Nature conservation in a digitalized world: echo chambers and filter bubbles

Digital echo chambers and filter bubbles are increasingly the subject of societal, political, and scientific discourse. However, the impact of these phenomena on nature conservation remains understudied. This study provides an explorative overview of the potential relevance of digital echo chambers and filter bubbles for nature conservation practice. For this purpose, data collected during a literature review as well as a digital expert survey of German conservation actors was evaluated. The data show that the phenomena are already considered in conjunction with conservation topics with a focus on climate protection in the scientific literature and nature conservation practice to a small but increasing extent. Furthermore, it is recognized that they pose more risks than potential benefits for nature conservation communication. However, the understanding of the exact processes associated with digital echo chambers and filter bubbles is insufficient. The study also identified an extensive need for action and research regarding the strategic consideration and handling of digital echo chambers and filter bubbles in nature conservation practice. There is significant potential to improve the societal acceptance upon which nature conservation depends and to increase the public participation in nature conservation issues. To make a responsible and effective contribution to society, nature conservation must keep abreast of new communication factors that are emerging in the age of digitalization.

However, the potential of the Internet as a diverse source of information and a tool for dialogue about conservation topics is often limited as users tend to remain in a familiar digital environment that corresponds to their personal worldview (Sunstein 2001, cf. Adamic andGlance 2005). So-called digital echo chambers and filter bubbles have the potential to amplify this phenomenon. The concept of the digital echo chamber was already addressed by Sunstein in 2001. Ten years later, Pariser introduced and discussed the filter bubble. Although both concepts have been examined in recent literature, their relevance for nature conservation practice has so far remained understudied. Therefore, the aim of this study is to create an explorative overview of the potential relevance and handling of echo chambers and filter bubbles in nature conservation practice. Because there is no universally valid definition of the term "nature conservation," this study defines it as follows: nature conservation describes the protection, maintenance, or restoration of the biological diversity, the capability, and functionality of the natural resources as well as the uniqueness, the beauty, and the recreational value of nature. Particularly the protection of biotopes, species and habitats are central aspects (German Federal Nature Conservation Act 2009 § 1).
The terms "echo chamber" and "filter bubble" have rather loose definitions and are frequently used interchangeably in public discourse (Terren and Borge-Bravo 2021). It should also be noted that the existence of echo chamber effects has been known and researched for some time, but the phenomenon has only been referred to by the term echo chamber since the beginning of the 21st century (cf. Sunstein 2001, Stark et al. 2021. For the purposes of this study, the two terms echo chamber and filter bubble are treated as different but interrelated phenomena and defined as follows: An echo chamber describes an environment in which a person only interacts with like-minded people, so that the encountered opinions or beliefs reflect their own (Dubois and Blank 2018). Existing views are reinforced and alternative ideas are not considered (Flaxman et al. 2016). Generally, echo chambers can exist wherever information is exchanged, whether offline or on the Internet. However, this study only considers the digital phenomenon.
The term filter bubble describes a figurative sphere in which filter algorithms personalize the content that search engines, news aggregators, and social networks provide for each individual user (Pariser 2011). Affected persons are often unaware of this and therefore consider the provided information to be neutral, objective, and true, the result of which can be a distorted 1 Technical University Berlin https://www.ecologyandsociety.org/vol26/iss3/art11/ perception of reality and a loss of information diversity (Pariser 2011). A person's awareness of such effects and their susceptibility to them depend on various factors such as geocultural context, socioeconomic circumstances, and personality (cf. Burbach et al. 2019, Sindermann et al. 2020, Tandoc et al. 2020.
To facilitate the creation of an explorative insight into the topic of echo chambers and filter bubbles in nature conservation, we aim to answer the following questions:

1.
To what extent are echo chambers and filter bubbles already considered in nature conservation literature and practice?

2.
What are possible effects of echo chambers and filter bubbles on nature conservation?

3.
To what extent is there a need for research and action regarding the relevance of echo chambers and filter bubbles for nature conservation?
To answer these questions, the current state of research was examined through a literature review. In addition, an expert survey was conducted to assess to what extent the topic is already known and considered in nature conservation practice.

Literature review
The systematic approach of the literature review enabled an extensive search for relevant literature, which was selected and evaluated according to predefined search strings and criteria Tranfield 2009, Briner andDenyer 2012). The literature review was carried out by combining key words from the field of nature conservation and the terms echo chamber or filter bubble into search strings (Appendix 1). To ensure a comprehensive review within the available resources, only literature that fulfilled the following conditions was taken into account: . the literature mentions echo chambers and/or filter bubbles (according to the understanding of this study exclusively in a digital context) and a nature conservation-related term, . was published after 2011, when Eli Pariser defined the term filter bubble in his book The Filter Bubble: What the Internet Is Hiding from You, . is considered to be a scientific study or grey literature, . is freely accessible in German or English.
The literature review was carried out in the search engine Google Scholar. The results were documented in a literature database (Appendix 2) and then categorized according to their content. The aim was to analyze to what extent each identified source deals with the topic of echo chambers and/or filter bubbles and their relevance for nature conservation. For this purpose, the categories pictured in Table 1 were defined.

