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1.
The expansion of oil palm monocultures into globally important Southeast Asian tropical peatlands has caused severe environmental damage. Despite much of the current focus of environmental impacts being directed at industrial scale plantations, over half of oil palm land-use cover in Southeast Asia is from smallholder plantations. We differentiated a first generation smallholder oil palm monoculture into 8 different sampling zones, and further divided the 8 sampling zones into oil palm root influenced (Proximal) and reduced root influence (Distal) areas, to assess how peat properties regulate in situ carbon dioxide (CO2) and methane (CH4) fluxes. We found that all the physico-chemical properties and nutrient concentrations except sulphur varied significantly among sampling zones. All physico-chemical properties except electrical conductivity, and all nutrient content except nitrogen and potassium varied significantly between Proximal and Distal areas. Mean CO2 fluxes (ranged between 382 and 1191 mg m−2 h−1) varied significantly among sampling zones, and between Proximal and Distal areas, with notably high emissions in Dead Wood and Path zones, and consistently higher emissions in Proximal areas compared to Distal areas within almost all the zones. CH4 fluxes (ranged between −32 and 243 µg m−2 h−1) did not significantly vary between Proximal and Distal areas, however significantly varied amongst sampling zones. CH4 flux was notably high in Canal Edge and Understorey Ferns zones, and negative in Dead Wood zone. The results demonstrate the high heterogeneity of peat properties within oil palm monoculture, strengthening the need for intensive sampling to characterize a land use in the tropical peatlands. 相似文献
2.
Bart&#x;omiej Glina Agnieszka Piernik Piotr Hulisz &#x;ukasz Mendyk Klara Tomaszewska Magda Podlaska Adam Bogacz Waldemar Spychalski 《Land Degradation u0026amp; Development》2019,30(12):1437-1448
The aim of this paper was to evaluate the link between environmental conditions and the vegetation pattern of mountain peatlands drained for forestry. We assumed that (a) water chemistry and soil properties differ between the investigated peatlands types—from fen to bog, (b) the vegetation pattern is dependent on water chemistry and soil properties, and (c) water chemistry and soil properties play different roles in determining peatland patterning. For our study, five ecologically and topographically diverse forestry‐drained shallow peatlands in Central Sudetes, Poland, were selected. A comparison between the studied peatlands and environmental variables was done by discriminant analysis, whereas vegetation–environmental relationship was analysed by canonical correspondence analysis. Results demonstrated that pH, HCO3−, NO3−, and Ca2+ best explained the variation in water chemistry (approximately 74%), whereas base saturation, pHwater, and plant‐available phosphorus best explained the variation in soil properties. Plant assemblages within the peatlands exhibited three vegetation clusters that did not always correspond to peatland ecological type. The vegetation was mostly affected by water chemistry (explained up to 54% of variation), rather than by soil properties. Vegetation within such ecosystems seems to be a good indicator of differences in water chemistry, caused by differences in bedrock (soligenic fen peatlands) or atmospheric inputs (ombrogenic bogs). Our results will help improve our understanding of vegetation–environment relationships in degraded mountain peatland ecosystems in the temperate climate zone. They might also be useful for proper planning of restoration and monitoring of these ecosystems. 相似文献
3.
C. M. H. Metzger J. Heinichen T. Eickenscheidt M. Drösler 《Grass and Forage Science》2017,72(1):50-63
Vegetation indices are widely used as model inputs and for non‐destructive estimation of biomass and photosynthesis, but there have been few validation studies of the underlying relationships. To test their applicability on temperate fens and the impact of management intensity, we investigated the relationships between normalized difference vegetation index (NDVI), leaf area index (LAI), brown and green above‐ground biomass and photosynthesis potential (PP). Only the linear relationship between NDVI and PP was management independent (R2 = 0·53). LAI to PP was described by a site‐specific and negative logarithmic function (R2 = 0·07–0·68). The hyperbolic relationship of LAI versus NDVI showed a high residual standard error (s.e.) of 1·71–1·84 and differed between extensive and intensive meadows. Biomass and LAI correlated poorly (R2 = 0·30), with high species‐specific variability. Intensive meadows had a higher ratio of LAI to biomass than extensive grasslands. The fraction of green to total biomass versus NDVI showed considerable noise (s.e. = 0·13). These relationships were relatively weak compared with results from other ecosystems. A likely explanation could be the high amount of standing litter, which was unevenly distributed within the vegetation canopy depending on the season and on the timing of cutting events. Our results show there is high uncertainty in the application of the relationships on temperate fen meadows. For reliable estimations, management intensity needs to be taken into account and several direct measurements throughout the year are required for site‐specific correction of the relationships, especially under extensive management. Using NDVI instead of LAI could reduce uncertainty in photosynthesis models. 相似文献
4.
