annual carbon storage changes ( ABM and SOM P ) suggests that
Los bosques tropicales almacenan una gran cantidad de reservas de carbono y contribuyen a la acumulación de biomasa tanto aérea como subterránea y al ciclo global del carbono. Las plantaciones forestales en los trópicos han sido reconocidas durante mucho tiempo como una solución efectiva para reducir la tasa de aumento del CO2 en la atmósfera. Además, la información sobre la biomasa forestal y la concentración de carbono es necesaria para apoyar la gestión sostenible de los recursos forestales tanto a nivel global como en Vietnam en particular. La mayoría de las plantaciones forestales incluyen solo una especie arbórea, sin embargo, el uso de dos o más especies arbóreas durante la fase de plantación y la diversificación de las plantaciones es cada vez más frecuente. En el marco del proyecto BioEcoN se estableció, en el Campus Hoa Lac de la Universidad Nacional de Vietnam, Hanoi, Vietnam, un aula de señalamiento (Marteloscope) de una superficie igual a 1 hectárea. Los datos recopilados en esta aula de señalamiento fueron el diámetro a la altura del pecho (1.3 m sobre el suelo), la altura total, la identidad de la especie y la posición de 507 árboles. Las reservas de carbono y la biomasa arbórea sobre el suelo por compartimientos se calcularon utilizando diferentes ecuaciones de biomasa obtenidas de la literatura relevante. La relación entre la biomasa arbórea aérea y la diversidad de especies se estudió mediante modelos lineales, en los que las variables predictoras fueron un conjunto de parámetros que caracterizan la estructura de los rodales como son la densidad y la diversidad del rodal, la mezcla de especies, el patrón de distribución horizontal y vertical de árboles. Los resultados muestran que en el área de estudio se almacenan 110.66 toneladas / ha de biomasa aérea y 55.33 toneladas / ha de carbono. Además, los resultados del cálculo de los índices para caracterizar la riqueza y diversidad de las especies indican una alta diversidad y una alta uniformidad en el rodal. Aunque el área de estudio es una plantación, los resultados de un conjunto de medidas, índices y métodos para la caracterización de patrones de distribución espacial de árboles se hayo un patrón de distribución aleatorio. El análisis de sensibilidad del modelo óptimo ajustado para explicar la relación entre la biomasa aérea y la diversidad de especies indica que la biomasa aérea y la cantidad de carbono disminuyen a medida que aumenta la diversidad de especies.
Numerous findings emerged from our investigation by incorporating climate variables into the estimation of belowground C stocks. First, climate variables can be used to adjust the US NGHGI estimates of belowground C stocks. Specifically, adjustment factors were specified to amend current coarse root C stocks estimated from allometric equations by incorporating mean annual tem- perature at various locations across the US. Second, for the US NGHGI, incorporating mean annual temperature increased national belowground C stocks by 6.4 %. In contrast, coarse root C stocks were projected to decrease through 2090, primarily due to lower partitioning to belowground components under warmer conditions. Third, whether or not a forest was planted or from natural origin, and its stand age were influential variables in deter- mining belowground C stocks. Future work that integrates both climate and stand origin will increase our ability to predict belowground C stocks across regions containing a mixture of management and climate regimes. Finally, as a means of refining NGHGIs, climate-adjusted mod- els depicting belowground C stocks should be adopted to incorporate the impacts of future global change and man- agement scenarios on C sequestration patterns and stocks.
PATTERNS AND PROCESSES IN OLD - GROWTH BEECH FORESTS
ecological (Age max , Age 5 , growth patterns and disturbance chronologies) as
well as historical analyses (e.g. chronosequences of aerial photos) confirmed that its dynamics were driven by natural processes for centuries. The remaining stands, which have not yet fully acquired advanced old-growth features, might be considered as secondary old-growth forests with different degree of naturalness, from the most developed (LAT, TRL) to the youngest ones (REG and CIM). Further historical investigations are needed to fully understand the degree of naturalness of COP.