Expert survey
This method was utilized to compile the insights nature conservation actors may have concerning the relevance of echo chambers and filter bubbles in their work. The expert survey was conducted by e-mail, involving nature conservation actors throughout Germany, thus providing access to a variety of legal, geographic, and academic backgrounds (Bowden and Galindo-Gonzalez 2015). The 232 selected actors stem from various sectors: research and teaching institutions, public authorities, registered associations, NGOs, national parks, and private corporations (foremost planning offices). Additionally, whenever possible, persons with a position linked to digital media, i.e., press officers, were selected. The survey form included an introductory text, an explanation of the terms echo chamber and filter bubble, as well as the survey questions (Appendix 3). To increase the response rate, the survey was kept short, including mainly multiple choice questions. More thorough responses were possible through a follow-up comment after each question.
The thematic analysis approach according to Braun and Clarke (2012) was utilized to evaluate the survey data. In this context, the qualitative survey answers were closely examined, coded, and consequential themes were derived ( Fig. 1 and Appendix 4). First, all responses recorded through the expert survey were split into "answer sections." An "answer section" is a sentence or phrase, i.e., part of a survey response, that contains at least one core statement. Only text sections with no relevance to the research topic remained unconsidered. If answer sections with identical or similar statements occur throughout the survey data, a pattern becomes recognizable. This pattern can then be formulated as a code, i.e., a summarizing statement. The identified codes were in turn combined into overarching themes during the last step of the thematic analysis. This process was backed by the quantitative results of the multiple-choice questions. The derived codes and themes were subsequently analyzed concerning their relevance for the research objective of this study-the creation of an explorative overview of the potential relevance of echo chambers and filter bubbles for nature conservation practice.

To what extent are echo chambers and filter bubbles already considered in nature conservation literature and practice?
The literature review revealed that scientific literature increasingly takes echo chambers and filter bubbles as well as their relevance for various nature conservation topics into account. A total of 40 scientific sources were gathered in the literature review until mid-January 2020 (see Appendix 2). A total of 10 sources used exclusively the term filter bubble, 18 exclusively the term echo chamber, and 12 contained both terms. In the systematic categorization of the sources according to their content, only 2 sources could be assigned to category A, 18 to category B, and 20 to category C. Nevertheless, there is a substantial increase in scientific publications on the subject from 2017 onwards (Fig. 2).  Table 2 shows the division of category A and B sources into subject areas of nature conservation. It is noticeable that the subject area "climate protection and climate change" has so far been most often scientifically investigated in connection with echo chambers and filter bubbles. Possible reasons for the focus on climate issues will be addressed in the discussion.
The results of the expert survey complement the findings from the literature review. They show that echo chambers and filter bubbles are already known to the nature conservation experts that responded to the survey, but that this awareness for the most part does not translate into concrete action.
Out of the 232 selected nature conservation experts working in Germany, 13 responded to the survey. They work in a variety of sectors, such as public environmental agencies, an environmental planning company, protected area administrations, a lobby organization, and an NGO. The multiple-choice responses depicted in Table 3 complemented the thematic analysis process. All survey answers or answer sections cited below were translated from German. The original data is available in Appendix 5.  Nature conservation should take digital echo chambers and/or filter bubbles into account in its work.
The 4 themes and 11 codes (Table 4) identified during the thematic analysis serve as summarizing statements of the answers to the open questions. The assignment of the individual response sections to the codes can be seen in Appendix 6. In the following, the four themes are used to provide further answers to the first research question concerning the current consideration of echo chambers and filter bubbles in nature conservation.
The first theme, "Different groups are affected by echo chambers and filter bubbles," reflects on the one hand the awareness of the responding experts that certain groups outside of nature conservation may be affected by the phenomena. For instance, one expert was concerned "when people are no longer reached with nature conservation issues/objectives because they are caught in medial filter bubbles" and others spoke of "opponents" and people with "contra" conservation opinions residing in echo chambers and filter bubbles. On the other hand, several survey participants expressed concern that they themselves may be situated in an echo chamber or filter bubble of nature conservation, mentioning "both one's own fanaticism and that of the opponents" as consequences of the phenomena. One of the experts stated that "it does not help nature conservation to solidify current facts as wisdom and to rally groups behind it that consider "People interested in nature conservation are also primarily provided with information that they wish to read." "Both one's own fanaticism and that of the opponents [can impact nature conservation work]." Nature conservation "adversaries" and persons without a stance on nature conservation are affected by echo chambers and filter bubbles 6 "Since they can radicalize in both directions (pro and contra nature conservation)." "Discussions pro and contra the establishment of the national park in the social networks as well." How echo chambers and filter bubbles can or cannot be handled Echo chambers and filter bubbles and their effects can be deliberately utilized 9 "The resulting channels can be deliberately used [by nature conservation] to launch campaigns." "The public discourse on nature conservation can also be influenced by targeted messages using psychological methods." If and how echo chambers and filter bubbles should be considered in nature conservation

