The value of linking paleoecological and neoecological perspectives to understand spatially-explicit ecosystem resilience     

Buma  B.  Harvey  B. J.  Gavin  D. G.  Kelly  R.  Loboda  T.  McNeil  B. E.  Marlon  J. R.  Meddens  A. J. H.  Morris  J. L.  Raffa  K. F.  Shuman  B.  Smithwick  E. A. H.  McLauchlan  K. K. 《Landscape Ecology》2019,34(1):17-33

Context

Predicting ecosystem resilience is a challenge, especially as climate change alters disturbance regimes and conditions for recovery. Recent research has highlighted the importance of spatially-explicit disturbance and resilience processes to long-term ecosystem dynamics. “Neoecological” approaches characterize resilience mechanisms at relatively fine spatio-temporal resolutions, but results are difficult to extrapolate across broad temporal scales or climatic ranges. Paleoecological methodologies can consider the effects of climates that differ from today. However, they are often limited to coarse-grained spatio-temporal resolutions.

Methods

In this synthesis, we describe implicit and explicit examples of studies that incorporate both neo- and paleoecological approaches. We propose ways to build on the strengths of both approaches in an explicit and proactive fashion.

Results

Linking the two approaches is a powerful way to surpass their respective limitations. Aligning spatial scales is critical: Paleoecological sampling design should incorporate knowledge of the spatial characteristics of the disturbance process, and neoecological studies benefit from a longer-term context to their conclusions. In some cases, modeling can incorporate non-spatial data from paleoecological records or emerging spatial paleo-data networks with mechanistic disturbance/recovery processes that operate at fine spatiotemporal scales.

Conclusions

Linking these two complementary approaches is a powerful way to build a complete understanding of ecosystem disturbance and resilience.

  相似文献   

Town ecology: for the land of towns and villages     

Forman  Richard T. T. 《Landscape Ecology》2019,34(10):2209-2211

  相似文献   

Climate change will affect the ability of forest management to reduce gaps between current and presettlement forest composition in southeastern Canada     

Boulanger  Yan  Arseneault  Dominique  Boucher  Yan  Gauthier  Sylvie  Cyr  Dominic  Taylor  Anthony R.  Price  David T.  Dupuis  Sébastien 《Landscape Ecology》2019,34(1):159-174

Landscape Ecology - Forest landscapes at the boreal–temperate ecotone have been extensively altered. Reducing the gap between current and presettlement forest conditions through...  相似文献   

Drivers of fine-scale avian functional diversity with changing land use: an assessment of the effects of eco-estate housing development and management     

Alexander  Jarryd  Ehlers Smith  David A.  Ehlers Smith  Yvette C.  Downs  Colleen T. 《Landscape Ecology》2019,34(3):537-549

Landscape Ecology - The effects of changing land use, and especially urbanisation, on species and functional diversity are of global concern. Eco-estates are a form of urban housing development...  相似文献   

Intensification of New Zealand beef farming systems     

T.A. White  W.McG. King 《Agricultural Systems》2010,103(1):21-35

This study used whole-farm management, nutrient budgeting/greenhouse gas (GHG) emissions and feed formulation computer tools to determine the production, environmental and financial implications of intensifying the beef production of typical New Zealand (NZ) sheep and beef farming systems. Two methods of intensification, feeding maize silage (MS) or applying nitrogen (N) fertiliser, were implemented on two farm types differing in the proportions of cultivatable land to hill land (25% vs. 75% hill). In addition, the consequences of intensification by incorporating a beef feedlot (FL) into each of the farm types were also examined.Feeding MS or applying N fertiliser substantially increased the amount of beef produced per ha. Intensifying production was also associated with increased total N leaching and GHG emissions although there were differences between the methods of intensification. Feeding MS resulted in lower environmental impacts than applying N even after taking into account the land to grow the maize for silage. Based on 2007/08 prices, typical NZ sheep and beef farms were making a financial loss and neither method of intensification increased profitability with the exception of small annual applications of N, especially to the 75% hill farm. These small annual additions of N fertiliser (<50 kg N/ha/yr applied in autumn and late winter) resulted in only small increases in annual N leaching (from 11 to 14 kg N/ha) and GHG emissions (from 3280 to 4000 kg CO₂ equivalents/ha). Limited N applications were particularly beneficial to 75% hill farms because small increases in winter carrying capacity resulted in relatively large increases in the utilisation of pasture growth during spring and summer than the 25% hill farms. Intensification by incorporating a beef feedlot reduced environmental emissions per kg of beef produced but considerably decreased profitability due to higher capital, depreciation and labour costs. The lower land-use capability farm type (75% hill) was able to intensify beef production to a proportionally greater extent than the higher land-use capability farm (25% hill) because of greater potential to increase pasture utilisation associated with a lower initial farming intensity and inherent constraints in the pattern of pasture supply.  相似文献   

