Nitrogen turnover in the leaf litter and fine roots of sugar maple

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117199/1/ecy201091123456.pd

Predicting Resource Management Benefits By Simulating Angler Demand and Supply Responses

The “product” travel cost model (PTC) improves supply and substitution specification in travel cost models (TCM), eliminating common biases in estimating welfare effects of qualitative changes at specific sites. Angling sites and participation are modeled as a system of product supplies and demands; changes in angling quality at specific sites are evaluated as changes in the supplies of relevant products. PTC assumes that each angler chooses from a selection of angling opportunities (i.e., products) based on access cost (i.e., travel cost) and the nature of each angling product. Key factors defining angling products (e.g., success rate, fish size) are derived from angler travel patterns: Anglers are assumed indifferent between sites providing identical angling products, so choose the lowest cost site. Therefore, the benefits of any management action not only differ from average welfare-change values, but are also site-specific. Changing angling attributes at a site changes its angling product: a unit of the existing product (potentially decreasing its supply) is lost while a unit of the newly created product is produced (potentially increasing its supply). Changes in supply at one site may alter angler participation patterns and the value of angling opportunities at the affected site plus at many other sites as well. Credit Valley Conservation contracted the application of the PTC examined here, namely angling in the Credit River watershed near Toronto, Canada. Average angler consumer surplus was estimated at $40 per angler day and varied according to angling product, location and season.Keywords: Fishery Management, Special Topics, Fisheries Economics, Valuing Recreational Fisheries and Modelling Human Responses to Changes in their Management Regime

Folk beliefs of cultural changes in China

For the last several decades, Chinese society has experienced transformative changes. How are these changes understood among Chinese people? To examine this question, Part 1 in this research solicited folk beliefs of cultural change from a group of Chinese participants in an open-ended format, and the generated folk beliefs were rated by another group of participants in Part 2 to gage each belief's level of agreement. Part 3 plotted the folk beliefs retained in Part 2 using the Google Ngram Viewer in order to infer the amount of intellectual interests that each belief has received cross-temporarily. These analyses suggested a few themes in Chinese folk beliefs of cultural change (1) rising perceived importance of materialism and individualism in understanding contemporary Chinese culture and Chinese psychology relative to those of the past (2) rising perceived importance of freedom, democracy and human rights and (3) enduring perceived importance of family relations and friendship as well as patriotism. Interestingly, findings from Parts 2 and 3 diverged somewhat, illuminating possible divergence between folk beliefs and intellectual interests especially for issues related to heritage of Confucianism

Elevated carbon dioxide and ozone alter productivity and ecosystem carbon content in northern temperate forests

Three young northern temperate forest communities in the north‐central United States were exposed to factorial combinations of elevated carbon dioxide ( CO 2 ) and tropospheric ozone (O 3 ) for 11 years. Here, we report results from an extensive sampling of plant biomass and soil conducted at the conclusion of the experiment that enabled us to estimate ecosystem carbon (C) content and cumulative net primary productivity ( NPP ). Elevated CO 2 enhanced ecosystem C content by 11%, whereas elevated O 3 decreased ecosystem C content by 9%. There was little variation in treatment effects on C content across communities and no meaningful interactions between CO 2 and O 3 . Treatment effects on ecosystem C content resulted primarily from changes in the near‐surface mineral soil and tree C, particularly differences in woody tissues. Excluding the mineral soil, cumulative NPP was a strong predictor of ecosystem C content ( r 2  = 0.96). Elevated CO 2 enhanced cumulative NPP by 39%, a consequence of a 28% increase in canopy nitrogen (N) content (g N m −2 ) and a 28% increase in N productivity ( NPP /canopy N). In contrast, elevated O 3 lowered NPP by 10% because of a 21% decrease in canopy N, but did not impact N productivity. Consequently, as the marginal impact of canopy N on NPP (∆ NPP /∆N) decreased through time with further canopy development, the O 3 effect on NPP dissipated. Within the mineral soil, there was less C in the top 0.1 m of soil under elevated O 3 and less soil C from 0.1 to 0.2 m in depth under elevated CO 2 . Overall, these results suggest that elevated CO 2 may create a sustained increase in NPP , whereas the long‐term effect of elevated O 3 on NPP will be smaller than expected. However, changes in soil C are not well‐understood and limit our ability to predict changes in ecosystem C content.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108065/1/gcb12564.pd