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"Therefore, one should know the mechanisms [digital echo chambers and filter bubbles], avoid them in one's own work and as far as possible avoid becoming "operationally blind" oneself. can be] as relevant as in all areas of society." "As in every emotionalized subject area, people who are interested in nature conservation are also mainly supplied with information they would like to read." Echo chambers and filter bubbles are tied to economic interests 2 "The ecological impacts of electromobility are sometimes deliberately not considered from a holistic perspective," "The driver for this is of course the questioning of the business model of one's own company or the industry in which not only electric cars, but also charging infrastructure and a lot of equipment are the commercial products." Echo chambers and filter bubbles are tied to political interests 3 "Filter bubbles or digital echo chambers are relevant for all social issues, because opinions can be generated automatically with the help of algorithms, as described here at the beginning. A good example is the success of Cambridge Analytica." "People who are interested in nature conservation are also mainly supplied with information they would like to read. This is of particular benefit to commercially or politically interested groups." Echo chambers and filter bubbles are tied to technological and digital factors 14 "In the social media of this industry, messages for clean electromobility are therefore deliberately spread, and critical messages are not shared on, e.g., Twitter. Algorithms reinforce this path, which results in classic filter bubbles, as algorithms place information in their own online networks that corresponds to this opinion." "In the exchange with like-minded people in forums, on blogs, and other social channels, the own opinion is strengthened." https://www.ecologyandsociety.org/vol26/iss3/art11/ this fact as ultimate and can no longer be convinced otherwise." The consideration of echo chambers and filter bubbles in nature conservation practice thus extends to their occurrence both outside and inside the nature conservation community.
The second theme was named "How echo chambers and filter bubbles can or cannot be handled." Although the active handling of the phenomena by nature conservation was the subject of the survey questions, their deliberate utilization was not. The frequent mention of the latter by the survey participants demonstrates that their consideration of the phenomena comprises a worry of active manipulation in addition to (ostensibly) inadvertent consequences of echo chambers and filter bubbles. The experts expressed concern about uses such as "influencing public opinion," opinions being "generated automatically using algorithms," or reinforcing peoples' perception of reality by steering their thoughts through "an automated algorithm or emotionalized group dynamics in social networks." Some answers even accused ostensibly proenvironment actors of these behaviors, for example when "the ecological consequences of electric mobility are sometimes deliberately not considered from a holistic perspective." At the same time, most of the experts were unable to report specific actions that are or could be taken to actively consider echo chambers and filter bubbles in nature conservation practice. This fact will be examined in more detail when answering the third research question regarding the identified need for research and action.
The third theme and its 42 answer sections show that "Echo chambers and filter bubbles are of relevance in the communication of nature conservation topics." All of the potential impacts of echo chambers and filter bubbles on nature conservation will be covered in depth in regard to the second research question. In the context of this third theme, it should be mentioned that although all respondents consider the phenomena to be relevant to nature conservation in general, only half of the experts believe that they have already played a role in their own work (Table 3). Once again it is evident that the consideration of the phenomena in conservation practice usually does not go beyond theoretical considerations and does not extend to practical measures and one's own work. We will address this in further detail in our answer to the third research question on the needs for research and action.
The answer sections assigned to the fourth theme "Echo chambers and filter bubbles are tied to different societal factors" concern the relationship of the phenomena with other parts of society. It shows that the consideration of the phenomena by conservation actors goes beyond their relevance for environmental topics. Several of the experts even consider echo chambers and filter bubbles to be as relevant for conservation "as in all areas of society" and "as in any emotionalized subject area." According to the survey participants, the phenomena also connect to economic, political, technological, and other societal factors. They mentioned, for example, the relevance and use for "commercially or politically interested groups" and "democratic processes, as in the example of Cambridge Analytica." Another strong focal point in the considerations about the phenomena seemed to be technological and media topics, such as "forums, blogs and other social channels," "false facts about climate change being disseminated en masse in social media" and society's lack of "sovereignty (control, influence) over algorithms on the Internet." In summary, it can be said that the consideration of echo chambers and filter bubbles in conservation practice mainly covers their possible effects and connections to other societal areas but lacks concrete approaches for action. Furthermore, although all survey respondents indicated that they already knew at least one of the two terms echo chamber and filter bubble, their further answers revealed that the understanding of the phenomena is not homogeneous, even though definitions of the terms were provided with the survey form. One respondent wrote that the "terms are both very diffuse and not clearly defined." Inconsistencies regarding the use of both terms can also be found in the identified scientific literature. Definitions of the two terms can be found in all sources of categories A and B, except for Paulo On the one hand, the survey respondents pointed out that echo chambers and filter bubbles make it difficult to reach people without an attitude toward nature conservation or engage them. On the other hand, nature conservation "opponents" can be subject to polarization, which can worsen their opinion on nature conservation. According to one survey expert, this process is promoted if only interested parties are addressed with educational efforts and supplied with nature conservation information, e.g., during participation campaigns. In addition to polarization, echo chambers and filter bubbles can reinforce processes of politicization, ideologization, and postfactual thinking (Paulo 2018). The survey respondents stated that the named effects https://www.ecologyandsociety.org/vol26/iss3/art11/ particularly concern emotionally charged issues and hinder attempts of nature conservation actors to communicate with nature conservation opponents. For instance, one expert criticized the lack of factual exchange with a strongly polarized group opposing the reintroduction of the wolf in Germany.
If the above-mentioned effects of echo chambers and filter bubbles are particularly strong, they can lead to the emergence of anti-scientific movements that propagate disinformation, e.g., in the field of climate protection (Paulo 2018, Colston andThomas 2019). Although false information may be distributed unintentionally by faulty scientific models or decontextualization of scientific evidence, it can also be deliberately caused by targeted campaigns (Colston and Thomas 2019). This was also pointed out by one of the surveyed experts, who stated that "targeted messages using psychological methods can also influence public discourse on nature conservation, e.g., by spreading false facts about climate change en masse in social media." It is particularly aggravating for nature conservation work when mis-or disinformation influences the public discourse on nature conservation topics (Metson 2018, Paulo 2018, Colston and Thomas 2019. This is underlined, for example, by Jasny and Fisher (2019), who address changes in existing echo chambers of the U.S.-climate-policy-network after Donald Trump became President. The thematic focus of the political echo chambers shifted to the question of whether climate change is humaninduced or not, a consequence of the opinions and policies expressed by Trump on climate change (Jasny and Fisher 2019). This change in thematic focus forced nature conservation to react accordingly, e.g., with climate science information campaigns (Jasny and Fisher 2019), illustrating how the affliction of other societal groups by echo chambers can have an indirect impact on nature conservation work.
In addition to the consequences for nature conservation outlined above, when uninterested citizens or conservation adversaries are located in echo chambers and filter bubbles, it can be just as damaging for nature conservation proponents to be affected by the phenomena. In this context, one expert stated: "We tend to prefer information that is consistent with our own point of view. Counterarguments are hardly allowed." A possible consequence of this one-sided information procurement was addressed by the survey respondents and is summarized by the code "Echo chambers and filter bubbles can reinforce views on nature conservation topics." Some of the experts argue that this effect can even contribute to fanaticism or radicalization of nature conservation proponents, just as it does with nature conservation adversaries.
The described reinforcement of views held by nature conservation actors in echo chambers or filter bubbles may also hinder their communication with society. One respondent warned that being in an echo chamber or filter bubble may lead to "misconceptions about the effect of arguments" among people with different views on nature conservation. On the one hand, this can lead to conflicts with related fields like climate protection. In this context, "nature conservation blocking the construction of wind parks" is one of the examples named in the expert survey. On the other hand, several of the surveyed experts mentioned difficulties in reaching conservation adversaries as well as new target groups who are not yet involved in nature conservation as a result. As one respondent points out, communication issues like these may impact the "social acceptance on which nature conservation depends." All things considered, the code "Echo chambers and filter bubbles can hinder nature conservation communication processes and make it hard to reach people" seems to apply regardless of who is affected by the phenomena. In addition to communication problems with society, nature conservation actors may have a distorted picture of reality when they are affected by echo chambers and filter bubbles. Coupled with an unawareness of their situation, which several survey respondents warned against, this skewed view of reality can result in an inability to act effectively. A practical example identified in the literature review describes how in the Democratic Republic of Congo wrong decisions are made on the issue of poaching control because decision makers create their own echo chambers (Titeca and Edmond 2019). As a result, local dynamics and practical conservation actors are less involved and ineffective or counterproductive measures against poaching are selected (Titeca and Edmond 2019). Another study describes how echo chambers and filter bubbles influence decision makers' intake of information on biodiversity science (Clermont 2018). This affects their choices to either protect or further threaten fragile or endangered ecosystems and species, which creates two camps among decision makers in an "economy versus environment" conflict (Clermont 2018). These cases illustrate how nature conservation actors in echo chambers and filter bubbles may not receive or consider important information that could improve their work, leading to a loss of effectiveness of nature conservation.
However, the effects of echo chambers and filter bubbles may also produce beneficial outcomes for nature conservation. Two survey respondents specifically mentioned that the reinforcement of nature conservation views described above may lead to an "increased motivation and engagement" among conservation proponents, e.g., in the case of the Fridays For Future movement. Additionally, a number of studies and experts addressed the active utilization of echo chambers and filter bubbles by nature conservation.
To what extent is there a need for research and action regarding the relevance of echo chambers and filter bubbles for nature conservation?
A close analysis of the survey answers with regard to the first research question revealed that the understanding of the terms echo chamber and filter bubble among the experts is inconsistent and often unclear. Inconsistencies regarding the use of both terms can also be found in the identified scientific literature. At the same time, the survey respondents frequently stated that nature conservation actors should have an awareness of the phenomena, which arguably cannot be created without a proper, uniform understanding of the terms. Therefore, action and research are required to create and disseminate an improved terminological basis, comprehension and awareness of the phenomena, and their effects. In this context, implementing some of the expert suggestions like "training of the own people" and reminding oneself "to obtain information not only unilaterally" could be beneficial.
Moreover, although almost all experts were in favor of taking the phenomena into account in nature conservation work (Table 3) https://www.ecologyandsociety.org/vol26/iss3/art11/ and the code "If and how echo chambers and filter bubbles should be considered in nature conservation" contains 22 answer sections, most respondents were unable to formulate specific, comprehensive actions to be taken. Additionally, only half of the experts thought that echo chambers and filter bubbles were previously relevant for their own work. Some of them also showed great uncertainty concerning the question of how they could consider the phenomena in their daily work. One stated "I just do not see that I could or wanted to consciously incorporate them into my work" and another questioned "whether nature conservation can do anything special." Although some proposals for active consideration of the phenomena were voiced, most were limited to general suggestions such as "avoid or counteract [them] professionally" or "use the best and most far-sighted communication concepts and public outreach possible." This general uncertainty and lack of action demonstrate that it is necessary to explore strategies for dealing with echo chambers and filter bubbles.
So far, only a few suggestions for action can be found in scientific literature. For example, Fraser and Fraser (2017) suggest countering the effects of both digital and analogue echo chambers by using methods with high visibility that are accessible to everyone, such as an eye-catching art installation in a public space. This could increase public awareness and participation in a conservation issue (Fraser and Fraser 2017). Furthermore, Walter et al. (2018) advise climate scientists to make evidence-based knowledge accessible to the general public. To achieve this goal, nature conservation actors could go beyond the liberal elite media and engage with tabloid and conservative media to better inform a wider range of social groups in their echo chambers and filter bubbles (Walter et al. 2018). A target-oriented and strategic communication was also endorsed by several of the survey respondents, for example through "trust promotion with "colorful messages"" and using "more digital media to document successful measures, e.g., in species protection." In contrast, other answers suggested avoiding filter bubbles altogether by using "exclusively open source solutions" or by setting up a transparent "platform for the exchange of positions" to counteract echo chambers. However, as one of the respondents pointed out, distancing oneself from mainstream communication channels like this may lead to an increased isolation of nature conservation actors and their subsequent inability to reach other societal groups. In summary, the few, sometimes contradictory and unverified concrete recommendations for action from the experts and literature show a need for research into the validity of these suggestions and if possible, their refinement. In a further step, action should be taken to implement the developed strategies in nature conservation practice.
In this context, potential opportunities offered by echo chambers and filter bubbles should not be neglected. Although one survey respondent reported that "pro-nature conservation messages are moved up in Google's ranking, thus emphasizing their importance," the overwhelming majority of positive effects addressed by the experts concerned increased motivation and commitment of conservationists, as we explained in detail in our response to the second research question. Moreover, Hermwille and Siemons (2018) addressed another positive side of echo chambers, namely their potential strategic modification to encourage pro-conservation politics. It would therefore be recommendable to conduct further research concerning the active harnessing of potential positive effects of echo chambers and filter bubbles, even though they are already, arguably unconsciously, used to promote motivation and commitment.
At the same time, as several survey respondents and Titeca and Edmond (2019) noted, attention should be paid to ensure that the utilization of echo chamber and filter bubble effects does not lead to radicalization or ineffective nature conservation work. Madzwamuse et al. (2020), for example, describe how Western organizations create echo chambers to justify each other's campaigns in African wildlife conservation. The fact that these are often less effective because local stakeholders are not involved is not considered by those organizations (Madzwamuse et al. 2020). Similarly, Pilkington (2016) criticizes that some scientists use the echo chamber of public discourse to masquerade value judgements as facts in order to spread opinions to promote their own interests. One of the experts expressed the following opinion on this subject: "Sustainable nature conservation only works through long-term commitment and a constant reassessment of the facts. Echo chambers and filter bubbles work in the short term and lead to a hardening of positions, as a result of which nature conservation can only lose in the long term."