In situ net N transformations in pine,fir, and oak stands of different ages on acid sandy soil, 3 years after liming     

W. De Boer  M. P. J. Hundscheid  J. M. T. Schotman  S. R. Troelstra  H. J. Laanbroek 《Biology and Fertility of Soils》1993,15(2):120-126

Summary The effect of liming on in-situ N transformations was studied in two stands of different ages of each of Scots pine (Pinus sylvestris L.), Douglas fir [Pseudotsuga menziesii (Mirb.) Franco], and common oak (Quercus robur L.). The stands were located on acid sandy soils in an area with high atmospheric N input. The organic matter of the upper 10-cm layer of the soil, including the forest floor, had a relatively high N content (C: N ratio <25) in all stands. Using a sequential core technique, N transformations were measured in both control plots and plots that had been limed 3 years previously with 3 t ha^-1 of dolomitic lime. Limed plots had a higher net NO _inf3 ^sup- production and a higher potential for NO _inf3 ^sup- leaching than the controls in all stands except that of the younger oak. Net N mineralization did not differ significantly between limed and control plots in oak stands and younger coniferous stands but was significantly lower in the limed plots of the older coniferous stands. It is concluded that long-term measurements of net N mineralization in limed forest soils are needed to evaluate the effect of liming with respect to the risk of groundwater pollution.  相似文献   

Soluble organic nitrogen in agricultural soils   总被引：36，自引：0，他引：36  

D. V. Murphy  A. J. Macdonald  E. A. Stockdale  K. W. T. Goulding  S. Fortune  J. L. Gaunt  P. R. Poulton  J. A. Wakefield  C. P. Webster  W. S. Wilmer 《Biology and Fertility of Soils》2000,30(5-6):374-387

 The existence of soluble organic forms of N in rain and drainage waters has been known for many years, but these have not been generally regarded as significant pools of N in agricultural soils. We review the size and function of both soluble organic N extracted from soils (SON) and dissolved organic N present in soil solution and drainage waters (DON) in arable agricultural soils. SON is of the same order of magnitude as mineral N and of equal size in many cases; 20–30 kg SON-N ha^–1 is present in a wide range of arable agricultural soils from England. Its dynamics are affected by mineralisation, immobilisation, leaching and plant uptake in the same way as those of mineral N, but its pool size is more constant than that of mineral N. DON can be sampled from soil solution using suction cups and collected in drainage waters. Significant amounts of DON are leached, but this comprises only about one-tenth of the SON extracted from the same soil. Leached DON may take with it nutrients, chelated or complexed metals and pesticides. SON/DON is clearly an important pool in N transformations and plant uptake, but there are still many gaps in our understanding. Received: 10 June 1999  相似文献   

Investigations into genotypic variations of peanut carbohydrates     

Pattee HE  Isleib TG  Giesbrecht FG  McFeeters RF 《Journal of agricultural and food chemistry》2000,48(3):750-756

Carbohydrates are known to be important precursors in the development of roasted peanut quality. However, little is known about their genotypic variation. A better understanding of the role of carbohydrates in roasted peanut quality requires first an understanding of the genotypic variation in the soluble carbohydrate components. Ion exchange chromatography was used to isolate 20 different carbohydrate components in 52 genotypes grown in replicated trials at two locations. Inositol, glucose, fructose, sucrose, raffinose, and stachyose were quantitated, and 12 unknown peaks were evaluated on the basis of the peak height of the unknown relative to the cellobiose internal standard peak height. Peaks tentatively identified as verbascose and ajugose could not be properly integrated because of tailing. Of the 18 carbohydrates that were estimated, 9 exhibited significant variation between test environments, 5 among market types, 14 among genotypes within market types, and 11 exhibited some significant form of genotype x environment interaction. Genotypes accounted for 38-78% of the total variation for the known components, suggesting that broad-sense heritability for these components is high. The observed high genotypic variation in carbohydrate components is similar to the high genotypic variation observed for the sweetness attribute in roasted peanuts, which raises the question regarding possible interrelationships. The establishment of such interrelationships could be most beneficial to peanut breeding programs to ensure the maintenance of flavor quality in future peanut varieties.  相似文献   

