Early vegetation recovery and element cycles on a clear-cut watershed in western Oregon

1985 ◽  
Vol 15 (2) ◽  
pp. 400-409 ◽  
Author(s):  
Henry L. Gholz ◽  
Glenn M. Hawk ◽  
Alsie Campbell ◽  
Kermit Cromack Jr. ◽  
Alfred T. Brown

Aboveground biomass and leaf area, net primary production, and nutrient cycling through vegetation were studied for 3 years after clear-cutting (stems only) of a 10.24-ha watershed in the Oregon Cascade Mountains. The riparian zone and four main habitats were analyzed separately. In 3 years, aboveground net primary production increased from 5 to 112 g•m−2•year−1 in the ridgetop habitat; midsummer aboveground biomass increased from 8 to 196 g/m2 in the riparian zone and from 198 to 327 g/m2 on the ridgetop. Other values were intermediate to these. Litter fall of species with perennial aboveground parts averaged 20–27% of standing biomass. Native annuals, especially Araliacalifornica Wats., dominated the riparian zone. Seneciosylvaticus L., an introduced species, dominated most of the rest of the watershed, except for the ridgetop habitat, which was dominated by residual woody shrubs. Uptake of N exceeded losses in streamflow the 1st year and was six times greater in the 2nd; uptake of P and K in that year was 2.5 and 3 times greater than losses. In the 3rd year, total uptake of K (2.5 g•m−2•year−1) equaled the preclear-cutting level, and uptake of N (1.3 g•m−2•year−1) and P (0.3 g•m−2•year−1) was about half that level. No correlation was found between plant uptake and nutrient loss in streamflow. Uptake of all elements exceeded return through leaching and litter fall by 16%, except that of Mg, which exceeded return by 44%. Because of early dominance by species with annuals, the proportion of elements redistributed internally by vegetation was generally low. The amount of nutrients in flux through vegetation, atmosphere, and stream was small in comparison to the amount lost in the removal of tree stems.

1989 ◽  
Vol 19 (4) ◽  
pp. 515-518 ◽  
Author(s):  
Stith T. Gower ◽  
Charles C. Grier

Aboveground biomass and production were determined for a 70-year-old mixed conifer forest of western larch (Larixoccidentalis Nutt.), lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on the eastern slopes of the Cascade Range in Washington state. Live aboveground biomass, projected leaf area, and aboveground net primary production for the mixed conifer forest were 194 Mg•ha−1, 4.2 m−2•m−2, and 6.1 Mg•ha−1•year−1, respectively. Based on the few studies of montane forests on the eastern slope of the Cascades, aboveground biomass, leaf area index, and aboveground net primary production of these forests are more similar to those of montane coniferous forests in the Rocky Mountains than to those of similar forests located on the western slopes of the Cascades.


2020 ◽  
Author(s):  
Jake D. Graham

Northern peatlands are a major terrestrial carbon (C) store, with an annual sink of 0.1 Pg C yr-1 and a total storage estimate of 547 Pg C. Northern peatlands are also major contributors of atmospheric methane, a potent greenhouse gas. The microtopography of peatlands helps modulate peatland carbon fluxes; however, there is a lack of quantitative characterizations of microtopography in the literature. The lack of formalized schemes to characterize microtopography makes comparisons between studies difficult. Further, many land surface models do not accurately simulate peatland C emissions, in part because they do not adequately represent peatland microtopography and hydrology. The C balance of peatlands is determined by differences in C influxes and effluxes, with the largest being net primary production and heterotrophic respiration, respectively. Tree net primary production at a treed bog in northern Minnesota represented about 13% of C inputs to the peatland, and marks tree aboveground net primary production (ANPP) as an important pathway for C to enter peatlands. Tree species Picea mariana (Black spruce) and Larix Laricina (Tamarack) are typically found in wooded peatlands in North America, and are widely distributed in the North American boreal zone. Therefore, understanding how these species will respond to environmental change is needed to make predictions of peatland C budgets in the future. As the climate warms, peatlands are expected to increase C release to the atmosphere, resulting in a positive feedback loop. Further, climate warming is expected to occur faster in northern latitudes compared to the rest of the globe. The Spruce and Peatland Responses Under Changing Environments (SPRUCE; https://mnspruce.ornl.gov/) manipulates temperature and CO2 concentrations to evaluate the in-situ response of a peatland to environmental change and is located in Minnesota, USA. In this dissertation, I documented surface roughness metrics for peatland microtopography in SPRUCE plots and developed three explicit methods for classifying frequently used microtopographic classes (microforms) for different scientific applications. Subsequently I used one of these characterizations to perform a sensitivity analysis and improve the parameterization of microtopography in a land surface model that was calibrated at the SPRUCE site. The modeled outputs of C from the analyses ranged from 0.8-34.8% when microtopographical parameters were allowed to vary within observed ranges. Further, C related outputs when using our data-driven parameterization differed from outputs when using the default parameterization by -7.9 - 12.2%. Finally, I utilized TLS point clouds to assess the effect elevated temperature and CO2 concentrations had on P. mariana and L. laricina after the first four years of SPRUCE treatments. I observed that P. mariana growth (aboveground net primary production) had a negative response to temperature initially, but the relationship became less pronounced through time. Conversely, L. laricina had no growth response to temperature initially, but developed a positive relationship through time. The divergent growth responses of P. mariana and L. laricina resulted in no detectable change in aboveground net primary production at the community level. Results from this dissertation help improve how peatland microtopography is represented, and improves understanding of how peatland tree growth will respond to environmental change in the future.