Methodological limitations
For some of the search strings used in the literature review, the number of literature sources suggested by Google Scholar was in the five-digit range, which made a complete review of all literature impossible. After Google Scholar successively suggested 30 literature sources that proved to be irrelevant for the literature review, the search was stopped. Therefore, it cannot be ruled out that relevant sources remained unnoticed, which could be improved in future studies by a more extensive literature search. Furthermore, the definition of nature conservation used in this study is based on the Federal Nature Conservation Act of Germany and does not necessarily reflect the international understanding of the term. Because of this, some studies based on a different definition of nature conservation may have remained undiscovered during the literature review. Additionally, the definition used here leads to overlaps with the areas of climate and environmental protection. Because it is difficult to separate the fields in these overlapping areas, sources that could also be allocated to climate protection and environmental conservation were also included in the literature review.
Because all the respondents work in German nature conservation, the survey results are not necessarily internationally representative. Further research could hence embrace an international scope to complement the findings presented here.
To gather data from a wider range of nature conservation actors than the experts contacted for the survey, future studies could also consider conducting less targeted surveys in terms of content and target group. Additionally, the expert survey was based on the aim of this study to provide solely an initial explorative insight into the relevance of echo chambers and filter bubbles for nature conservation. In the future, the collection and analysis of statistically representative data could complement the insights presented here. More elaborate qualitative methods such as faceto-face surveys are also recommended to collect more in-depth https://www.ecologyandsociety.org/vol26/iss3/art11/ information and to allow for follow-up questions. Respective interview questions could be based on the findings of this study.