[目的]揭示引种鹅掌楸和杉木人工林在广西自治区融水县的生长特性,为杉木连栽迹地造林树种的选择提供科学依据。[方法]对广西自治区融水苗族自治县杉木采伐迹地的鹅掌楸和杉木人工林的生长特性进行了5年的定位监测,并进行了比较研究。[结果]在相似立地条件下,1～5年生鹅掌楸人工林的平均树高、平均胸径和平均蓄积量均明显高于杉木人工林,其中,5年生杉木人工林年均胸径生长量为1.43 cm,年均树高生长量为1.23 m,年平均蓄积量为17.02 m3/hm2,而5年生鹅掌楸人工林的上述3个数据分别为2.19 cm、1.78 m和31.80 m3/hm2,是杉木人工林的1.53、1.45和1.87倍。[结论]鹅掌楸是一种早期速生树种,其生长速度比杉木快,成材比杉木早,可以作为杉木的替代轮作树种进行推广。 相似文献
5.
香格里拉市高寒地区分布有众多泥炭沼泽生态系统,在云南省具有典型性、代表性,在湿地生态系统功能调节过程中具有不可估量的作用。根据《云南省泥炭沼泽碳库调查报告》,结合香格里拉市泥炭沼泽生态系统特点,构建了泥炭沼泽生态系统服务功能价值评估指标体系,评估了支持功能、调节功能和文化功能3项服务功能价值,包括8个具体评价指标。估算结果表明,香格里拉市泥炭沼泽生态系统服务功能总价值为5.99亿元/a,单位面积价值为110.86元/(m2·a),其中：间接价值占总价值的95.32%,蓄水调洪、固氮释氧以及气候调节价值最显著。 相似文献
6.
S. Hughes B. Reynolds S. A. Brittain J. A. Hudson C. Freeman 《Soil Use and Management》1998,14(4):248-251
Abstract. Recently, there has been interest in the occurrence of bromide (Br- ) in natural waters since it has been demonstrated that Br- , in association with humic substances in raw waters, is readily incorporated into haloacetic acids in the form of organically bound bromine (Br) during water chlorination. We report results of the effects of experimentally rewetting a naturally drained gully mire on the hydrochemistry of Br- , iron (Fe) and dissolved organic carbon (DOC) in the peat water. Results obtained over a three year period showed that rewetting substantially increased the concentrations of these solutes in the pore water, with peak values of 1 mg dm-3 (Br- ), > 60 mg dm-3 (Fe) and > 300 mg dm-3 (DOC) detected in some samples after rewetting, compared with typical values < 0.05 mg dm-3 (Br- ), < 1 mg dm-3 (Fe) and < 15 mg dm-3 (DOC) under the drained conditions. Bromide, Fe and DOC release were highly seasonal, with the largest concentrations observed in late-summer to autumn. However, whereas seasonal peak concentrations of Fe and DOC have since remained at these higher levels, seasonal peak concentrations of Br- were progressively attenuated over time, suggesting the latter phenomenon is a flush effect, with no longer-term consequences for water quality. 相似文献
7.
During winter when the active layer of Arctic and alpine soils is below 0 °C, soil microbes are alive but metabolizing slowly, presumably in contact with unfrozen water. This unfrozen water is at the same negative chemical potential as the ice. While both the hydrostatic and the osmotic components of the chemical potential will contribute to this negative value, we argue that the osmotic component (osmotic potential) is the significant contributor. Hence, the soil microorganisms need to be at least halotolerant and psychrotolerant to survive in seasonally frozen soils. The low osmotic potential of unfrozen soil water will lead to the withdrawal of cell water, unless balanced by accumulation of compatible solutes. Many microbes appear to survive this dehydration, since microbial biomass in some situations is high, and rising, in winter. In late winter however, before the soil temperature rises above zero, there can be a considerable decline in soil microbial biomass due to the loss of compatible solutes from viable cells or to cell rupture. This decline may be caused by changes in the physical state of the system, specifically by sudden fluxes of melt water down channels in frozen soil, rapidly raising the chemical potential. The dehydrated cells may be unable to accommodate a rapid rise in osmotic potential so that cell membranes rupture and cells lyse. The exhaustion of soluble substrates released from senescing plant and microbial tissues in autumn and winter may also limit microbial growth, while in addition the rising temperatures may terminate a winter bloom of psychrophiles.Climate change is predicted to cause a decline in plant production in these northern soils, due to summer drought and to an increase in freeze-thaw cycles. Both of these may be expected to reduce soil microbial biomass in late winter. After lysis of microbial cells this biomass provides nutrients for plant growth in early spring. These feedbacks, in turn, could affect herbivory and production at higher trophic levels. 相似文献
8.