Trees ◽  
2000 ◽  
Vol 14 (7) ◽  
pp. 415-421 ◽  
Author(s):  
J. Oleksyn ◽  
P.B. Reich ◽  
L. Rachwal ◽  
M.G. Tjoelker ◽  
P. Karolewski

2011 ◽  
Vol 8 (8) ◽  
pp. 2099-2106 ◽  
Author(s):  
Y. Wang ◽  
J. Y. Fang ◽  
T. Kato ◽  
Z. D. Guo ◽  
B. Zhu ◽  
...  

Abstract. Recent studies based on remote sensing and carbon process models have revealed that terrestrial net primary production (NPP) in the middle and high latitudes of the Northern Hemisphere has increased significantly; this is crucial for explaining the increased terrestrial carbon sink in the past several decades. Regional NPP estimation based on significant field data, however, has been rare. In this study, we estimated the long-term changes in aboveground NPP (ANPP) for Japan's forests from 1980 to 2005 using forest inventory data, direct field measurements, and an allometric method. The overall ANPP for all forest types averaged 10.5 Mg ha−1 yr−1, with a range of 9.6 to 11.5 Mg ha−1 yr−1, and ANPP for the whole country totaled 249.1 Tg yr−1 (range: 230.0 to 271.4 Tg yr−1) during the study period. Over the 25 years, the net effect of increased ANPP in needle-leaf forests and decreased ANPP in broadleaf forests has led to an increase of 1.9 Mg ha−1 yr−1 (i.e., 0.79 % yr−1). This increase may be mainly due to the establishment of plantations and the rapid early growth of these planted forests.


2020 ◽  
Author(s):  
Raphael Manu ◽  
Marife D. Corre ◽  
Edzo Veldkamp ◽  
Oliver van Straaten

<p>Nutrient availability in tropical forest ecosystems plays a critical role in sustaining forest growth and productivity. Observational evidence for nutrient limitations on net primary productivity (NPP) in the tropics is rare yet crucial for predicting the impacts of human-induced changes on tropical forests, particularly for underrepresented tropical regions in Africa. In an ecosystem-scale nutrient manipulation experiment, we assessed the response of different components of above-ground net primary production (ANPP) to nutrient addition of nitrogen (N), phosphorus (P), potassium (K) and all possible combinations (NP, NK, PK, and NPK) at rates of 125 kg N ha<sup>-1</sup>yr<sup>-1</sup>, 50 kg P ha<sup>-1</sup> yr<sup>-1</sup> and 50 kg K ha<sup>-1</sup>yr<sup>-1</sup>.</p><p>We established 32 (8 treatments × 4 replicates) experimental plots of 40 × 40 m<sup>2</sup> each and measured stem growth of over 15,000 trees with diameter at breast height (dbh) ≥ 1 cm as well as litter production and above-ground woody biomass production (AWBP), of a lower-montane tropical forest (1100 m a.s.l.) in northwestern Uganda.</p><p>After 18 months of nutrient addition, we found that different aspects of ANPP, including litter production and AWBP are controlled by multiple soil nutrients. Specifically, we measured higher total fine-litter production in the N (13.6 ± 1.4 Mg ha<sup>-1 </sup>yr<sup>-1</sup>) and K (13.3 ± 1.8 Mg ha<sup>-1 </sup>yr<sup>-1</sup>) addition plots than the control (11.1 ± 0.6 Mg ha<sup>-1 </sup>yr<sup>-1</sup>) plots. Both reproductive litter (flowers and fruits; 10% of total fine-litter fall) and leaf litter (62% of total fine-litter fall) significantly increased with K addition. In general, fine-litter production in our plots is higher than what has been reported so far for lower-montane tropical forests. Increased AWBP is associated with N addition plots. The response of trees to nutrient addition however, varied with tree sizes. Trees with dbh between 10 – 30 cm increased significantly in AWBP under PK addition. There was no effect of nutrient addition associated with either smaller (1 – 10 cm dbh) or larger trees (dbh > 30 cm). The medium-sized trees which may have experienced resource competition but have now transitioned into the canopy layer (exposed to sunlight) are able to use additional nutrient for active growth. In contrast, bigger trees may allocate extra nutrient for reproduction and leaf-vitality, while smaller trees remain shaded, co-limited by sunlight and therefore unable to utilize increased available nutrients for stem diameter growth. ANPP increased by 39% with N addition and marginally by 23% with K additions relative to the control. In conclusion, our experiment provides evidence of N and potentially K limitation of ANPP in this lower-montane tropical forest, and highlights that, in a highly diverse ecosystem different components of ANPP may be regulated by multiple nutrients. </p>


Sign in / Sign up

Export Citation Format

Share Document