Discord concerning echo chambers and filter bubbles in the scientific community
This study has revealed a growing concern regarding the potential impact of echo chambers and filter bubbles on nature conservation. However, the overall scientific community is divided when it comes to the question of the actual existence and practical relevance of the two phenomena. Some studies completely question the relevance of the phenomena or attribute them with only minor influence on public opinion and processes of polarization ( Some of the aspects that may have contributed to the disagreement about echo chambers and filter bubbles in the scientific community should be considered in future research endeavors. First, following a holistic approach, the formation of opinions and public polarization in social networks should be regarded in the context of individual user characteristics and offline environment (Nguyen et al. 2014, Barberá et al. 2015, Vaccari et al. 2016. Second, empirical studies should avoid generalized statements that transcend their subject-matter. This is due to the highly heterogeneous factors that can influence study results concerning echo chambers and filter bubbles, such as a fluctuating societal context, different functionalities of social networks, as well as nontransparent and ever-evolving filter algorithms (Nguyen et al. 2014, Zuiderveen Borgesius et al. 2016. Last, as this study has shown, the understanding of echo chambers and filter bubbles is inconsistent both in literature and conservation practice. Therefore, in future research, it is essential to ensure that the terms are correctly defined and used to avoid any disagreement based on a semantic misunderstanding.