The relation between stem density and AGB CS showed that the smaller size classes held most of the stems, but contributed to a small fraction of the live AGB CS. This suggests that the size of tree species explained more of the observed variation of AGB CS than stem density. The basal cover of adult trees showed a significant posi- tive relationship with AGB CS, reflecting that different size responds differently and develops different adaption mechanisms to resist disturbances and environmental stress. This result agrees with previous studies that showed a positive relationship between carbonstocks and basal cover (Bohn and Huth 2017; Vilanova et al. 2018). Increasing height and stem diameter of species played a positive role in increasing biomass and carbons stocks similar to the results reported from a previous study (Rubin et al. 2006). Canopy cover also showed a positive association with AGB CS. Multilayered indivi- dual species exhibited higher efficiency to capture and use light (Yachi and Loreau 2007) and, thus, a particular capacity for carbon storage and sequestration. The multilayered canopy cover makes the largest contribu- tion to forest biomass and carbonstocks.
reasons for this phenomenon is the increase in greenhouse gases, especially CO2. Therefore, the authors investigated CO2 absorption from forests of 45 plots in Ba Be National Park, characterized by 3 forest states as rich, medium and poor forest, rehabilitated forest after exploitation to estimate carbon sequestration of the forest. In which, the carbon stock of rich forest reaches 273.17 tones/ha, the medium forest is 136.23 tones/ha and the poor forest, rehabilitated forest is 42.06 tones/ha. With a forest growth rate of 1.8% per year, the carbon sequestration in Ba Be National Park for 3 forest states is about 16,499 tones per year. This will contribute to improve environmental quality, reducing greenhouse gas emissions and creating a scientific basis for managers to develop a payment mechanism of forest carbon sequestration services.
Community-managed natural forests. A forest, in which management has substantially altered the structure and ecological processes such as the water cycle, biogeochemical (or nutrient) cycling, energy flow, and community dynamics. The management focuses on the importance of participation and benefit-sharing (Agrawal et al. 2008; Sunderlin et al. 2008). However, growth is still mainly a natural process with no regular and/or continuous human intervention. The dominant tree species in the study area are J. procera and A. abyssinica , and the woody cover of the forest was visually estimated to be >60%. The economic and social benefits of community forest to the local community comprised collecting dead wood, fodder, and roof grass and providing income from beekeeping activities. Collecting live trees from the natural forest was prohibited.
INTRODUCTION In Romania, the area covered by forests has drastically decreased in the 20th century, thus reaching nowadays 29.36% (1). Therefore, Romania is under the EU mean of 43% (2) and well below the capacity and optimal quantity calculated as 45% (3). Biodiversity is the basic element for the significance of Romanian forests. There still are virgin forests, which are home to unique flora and fauna, the biggest bear population in Europe, rare and endemic species and large carnivore mammals, such as the lynx and the wolf. Only 30 thousand hectares out of a total of 130 thousand of such forests are now protected by law. Other 300 thousand hectares of forest play an important part in nature and are now exploited industrially, be it legally or illegally.
S ummary .—Little is known about the distribution, ecology and behaviour of hummingbirds in the Andean foothills of Bolivia, where many lowland hummingbird species reach their south-western distributional limits. In November 2007–October 2008, we surveyed hummingbirds at six sites along a 660-km transect, from tropical Amazonian humid forest to subtropical spiny forest of the Gran Chaco. In total, we found 21 hummingbird species. For ten of these, we provide new information on latitudinal and elevational movements, feeding or breeding behaviour. In particular, we provide evidence for seasonal movements of five species, including such widespread taxa as White-chinned Sapphire Hylocharis cyanus and Fork-tailed Woodnymph Thalurania furcata, which are considered sedentary throughout most of their ranges, but which appear to undergo seasonal movements at their range limits in Bolivia.
In conclusion, our meta-analysis has enabled us to identify heteroge- neity in the short-term responses of Bornean bird and mammal species to selective logging. Such heterogeneity in response resulted in appar- ently little effect of logging on overall abundance across all species (Fig. 1), while species with similar ecologies and evolutionary related- ness differed strongly in how they are affected by logging, indicating the importance of studies on individual species. The substantial hetero- geneity present in our ﬁ nal models (Table 3) suggests that there are as yet unidenti ﬁ ed moderating variables that determine a species re- sponse to selective logging. Unpicking this variation is a major frontier in understanding which species will be winners and losers from logging, and thus planning selective logging that prevents species extinctions. There is presently both insuf ﬁ cient life-history data for many Bornean species and surprisingly limited knowledge about the physiological and population genetic responses of species to selective logging. Future work in this direction will be pivotal if we wish to identify the proxi- mate factors that drive species to success or failure after logging.