Shaun M Allingham Felix C Nwaishi Roxane Andersen Louis J Lamit David R Elliott 《Land Degradation u0026amp; Development》2023,34(5):1504-1521
Peatlands play an important role in global biogeochemical cycles and are essential for multiple ecosystem functions. Understanding the environmental drivers of microbial functioning and community structure can provide insights to enable effective and evidence-based management. However, it remains largely unknown how microbial diversity contributes to the functioning of belowground processes. Addressing this gap in knowledge will provide a better understanding of microbial-mediated processes in peatlands that are undergoing restoration or reclamation. This study assessed the changes in microbial community diversity and structure as well as soil function by measuring microbial respiration on a range of substrates from three natural fen types found in the Athabasca Oil Sands region of Alberta, Canada (a poor fen, a hypersaline fen, and a tree-rich fen) and a nearby constructed fen undergoing reclamation following open pit mining. Overall, substrate induced respiration was significantly higher in the constructed fen. Alpha diversity of fungi and prokaryotes was highest in the tree-rich fen, and the composition of microbial communities was significantly different between fens. Both fungal and prokaryotic communities were strongly related to pore water pH and temperature, with plant richness also contributing to the shape of fungal communities. In summary, microbial community structure reflects the underlying differences in soil condition across different fens but plays essential roles in the ecological functions of soil. These findings provide a new outlook for the management of peatlands undergoing post-mining reclamation. Future research on peatland reclamation should consider the dynamic interaction between communities and ecosystem functionality, for which this study forms a useful baseline. 相似文献
9.
Anatol Helfenstein;Vera L. Mulder;Mirjam J. D. Hack-ten Broeke;Bas C. Breman; 《European Journal of Soil Science》2024,75(4):e13529
Nature-inclusive scenarios of the future can help address numerous societal challenges related to soil health. As nature-inclusive scenarios imply sustainable management of natural systems and resources, land use and soil health are assumed to be mutually beneficial in such scenarios. However, the interplay between nature-inclusive land use scenarios and soil health has never been modelled using digital soil mapping. We predicted soil organic matter (SOM), an important indicator of soil health, in 2050, based on a recently developed nature-inclusive scenario and machine learning in 3D space and time in the Netherlands. By deriving dynamic covariates related to land use and the occurrence of peat for 2050, we predicted SOM and its uncertainty in 2050 and assessed SOM changes between 2022 and 2050 from 0 to 2 m depth at 25 m resolution. We found little changes in the majority of mineral soils. However, SOM decreases of up to 5% were predicted in grasslands used for animal-based production systems in 2022, which transitioned into croplands for plant-based production systems by 2050. Although increases up to 25% SOM were predicted between 0 and 40 cm depth in rewetted peatlands, even larger decreases, on reclaimed land even surpassing 25% SOM, were predicted on non-rewetted land in peat layers below 40 cm depth. There were several limitations to our approach, mostly due to predicting future trends based on historic data. Furthermore, nuanced nature-inclusive practices, such as the adoption of agroecological farming methods, were too complex to incorporate in the model and would likely affect SOM spatial variability. Nonetheless, 3D-mapping of SOM in 2050 created new insights and raised important questions related to soil health behind nature-inclusive scenarios. Using machine learning explicit in 3D space and time to predict the impact of future scenarios on soil health is a useful tool for facilitating societal discussion, aiding policy making and promoting transformative change. 相似文献
10.
Litter quality and environmental effects on Scots pine (Pinus sylvestris L.) fine woody debris (FWD) decomposition were examined in three forestry-drained peatlands representing different site types along a climatic gradient from the north boreal (Northern Finland) to south (Southern Finland) and hemiboreal (Central Estonia) conditions. Decomposition (percent mass loss) of FWD with diameter ≤10 mm (twigs) and FWD with diameter >10 mm (branches) was measured using the litter bag method over 1–4-year periods. Overall, decomposition rates increased from north to south, the rate constants (k values) varying from 0.128 to 0.188 year−1 and from 0.066 to 0.127 year−1 for twigs and branches, respectively. On average, twigs had lost 34%, 19% and 19%, and branches 25%, 17% and 11% of their initial mass after 2 years of decomposition at the hemiboreal, south boreal and north boreal sites, respectively. After 4 years at the south boreal site the values were 48% for twigs and 42% for branches. Based on earlier studies, we suggest that the decomposition rates that we determined may be used for estimating Scots pine FWD decomposition in the boreal zone, also in upland forests. Explanatory models accounted for 50.4% and 71.2% of the total variation in FWD decomposition rates when the first two and all years were considered, respectively. The variables most related to FWD decomposition included the initial ash, water extractives and Klason lignin content of litter, and cumulative site precipitation minus potential evapotranspiration. Simulations of inputs and decomposition of Scots pine FWD and needle litter in south boreal conditions over a 60-year period showed that 72 g m−2 of organic matter from FWD vs. 365 g m−2 from needles accumulated in the forest floor. The annual inputs varied from 5.7 to 15.6 g m−2 and from 92 to 152 g m−2 for FWD and needles, respectively. Each thinning caused an increase in FWD inputs, up to 510 g m−2, while the needle inputs did not change dramatically. Because the annual FWD inputs were lowered following the thinnings, the overall effect of thinnings on C accumulation from FWD was slightly negative. The contribution of FWD to soil C accumulation, relative to needle litter, seems to be rather minor in boreal Scots pine forests. 相似文献