Reasons for the special consideration of digital echo chambers and filter bubbles
One fact that has long been accepted by the scientific community is the existence of offline echo chambers (Chitra and Musco 2019). Three main aspects distinguish digital echo chambers from their analogue counterparts and make them and the recently emerged phenomenon of filter bubbles particularly noteworthy in conservation research.
First, digital echo chambers and filter bubbles can reinforce analogue echo chambers (Müller et al. 2020). To avoid this, nature conservation should research and manage digital echo chambers, filter bubbles, and their effects on offline echo chambers. This can also help nature conservation to improve its communication with the public and break out of existing analogue echo chambers. This would be especially useful for conservation disciplines strongly reliant on public participation processes, such as landscape planning or environmental education. Overall, the comprehension and active consideration of these novel communication phenomena is crucial for the societal acceptance upon which nature conservation depends (cf. Brendle 2002, Schuster 2008, Lichtl 2009).
Second, various societal powers advance their interests using social media, frequently in morally questionable ways. This stands in stark contrast with the supposed merit of new digital communication channels for the democratic public (cf. Lange and Santarius 2018). Examples of this sort of behavior include manipulation of Twitter discourse by regimes in the ongoing military Persian Gulf Crisis (Leber and Abrahams 2019) and mass fabrication of social media posts by the Chinese government to distract the public from criticizing the regime (King et al. 2017). These propagandic utilizations of social media for political purposes can have devastating effects on human rights and the foundations of democracy (cf. King et al. 2017, Leber andAbrahams 2019). Such misuse of new media can also concern nature conservation topics as our study results demonstrate most prominently in the rise of mis-and disinformation about climate protection amongst policy makers and the public (cf. Paulo 2018, Colston and Thomas 2019, Jasny and Fisher 2019. Furthermore, these intentional polarization processes are far reaching and highly efficacious because of the globalized, immediate, and easyto-use nature of social networks and can be reinforced by digital echo chambers and filter bubbles (Geschke et al. 2019, Müller et al. 2020. Such utilization of social media and the two phenomena should therefore be actively taken into account by nature conservation. Third, digital echo chambers and filter bubbles are particularly prone to enhancing other problematic digital phenomena such as populism, polarization, as well as mis-and disinformation (Chitra and Musco 2019, Müller et al. 2020, Shu et al. 2020). These processes have a negative impact on the representation of environmental interests on the Internet and promote environmental skepticism (Cox 2010, Frohn andRosebrock 2018). As a result, the seriousness of environmental issues is disputed and the credibility of conservation science is questioned (Cox 2010). Overall, digital echo chambers and filter bubbles make the handling of nature conservation issues in a post-truth world particularly difficult and should thus be specially considered (cf. Shu et al. 2020).