In one notable study investigating the forest land policy in five provinces in the Central Highlands, Uyen (2013: 3) found ‘the majority of the rubber plantation projects occupy forestland, exploit forests, and then abandon them’. Among the forest areas devoted to rubber plantation projects, over 7,400 hectares had been logged illegally. In the Central Highlands, some of the latest violations can be observed in two Inspection Conclusions announced by the Government Inspectorate (2014a, 2014b). These indicate problems associated with the mismanagement of projects of forest land conversion in the Dak Nong and Gia Lai provinces. Consequently, a number of project owners have been criminally charged (Dang 2014). There are now several policies in Vietnam that notoriously enable illegitimately acquiring large-scale quantities of timber. Perhaps the most notable concerns forest land conversion. Indeed, in the last decade, some 363,500 hectares of forest throughout Vietnam have been used for approximately 2,400 projects of forest land conversion, including exploitation of natural resources, hydropower plants, irrigation construction, plantations, resettlement and building of spiritual sites, and road building (FPD 2014). While each option offers economic and social benefits, all present certain opportunities for the illegal acquisition of large amounts of timber. The majority of interviewees indicated that forest land conversion for the purposes of hydropower construction and rubber plantation development are likely to bring about illegal logging. These two practices also represent the larger portion (around 73%) of the total area of converted forests in Vietnam (To, Tran and Nguyen 2014).
increasing the loss of physical and chemical soil quality (Alfsen et al. 2001; Jaramillo et al. 2004; Loaiza Usuga et al. 2010). In the present study, soil depth-specific bulk density did not change in the stands. Therefore, it can be considered that the quality, stability, physical and chemical structure of the soil aggregates was similar in the three studied stands. Some studies suggested that SOC stocks differ between the different land uses depending on the inputs of organic matter, soil microclimates, increase/decrease in decomposability of organic matter, of crop residues due to changed litter qual- ity (for example, lowered C:N ratio and lignin con- tent) and soil disturbances (Post, Kwon 2000; Lal 2005; Haghdoost et al. 2013). The result is prob- ably attributed to high homogeneity of soil organic carbon, most likely associated with the similarity in the amount of tree biomass carbon, litter, microcli- mate on a local scale and invariability in topography due to the flatness of the forest site. High heteroge- neity in the edaphic carbon stock on a local scale is associated with the variability in topography, soil structure and texture, parent material, soil depth and microclimate, although it has interrelations with other components like forest floor and tree biomass (Loaiza Usuga et al. 2010). Here, carbon stock in soils contributed the majority of ecosystem carbon storage; however, the ground carbon stock layers (herbs and litter) were the smallest carbon pools. Although the carbonstocks of ground layers were relatively small, plant matter (and litter layer) was the most important source of carbon inputs in the soil (Leake et al. 2006; Loaiza Usuga et al. 2010). Nevertheless, the mineral soil provides a major carbon reservoir and remains an important component of the overall forest ecosystem carbon budget (Peichl, Arain 2006).
Malhi et al., 2013; Slik et al., 2013). Due to their greater AGB and larger trees, which decay more slowly than small trees, Central African forests might store higher levels of carbon in deadwood and have higher N/AGB than Neotropical forests. Thus, depending on the relative importance of and interactions among deadwood drivers, both deadwood stocks and N/AGB could be higher, lower, or similar in Central African tropical forests compared to Neotropical forests. Understanding the differences or similarities in carbon dynamics between the world's two largest tropical rainforests is an important component of accurate global carbon monitoring. The goal of this study was to quantify the stocks and evaluate the drivers of deadwood in Central African forests. With samples from 47 sites in Gabon, we examine the effects of disturbance (selective logging), forest structure variables (AGB, wood density, basal area, and density of large trees), and abiotic variables (annual temperature and precipitation) on deadwood stocks and N/AGB. We compare our findings to the more commonly studied Neotropical forests to identify whether regional differences in disturbance or forest structure affect deadwood stocks and N/AGB. Finally, we provide estimates of nationwide deadwood stocks for Gabon as a means of contributing to national and regional carbon accounting and management.