Distribution of microbial biomass and phospholipid fatty acids in Podzol profiles under coniferous forest   总被引：12，自引：0，他引：12  

H. Fritze  J. Pietikäinen  & T. Pennanen 《European Journal of Soil Science》2000,51(4):565-573

Microbial‐derived phospholipid fatty acids (PLFAs) can be used to characterize the microbial communities in soil without the need to isolate individual fungi and bacteria. They have been used to assess microbial communities of humus layers under coniferous forest, but nothing is known of their distribution in the deeper soil. To investigate the vertical distribution we sampled nine Podzol profiles on a 100‐m‐long transect in a coniferous forest and analysed for their microbial biomass and PLFA pattern to a depth of 0.4 m. The transect covered a fertility gradient from Vaccinium vitis‐idaea forest site type to Vaccinium myrtillus forest site type. The cores were divided into humus (O) and eluvial (E) layers and below that into 10‐cm sections and designated as either illuvial (B) or parent material (C), or as a combination (BC). Two measures of microbial biomass analyses were applied: substrate‐induced respiration (SIR) to determine microbial biomass C (C_mic), and the sum of the extracted microbial‐derived phospholipid fatty acids (totPLFA). The soil fertility had no effect on the results. The C_mic correlated well with totPLFA (r= 0.86). The microbial biomass decreased with increasing depth. In addition the PLFA pattern changed with increased depth as assessed with principal component analysis, indicating a change in the microbial community structure. The composition of the PLFAs in the O layer differed from that in the E layer and both differed from the upper part of the B layer and from the rest of the BC layers. The deeper parts of the B layer (BC₁, BC₂ and BC₃) were similar to one other. The O layer had more 18:2ω6, a PLFA indicator of fungi, whereas the E layer contained relatively more of the PLFAs 16:1ω9, 18:1ω7 and cy19:0 common in gram‐negative bacteria. With increased depth the relative amount of 10Me18:0, the PLFA indicator for actinomycetes, increased. We conclude that the PLFA method is a promising discriminator between the microbial community structures of the horizons in Podzols.  相似文献   

甘蓝黑腐病菌rPf基因簇对胞外蛋白酶Ⅰ基因表达的调控     

冯家勋  唐纪良  马庆生 《广西农业生物科学》1996,(1)

甘蓝黑腐病黄单胞菌（ＸａｎｔｈｏｍｏｎａｓｃａｍｐｅｓｔｒｉｓＰｖ．ｃａｍｐｅｓｔｒｉｓ）产生的胞外蛋白酶Ⅰ在致病的早期阶段起重要作用，该酶以及其它胞外酶和胞外多糖的合成受一致病因子调控基因簇（ｒＰｆ基因簇）的正向调控。本研究利用带有β－半乳糖苷酶报道基因（ｌａｃＺ）的转座子Ｔｎ５－Ｂ２０诱变蛋白酶Ⅰ基因克隆，获得了ｌａｃＺ在蛋白酶Ⅰ基因启动子控制下表达的Ｔｎ５－Ｂ２０插入突变质粒。通过将这种突变质粒导入野生型和各ｒｐｆ基因突变体菌株后，测定ｌａｃＺ基因在细胞生长周期中的表达水平，不仅进一步证实了这些ｒｐｆ基因对蛋白酶Ⅰ基因的正向调控作用，而且明确了它们的调控水平．发现ｒｐｆＡ、ｒｐｆＣ、ｒｐｆＥ、ｒｐｆＧ或ｒｐｆＨ突变后，蛋白酶Ⅰ基因的转录会降低９０％左右，而ｒｐｆＢ突变后，蛋白酶Ⅰ基因的转录只降低４８％。  相似文献