Limited awareness of echo chambers and filter bubbles in the field of nature conservation
The occurrence and effects of digital echo chambers and filter bubbles in the context of nature conservation seem to have aroused little interest in nature conservation literature and practice so far. The sparse discussion of the two phenomena in this field seems to indicate a limited awareness of the topic.
One indicator for this observation is the fact that nature conservation research of the two phenomena has only emerged in recent years, as the literature review showed. Furthermore, only 2 of 40 identified sources focused on possible effects of echo chambers on nature conservation as the main topic of the source (category A sources). Additionally, all of the experts knew at least one of the phenomena. This fact could indicate a nonresponse bias, which would mean that only people with preexisting knowledge or views on the phenomena responded to the survey https://www.ecologyandsociety.org/vol26/iss3/art11/ (Marsden and Wright 2010). In this case, the response rate of around 6% would demonstrate a lack of sensibilization or interest for the topic in nature conservation (Marsden and Wright 2010).
A possible reason for the low level of attention given to the topic in conservation literature and practice could be the relatively recent emergence of the two phenomena and increasing digitalization (Pariser 2011, Barberá et al. 2015. However, the abundance of literature on echo chambers and filter bubbles in other scientific sectors such as political science, economic science, or sociology contradict this hypothesis (e.g., Flaxman et al. 2016, Dubois and Blank 2018, Sindermann et al. 2020. In general, nature conservation appears to be making slow progress in dealing with new aspects of the ongoing digitalization. Even in 2005, 12 years after the commercial introduction of the Internet, there was a lack of research on online communication in the conservation field (Peters et al. 2005). Perhaps this slow approach to digital issues contributed to the limited but increasing awareness of echo chambers and filter bubbles in nature conservation practice and literature.

Strong focus on climate protection in scientific literature
The literature review shows that echo chambers and filter bubbles have so far been scientifically investigated mainly in connection with climate protection. The reason for this focus in the identified literature cannot be determined with certainty. Out of the eleven search terms used in the literature review, only one was chosen that specifically addresses the topic of climate protection. The search term "climate protection" was chosen because the German Federal Nature Conservation Act (2009) states in § 1 that air and climate must also be protected by nature conservation and landscape management measures. As addressed in the methodological discussion, this legally based thematic overlap between nature conservation and climate protection is the reason for the inclusion of sources focused on climate protection in the literature review.
The focus on climate protection can probably be explained by the increasing importance of the topic. In this context, the attention of the mass media and politicians to climate change and climate protection issues has increased significantly in the last three decades (Weingart et al. 2008, Schmidt et al. 2013, Hoffman 2015. It has also become clear that social media discussions on climate change often take place in polarizing debates with climate change "sceptics" on the one hand and "activists" on the other (Williams et al. 2015). In this context, like-minded people support each other, opposing fronts are hardened, and the formation of echo chambers is favored (Williams et al. 2015). All in all, the global prominence and polarizing nature of climate issues could thus explain the focus on them in the identified conservation literature on echo chambers and filter bubbles.

Active consideration of echo chambers and filter bubbles in nature conservation practice
As the expert survey has shown, the consideration of echo chambers and filter bubbles in nature conservation practice is lacking and for the most part does not extend beyond a basic awareness. Although this basic awareness may at least enable nature conservation actors to rudimentarily take into account the effects of echo chambers and filter bubbles on their work, specific handling strategies are necessary to achieve a greater effect. In this context, the surveyed experts and identified studies made a few broad suggestions for action, including the avoidance, reduction, and utilization of echo chambers and filter bubbles. Although these may prove valuable for nature conservation, they should only be implemented with caution to prevent any unforeseen and undesirable side effects.
Concerning the potential utilization of echo chambers and filter bubbles by nature conservation to sway public opinion, several studies and respondents warned of a potential loss of nature conservation effectiveness (cf. Titeca and Edmond 2019, Madzwamuse et al. 2020). In addition to this risk and the moral questionability of such practices, it is also doubtful whether the views of nature conservation adversaries or uninterested people could be affected by such an approach. This is due to the fact that echo chambers and filter bubbles merely reinforce already existing interests and views by amplifying the confirmation bias of people (Geschke et al. 2019, Müller et al. 2020. The two phenomena are therefore unsuitable for engaging people who do not already hold a positive view of nature conservation. Furthermore, previous research has shown that communication in social media-where echo chambers and filter bubbles are most prominent-is not suited for short-term sway of public opinion (cf. Harris and Harrigan 2015). Instead, long-term communication strategies are required to effectively communicate with the public (Harris and Harrigan 2015). This was also pointed out by several of the surveyed nature conservation experts.
An additional proposal for action is the publication of nature conservation science in tabloid and conservatively oriented media to avoid communicational obstacles caused by echo chambers and filter bubbles (Walter et al. 2018). However, if such outlets were willing to publish nature conservation content, it may prove difficult to write articles that are well received by the respective target groups without risking a loss of scientific accuracy or focusing heavily on negative news (Boykoff 2008). The same caution should be applied when trying to reach people in their echo chambers and filter bubbles by communicating in social networks like Twitter (cf. Brossard 2013, Bombaci et al. 2016).
Another approach suggested by the interviewed experts is target group-oriented communication to bypass echo chambers and filter bubbles. To effectively address the public, nature conservation practitioners must not only adapt the conveyed contents to the audience but also their choice of media and communication style (cf. Schuster 2008). This can be quite difficult however, because the respective needs and preferences of the public are diverse and complex. For this reason, target-group oriented communication utilizes various models that cluster citizens into groups (Scholl and Hage 2004). This strategy has previously been discussed and employed in nature conservation (e.g., Scholl andHage 2004, Schuster 2008) as well as other societal sectors, particularly in marketing (e.g., Sathish andRajamohan 2012, Piatykop andPronina 2020). However, although such sociological models may be profitable in a commercial context, their cost-benefit-ratio is a point of concern for non-profit conservation actors (Scholl and Hage 2004). Furthermore, just like in the marketing sector (Crane and Desmond 2002), nature conservation must carefully consider to what extent tailoring communication methods and contents to a target group may constitute manipulation. Last, such strategies https://www.ecologyandsociety.org/vol26/iss3/art11/ could potentially reinforce existing echo chambers and filter bubbles by adapting to the views and interests of the audience.
In addition to further researching and testing the existing strategies for dealing with the phenomena in nature conservation practice, a review of methods stemming from other fields of research could provide valuable insights. Potentially relevant strategies could be adjusting educational curricula to prevent echo chambers (cf. Passe et al. 2018), advocating transparency of algorithms that generate filter bubbles (cf. Nguyen et al. 2014), using urban interfaces such as pervasive displays to expose citizens to informational diversity (cf. Foth et al. 2016), or promoting software solutions to escape filter bubbles (cf. Bozdag and van den Hoven 2015). Furthermore, nature conservationists can refer to literature on digital mis-and disinformation to reduce their own susceptibility to echo chambers and filter bubbles. In this context, they could cultivate fact checking practices (cf. Dubois et al. 2020), use computational resources to detect disinformation (cf. Shu et al. 2020), or learn about neurological factors in rectifying incorrect beliefs (cf. Seifert 2002). In any case, research into the strategies employed in other fields is highly recommended because most nature conservation issues are deeply intertwined with other societal factors. An awareness of how echo chambers and filter bubbles are studied, handled, and used in other fields like politics (e.g., Bozdag and van den Hoven 2015, Jasny and Fisher 2019) can enable nature conservation to communicate and function more effectively in its overall societal context.

CONCLUSION
The results of this study indicate that echo chambers and filter bubbles are being addressed in nature conservation literature and practice to a small but increasing extent. Furthermore, it is recognized that they pose more risks than potential advantages for nature conservation communication. On the one hand, nature conservation actors can use echo chambers to increase each other's motivation and commitment to the cause. On the other hand, echo chambers and filter bubbles may lead to communication issues and hinder the exchange between nature conservation actors and other societal groups. However, the understanding of the exact processes associated with echo chambers and filter bubbles is insufficient and should be subject to further investigation. The study also identified a significant need for action and research concerning the strategic consideration and handling of echo chambers and filter bubbles in nature conservation practice. Existing research from other scientific fields could be of use for this purpose.
Nature conservation issues are intertwined with many parts of modern society. Issues of global importance such as climate change are part of political, public, and scientific discourse. At the same time, regional issues such as the reintroduction of wolves near human-populated areas are being discussed by a wide range of actors. Regardless of scale, topic, or involved parties, echo chambers and filter bubbles can influence the communication of nature conservation topics. To make a responsible and effective contribution to the well-being of nature and society, nature conservation must keep abreast of new communication factors that arise in the age of digitalization.